ArticlePDF Available

Decreased myo-inositol to chiro-inositol (M/C) ratios and increased M/C epimerase activity in PCOS theca cells demonstrate increased insulin sensitivity compared to controls


Abstract and Figures

Previous studies from our and other labs have shown that insulin resistance is associated with an inositol imbalance of excess myo-inositol and deficient chiro-inositol together with a deficiency of myo-inositol to chiro-inositol epimerase in vivo and in vitro. In this report, we utilized well characterized theca cells from normal cycling women, with normal insulin sensitivity, and theca cells from women with polycystic ovary syndrome (PCOS), with increased insulin sensitivity to examine the myo-inositol to chiro-inositol ratio (M/C) and the myo-inositol to chiro-inositol epimerase activity. PCOS theca cells with increased insulin sensitivity were specifically used to investigate whether the inositol imbalance and myo-inositol to chiro-inositol epimerase are regulated in a similar or the opposite direction than that observed in insulin resistant cells. The results of these studies are the first to demonstrate that in insulin sensitive PCOS theca cells the inositol imbalance goes in the opposite direction to that observed in insulin resistant cells, and there is a decreased M/C ratio and an increased myo-inositol to chiro-inositol epimerase activity. Further biochemical and genetic studies will probe the mechanisms involved.
Content may be subject to copyright.
POLYCYSTIC ovary syndrome (PCOS) affects
approximately 7-12% of women, and is the most com-
mon cause of infertility in reproductive aged women
[1]. Reproductive endocrine abnormalities in PCOS
include amenorrhea or oligomenorrhea, infertility,
hirsutism, and acne resulting from increased ovar-
ian androgen production [2-6]. Although there have
been reports suggesting as high of 50% of women with
PCOS have hyperinsulinemia and peripheral insulin
resistance in adipose and skeletal muscle, ovarian theca
and granulosa cells have been reported to be exquisitely
sensitive to insulin and are not insulin resistant. Thus,
a dichotomy is present with peripheral tissue insulin
resistance and ovarian insulin sensitivity.
We have proposed an inositol imbalance consist-
ing of excess myo-inositol and decient chiro-inositol
as a measure of insulin resistance [7]. This imbalance
Endocrine Journal 2014, 61 (2), 111-117
Decreased myo-inositol to chiro-inositol (M/C) ratios and
increased M/C epimerase activity in PCOS theca cells
demonstrate increased insulin sensitivity compared to controls
Douglas Heimark 1), Jan McAllister 2) and Joseph Larner 1)
1) Department of Pharmacology, University of Virginia, Charlottesville, VA 22903 USA
2) Department of Pathology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033 USA
Abstract. Previous studies from our and other labs have shown that insulin resistance is associated with an inositol
imbalance of excess myo-inositol and decient chiro-inositol together with a deciency of myo-inositol to chiro-inositol
epimerase in vivo and in vitro. In this report, we utilized well characterized theca cells from normal cycling women, with
normal insulin sensitivity, and theca cells from women with polycystic ovary syndrome (PCOS), with increased insulin
sensitivity to examine the myo-inositol to chiro-inisitol (M/C) ratio and the myo-inositol to chiro-inositol epimerase
activity. PCOS theca cells with increased insulin sensitivity were specically used to investigate whether the inositol
imbalance and myo-inositol to chiro-inositol epimerase are regulated in a similar or the opposite direction than that observed
in insulin resistant cells. The results of these studies are the rst to demonstrate that in insulin sensitive PCOS theca cells
the inositol imbalance goes in the opposite direction to that observed in insulin resistant cells, and there is a decreased M/C
ratio and an increased myo-inositol to chiro-inositol epimerase activity. Further biochemical and genetic studies will probe
the mechanisms involved.
Key words: Chiro-Inositol, Myo-Inositol, Epimerase, Polycystic ovary syndrome, Theca
has been demonstrated in urine of type 2 diabetics [8],
Rhesus monkeys progressing from normal to obese to
diabetic [8], in muscle biopsies of type 2 diabetics dur-
ing an insulin clamp [8], as well as in autopsy muscle
specimens of type 2 diabetics [9]. In addition, de-
ciency of chiro-inositol in urine of Japanese subjects
has been demonstrated to be linearly related to insulin
resistance in type 2 diabetics, subjects with impaired
glucose tolerance and normal subjects [10]. Further,
lack of appearance of chiro-inositol glycan bioactiv-
ity (measured as PDH phosphatase (PDHP) activity)
in blood of type 2 diabetic subjects during a glucose
tolerance test, lack of chiro-inositol glycan bioactiv-
ity in women with PCOS during an insulin clamp, and
lack of appearance of chiro-inositol glycan bioactivity
release from placental membranes with insulin admin-
istration in vitro in women with preeclampsia have
also been shown [11-13]. One glycan isolated from
beef liver, named INS-2, has been identied, struc-
ture determined and chemically synthesized. Its struc-
ture is galactosamine-β-1,4 pinitol (3-O-methyl ether
of D-Chiro-Inositol). It is insulin mimetic and insulin
Submitted Jun. 25, 2013 as EJ13-0265; Accepted Oct. 16, 2013 as EJ13-0423
Released online in J-STAGE as advance publication Nov. 2, 2013
Correspondence to: Jan McAllister, Professor Pathology/OB/GYN,
Hershey College of Medicine, The Pennsylvania State University,
Hershey, PA 17033 USA. E-mail:
Or i g i n a l
©The Japan Endocrine Society
112 Heimark et al.
ing previously described growth medium (1:1 mixture
of Dulbecco’s Eagles Medium (DME) and Hams F-12
medium containing 5% FBS, 5% horse serum (HS),
2% UltroSer G, 20 nM insulin, 20 nM selenium, 1 µM
vitamin E and antibiotics). The cells were grown in
reduced oxygen tension (5% O2, 90% N2, and 5% CO2)
and given supplemental antioxidants (vitamin E and
selenium) to prevent oxidative damage.
The theca cell cultures utilized in these studies
were described and functionally characterized previ-
ously [18-20]. Experiments comparing PCOS and nor-
mal theca were performed utilizing 4th-passage (31-38
population doublings) theca cells isolated from size-
matched follicles obtained from age-matched subjects.
The use of fourth passage cells allowed us to perform
multiple experiments from the same patient population,
and were propagated from frozen stocks of second pas-
sage cells in the media described above. For all stud-
ies, theca cell cultures obtained from at least 5 inde-
pendent normal and 5 independent PCOS patients were
examined. The passage conditions and split ratios for
all normal and PCOS cells were identical. For each of
the experiments outlined in these studies fourth pas-
sage theca cells cells were grown to subconuence
and transferred into serum-free medium, containing
DMEM/F12 1.0 mg/mL BSA, 100 µg/mL transferrin,
20 nM insulin, 20 nM selenium, 1.0 µM vitamin E and
antibiotics, 48 h prior to being rinsed in PBS, ash fro-
zen and processed for assay of myo-inositol to chiro-
inositol epimerase.
The PCOS and normal ovarian tissue came from
age-matched women, 28-40 years old. The diagno-
sis of PCOS was made according to established guide-
lines [21], including hyperandrogenemia, oligoovula-
tion, and the exclusion of 21α-hydroxylase deciency,
Cushing’s syndrome, and hyperprolactinemia. All of
the PCOS theca cell preparations studied came from
ovaries of women with fewer than six menses per
year and elevated serum total testosterone or bioavail-
able testosterone levels, as previously described [18,
22, 23]. Each of the PCOS ovaries contained multi-
ple subcortical follicles of less than 10 mm in diame-
ter. The control (normal) theca cell preparations came
from ovaries of fertile women with normal menstrual
histories, menstrual cycles of 21-35 days, and no clini-
cal signs of hyperandrogenism. Neither PCOS nor nor-
mal subjects were receiving hormonal medications at
the time of surgery. Indications for surgery were dys-
functional uterine bleeding, endometrial cancer, and/or
sensitizing in vivo and in vitro [14].
Based on these studies of inositol imbalance; i.e.
increased M/C ratio and of chiro-inositol glycan de-
ciency associated with insulin resistance, we hypothe-
sized a defective epimerization of myo-inositol to chi-
ro-inositol, an inversion of carbon 3 hydroxyl [7], as a
cause of the inositol imbalance and chiro-inositol gly-
can deciency. We next demonstrated in vivo in the
GK type 2 diabetic rat that in the insulin sensitive tis-
sues, muscle, liver and fat [3H]myo-inositol conversion
to [3H]chiro-inositol was reduced from about 20–30%
to under 5% [15]. We partially puried the myo-inos-
itol to chiro-inositol epimerase from rat liver and dem-
onstrated its absolute requirement for nucleotide, indi-
cating that it acted via an oxido-reductive mechanism
[16]. Analyses of tissue extracts from type 2 diabetic
GK rat tissues compared to control Wistars demon-
strated reduced epimerase enzyme activity [16].
As mentioned above, it is well established that ovar-
ian cells from PCOS subjects are insulin sensitive com-
pared to peripheral tissues, which are insulin resistant.
In view of the above mentioned results demonstrating
increased M/C ratios and decreased myo-inositol to
chiro-inositol epimerase activity associated with insu-
lin resistance in type 2 diabetes, GK type 2 diabetic rat
and the lack or deciency of chiro-inositol glycan in
type 2 diabetes, PCOS and preeclampsia, we wished
to determine whether ovarian theca cells from women
with PCOS with increased ovarian insulin sensitivity
demonstrated the opposite, i.e. decreased M/C ratios
and increased epimerase activity. We now show this
is in fact the case.
Research Design and Methods
Human theca interna tissue was obtained from fol-
licles of women undergoing hysterectomy, following
informed consent under a protocol approved by the
Institutional Review Board of the Pennsylvania State
University College of Medicine. Individual follicles
were dissected away from ovarian stroma, dissected,
and dispersed with 0.05% collagenase I, 0.05% colla-
genase IA, and 0.01% deoxyribonuclease, in medium
containing 10% fetal bovine serum (FBS), as previ-
ously described [17]. The isolated follicles were size-
selected for diameters ranging from 3-5 mm so that
theca cells derived from follicles of similar size from
normal and PCOS subjects could be compared. Theca
cells were cultured on bronectin coated dishes utiliz-
Dec M/C incr epimerase in theca cells
and dried in vacuo in order to remove excess HCl.
Samples were reconstituted in 1 mL H2O and
then loaded onto a 3 mL bed volume mixed-bed ion
exchange column and the pass-through collected.
Column was washed with an additional aliquot of 19
mL H2O. Samples were then dried in vacuo prior to
Samples reconstituted in 400 µL H2O were centri-
fuged through a 0.2 μm lter and the ltrate injected
onto Dionex MA-1 HPLC column. Myo-inositol and
chiro-inositol were detected with an electrochemical
detector consisting of a Au electrode and a Ag/AgCl
reference electrode. The solvent was 100 mM NaOH
running at 0.4 mL/min. The detected peaks were inte-
grated and quantitated using Dionex PeakNet 6.4 soft-
ware by comparing the area of the unknown to the area
of the known standard (D-chiro-inositol was obtained
from Cyvex, Inc. and myo-inositol from Sigma-Aldrich
Chemical Company). The amounts of myo-inositol and
chiro-inositol were expressed as nmoles and the ratio
of myo-inositol to chiro-inositol (M/C) calculated.
For all the above experiments, Sera and growth fac-
tors were obtained from the following sources: FBS
and DME/F12 (Irvine Scientic, Irvine, CA): horse
serum (Life Technologies, Grand Island, NY); UltroSer
G (Reactifs IBF, Villeneuve-la-Garenne, France): other
compounds were purchased from Sigma (St. Louis,
MO). All other chemicals were analytical grade or bet-
ter and purchased from Cyvex Inc., Fisher Scientic
and Sigma-Aldrich Chemical Company.
Statistical analysis
Unpaired t-test was performed using GraphPad
Prism version 5.0f for Mac, GraphPad Software, San
Diego California USA,
The myo-inositol to chiro-inositol epimerase activi-
ties and M/C ratios for both normal and PCOS ovar-
ian theca cells are plotted separately as shown in Figs
1 and 2. Fig. 1 shows the epimerase values in a scat-
tergram with mean ± SE as shown by horizontal lines.
The myo-inositol to chiro-inositol epimerase specic
activity (Units/µg protein) mean value for PCOS is 3
times as high as that for the normals (0.017 ± 0.003
(n=11) vs. 0.006 ± 0.002 (n=10), resp.). There is also
more scatter for the PCOS ovarian theca cells values
than for the normal ovarian theca cells (0.002 → 0.034
pelvic pain.
Ovarian theca cells from women with polycystic
ovarian syndrome and control normals were cultured,
scraped, processed and analyzed for myo-inositol con-
tent, chiro-inositol content (plotted as a M/C ratio) and
a myo-inositol to chiro-inositol epimerase assay was
performed. Data obtained from these assays were plot-
ted as scattergrams. The mean ± SE was determined
and plotted as horizontal lines for normal and PCOS
tissues. Unpaired t-tests were performed.
Myo-inositol to chiro-inositol epimerase
Plates were partially thawed at 4ºC. 500 μL of 10
mM HEPES pH 7 with protease inhibitor cocktail con-
taining 1 mM AEBSF, 1:200 of 1.4 mg/mL protein
stock aprotinin, 10 μM leupeptin, 10 μM pepstatin, 10
μM E64 and 1 mM mercaptoethanol was added (10
HPic). Cells were scraped, transferred to microcentri-
fuge tubes and homogenized by hand using a microcen-
trifuge tube homogenizer. Samples were centrifuged
for 5 min at 4ºC. Assay tubes containing ± nucleotides
(1 mM ea NAD+, NADP, NADH and NADPH), 1 mM
nicotinamide, 1 mM MgCl2, 1 mM myo-inositol, 10
HPic were set up in total volume of 450 μL. Fifty
μL of the cell supernatant from above centrifugation
was added at timed intervals, vortexed, covered and
placed in a 37°C incubator for 6 hours with gentle mix-
ing. To stop the reaction 2 mL of ice-cold abs. ethanol
was added, vortexed and incubated on ice for 20 min.
Samples were dried in vacuo.
Samples were then processed as described below
for chiro-inositol content. Total Units were calculated
by subtracting the chiro-inositol content in the minus
nucleotides tube from the chiro-inositol content in the
plus nucleotides tube. Protein was analyzed by modi-
ed Bradford Protein Assay (Pierce® 660 nm Protein
Assay kit). The Specic Activity (Units/μg protein)
was calculated by dividing the Total Units by the Total
Myo-inositol and chiro-inositol content
Centrifugation lters were purchased from Fisher.
An aliquot from the ovarian theca cell homogenate was
transferred to a ame-seal ampoule, diluted to 6N HCl
from 12N HCl, ame sealed and hydrolyzed at 100ºC
for 48 hours. Samples were then transferred to centri-
fuge tubes, with the original vial washed three times
with HPLC grade H2O and dried in vacuo. Several 400
µL aliquots of H2O were added to the centrifuge vial
114 Heimark et al.
CYP11 mRNA abundance results from both increased
transactivation of the promoter and augmented mRNA
stability in PCOS cells [20, 29] [23]. Moreover the
5’ untranslated region of CYP17A1 and CYP11A1
mRNA have been shown to confer increased mRNA
half life in PCOS theca cells as compared to normal
theca cells, thus increasing CYP17A1 and CYP11A1
expression and androgen production in PCOS theca
cells [23, 29].
Insulin acting through the insulin receptor stimu-
lates androgen (i.e., testosterone) production in theca
cells, as does LH acting via cAMP [26]. Antibody
blockade of the insulin receptor abolished insulin’s
stimulatory action, whereas effective antibody block-
ade of the insulin-like growth factor 1 receptor did
not alter insulin’s stimulation of theca cell testoster-
one biosynthesis [26]. Insulin’s action on PCOS theca
cells to produce testosterone is massively greater than
on control theca cells [26], a measure of markedly
increased insulin sensitivity. Nestler et al. have ele-
gantly shown that chiro-inositol glycans are the sig-
nal transduction system for theca cell testosterone
synthesis. A chiro-inositol containing glycan (INS-2)
increased theca testosterone biosynthesis similarly to
insulin [30]. Further, an INS-2, anti inositol glycan
antibody, abolished insulin’s stimulatory effect, but
not that of hCG [30]. These ndings suggest that inos-
itol glycans serve as the signal transduction system
for insulin’s stimulation of human theca cell testos-
terone biosynthesis. Specically, they demonstrated
that external INS-2 activates theca cell testosterone
production dose dependently as effectively as insulin.
vs. 0.0005 → 0.019, resp.).
Fig. 2 shows the M/C ratio in a scattergram with
mean ± SE as shown by horizontal lines. The mean
value for the M/C ratio of normals is about 4 times as
high as that for PCOS (18 ± 3 (n=6) vs. 5 ± 2 (n=7),
resp. and a range of (7 → 24 vs. 2 → 15, resp.). These
results are in keeping what is seen with the epimerase
results, and demonstrate that the PCOS ovary is insulin
sensitive compared to control by these two parameters.
Two-tailed unpaired t-test (p < 0.05 was considered
statistically signicant) was performed resulting in p <
0.01 vs. PCOS for the epimerase and p < 0.002 vs. nor-
mals for the M/C ratios.
Ovarian theca cells are recognized as one of the pri-
mary sources of excess androgen biosynthesis in the
PCOS ovary [3, 24-26]. Using long-term cultures of
normal and PCOS theca cells grown for successive
population doublings in long-term culture, we have
demonstrated that androgen production is elevated in
theca cells isolated from the ovaries of women with
PCOS, as compared to theca cells from the ovaries
of normal cycling women [18, 27]. This increase in
androgen production in PCOS theca cells results from
increased mRNA accumulation of several steroido-
genic enzymes, including cholesterol side chain cleav-
age (CYP11A1), 17α-hydroxylase (CYP17A1), and
HSD3B2 [18, 28]. Extensive examination of CYP17A1
and CYP11A1 gene expression in normal and PCOS
theca cells has revealed that increased CYP17 and
Fig. 1 Myo-inositol to chiro-inositol epimerase assay
Data points for PCOS and normals shown in scatter plot
with mean ± SE shown as horizontal bars. ***, p < 0.01 vs.
Fig. 2 Myo-inositol to chiro-inositol ratios
Data points for PCOS and Normals shown in scatter plot
with mean ± SE shown as horizontal bars. *, p < 0.002 vs.
Dec M/C incr epimerase in theca cells
myo-inositol to chiro-inositol epimerase activity and
a decreased myo-inositol to chiro-inositol ratio. In
all previous papers, we have provided evidence for
decreased epimerase activity and increased myo-inosi-
tol to chiro-inositol ratios in cases of insulin resistance
Our experiments do not shed light on the continu-
ing enigma of the primacy of increased testosterone
versus the peripheral insulin resistance as the initiating
event in PCOS. They do however provide evidence
for the utility of both myo-inositol and chiro-inositol
as effective agents in treatment. Certainly, a balance
between the two inositols is required for normal phys-
iological function and regulation of the myo-inositol
to chiro-inositol epimerase opens a new avenue for
future studies. Thus, IP3 [41], IP2 [42] and IP7 [43]
as well as INS-2 [44] all inositol-containing molecules
have been shown to act to allosterically control insu-
lin signaling.
In this connection it is important to point out that
the presence of the myo-inositol to chiro-inositol
epimerase has been questioned in a recent paper by
Lin, Gopalan and Ostlund entitled, “D-chiro-inositol
is Absorbed but not Synthesized” [45]. The authors
fed rats a chiro-inositol free diet for 10 or 12 weeks
and then tested for chiro-inositol synthesis with heavy
water or labeled myo-inositol. They conclude that
there is no synthesis of chiro-inositol. Their fail-
ure in logic derives from the omission of the phrase
“under our conditions”; i.e. the prolonged chiro-inos-
itol free diet. The authors further fail to cite our in
vivo epimerization of [3H]myo-inositol to [3H]chiro-
inositol [15] and our partial purication, characteriza-
tion with a demonstration of an absolute nucleotide
requirement for a rat liver epimerase [16]. As stated
above, in both in vivo and in vitro experiments, epim-
erase enzyme activity [16] was reduced in vivo in dia-
betic animals and in diabetic tissue extracts [15].
The present data on the decreased M/C ratios and
the increased myo-inositol to chiro-inositol epimerase
activity in PCOS ovarian theca cells further strength-
ens our argument that these two parameters are associ-
ated with insulin resistance and sensitivity. They open
a new area of insight into this much-studied area.
Conict of Interest
No conict of interest for all authors of this manuscript.
Extracellular inositol glycan generation [31] as well as
an ATP dependent inositol glycan transporter in liver
have been demonstrated [32].
Our new data demonstrating increased M/C epim-
erase and decreased M/C ratios in PCOS theca cells
provides a mechanistic explanation of how the PCOS
ovary is more insulin sensitive. Increased M/C epi-
merase would provide increased chiro-inositol to be
incorporated into precursor GPI-phospholipid and or
precursor GPI-protein, which could then be cleaved
into INS-2, thus enhancing insulin sensitivity by
increasing glucose disposal [14]. INS-2 allosterically
activates protein phosphatase PP2Cα to activate GS
and mitochondrial PDHP to activate pyruvate dehy-
drogenase (PDH), both Mg2+ or Mn2+ requiring phos-
phatases (PPM family) leading to intracellular non-ox-
idative and oxidative glucose disposal and reduction of
hyperglycemia [33]. This increased insulin sensitiv-
ity would also increase testosterone supply to induce
peripheral insulin resistance. Mechanisms of testos-
terone inducing peripheral insulin resistance are not
fully understood, but in an animal model, decreased
GLUT4 and decreased glucose transport was observed
[34]. In other studies, increased insulin sensitivity with
administered testosterone has been observed [35, 36].
How the ovary is induced to increased insulin sensi-
tivity via ovarian upstream mechanisms is unclear and
requires further experimentation.
It is abundantly clear that there is marked periph-
eral insulin resistance in vivo in PCOS subjects [37].
However, when peripheral tissue cell lines from PCOS
subjects are tested for the stability of the insulin resis-
tance in vitro, variable results are seen [38, 39]. Thus
at present there is not yet an agreed upon cell line
that demonstrated stable insulin resistance in PCOS
in vitro. For this reason we have not studied inosi-
tols and epimerase in peripheral cell lines from PCOS
In a paper entitled “The D-Chiro-Inositol Paradox
in the Ovary” [40], the authors speculate that “PCOS
patients with hyperinsulinemia likely present an
enhanced MI to DCI epimerization in the ovary; this
would result in an increased DCI/MI ratio (i.e. over-
production of DCI), which would in turn would lead to
a MI deciency in the ovary.”
The present data with theca cells from PCOS sub-
jects and controls demonstrates that this is indeed the
case. This is the rst instance in which a cell with
increased insulin sensitivity manifests an increased
116 Heimark et al.
of a novel putative insulin mediator. A galactosamine
chiro-inositol pseudo-disaccharide Mn2+ chelate with
insulin-like activity. J Med Chem 46: 3283-3291.
15. Pak Y, Hong Y, Kim S, Piccariello T, Farese RV, et al.
(1998) In vivo chiro-Inositol metabolism in the rat: A
defect in chiro-Inositol synthesis from myo-Inositol and
an increased incorporation of chiro-[3H]Inositol into
phospholipid in the Goto-Kakizaki (G.K.) rat. Mol Cells
8: 301-309.
16. Sun T, Heimark D, Nguygen T, Nadler J, Larner J (2002)
Both myo-inositol to chiro-inositol epimerase activities
and chiro-inositol to myo-inositol ratios are decreased
in tissues of GK type 2 diabetic rats compared to Wistar
controls. Biochem Biophys Res Commun 293: 1092-
17. McAllister J, Simpson E. Human theca interna cells
in culture. Methods in Toxicology. 3. San Diego:
Academic Press; 1993. p. 330-339.
18. Nelson VL, Legro RS, Strauss JF, McAllister JM (1999)
Augmented androgen production is a stable steroido-
genic phenotype of propagated theca cells from poly-
cystic ovaries. Mol Endocrinol 13: 946-957.
19. Nelson-DeGrave VL, Wickenheisser JK, Cockrell JE,
Wood JR, Legro RS, et al. (2004) Valproate potentiates
androgen biosynthesis in human ovarian theca cells.
Endocrinology 145: 799-808.
20. Wickenheisser JK, Quinn PG, Nelson VL, Legro RS,
Strauss JF, et al. (2000) Differential activity of the cyto-
chrome P450 17α-hydroxylase and steroidogenic acute
regulatory protein gene promoters in normal and poly-
cystic ovary syndrome theca cells. J Clin Endocrinol
Metab 85: 2304-2311.
21. Zawadzki J, Dunaif A. Diagnostic criteria for polycys-
tic ovary syndrome: towards a rational approach. In:
Dunaif A, Givens J, Hazeltine F, Merriam G, editors.
Polycystic ovary syndrome Current issues in endocri-
nology and metabolism Boston: Blackwell. Boston:
Blackwell Scientic; 1992. p. 377-384.
22. Legro RS, Driscoll D, Strauss III JF, Fox J, Dunaif A
(1998) Evidence for a genetic basis for hyperandrogen-
emia in polycystic ovary syndrome. Proc Natl Acad Sci
U S A 95: 14956-14960.
23. Wickenheisser JK, Biegler JM, Nelson-DeGrave VL,
Legro RS, Strauss JF, et al. (2012) Cholesterol Side-
Chain Cleavage Gene Expression in Theca Cells:
Augmented Transcriptional Regulation and mRNA
Stability in Polycystic Ovary Syndrome. PLoS One 7:
24. Gilling-Smith C, Story H, Rogers V, Franks S (1997)
Evidence for a primary abnormality of thecal cell ste-
roidogenesis in the polycystic ovary syndrome. Clin
Endocrinol (Oxf) 47: 93-99.
Jakubowicz D, Nestler J (1997) 17 α-Hydroxyprogesterone
1. Franks S, Gharani N, Waterworth D, Batty S, White D,
et al. (1997) The genetic basis of polycystic ovary syn-
drome. Hum Reprod 12: 2641-2648.
2. Goldzieher J (1981) Polycystic ovarian disease. Fertil
Steril 35: 371-394.
3. Barnes R, Roseneld RL (1989) The polycystic ovary
syndrome: pathogenesis and treatment. Ann Intern Med
110: 386-399.
4. Barnes RB, Roseneld RL, Burstein S, Ehrmann DA
(1989) Pituitary-ovarian responses to nafarelin testing
in the polycystic ovary syndrome. N Engl J Med 320:
5. Goldzeiher JW, Green JA (1962) The polycystic ovary.
I. Clinical and histologic features. J Clin Endocrinol
Metab 22: 325-338.
6. Erickson GF, Magofn DA, Dyer CA, Hofeditz C
(1985) The ovarian androgen producing cells: a review
of structure/function relationships. Endocr Rev 6: 371-
7. Larner J, Craig J (1996) Urinary myo-inositol-to-chiro-
inositol ratios and insulin resistance. Diabetes Care 19:
8. Kennington A, Hill C, Craig J, Bogardus C, Raz I, et
al. (1990) Low urinary chiro-inositol excretion in non-
insulin-dependent diabetes mellitus. N Engl J Med 323:
9. Asplin I, Galasko G, Larner J (1993) chiro-inositol de-
ciency and insulin resistance: a comparison of the chiro-
inositol- and the myo-inositol-containing insulin media-
tors isolated from urine, hemodialysate, and muscle of
control and type II diabetic subjects. Proc Natl Acad Sci
U S A 90: 5924-5928.
10. Suzuki S, Kawasaki H, Satoh Y, Ohtomo M, Hirai M,
et al. (1994) Urinary chiro-inositol excretion is an index
marker of insulin sensitivity in Japanese type II diabe-
tes. Diabetes Care 17: 1465-1468.
11. Shashkin P, Shashkina E, Fernqvist-Forbes E, Zhou Y,
Grill V, et al. (1997) Insulin mediators in man: effects of
glucose ingestion and insulin resistance. Diabetologia
40: 557-563.
12. Baillargeon J-P, Iuorno MJ, Apridonidze T, Nestler JE
(2010) Uncoupling Between Insulin and Release of a
D-Chiro-Inositol–Containing Inositolphosphoglycan
Mediator of Insulin Action in Obese Women With
Polycystic Ovary Syndrome. Metab Syndr Relat Disord
8: 127-136.
13. Scioscia M, Gumaa K, Kunjara S, Paine M, Selvaggi L,
et al. (2006) Insulin resistance in human preeclamptic
placenta is mediated by serine phosphorylation of insu-
lin receptor substrate-1 and -2. J Clin Endocrinol Metab
91: 709-717.
14. Larner J, Price J, Heimark D, Smith L, Rule G, et al.
(2003) Isolation, structure, synthesis, and bioactivity
Dec M/C incr epimerase in theca cells
34. Livingstone C, Collison M (2002) Sex steroids and
insulin resistance. Clin Sci 102: 151-166.
35. Bhasin S (2003) Effects of Testosterone Administration
on Fat Distribution, Insulin Sensitivity, and
Atherosclerosis Progression. Clin Infect Dis 37: S142-
36. Mårin P, Holmäng S, Jönsson L, Sjöström L, Kvist H, et
al. (1992) The effects of testosterone treatment on body
composition and metabolism in middle-aged obese
men. Int J Obes Relat Metab Disord 16: 991-997.
37. Diamanti-Kandarakis E, Dunaif A (2012) Insulin
Resistance and the Polycystic Ovary Syndrome
Revisited: An Update on Mechanisms and Implications.
Endocr Rev 33: 981-1030.
38. Book C-B, Dunaif A (1999) Selective Insulin Resistance
in the Polycystic Ovary Syndrome. J Clin Endocrinol
Metab 84: 3110-3116.
39. Eriksen M, Pørneki AD, Skov V, Burns JS, Beck-Nielsen
H, et al. (2010) Insulin Resistance Is Not Conserved in
Myotubes Established from Women with PCOS. PLoS
One 5: e14469.
40. Carlomagno G, Unfer V, Roseff S (2011) The D-chiro-
inositol paradox in the ovary. Fertil Steril 95: 2515-
41. Farese RV, Rosic N, Babischkin J, Farese MG, Foster
R, et al. (1986) Dual activation of the inositol-triphos-
phate-calcium and cyclic nucleotide intracellular signal-
ing systems by adrenocorticotropin in rat adrenal cells.
Biochem Biophys Res Commun 135: 742-748.
42. York SJ, Armbruster BN, Greenwell P, Petes TD, York
JD (2005) Inositol Diphosphate Signaling Regulates
Telomere Length. J Biol Chem 280: 4264-4269.
43. Chakraborty A, Koldobskiy MA, Bello NT, Maxwell M,
Potter JJ, et al. (2010) Inositol Pyrophosphates Inhibit
Akt Signaling, Thereby Regulating Insulin Sensitivity
and Weight Gain. Cell 143: 897-910.
44. Brautigan D, Brown M, Grindrod S, Chinigo G,
Kruszewski A, et al. (2005) Allosteric activation of pro-
tein phosphatase 2C by D-chiro-inositol-galactosamine,
a putative mediator mimetic of insulin action.
Biochemistry 44: 11067-11073.
45. Lin X, Ma L, Gopalan C, Ostlund RE (2009) D- chiro-
Inositol is absorbed but not synthesised in rodents. Br J
Nutr 102: 1426-1434.
responses to leuprolide and serum androgens in obese
women with and without polycystic ovary syndrome
offer dietary weight loss. J Clin Endocrinol Metab 82:
26. Nestler J (1998) Inositolphosphoglycans (IPGs) as
mediators of insulin’s steroidogenic actions. J Basic
Clin Physiol Pharmacol 9: 197-204.
27. Nelson VL, Qin K, Roseneld RL, Wood JR, Penning
TM, et al. (2001) The biochemical basis for increased
testosterone production in theca cells propagated
from patients with polycystic ovary syndrome. J Clin
Endocrinol Metab 86: 5925-5933.
28. Daneshmand S, Weitsman SR, Navab A, Jakimiuk AJ,
Magofn DA (2002) Overexpression of theca-cell mes-
senger RNA in polycystic ovary syndrome does not cor-
relate with polymorphisms in the cholesterol side-chain
cleavage and 17α-hydroxylase/C17-20 lyase promoters.
Fertil Steril 77: 274-280.
29. Wickenheisser JK, Nelson-DeGrave VL, McAllister
JM (2005) Dysregulation of cytochrome P450 17α-
hydroxylase messenger ribonucleic acid stability in
theca cells isolated from women with polycystic ovary
syndrome. J Clin Endocrinol Metab 90: 1720-1727.
30. Nestler JE, Jakubowicz DJ, Falcon de Vargas A, Brik C,
Quintero N, et al. (1998) Insulin Stimulates Testosterone
Biosynthesis by Human Thecal Cells from Women with
Polycystic Ovary Syndrome by Activating Its Own
Receptor and Using Inositolglycan Mediators as the
Signal Transduction System. J Clin Endocrinol Metab
83: 2001-2005.
31. Alvarez JF, Varela I, Ruiz-Albusac JM, Mato JM (1988)
Localisation of the insulin-sensitive phosphatidylinos-
itol glycan at the outer surface of the cell membrane.
Biochem Biophys Res Commun 152: 1455-1462.
32. Alvarez J, Sánchez-Arias J, Guadaño A, Estévez F,
Varela I, et al. (1991) Transport in isolated rat hepato-
cytes of the phospho-oligosaccharide that mimics insu-
lin action. Effects of adrenalectomy and glucocorticoid
treatment. Biochem J 274 369-374.
33. Hans SK, Camara F, Altiti A, Martín-Montalvo A,
Brautigan DL, et al. (2010) Synthesis of C-glycoside
analogues of β-galactosamine-(1-->4)-3-O-methyl-D-
chiro-inositol and assay as activator of protein phos-
phatases PDHP and PP2Cα. Bioorg Med Chem 18:
... How could we explain this abnormal sensitivity? A significant contribution in explaining this puzzle has been provided by Larner's seminal paper demonstrating that ovarian abnormal response to insulin alters the specific myo-Inositol/D-Chiro-Inositol (myo-Ins/D-Chiro-Ins) ratio within the ovary [15]. Previous studies have shown that diabetes and insulin resistance is associated with the reduced transformation of myo-Ins into D-Chiro-Ins in high-glucose-consuming tissues. ...
... In theca cells from both normal and PCOS women, myo-Ins, D-Chiro-Ins levels, and epimerase activity have been investigated, showing that epimerase activity was three times higher than normal in PCOS subjects, while the myo-Ins/D-Chiro-Ins ratio was four times lower in PCOS subjects when compared to normal theca cells. It is worth noting that, in this study, theca cells were stimulated by using the same quantity of insulin [15]. Therefore, those results demonstrated that theca cells from PCOS subjects not only retain their insulin sensitivity, but they transform myo-Ins into D-Chiro-Ins with higher efficiency than normal theca cells, even under the same insulin stimulation. ...
... As previously recalled, myo to D-Chiro conversion is fostered by insulin, and in insulinresistant patients, this would lead to a significant deficit of D-Chiro-Ins in many tissues. However, insulin resistance is not associated with impairment in the transduction of the insulin signal at the ovarian level, given that hyperinsulinemia still stimulates ovarian androgen production in PCOS, and can likely act similarly upon D-Chiro-Ins synthesis, thus finally impairing myo-Ins availability [15]. ...
Full-text available
Polycystic ovarian syndrome (PCOS) is the most common endocrinological disorder in women, in which, besides chronic anovulation/oligomenorrhea and ovarian cysts, hyperandrogenism plays a critical role in a large fraction of subjects. Inositol isomers—myo-Inositol and D-Chiro-Inositol—have recently been pharmacologically effective in managing many PCOS symptoms while rescuing ovarian fertility. However, some disappointing clinical results prompted the reconsideration of their specific biological functions. Surprisingly, D-Chiro-Ins stimulates androgen synthesis and decreases the ovarian estrogen pathway; on the contrary, myo-Ins activates FSH response and aromatase activity, finally mitigating ovarian hyperandrogenism. However, when the two isomers are given in association—according to the physiological ratio of 40:1—patients could benefit from myo-Ins enhanced FSH and estrogen responsiveness, while taking advantage of the insulin-sensitizing effects displayed mostly by D-Chiro-Ins. We need not postulate insulin resistance to explain PCOS pathogenesis, given that insulin hypersensitivity is likely a shared feature of PCOS ovaries. Indeed, even in the presence of physiological insulin stimulation, the PCOS ovary synthesizes D-Chiro-Ins four times more than that measured in control theca cells. The increased D-Chiro-Ins within the ovary is detrimental in preserving steroidogenic control, and this failure can easily explain why treatment strategies based upon high D-Chiro-Ins have been recognized as poorly effective. Within this perspective, two factors emerge as major determinants in PCOS: hyperandrogenism and reduced aromatase expression. Therefore, PCOS could no longer be considered a disease only due to increased androgen synthesis without considering the contemporary downregulation of aromatase and FSH receptors. Furthermore, these findings suggest that inositols can be specifically effective only for those PCOS phenotypes featured by hyperandrogenism.
... The narrow distribution of DCI in nature meant that it would be costly to apply DCI to therapy, whereas pinitol is more readily available as an alternative to DCI since pinitol is abundant in various beans (27). Meanwhile, MI can be converted to DCI through NAD-NADH-dependent epimerization with an insulin stimulus (22,28). Even though DCI is distributed in the human body in very low concentrations, it plays an important role in the regulation of energy metabolism by acting as a secondary insulin mediator (29). ...
... It has been clearly documented that PCOS has major symptom related to insulin resistance (34). However, Heimark et al. (28) reported that ovarian theca and granulosa cells from PCOS patients remain sensitive to insulin and are never insulin resistant due to increased MI to DCI epimerase activity, which is accompanied by high levels of DCI. Some researchers, therefore, have suggested that the enhancement of MI to DCI epimerization in ovaries is caused by high levels of insulin in the blood. ...
A natural sugar alcohol, D-pinitol, has been reported to be a potential compound for osteoporosis treatment via inhibiting osteoclastgenesis. However, research on the effects of pinitol on osteoporosis in vivo is still limited. The present study investigated the protective effects of pinitol on ovariectomized mice and attempted to elucidate this mechanism in vivo. Four-week-old female ovariectomized ICR mice were employed as a postmenopausal osteoporosis model and treated with pinitol or estradiol (E2) for 7 wk. Thereafter, serum calcium content, phosphorus content, tartrate-resistant acid phosphatase (TRAcP) and bone-specific alkaline phosphatase activity (BALP) were measured. Bilateral femurs were isolated, and bone marrow protein was collected through centrifuge. Dry femurs were weighed, while femur length, cellular bones, and bone mineral content were measured. D-chiro-Inositol (DCI) and myo-inositol (MI) content in serum and bone marrow was measured by GC-MS. At the end of experiment, the serum BALP and TRAcP activities of the OVX mice were suppressed significantly by treatment with either pinitol or E2. Femur weight, cellular bone rate, Ca and P content were improved by pinitol or E2. The DCI content of the serum of OVX decreased significantly, although it recovered to some extent after pinitol treatment. Pinitol significantly increased the ratio of DCI to MI in serum or bone marrow protein in the observed OVX mice. Besides, pinitol had no significant effects on osteoblast viability and differentiation. The present results showed that continuous pinitol intake exerts potent anti-osteoporosis activity via elevating DCI content in serum and bone marrow in OVX mice.
... Кроме того, ДХИ участвует во внутриклеточной продукции энергии через фермент пируватдегидрогеназа за счет смещения равновесия в сторону гликолиза. Избытки пирувата, являющегося конечным продуктом превращения глюкозы, через цикл Кребса, в свою очередь, участвуют в выработке АТФ [32,33]. Благодаря всем этим механизмам инозитолы могут проявлять себя в качестве ИС, снижая концентрацию инсулина в сыворотке крови [34]. ...
... Результаты исследований демонстрируют, что соотношение МИ к ДХИ в фолликулярной жидкости здоровых женщин составляет примерно 100:1, в то время как у пациенток с СПКЯ -около 0,2:1. Увеличение концентрации ДХИ способствует синтезу андрогенов, а истощение МИ ухудшает передачу ФСГ-опосредованных сигналов и качество ооцитов [32,37]. Гипотеза яичникового парадокса при СПКЯ может объяснять, почему монотерапия D-хиро-инозитолом даже в высоких его концентрациях в ряде случаев не приводит к ожидаемым улучшениям метаболического и эндокринного профиля у данной группы пациенток [38]. ...
Insulin resistance is the main pathogenetic component of many metabolic diseases, including obesity, type 2 diabetes mellitus, gestational diabetes mellitus, and polycystic ovary syndrome (PCOS). Despite the fact that to date the mechanisms of insulin resistance formation have not been established, one of the promising directions at present is the search for potential therapeutic strategies for its correction, due to the fact that this also improves the course of the concomitant underlying disease. Insulin sensitizers are a generally recognized method of PCOS therapy due to their safety and effectiveness in normalizing the metabolic and endocrine profile of patients with polycystic ovary syndrome. The leading position in this direction is occupied by the combination of myo-inositol (MI) with D-chiro-inositol (DHI) in a ratio of 40:1, which, according to the conducted studies, is comparable to the concentration of inositols in the blood plasma of healthy women. This ratio of MI/DHI is effective both for normalization of the metabolic profile, and for regulation of the menstrual cycle and overcoming anovulatory infertility. An analysis of the literature has shown that a number of biologically active substances, such as folic acid, vitamin D and alpha-lipoic acid, in combination with insulin sensitizers, have additional advantages, which gives grounds for continuing research on their significance as components of combined treatment, as well as in the search for the optimal dose and duration of such therapy.
... 10 When this approach does not work, insulin is required with or without the addition of an oral hypoglycemic agent. 11 There is a need for treatments including nutritional supplements which can prevent occurrence of gestational diabetes or hyperglycemia in pregnancy. The treatments must be effective, safe in pregnancy and do not cause any side effects. ...
Full-text available
Background: Aim of study was to evaluate the impact of myoinositol and D-chiro inositol plus vitamin D supplementation on the prevention of gestational diabetes mellitus (GDM) in pregnant women. Methods: In the multi-centric, prospective, randomised, double-blind clinical trial, either vitamin D alone (group I) or myoinositol and D-chiro inositol plus Vitamin D (group II) were administered to pregnant women from 12 weeks of gestation. The administration was continued until delivery to primigravids who were normoglycemic at 12 weeks of gestation and consented. From October 2018 to December 2019. A total of 1250 women were enrolled, and randomly allocated to either of the groups: 630 women in Group I and 620 in Group II. The allocation was blinded. The primary outcome was the rate of GDM as assessed by oral glucose tolerance test (OGTT) recommended by diabetes in pregnancy Study Group India (DIPSI), International Federation of Gynecology and Obstetrics (FIGO) and the Government of India, at first antenatal visit followed by at weeks 24 to 28 in both the groups. Results: The rate of GDM was found more in group I as compared to group II treated with myoinositol and D-chiro Inositol plus vitamin D, but the difference was not statistically significant (5.08% in group I and 3.22% in group II). Conclusions: In conclusion, an improved trend has been noticed in the reduction of the rate of GDM with myoinositol and D-chiro inositol plus vitamin D as compared to vitamin D alone. Myoinositol and D-chiro inositol plus vitamin D supplementation may be a good option for pregnant women to prevent the GDM occurrence especially in women having positive risk factors for GDM.
... Healthy ovaries in women exhibit a higher level of myo-Ins and a lower level of D-chiro-Ins (at a ratio of approximately 100:1). In contrast, the ovaries of PCOS patients are characterized by a significant deficiency of myo-inositol and an increased content of D-chiro-inositol (with a decreasing ratio of 0.2:1) [46,47] . ...
Full-text available
Introduction: Polycystic ovary syndrome is a common hormonal disorder in women and the leading cause of female infertility. Traditional therapeutic methods often do not yield the expected results, hence the need to explore new treatment strategies. Promising results have been observed in studies on inositol. Objective: The aim of this study is to summarize the current knowledge regarding the effectiveness and safety of inositol and herbal preparations in the treatment of PCOS based on available scientific literature. Materials and Methods: A literature review was conducted using PubMed and Google Scholar databases, using search terms: inositol, PCOS treatment, herbal medicine in PCOS. Current knowledge: Inositol is an oral supplement used in the therapy of PCOS. It is characterised by high safety and minimal risk of side effects. Herbal extracts alleviate symptoms in patients with PCOS. Conclusions: Analysis of scientific research has provided evidence of the effectiveness of inositol, particularly myo-inositol, in complementary therapy for PCOS. Herbal medicine also appears to be an effective supportive treatment. However, these substances should not be considered as primary therapy but rather as an adjunct. Only both - primary medications and complementary treatment methods, can yield a therapeutic effect.
... Важливо зауважити, що велике значення має співвідношення МІ та DХІ 40:1, що є подібним до такого у плазмі крові. Збільшення концентрації DХІ у цьому співвідношенні до 5:1 або навіть 20:1 може бути шкідливим для фізіології яєчників та репродукції, оскільки надлишок DХІ потенційно несприятливий для якості бластоцисти [11,13,26]. ...
Full-text available
Objectives: to evaluate the benefits of delayed conservative myomectomy with the aim of reducing body weight and correcting hematological and metabolic parameters against the background of the use of gonadotropin-releasing hormone (GnRH) agonists and a combination of myo-inositol and D-chiro-inositol (Inofolic combi) in obese patients with metabolic syndrome by comparing this technique with immediate surgery.Materials and methods. The study included 72 patients with uterine fibroids and obesity who required conservative myomectomy. Patients were offered to postpone surgical intervention in order to correct body weight, metabolic and hematological indicators. As a preoperative preparation, patients were recommended to use GnRH agonists (goserelin), inositols, and iron preparations for anemia. Patients were divided into 2 groups: the first group (n = 31) followed all these recommendations, the second group (n = 41) refused to follow the recommendations and postponed surgical treatment. Group 1 underwent surgical treatment 3 months after the start of treatment, group 2 – after the initial consultation.Results. Patients of the first group lost an average of 7.3 ± 1.4 kg of body weight during preoperative preparation, their hemoglobin level increased by an average of 21.78%, and the volume of the largest myomatous node decreased by an average of 21.82%. The duration of the operation was significantly shorter in group 1 (75 ± 3.84 min) than in group 2 (118 ± 5.33 min). Laparotomy in the first group was not performed in any patient, in the second group it was performed in 9 patients (21.95%) (p < 0.05). There was a decrease in the severity of postoperative pain in group 1, (3.4 В± 1.25 points on the visual analog scale), which was significantly lower than in group 2 (5.1 В± 3.4 points).Conclusions. Body weight reduction against the background of the use of GnRH agonists (goserelin) and inositols (Inofolic combi) due to the improvement of the technical conditions of the operation, metabolic and hematological indicators allow to reduce the duration of surgical intervention and the frequency of laparotomies in patients with uterine fibroids against the background of obesity and metabolic syndrome.
... Insulin directly stimulates the production of androgens in the ovarian theca cells and additionally inhibits the synthesis of SHBG in the hepatocyte, thus causing an increase in the levels of circulating free androgens [26]. Hence, high insulin levels and IR directly impair ovarian function by inducing an upregulation of androgen production [36]. ...
Full-text available
Background: The aim of the present study is to investigate the effects produced by a treatment with myo-Inositol (myo-Ins) in women presenting polycystic ovary syndrome (PCOS) of different phenotypes. Methods: We performed a retrospective study to evaluate whether patients presenting different PCOS phenotypes, treated for 6 months with myo-Ins, might exhibit a differential response to the treatment. On this premise, we clustered women with PCOS phenotypes A, B, and C in the first study group (hyperandrogenic PCOS or H-PCOS), and women presenting PCOS phenotype D in a separate study group (non-hyperandrogenic PCOS or NH-PCOS) to evaluate if the presence of hyperandrogenism, shared by H-PCOS, might imply a metabolic/endocrine condition rather than a gynecological issue. Results: The administration of myo-Ins induced a significant improvement in metabolic and endocrine parameters in H-PCOS, while the effects on NH-PCOS were negligible. Additionally, myo-Ins treatment improved the endometrial thickness of H-PCOS. Conclusions: Subjects selected for the study exhibited a differential response to myo-Ins therapy according to their PCOS phenotypes. The data suggest that the same treatment might not equally improve the parameters of the PCOS condition in each sub-group of patients. It is crucial to distinguish the various phenotypes to properly select the therapeutical approach.
... Therefore, insulin increases the ovarian myo-Ins conversion into D-chiro-Ins. The resulting increase in D-chiro-Ins levels induced by insulin (or obtained following the administration of the isomer at high concentrations) impairs ovarian availability of myo-Ins, as demonstrated by Larner's seminal paper [89], determining an imbalance in the myo-Ins/D-chiro-Ins ratio. Consequently, D-chiro-Ins, while ameliorating the PCOS-related systemic metabolic parameters, exacerbates abnormal steroidogenesis within the ovary, thus providing a mechanistic rationale that supports the so-called Unfer paradox [47]. ...
Full-text available
Myo-inositol is a natural polyol, the most abundant among the nine possible structural isomers available in living organisms. Inositol confers some distinctive traits that allow for a striking distinction between prokaryotes and eukaryotes, the basic clusters into which organisms are partitioned. Inositol cooperates in numerous biological functions where the polyol participates or by furnishing the fundamental backbone of several related derived metabolites, mostly obtained through the sequential addition of phosphate groups (inositol phosphates, phosphoinositides, and pyrophosphates). Overall myo-inositol and its phosphate metabolites display an entangled network, which is involved in the core of the biochemical processes governing critical transitions inside cells. Noticeably, experimental data have shown that myo-inositol and its most relevant epimer D-chiro-inositol are both necessary to permit a faithful transduction of insulin and of other molecular factors. This improves the complete breakdown of glucose through the citric acid cycle, especially in glucose-greedy tissues, such as the ovary. In particular, while D-chiro-inositol promotes androgen synthesis in the theca layer and down-regulates aromatase and estrogen expression in granulosa cells, myo-inositol strengthens aromatase and FSH receptor expression. Inositol effects on glucose metabolism and steroid hormone synthesis represent an intriguing area of investigation, as recent results have demonstrated that inositol-related metabolites dramatically modulate the expression of several genes. Conversely, treatments including myo-inositol and its isomers have proven to be effective in the management and symptomatic relief of a number of diseases associated with the endocrine function of the ovary, namely polycystic ovarian syndrome.
D-chiro-inositol (DCI) is an isomer of inositol, abundant in many foods, such as beans and buckwheat, with insulin-sensitizing, anti-inflammatory, and antioxidant effects. DCI has been used to relieve insulin resistance in diabetes and polycystic ovary syndrome in combination with inositol or D-pinitol. Here, we investigated the effect of DCI on aging and stress resistance in C. elegans. We found that DCI could prolong the lifespan of C. elegans by up to 29.6 %. DCI significantly delayed the onset of neurodegenerative diseases in models of C. elegans. DCI decreased the accumulation of Aβ1-42, alpha-synuclein, and poly-glutamine, the pathological causes of Alzheimer's, Parkinson's, and Huntington's diseases, respectively. DCI significantly increased the stress resistances against pathogens, oxidants and heat shock. Moreover, D-chiro-inositol reduced the content of ROS and malondialdehyde by increasing the total antioxidant capacity and the activity of superoxide dismutase and catalase. Above effects of DCI requires the transcription factors FOXO/DAF-16 and Nrf-2/SKN-1. DCI also increased the expression of downstream genes regulated by FOXO/DAF-16 and Nrf-2/SKN-1. In conclusion, DCI enhanced the antioxidant capacity and healthy lifespan of C. elegans by activating DAF-16, SKN-1, and HSF-1. Our results showed that DCI could be a promising antiaging agent that is worth further research on the mechanism and health supplemental application of DCI.
Full-text available
Hyperandrogenism is characteristic of women with polycystic ovary syndrome (PCOS). Ovarian theca cells isolated from PCOS follicles and maintained in long-term culture produce elevated levels of progestins and androgens compared to normal theca cells. Augmented steroid production in PCOS theca cells is associated with changes in the expression of genes for several steroidogenic enzymes, including CYP11A1, which encodes cytochrome P450 cholesterol side-chain cleavage. Here, we further examined CYP11A1 gene expression, at both the transcriptional and post-transcriptional level in normal and PCOS theca cells propagated in long-term culture utilizing quantitative RT-PCR, functional promoter analyses, and mRNA degradation studies. The minimal element(s) that conferred increased basal and cAMP-dependent CYP11A1 promoter function were determined. CYP11A1 mRNA half-life in normal and PCOS theca cells was compared. Results of these cumulative studies showed that basal and forskolin stimulated steady state CYP11A1 mRNA abundance and CYP11A1 promoter activity were increased in PCOS theca cells. Deletion analysis of the CYP11A1 promoter demonstrated that augmented promoter function in PCOS theca cells results from increased basal regulation conferred by a minimal sequence between -160 and -90 bp of the transcriptional start site. The transcription factor, nuclear factor 1C2, was observed to regulate basal activity of this minimal CYP11A1 element. Examination of mRNA stability in normal and PCOS theca cells demonstrated that CYP11A1 mRNA half-life increased >2-fold, from approximately 9.22+/-1.62 h in normal cells, to 22.38+/-0.92 h in PCOS cells. Forskolin treatment did not prolong CYP11A1 mRNA stability in either normal or PCOS theca cells. The 5'-UTR of CYP11A1 mRNA confers increased basal mRNA stability in PCOS cells. In conclusion, these studies show that elevated steady state CYP11A1 mRNA abundance in PCOS cells results from increased transactivation of the CYP11A1 promoter and increased CYP11A1 mRNA stability.
Full-text available
The D-chiro-inositol-to-myo-inositol ratio is regulated by an insulin-dependent epimerase. Enzyme activity varies among tissues, likely owing to the specific needs of the two different molecules. We hypothesize that in the ovaries of polycystic ovary syndrome patients, epimerase activity is enhanced, leading to a local myo-inositol deficiency which in turn is responsible for the poor oocyte quality.
Polycystic ovary syndrome (PCOS) is now recognized as an important metabolic as well as reproductive disorder conferring substantially increased risk for type 2 diabetes. Affected women have marked insulin resistance, independent of obesity. This article summarizes the state of the science since we last reviewed the field in the Endocrine Reviews in 1997. There is general agreement that obese women with PCOS are insulin resistant, but some groups of lean affected women may have normal insulin sensitivity. There is a post-binding defect in receptor signaling likely due to increased receptor and insulin receptor substrate-1 serine phosphorylation that selectively affects metabolic but not mitogenic pathways in classic insulin target tissues and in the ovary. Constitutive activation of serine kinases in the MAPK-ERK pathway may contribute to resistance to insulin's metabolic actions in skeletal muscle. Insulin functions as a co-gonadotropin through its cognate receptor to modulate ovarian steroidogenesis. Genetic disruption of insulin signaling in the brain has indicated that this pathway is important for ovulation and body weight regulation. These insights have been directly translated into a novel therapy for PCOS with insulin-sensitizing drugs. Furthermore, androgens contribute to insulin resistance in PCOS. PCOS may also have developmental origins due to androgen exposure at critical periods or to intrauterine growth restriction. PCOS is a complex genetic disease, and first-degree relatives have reproductive and metabolic phenotypes. Several PCOS genetic susceptibility loci have been mapped and replicated. Some of the same susceptibility genes contribute to disease risk in Chinese and European PCOS populations, suggesting that PCOS is an ancient trait.