Synergistic Effects of d-Chiro-Inositol and Manganese on Blood Glucose and Body Weight of Streptozotocin-Induced Diabetic Rats

Abstract

d-chiro-inositol (DCI) and manganese were administered orally singly and together to streptozotocin (STZ)- induced diabetic rats for 21 days and blood glucose values and body weights determined. At blood glucose values above 500 mg/dL, values were unchanged with DCI, manganese sulfate, or both over ten days. Insulin was administered to reduce the hyperglycemia to approximately 300 mg/dL. Over 12 days, DCI alone significantly reduced blood glucose (23%), and the combination of DCI and manganese sulfate reduced hyperglycemia even more effectively (40%) as compared to control animals. Of further interest, body weights both of female and male rats administered DCI and manganese were reduced, with females 25% compared to controls and males 21% compared to controls over the 21-day period. Metabolic mechanisms of actions of DCI and manganese to explain these results are discussed.

Full text

90 Current Bioactive Compounds 2010, 6, 90-96
1573-4072/10 $55.00+.00 © 2010 Bentham Science Publishers Ltd.
Synergistic Effects of d-Chiro-Inositol and Manganese on Blood Glucose
and Body Weight of Streptozotocin-Induced Diabetic Rats
Gilbert Gluck1, Tatiana Anguelova1, Douglas Heimark2 and Joseph Larner*,2
1Cyvex Nutrition, Inc., California 92614, USA
2Allomed Pharmaceuticals, Virginia 22903, USA and Department of Pharmacology, University of Virginia,
Charlottesville, VA 22908, USA
Abstract: d-chiro-inositol (DCI) and manganese were administered orally singly and together to streptozotocin (STZ)-
induced diabetic rats for 21 days and blood glucose values and body weights determined. At blood glucose values above
500 mg/dL, values were unchanged with DCI, manganese sulfate, or both over ten days. Insulin was administered to
reduce the hyperglycemia to approximately 300 mg/dL. Over 12 days, DCI alone significantly reduced blood glucose
(23%), and the combination of DCI and manganese sulfate reduced hyperglycemia even more effectively (40%) as
compared to control animals. Of further interest, body weights both of female and male rats administered DCI and
manganese were reduced, with females 25% compared to controls and males 21% compared to controls over the 21-day
period. Metabolic mechanisms of actions of DCI and manganese to explain these results are discussed.
Keywords: d-chiro-inositol, chronic administration, type 2 diabetes, hyperglycemia, manganese.
INTRODUCTION
DCI and manganese have each been independently
identified as lowering elevated blood glucose in subjects
with type 2 diabetes [1,2]. In India, based on native folklore,
DCI as 1d-3-O-methyl-chiro-inositol (pinitol) was isolated
from bougainvillea leaves and shown to reduce hypergly-
cemia in STZ-induced diabetic mice [1]. In South Africa,
native alfalfa plant extracts used to treat diabetes were
examined and manganese identified as the active agent.
Administration of manganese itself reduced hyperglycemia
in diabetic subjects [2]. Further data has now shown that
both DCI and manganese are deficient in human type 2
diabetics [3-6].
We previously demonstrated that a single dose of DCI
administered intragastrically to STZ-induced type 2 model
diabetic rats and to normal rats administered an intra-
peritoneal injection of glucose lowered their elevated blood
glucose concentrations acutely within a period of 120 min
[7]. The diabetic animals had initial blood glucose values of
406 mg/dL, thus a model of type 2 diabetes, since the STZ
had only partially destroyed the pancreatic beta cells. In a
further study, an intravenous single dose of DCI in com-
bination with an intravenous infusion of manganese chloride
for 120 min produced a more pronounced effect on lowering
blood glucose in STZ-induced type 2 model diabetic rats
than DCI alone [8]. Manganese alone was without effect.
Again the initial blood glucose values of the diabetic rats
was 251 mg/dL indicating a partial destruction of the
pancreatic beta cells and a type 2 model of diabetes.
*Address correspondence to this author at the Department of Pharmacology,
1300 Jefferson Park Avenue, Charlottesville, VA 22908, USA; Tel: (434)
924-2321; Fax: (434) 924-5207; E-mail: jl6d@virginia.edu
This study was financed in whole by Cyvex Nutrition, Inc. Irvine, CA
92614
The purpose of the present study was to investigate the
possible effect of chronic oral administration of Chirositol™,
95% DCI alone (Cyvex Nutrition, Inc.) and in combination
with manganese sulfate on reducing elevated blood glucose
in STZ-induced Sprague-Dawley diabetic rats.
MATERIALS AND METHODS
Sprague-Dawley rats, 8 weeks old of both sexes weigh-
ing 180-260 g were injected with STZ (50 mg/kg, i.p.). After
72 h, blood glucose was sampled from the tail vein and
plasma glucose was measured with ACCU-CHEK®- softclix
plus kit. Diabetes was established with blood glucose values
greater than 500 mg/dL modeling type 1 diabetes. Blood
samples were collected once a day in the morning during the
whole study. Animals had access to water and food ad
libitum and were fed HARLAN-T7012.15 diet. Light was
switched on/off at 12 h intervals. Body weight of the animals
was measured every morning.
Phase I Study
Initially, four groups of animals were administered either
DCI, manganese, both DCI and manganese sulfate, or saline.
Group 1 (n=8) was administered Chirositol™ (20 mg/kg in
0.9 % w/v of NaCl, saline solution); administration by oral
gavage twice a day (at 8 h intervals). Group 2 animals (n=8)
received 3.3 mg/kg manganese sulfate (Jost Chemicals);
Group 3 animals (n=8) received 20 mg/kg Chirositol™ and
3.3 mg/kg manganese sulfate; Group 4 animals (n=8)
received saline solution (control group).
Phase II Study
Insulin was next administered to all animals to partially
decrease but still maintain hyperglycemic blood glucose
values. All animals were administered 2 units (72 mcg)
insulin per day (Lantus insulin from Sanofi-aventis) injected

Synergistic Effects of d-Chiro-Inositol and Manganese Current Bioactive Compounds 2010, Vol. 6, No. 2 91
subcutaneously post gavage. Insulin treatment reduced basal
blood glucose values to about 400 mg/dL. Animals in Group
1 (n=15) received Chirositol™ 95% d-chiro-Inositol (20
mg/kg in 0.9 % w/v of NaCl, saline solution); Group 2
(n=21) received 20 mg/kg Chirositol™ and 3.3 mg/kg
manganese sulfate; Group 3 (control group, n=6) received
saline solution only; administration by oral gavage twice a
day (at 8 h interval).
STATISTICAL ANALYSIS
Values are presented as mean ± SEM. Group mean diffe-
rences were compared by ANOVA followed by Bonferroni
and Newman-Keuls Multiple Comparison tests. Differences
with p<0.05 were considered significant.
RESULTS
No significant changes in the blood glucose levels were
observed with any of the administered agents during the ten
days of Phase I study. Initial injection of streptozotocin had
destroyed sufficient islet beta cells inducing a model of type
1 diabetes with blood glucose values of 600 mg/dL and
higher (Fig. 1).
Since our previous studies with DCI and manganese were
done with STZ-induced diabetic rats with blood glucose
values in the range of 250-400 mg/dL, closer to a model of
type 2 diabetes [7,8] we injected insulin to lower blood
glucose values to 300-400 mg/dL to more closely model our
previous conditions.
Insulin administration for 3 days, 10-12, during the Phase
II study reduced blood glucose levels of all animals to 400
mg/dL (Fig. 2). Blood glucose levels of the saline control
group were not further reduced by insulin administration for
the remaining nine days of the study and on day 21, blood
glucose values remained in the 400 mg/dL range. In contrast,
DCI alone administered for the remaining nine days at a
bolus dose of 20 mg/kg twice a day (Group 1) further
decreased blood glucose by 23%, which on day 21 was
significantly different from the control saline group (p<0.03)
(Figs. 2 and 3). Administration of 20 mg/kg DCI in combi-
nation with 3.3 mg/kg manganese sulfate twice a day
resulted in a 40% decrease in plasma glucose (Group 2),
which on day 21 was significantly different from the saline
(control) group (p<0.0001). This antihyperglycemic effect of
the combination of DCI and manganese sulfate on day 21
was also significantly different from that produced by DCI
alone (p<0.008) (Figs. 2 and 3).
Fig. (1). Mean blood glucose, male and female rats combined, for experiment modeling type 1 diabetes. Values are expressed as mean ±
SEM. A: control rats (n = 8); B: rats administered DCI alone (n = 8); C: rats administered Mn2+ alone (n = 8); D: rats administered DCI +
Mn2+ (n = 8). D1 POST, D2 POST and D3 POST denotes day 1, 2 and 3 post-STZ administration.

92 Current Bioactive Compounds 2010, Vol. 6, No. 2 Gluck et al.
Fig. (2). Mean blood glucose ± SEM, for both male and female rats,
for Phase 2 study. Group 1: DCI, n=15; Group 2: DCI + Mn2+,
n=21; Group 3: Control (0.9% NaCl), n=6. All animals received 2
units insulin per day.
Fig. (3). Mean blood glucose on days 19 to 21 for both male and
female rats. Glucose values for DCI, DCI + Mn2+ and control are
plotted. Values are expressed as mean ± SEM with p values above
each significant pair.
The rate of decrease in plasma glucose of Group 2 (DCI
+ MnSO4) was also more pronounced than that of Group 1
(DCI) (Fig. 4). Linear regression slopes of blood glucose
Fig. (4). Mean rate of decline of blood glucose of combined male
and female rats for days 17 to 21. Rats are administered either DCI
alone (n=15) or DCI + Mn2+ (n=21). The two regression slopes are
statistically different (p = 0.043).
decrease during days 17 to 21 were respectively -9 for DCI
(p=0.0362) and -16 for the combination of DCI and
manganese sulfate (p=0.0013). The two regression lines are
significantly different from each other (p = 0.043).
When body weights were measured, female rats of both
Group 1 (DCI, n=8) and Group 2 (DCI + MnSO4, n=12)
unexpectedly demonstrated a 35% net loss of weight as
compared to controls, (n=3) (Fig. 5A). Control male and
female rats gained body weight during the experimental
period. The weight loss for the female rats became
statistically significant starting on day 13 (p = 0.03 DCI vs.
control; p = 0.048 DCI + MnSO4 vs. control). The p values
progressively decreased and on day 21 were p = 0.0033 and
p = 0.006 respectively for DCI vs. control and DCI + MnSO4
vs. control. When body weights of males were measured
(Fig. 5B) DCI (n=8) and DCI+MnSO4 (n=12) also
demonstrated a net loss of weight compared to control males
(n=4) but did not decrease to the same extent as did females.
The Group 1 and Group 2 slopes for the female rats’ weight
loss was statistically different from those of the Group 1 and
Group 2 male rats (p<0.001). Differences in weight became
statistically significant for the male rats on day 10 for DCI
(p=0.0057); DCI + Mn2+ (p=0.026). Except for day 12, the
significance for male weight loss progressively lowered to
p<0.001 on day 21 for both DCI and DCI + Mn2+. Fig. (6), in
table format, summarizes the blood glucose values and body
weights.
Fig. (5). Female (A) and male (B) rat body weights measured
initially at day 0 and then daily from days 10 to 21. Rats are
administered DCI alone or DCI + Mn2+. Values are normalized
against control and expressed as % control ± SEM. A: The weight
loss becomes statistically significant in female rats starting on day
13 (p = 0.03 DCI vs. control; p = 0.048 DCI + Mn2+ vs. control) and
progressively lower p values until day 21 (p = 0.0033 DCI vs.
Control; p = 0.006 DCI + Mn2+ vs. control). B: The weight loss in
males becomes statistically significant starting on day 10 (p =
0.0057 DCI vs. Control; p = 0.0259 DCI + Mn2+ vs. control) and
progressively lower p values until day 21 (p < 0.001 DCI vs. control
and DCI + Mn2+ vs. control).

Synergistic Effects of d-Chiro-Inositol and Manganese Current Bioactive Compounds 2010, Vol. 6, No. 2 93
DISCUSSION
In a previous report, we observed an acute additive effect
of a single bolus dose of DCI and an infusion of MnCl2 for
120 min to further reduce hyperglycemia in STZ type 2
model diabetic rats (plasma glucose 251 ± 7 mg/dL) above
that of DCI alone [8]. Manganese alone was ineffective in
that experiment. In the present Phase I experiment, chronic
oral 10-day administration of DCI and manganese sulfate
alone and in combination was ineffective in decreasing high
blood glucose values of 600 mg/dL. Since previous expe-
riments had been done with diabetic animals with initial
blood glucoses in the 250-400 mg/dL range, we injected
insulin to lower initial blood glucose values from 600 mg/dL
to 400 mg/dL. This was termed Phase II. In the Phase II
experiment, we examined the effect of chronic oral adminis-
tration of DCI alone versus administration of DCI with
manganese sulfate in STZ-induced diabetic rats with
decreased initial blood glucose values. Under these condi-
tions, with adequate insulin present, the antihyperglycemic
effect of DCI was significantly further enhanced by the
addition of manganese sulfate.
The early folk medicine literature clearly demonstrates
the antihyperglycemic effects of Mn2+ in diabetic humans [2]
and of DCI as pinitol in diabetic mice [1]. More recent
literature clearly demonstrates the antihyperglycemic effec-
tiveness of DCI in type 2 diabetic rats [7], monkeys [9] and
human subjects with metabolic syndrome [10], type 2 dia-
betes [11-13] and with polycystic ovarian syndrome (PCOS)
associated with insulin resistance [14].
More specifically, we gavaged DCI (1-10 mg/kg) into
STZ-induced diabetic rats and demonstrated a dose-
dependent reduction of hyperglycemia of up to 40% [7],
Bates et al., administered pinitol (5-100 mg/kg) orally to
STZ-induced diabetic rats, and reported that it lowered
hyperglycemia in a dose-dependent manner over a 6-hour
period [15]. Pinitol and/or DCI (10 mg/kg/day) were
administered chronically (for 12 weeks) to STZ-induced
diabetic mice. Both inositols normalized hyperglycemia to
euglycemia in 6 weeks [16].
In hyperinsulinemic insulin-resistant monkeys, intrave-
nous (IV) administration of a single dose of DCI (100
mg/kg) significantly increased the rates of disappearance of
blood glucose by 129 ± 4 mg/dl [7] and of insulin by 89 ±
39%, while oral administration of DCI (500 mg/kg) with a
meal to these hyperinsulinemic insulin-resistant monkeys
decreased blood glucose and insulin compared with control
monkeys [7]. DCI (1000 mg/kg) was administered IV to
insulin-resistant and diabetic monkeys in the presence of
insulin under steady-state clamp conditions, and muscle
biopsy samples were assayed for GS activity. GS fractional
velocity was significantly increased (25 ± 6%) compared
with insulin alone, demonstrating an insulin-sensitizing
action [17].
In mild type 2 diabetics (n=57), DCI was administered
orally (1200 mg/day) for 28 days; metabolic parameters were
compared with diabetic individuals who were not adminis-
tered DCI. Those individuals who had received DCI showed
statistically significant decreases in diastolic blood pressure,
triglycerides, cholesterol and low-density lipoprotein (LDL)
cholesterol. There was a 49 mg/dL decrease in blood glucose
in the 2-hr oral glucose tolerance test (OGTT) and a 9.2 %
reduction in the OGTT blood glucose area under the curve
(AUC). Thus, administration of DCI improves aspects of the
metabolic syndrome. Surprisingly, a significant reduction in
HbA1c was observed after 28 days, much earlier than seen in
other clinical trials with anti-diabetic therapy [10]. DCI was
administered orally (1200 mg/day) for 6 to 8 weeks to 22
DCI DCI + Mn2+ Control
DCI DCI + Mn2+ Control
DCI DCI + Mn2+ Control
Day n = 15 n = 21 n = 6
n = 8 n = 12 n = 4
n = 8 n = 12 n = 3
0
244 ± 3 247 ± 2 251 ± 4
230 ± 4 204 ± 3 207 ± 6
10 599 ± 1 594 ± 4 598 ± 2
287 ± 2 302 ± 6 336 ± 12
187 ± 6 189 ± 7 198 ± 5
11 487 ± 21 474 ± 20 409 ± 37
12 398 ± 32 369 ± 24 368 ± 29
300 ± 15 302 ± 6 340 ± 12
188 ± 7 190 ± 7 220 ± 6
13 452 ± 31 472 ± 18 421 ± 32
287 ± 8 301 ± 6 342 ± 12
188 ± 6 188 ± 7 224 ± 7
14 392 ± 36 394 ± 20 434 ± 25
288 ± 8 296 ± 8 344 ± 12
190 ± 6 189 ± 7 226 ± 7
15 402 ± 29 383 ± 30 441 ± 39
286 ± 8 301 ± 6 350 ± 12
187 ± 6 187 ± 7 228 ± 7
16 395 ± 38 376 ± 29 374 ± 54
283 ± 8 300 ± 6 351 ± 12
185 ± 7 186 ± 7 228 ± 7
17 357 ± 34 314 ± 25 397 ± 44
282 ± 8 298 ± 6 352 ± 12
183± 6 184 ± 7 230 ± 7
18 359 ± 32 306 ± 21 430 ± 38
281 ± 8 297 ± 6 352 ± 13
182 ± 7 183 ± 7 232 ± 7
19 355 ± 29 280 ± 18 429 ± 34
278 ± 8 295 ± 6 354 ± 12
180 ± 7 181 ± 7 232 ± 6
20 331 ± 29 267 ± 18 413 ± 29
277 ± 8 293 ± 6 355 ± 12
179 ± 6 180 ± 7 233 ± 6
21 326 ± 24 252 ± 15 424 ± 29
275 ± 8 292 ± 6 356 ± 13
177 ± 6 178 ± 7 235 ± 7
Fig. (6). Summary of blood glucose and body weights. Glucose and body weights measured initially (day 0) and from day 10 to day 21.
Values are means ± SEM. Blood glucose for male and female are pooled and averaged.

94 Current Bioactive Compounds 2010, Vol. 6, No. 2 Gluck et al.
women with PCOS, and their metabolic parameters were
compared with those of control women with PCOS who
were not administered DCI. Administration of DCI increased
insulin action, improved ovulatory function, and decreased
serum androgen concentrations, blood pressure and serum
triglycerides [14].
Three clinical trials have been conducted in South Korea
to investigate administration of pinitol to individuals with
type 2 diabetes. In the first trial, 33 individuals with type 2
diabetes were administered 1200 mg pinitol/day for 13
weeks and compared with control diabetic individuals who
were administered placebo. This treatment regimen reduced
fasting blood glucose levels (157 ± 22 vs. 127 ± 77 mg/dL),
whereas no changes were observed in the group administered
placebo (158 ± 20 vs. 157 ± 17 mg/dL). In addition, the
levels of HbA1c decreased significantly in the group
administered pinitol (8.9 ± 1.1% vs. 7.8 ± 0.9%) compared
with the control group (8.8 ± 1.4% vs. 8.8 ± 1.4%) [11].
Similar reductions were observed in second trial in which 20
type 2 diabetics were administered 20 mg/kg/day pinitol for
12 weeks. Fasting blood glucose decreased significantly in
the group administered pinitol (200 ± 38 vs. 169 ± 50
mg/dL), as did HbA1c (9.8 ± 1.6% vs. 8.3 ± 1.1%) [12].
Finally, the third trial was a double-blind study in which 82
type 2 diabetics were randomized to receive pinitol (400 mg)
or placebo three times a day for 12 weeks. Again, fasting
blood glucose decreased significantly in the pinitol group
(184 ± 104 vs. 129 ± 47 mg/dL) but not in the placebo group
(173 ± 64 vs. 168 ± 67 mg/dL), as did HbA1c (Pinitol: 8.4 ±
1.6% vs. 7.8 ± 1.5%; Placebo: 8.4 ± 1.2% vs. 8.5 ± 1.3%)
[13]. Thus there is accumulated evidence for the effec-
tiveness of DCI and pinitol to ameliorate hyperglycemia and
restore metabolic balance in insulin resistance states.
In the body tissues, chiro-inositol is present linked to
amino sugars as chiro-inositol glycans. These glycans have
insulin-mimetic and insulin-sensitizing properties and have
been termed insulin second messengers or mediator-
modulators (see below). The literature clearly demonstrates
about a 50% decrease of chiro-inositol-glycan mediator bio-
activity and chiro-inositol content in urine, hemodialysate
and muscle of type 2 diabetic subjects compared to controls
[4]. In muscle biopsy studies strikingly, no chiro-inositol
was detected in chiro-inositol mediator preparations from
type 2 diabetic subjects before or after insulin adminis-
tration. Myo-inositol glycan was present and clearly inc-
reased after insulin administration [3]. By contrast, in control
healthy subjects chiro-inositol glycan and myo-inositol
glycan were present before insulin and increased after insulin
administration [3]. A deficit of chiro-inositol in urine in type
2 diabetic subjects has been correlated with severity of
insulin resistance [18]. With regard to manganese, there are a
number of conflicting reports comparing the contents in
diabetic and control urine and blood cells [5,6,19-21].
However, analyses of hair and scalp specimens reveal lower
levels in human type 2 diabetics than normals [5]. In animal
studies, a manganese deficient diet clearly results in
impaired glucose tolerance and the generation of reactive
oxygen species with resultant islet beta cell damage related
to manganese superoxide dismutase deficiency [22-24].
Therefore, replacement therapy with both agents appears
both reasonable and logical.
Considering replacement therapy, DCI administration has
been shown to have two beneficial effects. First, DCI itself
has beneficial antioxidant properties [25]. It prevents oxida-
tive damage by reducing reactive oxygen species formation
in endothelial cells exposed to high glucose, protects the
vascular endothelium and allows it to produce nitric oxide to
dilate blood vessels, a normal function of insulin [26]. By
protecting NO, DCI prevents the loss of and restores
endothelial function.
Second, in the body DCI is converted into DCI-glycan
precursor phospholipids [26], from which DCI-glycan me-
diators are released by insulin [27]. Decreased chiro-inositol
glycan release by insulin in blood has been observed in
human type 2 diabetes [28], in blood of women with
polycystic ovarian syndrome with insulin resistance [29],
and in placental membranes from women with preeclampsia
associated with insulin resistance [30]. Thus DCI is effective
alone as an antioxidant and as a chiro-inositol glycan to
restore metabolic intracellular glucose disposal.
What is the mechanism of action of DCI-glycan media-
tors and of manganese? We isolated from beef liver the first
example of a DCI-glycan mediator. It was chelated to man-
ganese [31]. It has insulin-mimetic and sensitizing
properties. We determined its structure as pinitol linked -
1,4 to galactosamine chelated to manganese. It has been
chemically synthesized as 2-amino-2-deoxy--d-galacto-
pyranosyl-(1,3)-1d-4-O-methyl-chiro-inositol and named
INS-2. INS-2 allosterically activates two key phosphoprotein
phosphatases, PP2C which dephosphorylates and activates
glycogen synthase (GS) and mitochondrial PDHP, which
dephosphorylates and activates pyruvate dehydrogenase
(PDH). Thus, INS-2 mimics two classical actions of insulin.
These two rate-limiting enzymes (GS and PDH) activate
intracellular glucose disposal via glycogen synthesis and
mitochondrial pyruvate oxidation and generation of ATP
[31,32].
Manganese is an important element not only in the
structure of chiro-inositol glycans, but also in the structure
and function of PP2C and PDHP. Both phosphatases are
members of the same PPM family with 20-25% amino acid
identity and both require manganese or magnesium for
bioactivity. Their X-ray crystal structures demonstrate that
both have bimetallic (Mn2+ or Mg2+) centers as elements of
their catalytic sites [33,34].
Thus, DCI and manganese are combined in vivo in the
cell in the form of chelated insulin mediator glycans such as
INS-2. In addition, both phosphoprotein phosphatases PP2C
and PDHP, which activate glycogen synthesis and pyruvate
oxidation, require manganese and/or magnesium for bioac-
tivity. By these mechanisms both DCI and manganese act to
restore normal physiological balance and their prolonged
combined supplementation demonstrates an enhanced
antihyperglycemic effect as compared to DCI alone.
No significant changes in plasma glucose values were
observed with any administered agent during the Phase I
study where STZ had destroyed sufficient islet beta cells to
produce a model of type 1 diabetes with glucose values of
600 mg/dL. In a previous short term acute experiment in
severely diabetic STZ-induced rats, a model of type 1
diabetes, with initial blood glucose values of 500-600 mg/dL

Synergistic Effects of d-Chiro-Inositol and Manganese Current Bioactive Compounds 2010, Vol. 6, No. 2 95
[32], we demonstrated that insulin alone was ineffective in
decreasing elevated blood glucose without the prior adminis-
tration of the DCI-glycan INS-2. When INS-2 was first
injected, then insulin was effective. This suggested that for
insulin to act there had to be available a tissue pool of DCI-
glycan to act as an intracellular mediator. Thus under these
conditions, INS-2 was acting in the presence of an ineffec-
tive insulin concentration as an insulin sensitizer. We
therefore in Phase II administered insulin to lower plasma
glucose values to about 300-400 mg/dL. Our hypothesis is
that in this chronic experiment, this administered insulin
resulted in the replacement of the inositol glycan precursor
phospholipid pool by the orally administered DCI and
manganese. We have previously shown that insulin stimu-
lates the incorporation of [3H]myo-inositol into [3H]chiro-
inositol precursor phospholipids in fibroblasts [26]. Thus
insulin acts both to generate the inositol glycan phospholipid
pool and to stimulate the release of the inositol glycan from
the precursor phospholipid. Both are defective in the absence
of insulin.
In the present experiment supplementation of DCI and
manganese sulfate prevented weight gain in male rats and
decreased body weight of female rats. The mechanism of
action will require further investigation, as well as the diffe-
rence between male and female weight response. However, it
is possible to speculate that insulin action in the hypotha-
lamus as an antiorexigenic agent may in part be related to the
generation of inositol-glycans, such as INS-2, which mimic
the action of insulin in the CNS.
ACKNOWLEDGEMENT
This study was financed in whole by Cyvex Nutrition,
Inc. Irvine, CA 92614.
ABBREVIATIONS
DCI = d-chiro-inositol
GS = Glycogen synthase
Pinitol = 1d-3-O-methyl-chiro-inositol
INS-2 = 2-amino-2-deoxy--d-galactopyranosyl-(1,3)-
1d-3-O-methyl-chiro-inositol
PDH = Pyruvate dehydrogenase
STZ = Streptozotocin
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Received: August 24, 2009 Revised: January 20, 2010 Accepted: February 03, 2010