The role of endogenous interleukin-1 in stress-induced adrenal activation and adrenalectomy-induced adrenocorticotropic hormone hypersecretion.

Abstract

To examine the role of IL-1 in the regulation of the hypothalamo-pituitary-adrenal (HPA) axis, mice with knockout of the IL-1 receptor type I (IL-1rKO) were exposed to psychological and metabolic stressors. When exposed to mild stressors (auditory stress or a low dose of 2-deoxyglucose), IL-1rKO mice displayed a significantly diminished corticosterone secretion, compared with wild-type (WT) controls. In response to more severe stressors (60-min restraint or a high dose of 2-deoxyglucose), both groups exhibited a similar increase in corticosterone secretion. To examine the role of IL-1 in HPA axis feedback regulation, serum ACTH levels were measured after adrenalectomy (ADX) in IL-1rKO mice and in mice with transgenic overexpression of IL-1 receptor antagonist within the brain (IL-1raTG). As expected, WT controls exhibited ADX-induced ACTH hypersecretion, whereas IL-1rKO and IL-1raTG mice showed no increase in ACTH levels, suggesting that brain IL-1 has a critical role in ADX-associated ACTH hypersecretion. Similarly, WT mice that were chronically exposed to IL-1ra in utero displayed a diminished ADX-induced ACTH hypersecretion, compared with vehicle-treated controls, suggesting a developmental role of IL-1 in HPA axis regulation. In conclusion, our results suggest that endogenous IL-1 plays a critical role in HPA axis activation after stress and ADX.

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The Role of Endogenous Interleukin-1 in Stress-Induced
Adrenal Activation and Adrenalectomy-Induced
Adrenocorticotropic Hormone Hypersecretion
I. GOSHEN, R. YIRMIYA, K. IVERFELDT, AND J. WEIDENFELD
Department of Psychology (I.G., R.Y.), The Hebrew University of Jerusalem, Jerusalem 91905, Israel; Department of
Neurochemistry and Neurotoxicology (K.I.), Stockholm University, SE-106 91 Stockholm, Sweden; and Department of Neurology
(J.W.), the Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital, Jerusalem 91120, Israel
To examine the role of IL-1 in the regulation of the hypo-
thalamo-pituitary-adrenal (HPA) axis, mice with knockout of
the IL-1 receptor type I (IL-1rKO) were exposed to psycholog-
ical and metabolic stressors. When exposed to mild stressors
(auditory stress or a low dose of 2-deoxyglucose), IL-1rKO
mice displayed a significantly diminished corticosterone se-
cretion, compared with wild-type (WT) controls. In response
to more severe stressors (60-min restraint or a high dose of
2-deoxyglucose), both groups exhibited a similar increase in
corticosterone secretion. To examine the role of IL-1 in HPA
axis feedback regulation, serum ACTH levels were measured
after adrenalectomy (ADX) in IL-1rKO mice and in mice with
transgenic overexpression of IL-1 receptor antagonist within
thebrain(IL-1raTG).Asexpected,WTcontrolsexhibitedADX-
induced ACTH hypersecretion, whereas IL-1rKO and IL-
1raTG mice showed no increase in ACTH levels, suggesting
that brain IL-1 has a critical role in ADX-associated ACTH
hypersecretion. Similarly, WT mice that were chronically ex-
posed to IL-1ra in utero displayed a diminished ADX-induced
ACTH hypersecretion, compared with vehicle-treated con-
trols, suggesting a developmental role of IL-1 in HPA axis
regulation. In conclusion, our results suggest that endoge-
nous IL-1 plays a critical role in HPA axis activation after
stress and ADX. (Endocrinology 144: 4453–4458, 2003)
A
thalamo-pituitary-adrenal (HPA) axis. The response of the
HPA axis to stressful stimuli depends on several neural in-
puts, mediated mainly by norepinephrine (NE) and seroto-
nine (5-HT), which project from discrete brain stem nuclei to
neuroendocrine cells located in the paraventricular nucleus
(PVN) of the hypothalamus (1). In response to stressful stim-
uli, these PVN neurons secrete CRH, the major ACTH secre-
tagogue,intotheanteriorpituitary;andsubsequently,ACTH
induces the secretion of glucocorticoids (GC) from the ad-
renal cortex (2). The responses of the HPA axis are also
regulated by an efficient negative feedback system, exerted
by GC via corticosteroid receptors, located mainly in the
hippocampus, PVN, and pituitary (3, 4). One notable exam-
ple for the action of this system is the marked increase in
ACTH levels after adrenalectomy (ADX) (5).
Other factors that were implicated in the activation of the
HPA axis are proinflammatory cytokines, particularly IL-1
(6–7), which is produced by many types of cells, including
immune cells in the periphery as well as glia and neurons
within the brain (8). IL-1 is expressed throughout the com-
ponents of the HPA axis (6–7) and influences all of its levels:
IL-1 induces the secretion of CRH from the hypothalamus (9,
10) and ACTH from the pituitary (11), via the IL-1 type I
receptorsintheseregions(6,7).Additionally,IL-1stimulates
VARIETY OF stressful physiological and psycholog-
ical conditions induce the activation of the hypo-
GC secretion from the adrenal, although no known IL-1
receptors were found in this gland (6, 7). IL-1 may be also
involvedintheGCnegativefeedbackmechanismbyaltering
the levels of brain CG receptors in the hippocampus (12, 13).
In addition to its role in immunoregulation of inflamma-
tory processes, IL-1 plays a major role in the modulation of
neuroendocrine systems during illness (14). Immune chal-
lenges, such as local inflammation, viral infection, and en-
dotoxin exposure, induce the production and secretion of
brain IL-1, followed by HPA axis activation (6, 7). It was
shown, by us and by others, that IL-1 blockade using IL-1
receptor antagonist (IL-1ra) during these conditions pre-
vents the increase in GC (7, 15). Endogenous IL-1 activates
the HPA axis not only during sickness, but also in various
stressful situations. IL-1 gene expression, protein levels, and
biological activity are increased after exposure to several
types of stress, such as restraint (16, 17) and inescapable
shock (18). Furthermore, impairments in IL-1 signaling,
causedbyeitherIL-1raadministrationorgeneticallyinduced
IL-1 deficiency, diminish the increase in GC secretion fol-
lowing stress (16, 19).
The interaction between IL-1 and the HPA axis is bidirec-
tional. On the one hand, IL-1 activates the HPA axis, as
detailed above; and on the other hand, GC suppress the
production of IL-1, mainly by decreasing IL-1 mRNA levels,
both by inhibiting its transcription and by destabilizing it
(20). Accordingly, it has been shown that removal of endog-
enous GC augments IL-1 secretion, e.g. the increase in IL-1
protein levels, after stress, is more distinct in adrenalecto-
mized rats (18, 21). Recently, we demonstrated an increase in
IL-1 gene expression in rats after ADX. Furthermore, we
found that IL-1 gene expression in astrocyte cultures can be
Abbreviations: ADX, Adrenalectomy; CNS, central nervous system;
CS, corticosterone; 2DG, 2-deoxyglucose; GC, glucocorticoids; HPA,
hypothalamo-pituitary-adrenal; 5-HT, serotonine; IL-1rKO, knockout of
the IL-1 receptor type I; IL-1raTG, transgenic overexpression of IL-1
receptorantagonist;NE,norepinephrine;PVN,paraventricularnucleus;
WT, wild-type.
0013-7227/03/$15.00/0
Printed in U.S.A.
Endocrinology 144(10):4453–4458
Copyright © 2003 by The Endocrine Society
doi: 10.1210/en.2003-0338
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detected only when cortisol is removed from the culture
medium(22).Therefore,wehypothesizedthat,inadditionto
its putative role in the stress response, brain IL-1 may be
involved in ADX-induced hypersecretion of ACTH.
In the present study, we further assessed the role of IL-1
in the regulation of adrenocortical activation after exposure
to various stressors, using IL-1 receptor type I-deficient mice
(IL-1rKO). Furthermore, we tested, for the first time, the role
of IL-1 in HPA axis regulation after ADX, using IL-1rKO
mice, as well as mice with transgenic overexpression of IL-1
receptor antagonist within the central nervous system (CNS)
(IL-1raTG). To assess whether the results found using the
genetically engineered mice can be ascribed to developmen-
tal influences of the IL-1 deficiency, we also tested ADX-
induced ACTH hypersecretion in mice that were prenatally
treated with IL-1ra.
Materials and Methods
Subjects
Subjects were male IL-1rKO mice and their 129/Sv X C57BL/6 wild-
type (WT) controls (23) (Jackson Laboratories, Bar Harbor, ME) and
IL-1raTG mice and their B6CBA WT controls (24) (Stockholm Univer-
sity).BothIL-1rKOandIL-1raTGmicedemonstrateadefectiveresponse
to IL-1 (23–24). No differences in vitality were found between these
strains and their respective controls. Subjects were 2–4 months old.
Animals were housed in an air-conditioned room (22 ? 1 C), with food
and water ad libitum. All the experiments were performed during the
first 2 h of the light phase of a reversed 12-h light, 12-h dark cycle (lights
offat0700h).TheexperimentswereapprovedbytheHebrewUniversity
Committee on Animal Care and Use.
Stressful stimuli
Twenty-four hours before the experiment, mice were divided into
separate cages. At the experiment day, control nonstressed mice were
taken from their new home-cages and killed by decapitation immedi-
ately, alternately with stressed mice. Mice subjected to acoustic stress
were exposed to a ringing bell (109 decibels) for 4 min and were killed
by decapitation 10 min after stress initiation. Mice subjected to restraint
stress were placed in a perforated cylinder (3 cm in diameter; 10 cm in
length) for 60 min and were killed immediately upon removal from the
cylinder. To induce metabolic stress (cytoglucopenia), mice were ip
injected with either 250 or 500 mg/kg 2-deoxyglucose (2DG, dissolved
in0.2ml;Sigma,Rehovot,Israel)orsaline(samevolume)andwerekilled
by decapitation 1 h after the injection. Administration of 2DG, which
inhibits intracellular glucose use, is commonly used as a model of met-
abolic stress, influencing the HPA axis via central mechanisms (25).
ADX
Mice were anesthetized with pentobarbital (60 mg/kg, ip), and the
adrenal glands were bilaterally removed. Sham operations were similar
in all aspects apart from the removal of the glands. After operation, mice
were provided with 0.45% NaCl as their drinking solution instead of
water.Eightdaysafteroperation,micewerekilledbyrapiddecapitation,
and trunk blood was collected. Blood was centrifuged for 20 min at 2000
rmp,andserumwascollectedforACTHanalysis.Thecompleteremoval
of the adrenal glands was confirmed by measuring corticosterone (CS)
levels, which were found to be below the detection limit of the kit in all
the ADX-operated mice.
Determination of ACTH and CS levels
CS was determined by RIA, as previously described (26). The sen-
sitivitylimitoftheassaywas0.5?g/100ml,andtheintra-andinterassay
coefficients of variation were 6.4% and 7.2%, respectively. The percent
of cross-reactivity of the antiserum with various steroids was: cortisol,
4.5; estradiol, less than 0.1; progesterone, 15.7; and testosterone, 7.9.
ACTH concentrations were determined by RIA kit (Nichols Institute
Diagnostics, San Juan Capistrano, CA). The sensitivity limit of the assay
was 10 pg/ml. There was no cross-reactivity of the antiserum with
?-MSH, ?-MSH, ?-lipotrophic hormone, or ?-endorphin.
Prenatal IL-1ra exposure
Pregnancy was determined by the presence of vaginal plugs, and
dams were sc implanted, on d 7 of gestation, with Alzet osmotic mi-
cropumps secreting human IL-1ra (20 mg/kg?d for 14 d; Amgen, Thou-
sand Oaks, CA). Using ELISA, we found that exogenous human IL-1ra
crossed both the placenta and the blood brain barrier and reached the
fetal CNS (34.22 ? 7.8 and 10.74 ? 3.08 pg/mg brain tissue in IL-1ra and
vehicle-treated fetuses, respectively) on d 15 of gestation. Two control
groups were used in this experiment: The first group was implanted
with vehicle-secreting micropumps, and the second group received no
treatment. Within 24 h of birth, pups from all groups were transferred
to untreated nursing dams. To minimize the influence of inherent fa-
milial effects, only one pup from each litter was assigned for each
experimental group. ACTH levels after ADX were tested, as described
above, at the age of 4 months.
Statistical analysis
The results were analyzed by a two-way ANOVA, followed by the
Tukey post hoc analysis.
Results
Effects of impaired IL-1 signaling on CS levels in response
to different stress modalities and intensities
In response to auditory stress, WT control mice exhibited
a significant increase in CS levels (P ? 0.01), whereas the
levels of CS in IL-1rKO mice remained unchanged (Fig. 1A).
Thisfindingwasreflectedbyasignificantstrainbytreatment
interaction (F1,36? 6.818, P ? 0.02). In response to 60-min
restraint stress, both groups exhibited a marked increase in
CS secretion (F1,20? 585.16, P ? 0.001), and there was no
difference between IL-1rKO and control mice (P ? 0.2).
Exposure to a mild metabolic stress (250 mg/kg 2DG in-
jection) resulted in a significant increase in CS levels in WT
mice (P ? 0.05), whereas the levels of CS in IL-1rKO mice
remained unchanged (Fig. 1B). This finding was reflected by
asignificantstrainbytreatmentinteraction(F1,31?4.498,P?
0.05). In contrast, exposure to the more severe metabolic
stress (500 mg/kg 2DG injection) resulted in a significant
increaseinCSlevelsinbothstrains(F1,27?59.11,P?0.0001),
and no difference was found between IL-1rKO and control
mice (P ? 0.2).
Effects of impaired IL-1 signaling on ADX-induced
ACTH hypersecretion
Eight days after ADX, the levels of ACTH were markedly
increased in C57BL/6x129/Sv WT mice (P ? 0.05), whereas
the levels of ACTH in IL-1rKO mice remained unchanged
(Fig. 2A). This finding was reflected by a significant strain by
treatment interaction (F1,22?4.78, P ? 0.05). Similarly, 8 d
after ADX ACTH, levels were significantly increased in
C57BL/6xCBA WT mice (P ? 0.01), whereas the levels of
ACTH in IL-1raTG mice remained unchanged (Fig. 2B). This
finding was reflected by a significant strain by treatment
interaction (F1,25? 12.4, P ? 0.005).
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Effects of impaired IL-1 signaling during brain
development on ADX-induced ACTH hypersecretion
Vehicle-treated and nontreated C57BL/6xCBA control mice
exhibitedasimilarpatternofACTHsecretion;hence,datafrom
these groups was merged. Eight days after ADX, there was a
significant overall increase in ACTH levels [F(1,43) ? 6.46, P ?
0.05]. However, post hoc tests showed that this increase was
significant in the control mice (P ? 0.05) but not in mice that
were prenatally treated with IL-1ra (P ? 0.5) (Fig. 3).
Discussion
ThepresentstudydemonstratesthatIL-1rKOmicedisplayed
impairedadrenocorticalactivationaftermildpsychologicaland
metabolic stressors. However, after exposure to severe stres-
sors, these mice demonstrated normal CS secretion. IL-1rKO
and IL-1raTG mice also exhibited an almost-complete abolish-
ment of ACTH hypersecretion after ADX. IL-1rKO mice are
shown to have no expression of IL-1 receptor type I, which
seems to mediate all of the known biological functions of IL-1,
andarereportedtohaveadefectiveresponsetoIL-1?andIL-1?
(23). IL-1raTG mice have astrocyte-directed overexpression of
the human IL-1ra gene under the control of the murine glial
fibrillary acidic protein promoter and are insensitive to the
administration of exogenous IL-1 (24). The deficits in ADX-
induced HPA axis activation that accompany the impairments
in IL-1 signaling cannot be attributed to any peripheral influ-
ences, because IL-1raTG mice overexpress IL-1ra only within
the CNS (24).
FIG. 1. EffectsofimpairedIL-1signalingonCSlevelsinresponsetodifferentstressmodalitiesandintensities.A,WTmice(n?10)andIL-1rKO
mice (n ? 10) displayed similar basal CS levels. IL-1rKO mice (n ? 10) displayed decreased CS secretion, compared with WT controls (n ? 10),
in response to auditory stress but not in response to 60 min of restraint (n ? 7 and 6, respectively). *, P ? 0.01, compared with nonstressed
WT and auditory-stressed IL-1rKO. B, WT mice (n ? 5) and IL-1rKO mice (n ? 10) displayed similar CS levels after saline injection. IL-1rKO
mice (n ? 12) exhibited no elevation in CS secretion in response to a low-dose 2DG (250 mg/kg) injection, compared with WT controls (n ? 5),
but a normal elevation in CS secretion in response to a high-dose (500 mg/kg) 2DG injection (n ? 10 and 6, respectively). *, P ? 0.05, compared
with WT mice injected with saline and IL-1rKO mice injected with a low dose of 2DG. Data are presented as mean ? SEM.
FIG. 2. Effects of impaired IL-1 signaling on ADX-induced ACTH hypersecretion. A, Sham-operated WT mice (n ? 7) and IL-1rKO mice (n ?
9) displayed similar basal ACTH levels. After ADX, WT controls (n ? 5) exhibited a marked ACTH hypersecretion, whereas IL-1rKO mice (n ?
5) showed no increase in ACTH levels. *, P ? 0.05, compared with sham-operated WT mice and ADX IL-1rKO mice. B, Sham-operated WT mice
(n ? 8) and IL-1raTG mice, which over-express IL-1ra within the brain (n ? 8), displayed similar basal ACTH levels. After ADX, WT controls
(n ? 7) demonstrated a marked ACTH hypersecretion, whereas IL-1raTG mice (n ? 6) displayed no change in ACTH secretion. *, P ? 0.0001,
compared with sham-operated WT mice and ADX IL-1raTG mice. Data are presented as mean ? SEM.
Goshen et al. • IL-1 and Pituitary-Adrenal Regulation Endocrinology, October 2003, 144(10):4453–4458
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OurresultsregardingtheroleofIL-1instressresponseare
in accordance with previous studies showing that IL-1 levels
are increased after exposure to various stressors, such as
restraint (16, 17) and inescapable shock (18), and that IL-1
receptor type I gene expression in the pituitary is also en-
hancedafterstressorCRHinjection(27,28).IL-1byitselfcan
activate the HPA axis, and either pharmacological or genetic
disruption of IL-1 signaling, using IL-1ra administration or
IL-1knockoutmice,diminishesstress-inducedincreaseinCS
secretion (6, 7, 19). In the present study, a diminished in-
crease in CS levels was found in IL-1rKO mice only in re-
sponse to relatively mild stressors, such as bell ringing and
cytoglucopenia induced by 250 mg/kg 2DG injection, sug-
gesting that IL-1 signaling via its type I receptor is important
foradrenocorticalactivationaftermoderatestress.However,
in response to more severe stressors, such as 60 min of re-
straint or 500 mg/kg 2DG injection, no difference was found
between IL-1rKO and WT controls. This finding is consistent
with the findings of a previous study reporting that, 2 h after
turpentine injection, IL-1-deficient mice demonstrate normal
HPA axis activation; whereas at 8 h after injection, their
response was abolished (19). In contrast with our findings,
treatment with IL-1ra before (but not during) exposure to
restraint stress significantly inhibited ACTH secretion in rats
(16). Differences between species and methodologies may
account for this inconsistency. For example, in the pharma-
cological study (16), young rats were subjected to stress in
relatively large restrainers; whereas in the present study,
adult mice were entered into much tighter restraining tubes.
Thus, it is possible that the stress induced in the pharmaco-
logical study was milder than the one induced in the present
study and, therefore, its effects were attenuated by blockade
of IL-1 receptors.
It is possible that the response to robust stressors may also
involve other mediators, which may compensate for the ab-
sence of IL-1 signaling. One of these mediators may be the
cytokine TNF-?, which often works in synergism with IL-1
(8, 29). Indeed, in a preliminary study, we found that TNF
p55 receptor-deficient mice demonstrated normal CS secre-
tion after exposure to auditory stress but decreased CS se-
cretion after 60 min of restraint stress. It should be noted that
the finding that mild stress-induced CS secretion in IL-1rKO
mice is blunted during a single time point (which coincides
with maximal activation in normal animals) (16, 25) cannot
exclude the possibility that the strain differences are attrib-
utable to changes in the kinetics, rather than the amplitude,
ofCSsecretionfromtheadrenal.Thus,thepossibilitythatthe
CS response to the auditory stress and the low dose of 2DG
are slower to develop in the IL-1rKO mice should be further
explored.
Feedback regulation of the HPA axis is considered to in-
volve inhibitory actions of GC via GC receptors. Several
studies (e.g. Ref. 3) suggest that the primary target for GC
feedback inhibition is not only the hypothalamic CRH neu-
ronsbutalsootherhypothalamicandextrahypothalamic(e.g.
hippocampus, pituitary) systems that regulate CRH expres-
sionandrelease(3,4).Theactionofthissystemisexemplified
by the marked increase in ACTH levels after ADX (5). In
addition to ACTH hypersecretion, ADX is also associated
with enhanced expression of IL-1 gene in the hypothalamus,
pituitary, and brain stem, as well as increased production of
IL-1 protein in the pituitary (22, 30). These findings suggest
that GC may have a tonic inhibitory effect on brain IL-1. In
the present study, after removal of this inhibitory effect by
ADX, ACTH levels were markedly elevated in WT controls
butdidnotincreaseinIL-1rKOorIL-1raTGmice,suggesting
that brain IL-1 may have an important role in ADX-induced
ACTH hypersecretion. Together, these findings suggest that
the removal of the direct inhibitory signal exerted by GC is
not sufficient for ADX-associated ACTH hypersecretion.
Rather, this hypersecretion is critically dependent on an ex-
citatorysignal,providedbytheelevatedlevelsofIL-1,which
is a potent HPA axis activator (6, 7).
The exact mechanism by which endogenous IL-1 is in-
volved in the regulation of the HPA axis is not clear. Among
the possible mediators of its actions are NE and 5-HT, which
are known to play an important role in regulating HPA axis
responses to various stressful stimuli (1, 31–33). Further-
more, it has been shown that IL-1 has a facilitatory role on
noradrenergic and serotonergic systems; for example, either
peripheral or intrahypothalamic IL-1 administration stimu-
lates NE secretion in the hypothalamus in vivo (16, 34, 35),
and intrahypothalamic or intrahippocampal IL-1 adminis-
tration induces the secretion of 5-HT in these regions (35, 36).
IL-1ra can block the increase in NE and 5-HT after stress, as
well as the increase in ACTH plasma levels (16). Addition-
ally, neurotoxic lesions that produce depletion of hypotha-
lamic NE inhibit the increase in plasma ACTH and CS levels
in response to IL-1 (37, 38). NE may be also involved in the
effects of IL-1 on ACTH hypersecretion after ADX, because
it was shown that hypothalamic NE depletion by 6-OHDA
injection does not affect basal ACTH levels but reduces the
increase in ACTH hypersecretion after ADX (39). Together,
these findings suggest that the influence of IL-1 signaling on
HPA axis regulation after stress or ADX may be, at least
partly, mediated by NE and/or 5-HT systems.
TheimpairmentinADX-inducedACTHhypersecretionin
FIG. 3. Effects of prenatal IL-1ra treatment on ADX-induced ACTH
hypersecretion in adult offspring: Sham-operated mice that were pre-
natally treated with IL-1ra during the last 2 wk of gestation (n ? 8),
vehicle-treated mice (n ? 7), and nontreated mice (n ? 5) displayed
similar basal ACTH levels. After ADX, control mice [vehicle-treated
(n ? 10) and nontreated (n ? 11)], but not prenatal IL-1ra-treated
mice (n ? 9), displayed a significant ACTH hypersecretion.
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IL-1rKO and IL-1raTG mice may result from the lack of IL-1
signaling, either acutely or during brain development. To
assess the latter possibility, we tested the effect of IL-1 block-
ade during the last 2 wk of gestation, mimicking the effect of
excess IL-1ra during the same developmental period in IL-
1raTG mice. IL-1 influences brain development both directly
by inducing neuronal differentiation (e.g. Ref. 40), as well as
indirectly by the enhancement of trophic factors, e.g. NGF
andCNTF(41,42).SimilartotheresultsfoundinthetwoIL-1
signaling-deficient mice strains, IL-1ra prenatally treated
mice exhibited no ACTH hypersecretion after ADX. This
resultsuggeststhatduringfetaldevelopment,IL-1mayhave
a role in the maturition of brain systems that regulate the
HPA axis. It should be noted that this developmental effect
does not rule out the possibility that IL-1 is also involved in
activation of the HPA axis after various stimuli, as suggested
by previous studies using IL-1ra in adult animals (7, 15, 16).
Further research will be needed to fully understand the de-
velopmental and acute influences of IL-1, or their combina-
tion, on the HPA axis.
In conclusion, the results of the present study demonstrate
that, in addition to its role in mediating illness-associated
neuroendocrine response, IL-1 has an important role in the
activation of CS secretion after exposure to different modal-
ities of mild, but not severe, stress. Furthermore, our study
demonstrates a novel modulatory role for IL-1 in ADX-
induced ACTH hypersecretion. Thus, alterations in IL-1
levels during noninflammatory conditions play a role in
HPA axis activation and its regulation by GC-associated
feedback control mechanisms.
Acknowledgments
The authors would like to thank Anna Itzik for her excellent help in
running the experiments.
Received March 18, 2003. Accepted June 30, 2003.
Addressallcorrespondenceandrequestsforreprintsto:RazYirmiya,
Ph.D., Department of Psychology, The Hebrew University of Jerusalem,
Mount Scopus, Jerusalem 91905, Israel. E-mail: razyirmiya@huji.ac.il.
R.Y. is a member of the Eric Roland Center for Neurodegenerative
Diseases at the Hebrew University of Jerusalem.
References
1. Plotsky PM, Cunningham ET, Widmaier EP 1989 Catecholaminergic mod-
ulation of corticotropin-releasing factor and adrenocorticotropin secretion.
Endocr Rev 10:437–358
2. Antoni FA 1986 Hypothalamic control of adrenocorticotropin secretion: ad-
vances since the discovery of 41-residue corticotropin-releasing factor. Endocr
Rev 7:351–378
3. Keller-Wood ME, Dallman MF 1984 Corticosteroid inhibition of ACTH se-
cretion. Endocr Rev 5:1–24
4. Jacobson L, Sapolsky R 1991 The role of the hippocampus in feedback
regulation of the hypothalamic-pituitary-adrenocortical axis. Endocr Rev 12:
118–134
5. Dallman MF, Jones MT, Vernikos-Danellis J, Ganong WF 1972 Corticoste-
roid feedback control of ACTH secretion: rapid effects of bilateral adrenalec-
tomy on plasma ACTH in the rat. Endocrinology 91:961–968
6. Besedovsky HO, del-Rey A 1996 Immune-neuro-endocrine interactions: facts
and hypotheses. Endocr Rev 17:64–102
7. Turnbull AV, Rivier CL 1999 Regulation of the hypothalamic-pituitary-ad-
renal axis by cytokines: actions and mechanisms of action. Physiol Rev 79:1–71
8. Dinarello CA 1996 Biologic basis for interleukin-1 in disease. Blood 87:2095–
2147
9. Berkenbosch F, van Oers J, del Rey A, Tilders F, Besedovsky H 1987 Cor-
ticotropin-releasing factor-producing neurons in the rat activated by interleu-
kin-1. Science 238:524–526
10. Sapolsky R, Rivier C, Yamamoto G, Plotsky P, Vale W 1987 Interleukin-1
stimulatesthesecretionofhypothalamiccorticotropin-releasingfactor.Science
238:522–524
11. Bernton EW, Beach JE, Holaday JW, Smallridge RC, Fein HG 1987 Release
of multiple hormones by a direct action of interleukin-1 on pituitary cells.
Science 238:519–521
12. Weidenfeld J, Abramsky O, Ovadia H 1898 Effect of interleukin-1 on ACTH
and corticosterone secretion in dexamethasone and adrenalectomized pre-
treated male rats. Neuroendocrinology 50:650–654
13. Miller AH, Pariante CM, Pearce BD 1999 Effects of cytokines on glucocorti-
coidreceptorexpressionandfunction.Glucocorticoidresistanceandrelevance
to depression. Adv Exp Med Biol 461:107–116
14. Rothwell NJ, Luheshi GN 2000 Interleukin 1 in the brain: biology, pathology
and therapeutic target. Trends Neurosci 23:618–625
15. Ben-Hur T, Cialic R, Itzik A, Yirmiya R, Weidenfeld J 2001 Acute effects of
purified and UV-inactivated Herpes simplex virus type 1 on the hypothalamo-
pituitary-adrenocortical axis. Neuroendocrinology 74:160–166
16. Shintani F, Nakaki T, Kanba S, Sato K, Yagi G, Shiozawa M, Aiso S, Kato
R, Asai M 1995 Involvement of interleukin-1 in immobilization stress-induced
increase in plasma adrenocorticotropic hormone and in release of hypotha-
lamic monoamines in the rat. J Neurosci 15:1961–1970
17. Suzuki E, Shintani F, Kanba S, Asai M, Nakaki T 1997 Immobilization stress
increasesmRNAlevelsofinterleukin-1receptorantagonistinvariousratbrain
regions. Cell Mol Neurobiol 17:557–561
18. Nguyen KT, Deak T, Owens SM, Kohno T, Fleshner M, Watkins LR, Maier
SF1998Exposuretoacutestressinducesbraininterleukin-1bproteinintherat.
J Neurosci 18:2239–2246
19. Horai R, Asano M, Sudo K, Kanuka H, Suzuki M, Nishihara M, Takahashi
M, Iwakura Y 1998 Production of mice deficient in genes interleukin (IL)-1?,
IL-1?, IL-1?/?, and IL-1 receptor antagonist shows that IL-1? is crucial in
turpentine-induced fever development and glucocorticoid secretion. J Exp
Med 187:1463–1475
20. Lee SW, Tsou AP, Chan H, Thomas J, Petrie K, Eugui EM, Allison AC 1988
Glucocorticoids selectively inhibit the transcription of the Interleukin-1? gene
and decrease the stability of Interleukin 1? mRNA. Proc Natl Acad Sci USA
85:1204–1208
21. Nguyen KT, Deak T, Will MJ, Hansen MK, Hunsaker BN, Fleshner M,
Watkins LR, Maier SF 2000 Timecourse and corticosterone sensitivity of the
brain,pituitary,andseruminterleukin-1proteinresponsetoacutestress.Brain
Res 859:193–201
22. Ben-Hur T, Cialic R, Itzik A, Barak O, Yirmiya R, Weidenfeld J 2001 A
novel permissive role for glucocorticoids in induction of febrile and be-
havioral signs of experimental herpes simplex virus encephalitis. Neuro-
science 108:119–127
23. Labow M, Shuster D, Zetterstorm M, Nunes P, Terry R, Cullinan EB, Bartfei
T, Solorzano C, Moldawer LL, Chizzonite R, McIntyre KW 1997 Absence of
IL-1 signaling and reduced inflammatory response in IL-1 type I receptor
deficient mice. J Immunol 159:2452–2461
24. Lundkvist J, Sundgren-Andersson AK, Tingsborg S, Ostlund P, Engfors C,
Alheim K, Bartfai T, Iverfeldt K, Schultzberg M 1999 Acute-phase response
in transgenic mice with CNS overexpression of IL-1 receptor antagonist. Am J
Physiol 276:644–651
25. Weidenfeld J, Corcos AP, Wohlman A, Feldman S 1994 Characterization of
the 2-deoxyglucose effect on the adrenocortical axis. Endocrinology 134:1924–
1931
26. Weidenfeld J, Yirmiya R 1996 Effects of bacterial endotoxin on the glucocor-
ticoid feedback regulation of adrenocortical response to stress. Neuroimmu-
nomodulation 3:352–357
27. Takao T, Hashimoto K, De Souza EB 1995 Modulation of interleukin-1 re-
ceptors in the brain-endocrine-immune axis by stress and infection. Brain
Behav Immun 9:276–291
28. Pournajafi-Nazarloo HP, Takao T, Nanamiya W, Asaba K, De-Souza EB,
Hashimoto K 2001 Effect of non-peptide corticotropin-releasing factor recep-
tortype1antagonistonadrenocorticotropichormonereleaseandinterleukin-1
receptors followed by stress. Brain Res 902:119–126
29. Yirmiya R, Weidenfeld J, Barak O, Avitsur R, Pollak Y, Gallily R, Wohlman
A, Ovadia H, Ben-Hur T 1999 The role of brain cytokines in mediating the
behavioral and neuroendocrine effects of intracerebral mycoplasma fermen-
tans. Brain Res 829:28–38
30. Goujon E, Parnet P, Laye S, Combe C, Dantzer R 1996 Adrenalectomy
enhances pro-inflammatory cytokines gene expression, in the spleen, pi-
tuitary, and brain of mice in response to lipopolysaccharide. Mol Brain Res
36:53–62
31. Szafarczyk A, Guillaume V, Conte-Devolx B, Alonso G, Malaval F, Pares-
Herbute N, Oliver C, Assenmacher I 1988 Central catecholaminergic system
stimulates secretion of CRH at different sites. Am J Physiol 255:463–468
32. Fuller RW 1992 The involvement of serotonine in regulation of pituitary-
adrenocortical function. Front Neuroendocrinol 13:150–170
33. Feldman S, Conforti N, Weidenfeld J 1995 Limbic pathways and hypotha-
lamic neurotransmitters mediating adrenocortical response to neural stimuli.
Neurosci Biobehav Rev 19:235–240
34. Dunn AJ 1988 Systemic interleukin-1 administration stimulates hypothalamic
Goshen et al. • IL-1 and Pituitary-Adrenal Regulation Endocrinology, October 2003, 144(10):4453–4458
4457

Page 6

norepinephrine metabolism paralleling the increased plasma corticosterone.
Life Sci 43:429–435
35. Shintani F, Kanba S, Nakaki T, Nibuya M, Kinoshita N, Suzuki E, Yagi G,
Kato R, Asai M 1993 Interleukin-1? augments release of norepinephrine,
dopamine, and serotonin in the rat anterior hypothalamus. J Neurosci 13:
3574–3581
36. Linthorst AC, Flachskamm C, Muller-Preuss P, Holsboer F, Reul JM 1995
Effect of bacterial endotoxin and interleukin-1? on hippocampal serotonergic
neurotransmission, behavioral activity, and free corticosterone levels: an in
vivo microdialysis study. J Neurosci 15:2920–2934
37. Weidenfeld J, Abramsky O, Ovadia H 1989 Evidence for the involvement of
the central nervous adrenergic system in interleukin-1-induced adrenocortical
response. Neuropharmacology 28:1411–1414
38. Chuluyan HE, Saphier D, Rohn WM, Dunn AJ 1992 Noradrenergic inner-
vation of the hypothalamus participates in adrenocortical responses to Inter-
leukin-1. Neuroendocrinology 56:106–111
39. Weidenfeld J, Feldman S 1991 Effects of norepinephrine depletion on median
eminence CRF-41 content and serum ACTH in control and adrenalectomized
rats. Brain Res 542:201–204
40. Potter ED, Ling ZD, Carvey PM 1999 Cytokine-induced conversion of mes-
encephalic-derived progenitor cells into dopamine neurons. Cell Tissue Res
296:235–246
41. Gadient RA, Cron KC, Otten U 1990 Interleukin-1? and tumor necrosis
factor-? synergistically stimulate nerve growth factor (NGF) release from
cultured rat astrodytes. Neurosci Lett 117:335–340
42. Kamiguchi H, Yoshida K, Sasaki H, Inaba M, Wakamoto H, Otani M, Toya
S 1995 Release of ciliary neurotrophic factor from cultured astrocytes and its
modulation by cytokines. Neurochem Res 20:1187–1193
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