Interleukin-7, a New Cytokine Targeting the Mouse
Hypothalamic Arcuate Nucleus: Role in Body Weight and
Food Intake Regulation
Laurence Macia1,2.¤, Odile Viltart1,2,3., Myriam Delacre1,2, Christelle Sachot1,3, Laurent He ´liot1,4, James P.
Di Santo5,6, Isabelle Wolowczuk1,2*
1Univ Lille Nord de France, Lille, France, 2Laboratory of Neuroimmunoendocrinology and IFR 142, Institut Pasteur de Lille, BP 447, Lille, France, 3USTL, Inserm U837,
JPARC, Development and Plasticity of Postnatal Brain, Lille, France, 4USTL, Interdisciplinary Research Institute, CNRS USR 3078, Villeneuve d’Ascq, France, 5Cytokines and
Lymphoid Development Unit, Institut Pasteur, Paris, France, 6Inserm U668, Paris, France
Body weight is controlled through peripheral (white adipose tissue) and central (mainly hypothalamus) mechanisms. We
have recently obtained evidence that overexpression of interleukin (IL)-7, a critical cytokine involved in lymphopoiesis, can
protect against the development of diet-induced obesity in mice. Here we assessed whether IL-7 mediated its effects by
modulating hypothalamic function. Acute subcutaneous injection of IL-7 prevented monosodium glutamate-induced
obesity, this being correlated with partial protection against cell death in the hypothalamic arcuate nucleus (ARC).
Moreover, we showed that IL-7 activated hypothalamic areas involved in regulation of feeding behavior, as indicated by
induction of the activation marker c-Fos in neural cells located in the ventromedial part of the ARC and by inhibition of food
intake after fasting. Both chains of the IL-7 receptor (IL-7Ra and cc) were expressed in the ARC and IL-7 injection induced
STAT-3 phosphorylation in this area. Finally, we established that IL-7 modulated the expression of neuropeptides that tune
food intake, with a stimulatory effect on the expression of pro-opiomelanocortin and an inhibitory effect on agouti-related
peptide expression in accordance with IL-7 promoting anorectic effects. These results suggest that the immunomodulatory
cytokine IL-7 plays an important and unappreciated role in hypothalamic body weight regulation.
Citation: Macia L, Viltart O, Delacre M, Sachot C, He ´liot L, et al. (2010) Interleukin-7, a New Cytokine Targeting the Mouse Hypothalamic Arcuate Nucleus: Role in
Body Weight and Food Intake Regulation. PLoS ONE 5(4): e9953. doi:10.1371/journal.pone.0009953
Editor: Carlo Polidori, University of Camerino, Italy
Received January 20, 2010; Accepted March 11, 2010; Published April 1, 2010
Copyright: ? 2010 Macia et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was in part supported by the Centre National de la Recherche Scientifique (CNRS), the Pasteur Institute in Lille, and the French Ministry for
Research and Education (to L.M.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: Isabelle.Wolowczuk@ibl.fr
. These authors contributed equally to this work.
¤ Current address: Neurobiology Research Program, Garvan Institute of Medical Research, Darlinghurst, Australia
Body weight is tightly regulated by complex and intertwined
processes involving peripheral tissues, such as the white adipose
tissue, as well as the central nervous system, especially the
hypothalamus. Alterations of this subtle equilibrium may lead to
obesity or lipodystrophy commonly associated with life threatening
diseases, like diabetes, insulin-resistance, cardiovascular disorders
and some cancers .
The hypothalamic arcuate nucleus (ARC) is the master central
coordinator of energy homeostasis that adjusts feeding behavior in
response to peripheral signals [2,3]. The ARC contains two major
neurons. Anabolic neurons co-express the orexigenic neuropeptides
agouti-related protein (AgRP) and neuropeptide-Y (NP-Y) ,
upregulation of which promotes weight gain. Catabolic neurons
express the anorexigenic neuropeptides cocaine-amphetamine related
transcript (CART)  or pro-opiomelanocortin (POMC) , and are
involved in hypophagia and weight loss. The level of expression of
these different neuropeptides is finely regulated notably by hormones
such as leptin and insulin, both considered as satiety factors .
Interestingly, the immune system also actively modulates
feeding behavior through a direct hypothalamic effect of the
cytokines. Indeed, pro-inflammatory cytokines have been reported
to act on the ARC not only during the early phase of the immune
response but also under physiological conditions. Thus, interleu-
kin-1b (IL-1b), IL-6 and tumor necrosis factor-a (TNF-a), released
by innate immune cells during bacterial infections, modulate
feeding behavior . On the other hand, IL-1 receptor antagonist-
deficient mice (IL-1Ra2/2mice) are resistant to monosodium
glutamate (MSG)-induced obesity  while IL-6-deficient mice
develop a late onset-obesity . Finally, while IL-18 deficiency
leads to obesity, the peripheral injection of IL-18 suppresses
We recently identified IL-7 as a novel cytokine regulating
whole-body metabolism, functioning in a fat-to-brain axis
(Wolowczuk et al., submitted). IL-7 plays a key role in lymphoid
homeostasis [13–15]. This cytokine is pleiotropic, mostly expressed
by bone marrow and thymus stromal cells [16,17] but also by non-
lymphoid cells and tissues such as dermal endothelial cells in skin
 and abdominal adipose tissue . While IL-7 is mostly
known for its potent immune function, we recently identified that
PLoS ONE | www.plosone.org1 April 2010 | Volume 5 | Issue 4 | e9953
mice over-expressing IL-7 were protected from diet-induced
obesity associated with decreased food intake (Wolowczuk et al.,
submitted). Remarkably, we further demonstrated that an
administration of acute recombinant IL-7 was sufficient to protect
mice from gold thioglucose-induced obesity, adipocyte lipid-
engulfment and insulin resistance commonly associated with this
type of hypothalamic hyperphagic obesity (Wolowczuk et al.,
Here we investigate the effects of IL-7 on the hypothalamic
areas that participate in the regulation of body weight
metabolism. Our results highlight the physiological effects of
IL-7 on energy homeostasis and provide evidence for a central
role of IL-7 on food intake regulation through a direct effect on
IL-7 protects against monosodium glutamate-induced
To assess the consequences of IL-7 administration on the
development of hypothalamic obesity, we used the well-defined
model of administration of monosodium glutamate (MSG), a
neurotoxic drug inducing lesions in the hypothalamic arcuate
nucleus (ARC) . As expected, MSG-treated mice (M-P group)
developed a significant weight gain from 4 month-old (28%
increase) compared to mice treated solely either with PBS (P-P
group) or IL-7 (P-7 group) (p,0.01; Figure 1A). Strikingly, mice
that were injected with both MSG and IL-7 (M-7 group) did not
show any weight gain (from 1 to 6 months), and displayed a body
Figure 1. IL-7 protects from MSG-induced body weight gain, increased fat mass, glucose- and insulin-resistance, and arcuate
nucleus lesioning. (A) Body weight evolution: Mice were injected with PBS (P) from post-natal day 5 (P5) to P12 (group P-P, n=4;D), with
monosodium glutamate (MSG) from P5 to P11 then PBS at P12 (group M-P, n=4;#), with PBS from P5 to P11 then IL-7 at P12 (group P-7, n=6;m) or
with MSG from P5 to P11 then IL-7 at P12 (group M-7, n=6;N). Body weights were measured monthly during 6 months. Results are expressed as
mean 6 SEM. * p,0.05. (B) Visualization of the fat mass of one representative mice per group using Dual Energy-X-ray Absorptiometry. (C) Glucose
tolerance test: At the age of 5 months, P-P (D), P-7 (m), M-P (#) and M-7 (N) mice were fasted 18 h before i.p. glucose injection. Glycaemia was
measured for each individual animal, from t=0 to t=330 min after glucose administration. Results are presented as mean 6 SEM. Statistical analysis
was performed with a 2-way ANOVA. (D) Insulin tolerance test: At the age of 5 months, P-P (D), P-7 (m), M-P (#) and M-7 (N) mice were fasted 4 h
before i.p. insulin injection. Glycaemia was measured from t=0 to t=105 min after insulin injection. Results are presented as mean 6 SEM. Statistical
analysis was performed with a 2-way ANOVA. * p,0.05. (E) Representative microphotographs of frontal hypothalamic sections stained with cresyl
violet staining. Brains were harvested from 2-month-old P-P (upper left), P-7 (down left), M-P (upper right) and M-7 (down right) animals. Arrows show
the partial cell survival in the M-7-treated group in comparison with the M-P group. Scale bar represents 100 mm. ARC: arcuate nucleus, ME: median
eminence, 3rdV: third ventricle, VMH: ventromedial hypothalamic nucleus.
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org2 April 2010 | Volume 5 | Issue 4 | e9953
weight curve similar to that of PBS- or IL-7-treated animals (P-P
and P-7 groups, respectively; Figure 1A). Determination of body
composition using Dual-Energy X-ray Absorptiometry (Figure 1B)
showed that M-P mice had a significant increase of their fat mass
(43.5%) compared to PBS- or IL-7-treated animals (16% and
19.3%, respectively). Additionally, IL-7 administration to MSG-
treated mice decreased the fat mass back to basal levels (M-7
group, 20.5%), therefore suggesting that the difference of body
weight between M-P and M-7 groups (Figure 1A) was likely due to
a decrease in fat mass in IL-7-MSG co-treated animals.
Since obesity is often associated with alteration of glucose
metabolism, we evaluated in vivo glucose tolerance and sensitivity
to insulin of mice from the four experimental groups. While
glycemia was similar after overnight fasting (respectively for P-P,
P-7, M-P and M-7 groups: 82.360.5, 79.664, 98.5617.8 and
71.2610.2 mg/dl), the MSG-treated mice demonstrated an
abnormal glucose tolerance test (Figure 1C). Indeed, as early as
fifteen minutes after glucose injection, the M-P and M-7 groups
showed significant hyperglycaemia compared to P-P mice (M-P vs
P-P, p,0.001; M-7 vs P-P, p,0.003) and P-7 mice (M-P vs P-7,
p,0.001; M-7 vs P-7, p,0.001). Thereafter, and for all the time-
points assessed, M-P mice had the highest glycaemia (p,0.05),
whereas mice from the P-P group had the lowest glucose levels (P-
P vs P-7, p,0.05). Interestingly, the M-7 group displayed glucose
values between the highest (M-P) and the lowest (P-P) groups, with
a slightly delayed return to euglycaemia compared to the M-P
group (M-7 vs M-P, p,0.05; and M-7 vs M-P, p,0.05).
Interestingly, despite the beneficial effects of IL-7 on the MSG
treatment, IL-7 alone was responsible for a slowly developing
(from 60 minutes after glucose administration) state of a mild, yet
significant, glucose intolerance (P-7 vs P-P, p,0.05). On the other
hand, during an insulin tolerance test, the two MSG-treated
groups had a significantly reduced response to the hypoglycaemic
effects of insulin, when compared with P-P and P-7 groups
(p,0.05) (Figure 1D), indicating a state of insulin resistance.
Interestingly, IL-7 administration to MSG-treated mice (M-7)
alleviated the state of insulin-resistance associated with MSG-
treatment (M-P) (with p,0.001 at t=15, 30, 45 and 60 minutes),
despite being ineffective in restoring the basal reactivity to insulin
(with p,0.05 at t=60 between M-7 and P-P).
Since MSG promotes obesity development via a neurotoxic
effect on the ARC , we evaluated if the beneficial effects of IL-
7 on MSG treatment were associated with changes in this
hypothalamic nucleus (Figure 1E). While MSG treatment induced
a specific lesion of the ARC (M-P group), visualized by a drastic
loss of cells in this area, the M-7 mice were partially protected
from MSG-induced lesions, particularly in the mediobasal region
of the ARC, where NPY-expressing neurons are located , at
eight week-old (Figure 1E) and also at six month-old (data not
shown). As expected, P-P and P-7 mice had an intact ARC
structure. Altogether, IL-7 protected from obesity and metabolic
alterations induced by MSG associated with a neuroprotective
effect in the ARC.
IL-7 prolongs the survival of arcuate nucleus cells in adult
The neuroprotection observed in mice co-treated with MSG
and IL-7 suggests that IL-7 promoted either ARC neurons
proliferation and/or survival. To understand the mechanisms
involved, we compared in vivo the effects of IL-7 or PBS treatment
on the incorporation of bromodeoxyuridine (BrdU) in mouse
hypothalamic cells. The quantification of BrdU positive cells was
performed either the day after the end of the BrdU treatment to
count the number of newly generated cells in the ARC, or 29 days
after the end of the treatment to measure hypothalamic cell-
survival rate (Figure 2A). We first observed that IL-7 had no
marked effect on the proliferation of cells in the ARC, since the
number of BrdU positive cells throughout this area was similar in
PBS- and IL-7-treated mice eight days after BrdU injections
(Figure 2B). Nevertheless, when analyzing the long-lasting effects
of IL-7 injection on cell-survival (i.e. 36 days after the first BrdU
injections), we observed a reduction of BrdU positive cells in both
groups when compared with 8 days post-injection, which is
consistent with physiological cell-death. However, we counted
more BrdU positive cells in the IL-7-treated mice compared to the
control group (p,0.05) at this later time point (Figure 2B). These
results showed that while IL-7 injection did not affect the ARC
cell-proliferation it significantly improved ARC cell-survival.
IL-7 directly activates arcuate nucleus cells in adult mice
These results suggest that the hypothalamus is a central target of
IL-7. To identify which hypothalamic areas were targeted, we
analyzed c-Fos expression, a marker of early cellular activation, in
the ARC of mice injected either with IL-7 or PBS. We found that
IL-7 administration led to a significant increase in the number of
c-Fos-immunoreactive (Fos-IR) cells in the ARC (11.262.4 Fos-IR
cells in PBS-treated mice and 20.262.7 Fos-IR cells in IL-7-
treated mice, p,0.001). Interestingly, the distribution of Fos-IR
cells was confined to the ventromedial part of the ARC (Figure 3A),
coincident with the specific areas protected by IL-7 from MSG-
induced lesion (Figure 1E).
To determine if the activation of ARC neurons by peripheral
IL-7 injection was mediated via a direct effect, we studied the
expression of IL-7 receptor, composed of two chains: IL-7Ra and
cc [22-24], both at the transcriptional and translational levels.
Both IL-7Ra and ccchains mRNAs were expressed in isolated
hypothalamus from wild-type mouse brain (Figure 3B) and were
localized in theARC asvisualized
(Figure 3C). While ccwas broadly distributed in the ARC, the
expression of IL-7Ra was restricted to the ventromedial part of the
ARC and the median eminence.
In the immune cells, IL-7R signaling results in robust
STAT5A/B phosphorylation and, to a lesser extent, in STAT3
phosphorylation [25,26]. To further investigate the mechanism of
IL-7-driven activation of arcuate nucleus cells, we analyzed the
expression of phosphorylated (p)-STAT5 and p-STAT3 in the
arcuate nucleus of IL-7-injected wild-type mice. While IL-7
treatment did not modify STAT5 phosphorylation (81.865.7 p-
STAT5-IR cells in PBS-treated mice and 90.665.9 p-STAT5-IR
cells in IL-7-treated mice), it significantly stimulated STAT3
phosphorylation (44.464.3 p-STAT3-IR cells in PBS-treated mice
and 54.963.2 in IL-7-treated mice, p,0.05) (Figure 3D).
We found a homogeneous distribution of phosphorylated
STAT5 in the ARC of both groups, but the IL-7-treated animals
exhibited more immunoreactive cells in the ventromedial ARC,
where NP-Y/AgRP neurons are located (Figure 3E). More
caudally, p-STAT5-IR cells were detected in the third ventricle
and were located in the dorsal part of the ARC in both groups
(data not shown). On the other hand, we detected STAT3-IR cells
specifically in the ventromedial ARC, all along the ARC, with an
overall significant higher number in the IL-7-treated mice.
Interestingly, we found a stronger labelling of p-STAT5 positive
fibers on the external part of the median eminence compare to p-
STAT3 (Figure 3E), area where we described the expression of IL-
7Ra (Figure 3C). These results show that both IL-7R chains were
present in the ARC and that IL-7 treatment activated the
ARC nucleus cells, correlated with the induction of STAT3
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org3April 2010 | Volume 5 | Issue 4 | e9953
IL-7 modulates the expression of hypothalamic
neuropeptides in adult mice
Subpopulations of neurons located in the ventromedial part of
the ARC express key neuropeptides controlling feeding behavior.
To determine if IL-7 modulated these neuropeptides expressions
and thus potentially food intake, we quantified the expression of
POMC and CART (anorexigenic peptides) and of NP-Y and
AgRP (orexigenic peptides) in the hypothalamus of IL-7- or PBS-
treated mice either fed ad libitum or re-fed after an overnight
fasting. Under fed conditions, while IL-7 treatment had no effect
on AgRP, CART and NP-Y mRNA expression, it induced a
significant increase (87%, p,0.05) in POMC mRNA expression
(Figure 4A). Moreover, after four hours of re-feeding after fasting
conditions, while POMC, CART and NPY had comparable level
of expressions between IL-7 and PBS-treated mice, the expression
of AgRP was significantly inhibited after IL-7 treatment (66%,
p,0.05) (Figure 4B). These results show a regulatory effect of IL-7
on ARC neuropeptides by stimulating POMC under fed
conditions and inhibiting AgRP under fasted re-fed conditions.
IL-7 inhibits food intake in re-feeding conditions in adult
To investigate if the changes induced by IL-7 on the ARC
neuropeptide expression modulated feeding behavior, we mea-
sured the effects of IL-7 treatment on basal food intake and on re-
feeding after fasting. While food consumption was similar between
IL-7 and PBS-treated mice under fed conditions (Figure 5A), we
observed that after an overnight-fast, IL-7 treatment significantly
reduced the food intake of mice for the first four hours post re-
feeding (Figure 5B). Moreover, the inhibitory effect of IL-7 on food
intake lasted for 24 hours before return to basal food intake (data
not shown). Importantly, to test whether the observed reducing
effects of IL-7 on food intake might rely on visceral illness, we
performed a taste aversion assay comparing the effects of IL-7 on
sucrose consumption to lithium chloride (LiCl) effects, as
previously described . We found that after an overnight
deprivation of water and one hour of habituation to a solution of
sucrose, mice treated with IL-7, PBS or saline consumed similar
amounts of sucrose 24 hours post injection (Figure 5C). On the
other hand, in the same experimental procedure, LiCl-treated
mice developed a taste aversion with a significant reduction of
sucrose consumption (Figure 5C). These results suggest that IL-7-
mediated inhibition of food intake is not secondary to taste
In this report, we provide evidence that IL-7 targets
hypothalamic brain areas to regulate body weight and feeding
behavior. IL-7 not only protected from obesity development but
also reduced food intake by directly targeting the hypothalamus,
and more precisely the ARC. This work and our recent
description of a new role of IL-7 in the regulation of energy
homeostasis (Wolowczuk et al. submitted) identify the novel role for
this cytokine in body weight and metabolic regulation.
Interestingly, while as previously described, MSG treatment was
associated to significant neural cell-loss in the ARC leading to the
obesity development, a single injection of IL-7 completely
protected the mice from gaining weight. Moreover, IL-7 treatment
Figure 2. IL-7 improves neural cell-survival. (A) Bromodeoxyuridine (BrdU) treatment experimental procedure. (B) BrdU positive cells in the ARC
of PBS- (%) or IL-7- (&) treated mice. Animals were sacrificed one day after BrdU treatment (post-natal day 8 (P8)) for neural cell proliferation analysis
(n=5 per group), or 29 days after BrdU treatment (P36) for neural cell survival analysis (n=5 per group). Data were represented as mean 6 SEM of
BrdU-positive cells within the ARC per animal and per slice. *p,0.05.
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org4 April 2010 | Volume 5 | Issue 4 | e9953
also greatly improved obesity-associated disorders with a complete
restoration of insulin sensitivity, and a partial improvement of the
glucose tolerance in adulthood. These metabolic changes were
associated with a partial protection of the mediobasal part of the
ARC, where are located NP-Y and somatostatin neurons ,
underlying a potential central role of IL-7. This protection was
correlated with the pro-survival effects of IL-7 on neural cells since
we showed that a single injection of IL-7 was sufficient to increase
neural cell-survival without affecting their proliferation rate. In
accordance with its pro-survival effects on lymphocytes , IL-7
might exert its neural protective role through the up-regulation of
the anti-apoptotic factor bcl-2, and thus counteract or compensate
for bcl-2 down-regulation in MSG-induced apoptosis .
However, despite this central effect, a peripheral role of IL-7 in
the protection against MSG-induced obesity and metabolic
alterations could not be excluded. Indeed, a protective effect by
targeting the white adipose tissue was previously described with
the pro-inflammatory cytokine IL-1  and our previous report
showed the critical role of IL-7 on white adipose tissue
(Wolowczuk et al., submitted).
Here we demonstrate that IL-7 has a central hypothalamic
effect. Indeed, as mentioned earlier, a single injection of IL-7 was
sufficient to trigger neuronal activation in the adult mice ARC, but
we also showed that IL-7 induced the expression of the early
activation marker c-Fos in the ventromedial area of the ARC. As
c-Fos activation might involve multisynaptic neuronal relay ,
its expression can be due to a direct but also by an indirect effect of
IL-7. However, the direct effect was strengthened by our
demonstration of the presence of both chains of the IL-7 receptor
in this area, respectively the IL-7Ra and the ccchains, distributed
in the ventromedial part of the ARC and in the median eminence.
IL-7 signaling during B and T lymphopoiesis involves primarily
Figure 3. IL-7 activates hypothalamic cells and IL-7 receptor is expressed on hypothalamic cells. (A) Representative microphotographs
of Fos expression induced by peripheral IL-7 injection in C57BL/6 mice. Fos-immunoreactive cells in arcuate nucleus (ARC) in PBS-treated and IL-7-
treated mice. Arrows indicate Fos-imunoreactive cells. 3rdV: third ventricule; VMH: ventromedial hypothalamic nucleus. Scale bars represent 100 mm.
(B) mRNA expression of IL-7Ra and ccchains in the whole hypothalamus of 2-month-old C57BL/6 mice (n=3). Lanes (1, 2, 3) represent one animal.
The - lane represents the negative control i.e. without retro-transcription. (C) Representative microphotographs of frontal hypothalamic frozen
sections from 2-month-old mice showing fluorescent immunostaining of IL-7Ra and ccchains in the arcuate nucleus. Frozen section from IL-7Ra KO
were used as control for the IL-7Ra specific staining. ARC: arcuate nucleus, ME: median eminence, 3rdV: third ventricule; VMH: ventromedial
hypothalamic nucleus. (D) Mean number of phosphorylated (p)-STAT5 and p-STAT3 immunoreactive (IR) cells in the hypothalamic arcuate nucleus of
C57BL/6 mice injected with recombinant IL-7 (&; n=5) or with PBS (%; n=5). Results are expressed as mean of immunoreactive cells 6SEM per
animal and per slice. *p,0.05. (E) Representative microphotographs of p-STAT5 and p-STAT3-IR cells in the ARC in PBS-treated and IL-7-treated mice.
Scale bar represent 100 mm. ARC: arcuate hypothalamic nucleus; ME: median eminence; 3rd: third ventricle.
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org5 April 2010 | Volume 5 | Issue 4 | e9953
STAT5 phosphorylation [25,30,31], although a specific role for
STAT3 phosphorylation has been reported in mediating early B-
cell progenitor survival . Based on the knowledge that IL-7R
(our results) and STAT5  are present in hypothalamic
neurons, we asked whether STAT5A/B and/or STAT3 contrib-
uted to IL-7-mediated regulation of hypothalamic arcuate nucleus
cells. Interestingly, we showed that while IL-7 administration did
not modify STAT5 activation when compared with PBS-treated
animals, it significantly increased the number of p-STAT3-IR
cells. Although IL-7R signaling is known to induce STAT1,
STAT3 and STAT5 phosphorylation [25,26], our results suggest
that STAT3 plays the dominant role in IL-7-mediated arcuate
nucleus neuronal activation and/or survival. This result is similar
to the reported effects of leptin in hypothalamic neurons in which
it induced STAT3 phosphorylation through leptin receptor prior
to c-Fos induced expression . Strikingly, IL-7-treatment
induced the expression of c-Fos in the ventromedial part of the
ARC, close to the third ventricle, precisely where IL-7 induced p-
STAT3 activated cells were located. The p-STAT5 staining was
more homogeneously distributed in this area, with a highest
number of p-STAT5-IR cells located caudally in the dorsal ARC.
Altogether, this further supported our demonstration of a
preferential activation of STAT3 in IL-7-responsive hypothalamic
cells. Moreover, few p-STAT5-IR cells were also detected in
paraventricular hypothalamus, periventricular nuclei and lateral
hypothalamus, areas where anorexigenic and orexigenic neurons
were found (data not shown).
Since the ARC modulates body weight and feeding behavior
through the differential expression of anorexigenic and orexigenic
neuropeptides, we further investigated the central effect of IL-7 on
these key hypothalamic neuropeptides in adult mice. In condition
of ad libitum feeding with a normal chow diet, we found that a
single administration of IL-7 in mice drastically increased the
expression of hypothalamic POMC, a major anorexigenic
neuropeptide  without affecting food intake. However, we
show that under re-feeding conditions after fasting, IL-7 treatment
significantly decreased mice food intake showing the potent
anorectic effect of this cytokine. Like IL-7, the mammalian target
of rapamycin (mTOR) is an anti-apoptotic factor promoting cell-
growth [36,37] and regulates food intake . Thus, as previously
reported in lymphocytes, IL-7 might mediate its central effect on
neuronal cell-survival and on feeding behavior via mTOR.
Figure 4. IL-7 modulates hypothalamic neuropeptide mRNA gene expression. PBS (=5, %) or IL-7 (n=5, &) was i.p. injected in 2-month-
old C57BL/6 mice. The expression of hypothalamic neuropeptides was assessed by real-time PCR, in fed (A) or in re-fed (B) condition. The effects of IL-
7 treatment were evaluated by calculating the relative expression levels as follows: 2DCt(DCt=mean Ct genes of interest - mean Ct GAPDH), using the
raw cycle-threshold (Ct) values. *p,0.05, *** p,0.001. POMC: pro-opiomelanocortin, CART: cocaine-amphetamine related peptide, NP-Y:
neuropeptide-Y, AgRP: Agouti-related peptide.
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org6 April 2010 | Volume 5 | Issue 4 | e9953
Interestingly, this inhibitory effect of IL-7 on food intake was
correlated with a specific inhibition of AgRP as described in a
transactivation-deficient FoxO1 (Forkhead box containing protein,
O subfamily1) mutant mice , with no change of expression of
the other key neuropeptides studied. Importantly, contrary to
other cytokines described to induce anorexia secondary to nausea
, we demonstrate that this modulation of feeding is mediated by
IL-7 per se and not by sickness.
In conclusion, we show here for the first time the potent central
role of IL-7 on energy regulation by directly signaling in the ARC,
key hypothalamic area controlling feeding behavior and metabolism.
Our initial work, in which we used a model of IL-7 overexpressing
mice , revealed a novel aspect of IL-7 biology, namely its role in
the regulation of whole-body metabolism (Wolowczuk et al.,
submitted). Indeed, beside defective white adipose tissue formation
and functionality in IL-7 transgenic animals, we also observed
evidence of IL-7’s central action. The present work furthered these
initial observations, notably regarding the effects of IL-7 on the
key regulator of food intake under specific conditions like re-feeding
after fasting (present paper), feeding with sucrose-enriched regimen
(Viltart et al., manuscript in preparation) or feeding with a high-fat
diet (Wolowczuk et al., submitted). We thus propose IL-7 as a new
essential factor participating in the complex integration of peripheral
hormonal-immune signals in the central nervous system to control
Our work thereby opens a wide avenue for identifying novel
targets to improve the existing treatment and/or to develop new
treatments for obesity and/or appetite disorders.
Materials and Methods
Adult female and male mice C57BL/6J@Rj (8–12 week-old;
Janvier Laboratory, Le Genest-St-Isle, France) were used. For the
monosodium glutamate experiments, newborn mice from our
breeding colonies were utilized. Mice were housed in a pathogen-
free area in our animal facilities and maintained in a temperature-
(2062uC) and humidity- (60%) controlled room on a daily cycle of
12 h light and darkness. Animals had ad libitum access to water and
food (standard chow diet, U.A.R., Epinay s/Orge, France) unless
Experiments were done according to the institutional ethical
guidelines for laboratory animal care (European Communities
Figure 5. IL-7 regulates food intake after fasting. (A) Food intake during basal conditions in IL-7- (&) or PBS- (%) treated C57BL/6 mice (n=7
per group). Results are expressed as the mean 6 SEM of cumulative food intake in g/g of body weight. (B) Animals were overnight-fasted, treated
with IL-7 (&) or PBS (%) before getting free access to food (n=5 per group). Food intake was measured during the 5 h following re-access to food
and was expressed as mean 6 SEM of cumulative food intake in g/g of body weight. *p,0.05. (C) Prior to the taste aversion assay, water was
removed from animal cages overnight. Taste solution of 5% sucrose was offered for 30 min and mice were either s.c. injected with 0.3 mg of IL-7
(n=5,N) or PBS as control (n=4,#), or i.p. injected with 6 mEq of LiCl (n=5,&) or NaCl as control (n=4,%). After injection, animals got free access to
water containing 0.5% of sucrose. Sucrose cumulative consumption was individually measured 1 h, 3 h, 6 h and 24 h after injection. Results are
expressed as mean of sucrose consumption in ml/body weight in g 6 SEM. *p,0.05.
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org7 April 2010 | Volume 5 | Issue 4 | e9953
Council Directive of 1986, 86/609/EEC) and approved by the
Departmental Direction of Veterinary Services (Prefecture of Lille,
France; authorization number: 59–350152).
Monosodium glutamate and IL-7 treatments
Neurotoxic lesion of hypothalamic arcuate nucleus was
performed by subcutaneous (s.c.) injection of monosodium
glutamate (MSG; 2 mg/g body weight/day; Sigma, L’Isle
d’Abeau Chesnes, France) in neonate mice. The following
experimental groups were designed: The M-P group concerned
mice (n=4) s.c. injected with MSG from postnatal days 5 to 11 (P5
to P11), then with PBS at P12. The M-7 group (n=6) received
MSG from P5 to P11, then were s.c. injected with murine
recombinant IL-7 (0.3 mg/mouse; Peprotech, London, UK) at
P12. The P-P group (n=4) was s.c. treated by PBS from P5 to
P12. The P-7 group (n=6) received PBS from P5 to P11, before
receiving IL-7 (0.3 mg/mouse) on P12. Body weights were
individually recorded weekly during six months. Glucose and
insulin tolerance testing were done 5 months post-MSG treatment
with a two-week interval between either testing. Glucose (i.p.
injection, 2 g/kg body weight, D-glucose; Sigma) tolerance test
was performed in overnight-fasted mice. Blood samples were
obtained from the tail vein at 0, 15, 30, 60, 120, 180 and 330
minutes. Insulin (i.p. injection, 0.75 mU/g body weight, human
insulin; Novo Nordisk Pharmaceutique S.A., Boulogne-Billan-
court, France) tolerance test was performed on 4 h-fasted mice.
Blood was collected from the tail vein before injection (time 0) and
15, 30, 45, 60, 75 and 105 minutes after insulin administration.-
Glucose levels were measured using glucose strips and an
automatic glucometer (GlucotrendH, Roche Diagnostics, Meylan,
At the end of the experiment, one representative mouse of each
group was sacrificed by cervical dislocation and percentage of fat
mass was determined by Dual-Energy X-ray Absorptiometry
(DXA) (PIXIMUSTM, LUNAR, Lambesc, France). The experi-
ment was performed twice from independent breeding.
Histological analysis of the hypothalamus
Mice were deeply anesthetized with 5% pentobarbital (Ceva
Sante ´ Animale, Libourne, France) and perfused transcardially with
0.9% NaCl followed by a solution of PBS containing 4%
paraformaldehyde (PFA). Brains were dissected and post-fixed in
PFA 4% at 4uC for two days. Then, brains were cryo-protected by
immersion in a 20% sucrose solution, frozen in dry ice and stored
at 280uC before being further sectioned with a cryostat (Leica
microsystem, Nussloch, Germany). Hypothalamus frozen sections
of 12-mm thickness were serially collected onto gelatin-alum-
chrome-coated slides. Hypothalamus was delimited from Bregma
21.22 mm to 22.70 mm . To visualize the lesions induced by
MSG in the adult hypothalamus, cresyl violet staining was
performed. Slices were then dehydrated in graded alcohols,
cleared in xylene and coverslipped with Eukitt (Poly Labo,
In vivo Bromodeoxyuridin (BrdU) incorporation assay
In another set of experiments, 8-week-old mice (n=10 per
group) were s.c. injected with IL-7 (0.3 mg per mouse; Peprotech)
or with PBS, at day 0. From day 1 to day 7, mice received i.p.
injections of BrdU (25 mg/g body weight, Sigma, Steinheim,
Germany), diluted in 0.9% NaCl, twice a day every 8 hours. At
day 8, half of the mice were sacrificed, by transcardial perfusion as
described above (for the proliferation study) and the remaining
half were sacrificed at day 36 (for the survival study). After 4%
PFA post-fixation, brains were cut with a vibratome (Leica
microsystem) in serial free-floating coronal sections of 35-mm
thickness. Slices were collected in 0.1% azide phosphate buffer
before being stored at 4uC. One section on two was kept onto the
To reveal BrdU in vivo incorporation, the free-floating
hypothalamic slices were first incubated in HCl 2N at 37uC for
30 min and then transferred in 0.1M borate buffer (pH 8.5) for
10 min, at room temperature. Slices were incubated for 24 hours
with a rat monoclonal IgG anti-BrdU (1800; Abcys, Paris, France)
and then, the secondary biotinylated polyclonal goat anti-rat
(Fab’)2antiserum (1:500; Jackson ImmunoResearch, West Grove,
PA, USA) was applied for 2 h in PBS containing 0.1% TritonHX-
100. Sections were further revealed using the 3-39 di-aminobenzi-
dine (DAB) glucose oxidase protocol  and mounted on
gelatine-alum-chrome-coated slides, dehydrated, cleared in xylene
and coverslipped with Eukitt. Finally, BrdU positive cells were
counted bilaterally throughout the hypothalamic arcuate nucleus
on a photonic microscope (Axioskop50, Zeiss, Oberkochen,
Immunohistochemical detection of c-Fos protein,
p-STAT3 and p-STAT5 in the hypothalamus
Eight week-old mice were s.c. injected with IL-7 (0.3 mg per
mouse; Peprotech) or with PBS (n=6 in each group). Two hours
after injection, animals were anesthetized with 5% pentobarbital
sodium and were sacrificed. The hypothalamus were removed and
free-floating sections were prepared as described above. Coronal
35-mm thick hypothalamic sections were incubated 48 h with an
anti-c-Fos rabbit polyclonal IgG (sc-52, 1:10,000; Santa Cruz
Biotechnology, Santa Cruz, MA, USA), as primary antibody,
before a further 2 h-incubation with biotinylated polyclonal
donkey anti-rabbit (Fab’)2 (1:500 Jackson Immunoresearch,
Immunotech, Marseille, France), used as secondary antibody.
Finally, the immunolabelling was revealed using the DAB glucose
oxidase protocol . The Fos-immunoreactive cells were
bilaterally counted in the arcuate nucleus and in the suprachias-
matic area as control, using a photonic microcoscope (Zeiss,
In another set of experiments, 8-week-old mice were s.c.
injected with IL-7 (0.3 mg per mouse; Peprotech) or with PBS
(n=5 in each group). Forty minutes after injection, animals were
anesthetized with 5% pentobarbital sodium and then rapidly
perfused transcardially as described above. Brains were removed,
post-fixed for 2 h in the same fixative at 4uC, then sunk in a
solution of 0.02M K+in PBS (KPBS) with 20% sucrose at 4uC
before to be frozen in 2 methylbutane cooled to 250uC with dry
ice. Coronal 35-mm thick hypothalamic sections were performed
using a cryostat. Immunochemistry was carried out by slight
modifications of the method described by Hosoi et al. . Unless
noticed, all the following steps were done at room temperature.
Several rinses with 0.02M KPBS were performed between each
step. Firstly, slices were pre-treated for 20 min in a solution of 5%
NaOH and 0.5% H2O2in 0.02M KPBS before being incubated
for 10 min in a solution of 0.3% glycine in 0.02M KPBS. The
sections were secondly placed in 0.03% SDS for 10 min before a
20 min incubation in a solution of 0.02M KPBS containing 4%
normal goat serum (Sigma), 0.4% TritonHX-100 and 1% BSA.
Finally, the sections were incubated for 48 h at 4uC with rabbit
monoclonal antibody anti-phosphorylated STAT5 (Tyr694, Cell
Signaling Technology #9359, Danvers, MA, USA) or rabbit
monoclonal antibody anti-phosphorylated STAT3 (Tyr705, Cell
Signaling Technology #9131) respectively diluted at 1:200 and
1:1000 in 1% normal goat serum, 0.4% TritonHX-100 and 1%
BSA. The immunolabeling was revealed using a goat anti-rabbit
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org8April 2010 | Volume 5 | Issue 4 | e9953
Alexa568-conjugated secondary antibody (1:200; Jackson Immu-
noresearch, Immunotech) in 1% normal goat serum and 0.3%
TritonHX-100 for 2 h. Sections were counterstained with Hoescht
vital staining (2%; In Vitrogen, Cergy-Pontoise, France) for 3 min.
Slides were coverslipped with buffered glycerol mounting medium
(Sigma). Immunoreactive cells were bilaterally enumerated in the
arcuate nucleus using a fluorescent microscope equipped with an
apotome (Zeiss) and the ImageJ analysis system (NIH Image,
National Center for Biotechnology Information). The average
number of cells per section and per mice was taken for statistical
Immunohistochemistry for IL-7 receptor detection in the
The presence of the IL-7 receptor in the hypothalamus was
assessed by fluorescent microscopy (Leica microsystem). Briefly, 4
mice were transcardially perfused with 4% PFA as previously
described. After post-fixation, cryoprotection in 20% sucrose and
freezing in dry ice, 12 mm-thick coronal frozen sections were
obtained with a cryostat. Sections were saturated 30 min with
PBS-3% BSA and incubated overnight with the following primary
antibodies: rabbit polyclonal IgG anti-murine IL-7Ra (1:50; Santa
Cruz Biotechnology) and rabbit polyclonal IgG anti-IL-2Rc (1:50;
Santa Cruz Biotechnology). The secondary antibody used was a
donkey anti-rabbit coupled with CyTM2-conjugated F(ab’)2(1:500;
Jackson ImmunoResearch, Cambridge, UK) incubated during 90
minutes. At each step, 0.1% TritonHX-100 was used for
membrane permeabilization. Slides were mounted using Immu-
mount (Thermo Shandon, Pittsburgh, PA, USA). Mice genetically
deficient for the expression of IL-7Ra chain (IL-7Ra KO) 
were used as negative control.
PCR and quantitative real-time PCR analysis
To analyse the expression of both chains of the IL-7 receptor in
the hypothalamus (a and ccchains), eight-week-old mice (n=3)
were sacrificed by cervical dislocation. The hypothalamus were
carefully dissected and immediately frozen in liquid nitrogen
before being homogenized and extracted in TRIzolH (Invitrogen,
Paisley, Scotland). One mg of total RNA was reverse-transcribed
and amplified using the Qbiotaq polymerase (Q Biogen, Illkirch,
France). The housekeeping gene Glyceraldehyde-3-phosphate
dehydrogenase (GAPDH) was used as control. To test whether
IL-7 could modulate the expression of hypothalamic neuropep-
tides, eight-week-old mice (n=5 per group) were s.c. injected with
IL-7 (0.3 mg per mouse, Peprotech) or with PBS. Animals were
sacrificed 4 h later, the hypothalamuses were harvested and RNA
extraction and reverse transcription were performed as described
above. The resulting cDNA was used as template for real-time
quantitative PCR using a LightCycler (Roche). Results were
normalized to the expression of the GAPDH. All results of
quantitative PCR (Q-PCR) are expressed as relative mRNA
expression levels determined using a method (2DCt; Ct=Cycle
threshold) described previously . Primer sequences used are
indicated in Table 1.
First, to test the effect of IL-7 on basal food intake, mice were
s.c. injected with IL-7 (0.3 mg, Peprotech) or PBS (n=7 per
group), and cumulative food intake was measured each hour of a
6-h period. Concerning the re-feeding conditions, animals were
overnight-fasted (with free access to water) before being s.c.
injected with IL-7 (0.3 mg, Peprotech) or PBS (n=5 per group).
Ten minutes after injection, mice were given ad libitum access to
food. Food intake was measured every hour during 5 hours and
24 h later.For the determination of mRNA expression levels of
hypothalamic neuropeptides (described above), mice were sacri-
ficed by cervical dislocation 4 h after IL-7 injection (fed condition)
or 4 h after the re-feeding period (re-fed condition) (n=5 per
Taste aversion assay
On the experimental day, overnight water-deprived mice were
given access to a 5% sucrose solution for 30 min. At the end of the
30 min access to sucrose, mice were divided in the following four
groups: mice (n=5) i.p. injected with a solution of lithium chloride
(LiCl, Sigma-Aldrich, St Quentin Fallavier) diluted in NaCl 0.9%
and administrated at the concentration of 6 mEq/kg in a final
volume of 500 ml, an optimal concentration described elsewhere
; mice (n=4) s.c. injected with 500 ml of NaCl 0.9%; mice
(n=5) s.c. injected with 0.3 mg of IL-7 diluted in 30 ml of PBS;
mice (n=4) s.c. injected with 30 ml of PBS. Animals from each
group got then free access to a sucrose 5% solution. Sucrose
consumption was measured before treatment, 3 h, 6 h, and 24 h
All data were expressed as mean 6 SEM. Comparisons were
made using the Student’s t test or Mann Whitney test when the
normality test failed, and a two-way ANOVA followed by the
Tukey post hoc test, when appropriate. p values less than 0.05 were
considered statistically significant.
We thank Pr. Herbert Herzog, Pr. Fabienne Mackay and Dr. Amanda
Sainsbury-Salis for their critical reviewing of the manuscript.
Table 1. Primer sequences used for real-time PCR.
Gene Forward 59-39
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org9 April 2010 | Volume 5 | Issue 4 | e9953
Author Contributions Download full-text
Conceived and designed the experiments: LM OV IW. Performed the
experiments: LM OV MD CS. Analyzed the data: LM OV CS LH JPDS
IW. Contributed reagents/materials/analysis tools: JPDS. Wrote the
1. Stein CJ, Colditz GA (2004) The epidemic of obesity. J Clin Endocrinol Metab
2. Morton GJ, Cummings DE, Baskin DG, Barsh GS, Schwartz MW (2006)
Central nervous system control of food intake and body weight. Nature 443:
3. Horvath TL (2005) The hardship of obesity: a soft-wired hypothalamus. Nat
Neurosci 8: 561–565.
4. Hahn TM, Breininger JF, Baskin DG, Schwartz MW (1998) Coexpression of
Agrp and NPY in fasting-activated hypothalamic neurons. Nat Neurosci 1:
5. Kristensen P, Judge ME, Thim L, Ribel U, Christjansen KN, et al. (1998)
Hypothalamic CART is a new anorectic peptide regulated by leptin. Nature
6. Boston BA, Blaydon KM, Varnerin J, Cone RD (1997) Independent and
additive effects of central POMC and leptin pathways on murine obesity.
Science 278: 1641–1644.
7. Schwartz MW, Woods SC, Porte D, Seeley RJ, Baskin DG (2000) Central
nervous system control of food intake. Nature 404: 661–671.
8. Konsman JP, Parnet P, Dantzer R (2002) Cytokine-induced sickness behaviour:
mechanisms and implications. Trends Neurosci 25: 154–159.
9. Matsuki T, Horai R, Sudo K, Iwakura Y (2003) IL-1 plays an important role in
lipid metabolism by regulating insulin levels under physiological conditions.
J Exp Med 198: 877–888.
10. Wallenius V, Wallenius K, Ahren B, Rudling M, Carlsten H, et al. (2002)
Interleukin-6-deficient mice develop mature-onset obesity. Nat Med 8: 75–79.
11. Netea MG, Joosten LA, Lewis E, Jensen DR, Voshol PJ, et al. (2006) Deficiency
of interleukin-18 in mice leads to hyperphagia, obesity and insulin resistance.
Nat Med 12: 650–656.
12. Zorilla EP, Sanchez-Alavez M, Sugana S, Brennan M, Fernandez R, et al.
(2007) Interleukin-18 controls energy homeostasis by suppressing appetite and
feed efficiency. Proc Natl Acad Sci USA 104: 11097–11102.
13. von Freeden-Jeffry U, Vieira P, Lucian LA, McNeil T, Burdach SE, et al. (1995)
Lymphopenia in interleukin (IL)-7 gene-deleted mice identifies IL-7 as a
nonredundant cytokine. J Exp Med 181: 1519–1526.
14. Namen AE, Lupton S, Hjerrild K, Wignall J, Mochizuki DY, et al. (1988)
Stimulation of B-cell progenitors by cloned murine interleukin-7. Nature 333:
15. Maraskovsky E, O’Reilly LA, Teepe M, Corcoran LM, Peschon JJ, et al. (1997)
Bcl-2 can rescue T lymphocyte development in interleukin-7 receptor-deficient
mice but not in mutant rag-1-/- mice. Cell 89: 1011–1019.
16. Namen AE, Schmierer AE, March CJ, Overell RW, Park LS, et al. (1988) B cell
precursor growth-promoting activity. Purification and characterization of a
growth factor active on lymphocyte precursors. J Exp Med 167: 988–1002.
17. Wiles MV, Ruiz P, Imhof BA (1992) Interleukin-7 expression during mouse
thymus development. Eur J Immunol 22: 1037–1042.
18. Roye O, Delhem N, Trottein F, Remoue F, Nutten S, et al. (1998) Dermal
endothelial cells and keratinocytes produce IL-7 in vivo after human
Schistosoma mansoni percutaneous infection. J Immunol 161: 4161–4168.
19. Maury E, Ehala-Aleksejev K, Guiot Y, Detry R, Vandenhooft A, et al. (2007)
Adipokines oversecreted by omental adipose tissue in human obesity.
Am J Physiol Endocrinol Metab 293: E656–665.
20. Olney JW (1969) Brain lesions, obesity, and other disturbances in mice treated
with monosodium glutamate. Science 164: 719–721.
21. Meister B, Ceccatelli S, Ho ¨kfelt T, Anden NE, Theodorson E (1989)
Neurotransmitters, neuropeptides and binding sites in the rat mediobasal
hypothalamus: effects of monosodium glutamate (MSG) lesions. Exp Brain Res
22. Goodwin RG, Friend D, Ziegler SF, Jerzy R, Falk BA, et al. (1990) Cloning of
the human and murine interleukin-7 receptors: demonstration of a soluble form
and homology to a new receptor superfamily. Cell 60: 941–951.
23. Noguchi M, Nakamura Y, Russell SM, Ziegler SF, Tsang M, et al. (1993)
Interleukin-2 receptor gamma chain: a functional component of the interleukin-
7 receptor. Science 262: 1877–1880.
24. Fry TJ, Mackall CL (2002) Interleukin-7: from bench to clinic. Blood 99:
25. Rosenthal LA, Winestock KD, Findloom DC (1997) IL-2 and IL-7 induce
heterodimerization of STAT5 isoforms in human peripheral blood T
lymphoblasts. Cell Immunol 181: 172–181.
26. Lin JX, Migone TS, Tsang M, Friedmann M, Weatherbee JA, et al. (1995) The
role of shared receptor motifs and common stat proteins in the generation of
cytokine pleiotropy and redundancy by IL-2, IL-4, IL-7, IL-13, and IL-15.
Immunity 2: 331–339.
27. Ingram DK (1982) Lithium chloride-induced taste aversion in C57BL/6J and
DBA/2J mice. J Gen Psychol 106: 233–249.
28. Liu X, Zhu XZ (1999) Roles of p53, c-Myc, Bcl-2, Bax and caspases in
glutamate-induced neuronal apoptosis and the possible neuroprotective
mechanism of basic fibroblast growth factor. Brain Res Mol Brain Res 71:
29. Morgan JI, Curran T (1991) Stimulus-transcription coupling in the nervous
system: involvement of the inducible proto-oncogenes fos and jun. Ann Rev
Neurosci 14: 421–451.
30. Goetz CA, Harmon IR, O’Neil JJ, Burchill MA, Farrar MA (2004) STAT5
activation underlies IL7 receptor-dependent B cell development. J Immunol 172:
31. Sexl V, Piekorz R, Moriggl R, Rohrer J, Brown MP, et al. (2000) Stat5a/b
contribute to interleukin 7-induced B-cell precursor expansion, but abl- and bcr/
abl-induced transformation are independent of stat5. Blood 96: 2277–2283.
32. Chou WC, Levy DE, Lee CK (2006) STAT3 positively regulates an early step in
B-cell development. Blood 108: 3005–3011.
33. Lee JY, Muenzberg H, Gavrilova O, Reed JA, Berryman D, et al. (2008) Loss of
cytokine-STAT5 signaling in the CNS and pituitary gland alters energy balance
and leads to obesity. Plos ONE 3: e1639.
34. Cui H, Cai F, Belsham DD (2006) Leptin signaling in neurotensin neurons
involves STAT, MAP kinases ERK1/2, and p38 through c-Fos and ATF1.
FASEB J 20: 2654–2656.
35. Fan W, Boston BA, Kesterson RA, Hruby VJ, Cone RD (1997) Role of
melanocortinergic neurons in feeding and the agouti obesity syndrome. Nature
36. Asnaghi L, Bruno P, Priulla M, Nicolin A (2004) mTOR: a protein kinase
switching between life and death. Pharmacol Res 50: 545–549.
37. Lee CH, Inoki K, Guan KL (2007) mTOR Pathway as a Target in Tissue
Hypertrophy. Annu Rev Pharmacol Toxicol 47: 443–467.
38. Cota D, Proulx K, Smith KA, Kozma SC, Thomas G, et al. (2006)
Hypothalamic mTOR signaling regulates food intake. Science 312: 927–930.
39. Kitamura T, Feng Y, Kitamura YI, Chua Jr. SC, Xu EW, et al. (2006) Forkhead
protein FoxO1 mediates Agrp-dependent effects of leptin on food intake. Nat
Med 12: 535–540.
40. Williams IR, Rawson EA, Manning L, Karaoli T, Rich BE, et al. (1997) IL-7
overexpression in transgenic mouse keratinocytes causes a lymphoproliferative
skin disease dominated by intermediate TCR cells: evidence for a hierarchy in
IL-7 responsiveness among cutaneous T cells. J Immunol 159: 3044–3056.
41. Paxinos G, Watson C (2005) The Rat Brain in Stereotaxic Coordinates. In: The
New Coronal Set, Fifth Edition. San Diego: Elsevier Academic Press Inc. pp
42. Shu SY, Ju G, Fan LZ (1988) The glucose oxidase-DAB-nickel method in
peroxidase histochemistry of the nervous system. Neurosci Lett 85: 169–171.
43. Hosoi T, Kawagishi T, Okuma Y, Tanaka J, Nomura Y (2002) Brain stem is a
direct target for leptin’s action in the central nervous system. Endocrinology 143:
44. Maraskovsky E, Teepe M, Morrissey PJ, Braddy S, Miller RE, et al. (1996)
Impaired survival and proliferation in IL-7 receptor-deficient peripheral T cells.
J Immunol 157: 5315–5323.
45. Livak KJ, Schmittgen TD (2001) Analysis of relative gene expression data using
real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. Methods 25:
IL-7 and Hypothalamus
PLoS ONE | www.plosone.org10 April 2010 | Volume 5 | Issue 4 | e9953