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the brainstem. Medially directed collaterals of ST appear at E15 as
single unbranched fibers that extend to the IV ventricle. By E16,
ST collaterals differ in length and morphology, often with a beaded
appearance. Npn2 also labels ST at E13 and E14. At E14 and E15,
large Npn2 positive, tuft-like processes surround presumptive rNST
neurons located medial to ST. By E16, ST consists of a broad band
of Npn2 positive fascicles and medially directed collaterals. In
contrast, at E14, Npn1 labels ST and trigeminal tract and this
expression pattern persists through E18. At E14 and E16, co-
labeling Npn1 and 2 showed that both antibodies label ST, whereas
the trigeminal tract is only labeled with Npn1 and the tuft-like
processes are only labeled with Npn2. At E13, calbindin is
expressed in a group of cells medial to ST. Calbindin labeled cells
increase in number, have a migratory appearance and are scattered
across Npn2 positive fibers by E14. By E18, the rNST is obvious as
a cluster of calbindin-positive neurons. These results describe
formation of ST projections and their relation to developing rNST
neurons. Furthermore, results suggest that Npn 1 and 2 are
molecular determinants involved in formation of ST and rNST.
Acknowledgements: NIDCD, NIH Grant DC009982
#P57
POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Post-Oral Glucose Activates Central Taste Areas with
Dissociated Involvement of Parabrachial and Amygdalar
Projections: Fos Immunohistochemistry in Rats With
Asymmetrical Lesions
Andras Hajnal, Krisztian Toth, Han Li, Nelli Horvath,
Nikhil Acharya
Dept. of Neural & Behavioral Sciences, Penn State University,
College of Medicine Hershey, PA, USA
Whereas integration of intestinal chemosensory and metabolic
signals is required to generate appropriate homeostatic and
behavioral responses, the underlying neural substrates remain
obscure. This pilot study challenged the hypotheses that central
taste areas also play role in mediating post-oral effects of glucose,
and that projections from the pontine parabrachial nucleus (PBN) to
the central nucleus of the amygdala (CeA) influence activation of
the reward circuitries. First, rats received ibotenic acid (IBX, n=6)
or vehicle injections (n=6) in the PBN in one hemisphere and the
CeA in the other. IBX rats showed reduced 10-s lick-responses to
sucrose but no difference in body weight or food intake. Fos
immunoreactivity (IR) was used as an index of neural activity
following gastric gavage of glucose (IG, 20%, 2g/kg). IG glucose
stimulated Fos-IR in the NTS (caudal > rostral), the PBN (lateral >
medial), the hypothalamus (ARC, PVN, VMH, DMH, LH), the
lateral habenula, the amygdala (CeA > BLA), the lateral BNST, the
VTA and the NAcc (core > shell), the thalamus (VPMpc, CM, CL,
PVN, SPF), the gustatory and medial prefrontal cortices. Whereas
the lesions had no effect on glucose-induced activation of the NTS,
hypothalamus, VTA, and NAcc core, IBX rats showed decreased
Fos-IR in the NAcc shell, mPFC, and the gustatory cortex with all
effects limited to the side of CeA lesions. These findings
demonstrate the efficiency of IG glucose to activate – in addition to
energy regulatory circuits – all major central gustatory areas.
Moreover, this initial data suggests that amygdalo/BNST-(thalamo-
cortico)-striatal networks rather than direct (ipsilateral) PBN
projections to the CeA or to the VTA play a role in activating the
forebrain reward system – at least – when glucose stimulation
bypasses the oral receptors. Acknowledgements: Supported by
NIH grant DC000240 to A.H.
#P58
POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Anorectic Signaling Pathway Mediated by Salivary PYY
Maria D. Hurtado
1
, Andres Acosta
1
, Oleg Gorbatyuk
2
,
Valeriy G. Sergeyev
3
, Cedrick D. Dotson
4
, Herbert Herzog
5
,
Sergei Zolotukhin
1
1
Department of Pediatrics, University of Florida Gainesville, FL,
USA,
2
Department of Molecular Genetics and Microbiology,
University of Florida Gainesville, FL, USA,
3
Department of
Medical Biotechnology, Udmurt State University Izhevsk, Russia,
4
Departments of Neuroscience & Psychiatry and Center for
Smell and Taste, University of Florida Gainesville, FL, USA,
5
Garvan Institute of Medical Research Sydney, Australia
Peptide YY (PYY), a hormone that induces satiety, is synthesized
in L-endocrine cells of the distal gut epithelia. It is secreted into
circulation in response to food intake (FI) and induces satiation
upon interaction with its preferred receptor, Y2R. Recently we have
demonstrated the presence of the truncated form, PYY
3-36
, in saliva
from both mice and humans, as well as the expression of the Y2R
receptor in lingual epithelia cells. In the current report, we describe
a novel neural circuit activated in response to the acute
pharmacological augmentation of salivary PYY
3-36
at doses which
reliably results in a significant reduction of FI and body weight
(BW). In fasted mice, neurons in hypothalamic nuclei that
mediating feeding, hunger and satiation were activated significantly
in response to orally applied PYY
3-36
, similar to a fed control group
and a peripherally injected PYY group. Activated areas in the
nucleus of the solitary tract (NST), identified by the increased
numbers of c-Fos positive neurons, were markedly different for the
rostral relative to the caudal NST, in response to systemic vs local
oral PYY treatment. This distinctive pattern of neuronal activation
was corroborated by behavioral studies assaying liquid and solid
food intake after conditioned taste aversion (CTA) induction.
Remarkably, orally applied PYY
3-36
, while inducing strong
anorexigenic responses, did not induce CTA. Taken together, these
data provide support for the existence of a putative metabolic
circuit associated with Y2R-positive cells in the oral cavity which
extends through brainstem nuclei into hypothalamic satiety centers.
The discovery of this alternative metabolic pathway which
regulates ingestive behavior reinstates the potential of PYY
3-36
for the treatment of obesity.
#P59
POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Anxiety- and depression-like behaviors with decreased brain
dopaminergic activity in rats with lingual nerve transectomy
J. W. Jahng, J. Y. Kim, E.Y. Park, J. Y. Lee, J. -H. Lee
Department of Oral & Maxillofacial Surgery, Seoul National
University School of Dentistry Seoul, Korea
Sensory information plays an important role to determine
psycho-emotional behaviors of individuals. In this study, we have
examined changes in anxiety- and depression-related behaviors of
rats after blocking the oral sensory relay to brain. Male SD rats
were subjected to behavioral sessions two weeks after bilateral
transectomy of lingual nerve (LNX) or sham operation, and then
tissue contents of dopamine and its metabolites in each brain
regions were analyzed by high-performance liquid chromatography.
Initial weight loss after the surgery was bigger in LNX rats and this
effect remained during the whole experimental period, although
Abstracts | 47
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