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Nicotine acts through the perifornical hypothalamus
Author(s) -
Kramer Phillip R.,
Wellman Paul,
Bellinger Larry L.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a462
Subject(s) - chemistry , nicotine , hypothalamus , mecamylamine , medicine , endocrinology , dopamine , norepinephrine , antagonist , receptor
Intermittent administration of nicotine (NIC) decreases food intake (FI) and body weight (BW). Infusion of the NIC antagonist mecamylamine into the 4 th ventricle reduced this effect, suggesting NIC is acting on neurons adjacent to the fourth ventricle to reduce FI and BW. Norepinephrine (NE) [A2, A4, A6] and epinephrine (EPI) [C2, C3] cell bodies, adjacent to the fourth ventricle, directly innervate feeding areas in the hypothalamus including the perifornical hypothalamus (PFH). In the PFH NE release stimulates FI, while EPI release inhibits intake. NE and EPI fibers were eliminated (i.e. lesioned) in the PFH using 6‐OHDA hydrobromide. Bupropion HCl was also administered to protect dopamine (DA) neurons from damage. Lesioning significantly reduced PFH NE and EPI levels, while DA levels remained unchanged. Lesioned animals FI and BW were recorded by computer before and after intermittent NIC injections. PFH lesioned rats injected with NIC did not show the typical drop in FI and BW. We conclude that normally NIC normally attenuates FI, in part, by releasing EPI in the PFH. Remember EPI is a FI inhibitor and PFH lesioning will cause removal of the EPI fibers thus, leading to the observation of an attenuated effect of NIC on FI and BW suppression. The release of PFH DA can also suppress feeding in the PFH, but since PFH DA levels were unchanged in the lesioned rats NIC can not be suppressing FI through a DA mechanism.