Nicotine administration effects on feeding and cocaine-amphetamine-regulated transcript (CART) expression in the hypothalamus.
In previous studies food intake and meal size significantly decreased in rats two days after injecting 4 mg/kg/day nicotine tartrate. Food intake returned to normal after nine days of continued nicotine treatment, when reduced meal size is countered by an increase in meal number. Nicotine also reduced body weight after nicotine injection and body weight remained low after nine days. To begin characterizing the mechanism that modulates these changes in feeding behavior and/or body weight during nicotine exposure the transcript levels for agouti related protein (AGRP), cocaine-amphetamine-regulated transcript (CART), corticotropin releasing hormone receptor one (CRH-R1), melanocortin receptors three and four (MC3R/4R), neuropeptide Y (NPY), NPY Y1 and Y5 receptors and/or pro-opiomelanocortin (POMC) were analyzed in the arcuate (ARC), dorsomedial (DMN) and paraventricular (PVN)/periventricular (PE) hypothalamic nuclei on the second and ninth day of saline or nicotine treatment. Results show that the transcript levels of the anorexigenic molecule CART increased in the PVN and/or PE two days after nicotine treatment but after nine days CART levels equalize. In contrast, nine days of nicotine treatment reduced CART levels in the DMN as compared to saline controls. To investigate CART's role in regulating feeding, infusion of CART (55-102) into the third ventricle reduced food intake and meal size. These results are consistent with nicotine modulating feeding behavior and body weight, in part, by affecting CART transcript levels in the DMN, PVN and/or PE.
Kramer
Phillip R
PR
Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M University System Health Science Center, 3302 Gaston Ave., Dallas, TX 75246, USA. pkramer@bcd.tamhsc.edu
Kramer
Shannon F
SF
Marr
Karina
K
Guan
Guoqiang
G
Wellman
Paul J
PJ
Bellinger
Larry L
LL
D000704:Analysis of Variance; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D004302:Dorsomedial Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism; D004435:Eating / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D009419:Nerve Tissue Proteins; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D009538:Nicotine