title: Nicotine withdrawal upregulates nitrergic and galaninergic activity in the rat dorsal raphe nucleus and locus coeruleus.
abstract: The dorsal raphe nucleus (DRN), a major source of forebrain serotonin, mediates various neural functions including anxiety. The nucleus locus coeruleus (LC) is likewise involved in mediating central components of the stress response and anxiety. An anxiety-reducing effect is widely believed to underlie many cases of nicotine dependence. While much is known about nicotine-serotonin interactions, little is known about how nicotine engages the DRN non-serotonergic domain in specific physiological functions that influence organismal behavior. The aim of this study was to determine how chronic nicotine withdrawal influences neuronal nitric oxide (NO) synthase (nNOS) and galanin immunoreactivity in the DRN and LC of adult rats. Compared with saline, nicotine increased nicotinamide adenine dinucleotide phosphate diaphorase profiles within distinct DRN subregions and also enhanced intensity in nNOS and galanin cell bodies in the rostral DRN as well as galanin in the LC. Nicotine-induced nNOS/galanin staining of somata was abundant in the rostral ventromedial DRN. Galanin-positive terminals surrounded nNOS-containing cell bodies in the DRN lateral wing subregions. These observations suggest that the DRN NOS-galanin domain and galanin in the LC are engaged in the organism's neural adaptation to chronic nicotine exposure. Hence NO and galanin synthesized or released within the DRN and LC or at the respective target sites might regulate the whole animal behavioral response to nicotine exposure.
authors.affiliation: Department of Biological Sciences, Clark Atlanta University, Atlanta, GA 30314, USA. cokere@cau.edu
authors.forename: Chuma O
authors.initials: CO
authors.lastname: Okere
authors.forename: Barry D
authors.initials: BD
authors.lastname: Waterhouse
mesh_terms: D000818:Animals; D019004:Galanin / Q000378:metabolism*; D008125:Locus Coeruleus / Q000378:metabolism*; D008297:Male; D009538:Nicotine / Q000009:adverse effects*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D011903:Raphe Nuclei / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D009538:Nicotine; D019004:Galanin; D052248:Nitric Oxide Synthase Type I