title: Changes in mouse mu opioid receptor Exon 7/8-like immunoreactivity following food restriction and food deprivation in rats.
abstract: Opioid agonists and antagonists respectively increase and decrease food intake. That selective mu opioid antagonists are more effective than antisense probes directed against the mu opioid receptor (MOR-1) gene in reducing deprivation-induced feeding suggests a role for isoforms. Both food restriction and deprivation alter protein and mRNA levels of opioid peptides and receptors. Antisera directed against Exon 4 of the MOR-1-like immunoreactivity (LI) (Exon 4) clone or directed against mouse Exons 7/8 (mE7/8-LI) revealed high levels of immunoreactivity in brain nuclei related to feeding behavior. Therefore, the present study assessed MOR-1LI and mE7/8-LI in hypothalamic and extrahypothalamic sites in rats exposed to ad libitum feeding, food restriction (2, 7, 14 days), or food deprivation (24, 48 h). MOR-1-LI displayed robust reactivity, but was insensitive to food restriction or deprivation. mE7/8-LI, both in terms of cell counts and relative optical density, was significantly and selectively increased in the dorsal and ventral parvocellular subdivisions of the hypothalamic paraventricular nucleus in food-restricted (14 days) rats, but all other restriction or deprivation regimens were ineffective in other hypothalamic nuclei. In contrast, significant and site-specific decreases in relative optical density in the rostral part of the nucleus tractus solitarius (NTS) were observed in food-restricted (2, 7 days) or food-deprived (24, 48 h) animals, but these regimens were ineffective in the other extrahypothalamic sites. This study indicates the sensitivity of this mE7/8-LI probe in the hypothalamic parvocellular paraventricular nucleus and rostral NTS to food restriction and deprivation in rats.
authors.affiliation: Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, New York 11367, USA.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Hadjimarkou
authors.forename: Catherine
authors.initials: C
authors.lastname: Abbadie
authors.forename: Lora J
authors.initials: LJ
authors.lastname: Kasselman
authors.forename: Ying-Xian
authors.initials: YX
authors.lastname: Pan
authors.forename: Gavril W
authors.initials: GW
authors.lastname: Pasternak
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bodnar
mesh_terms: D000818:Animals; D001835:Body Weight; D001921:Brain / Q000378:metabolism; D002452:Cell Count; D004032:Diet; D005091:Exons; D005215:Fasting / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D010784:Photomicrography; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017552:Solitary Nucleus / Q000378:metabolism*
chemical_list: C404943:Oprm protein, mouse; C485765:Oprm1 protein, rat; D017450:Receptors, Opioid, mu