title: The secretory response of hypothalamic beta-endorphin neurons to acute and chronic nicotine treatments and following nicotine withdrawal.
abstract: In the present study, we determined the effect of acute and chronic nicotine treatments on the secretion of immunoreactive beta-endorphin (IR-beta-EP) and cell viability of cultured hypothalamic neurons. Also, we determined the secretory response of IR-beta-EP following withdrawal from a long-term nicotine treatment. Fetal hypothalamic cells were dissociated and maintained in cultures for 9 days and were treated with various doses of nicotine (1, 6, 12 and 18 microM) for 6 h (acute treatment) or treated with nicotine at 12 h intervals for 96 h (chronic treatment). Determination of IR-beta-EP concentrations in the media revealed that 6-18 microM doses of nicotine increased IR-beta-EP secretion from these cultures for a period of 24 h; after this period, the cultured cells did not respond to these doses of nicotine. The desensitization of beta-EP neurons 24 h after treatment with nicotine did not appear to be related to the loss of viable cells. Determination of withdrawal response after 72 h of constant nicotine (6 microM) treatments revealed that the hypothalamic neurons secrete elevated amounts of IR-beta-EP for a period of 72 h after nicotine withdrawal. These results suggest that: 1) acute treatment with nicotine stimulates hypothalamic IR-beta-EP release; 2) chronic nicotine treatment desensitizes beta-EP-secreting neurons and, 3) beta-EP neurons in primary culture show withdrawal response to nicotine.
authors.affiliation: Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman 99164-6520, USA.
authors.forename: N I
authors.initials: NI
authors.lastname: Boyadjieva
authors.forename: D K
authors.initials: DK
authors.lastname: Sarkar
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D007031:Hypothalamus / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009538:Nicotine / Q000008:administration & dosage* / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D001615:beta-Endorphin / Q000378:metabolism*
chemical_list: D001615:beta-Endorphin; D009538:Nicotine