title: Loss during aging of beta-endorphinergic neurons in the hypothalamus of female C57BL/6J mice.
abstract: Beta-endorphin (B-EP) content is often reduced in hypothalami of aging rodents. The objective of this study was to determine whether reduced B-EP content is associated with a reduced number of B-EP immunoreactive neurons. Serial coronal sections extending from the caudal hypothalamus through the retrochiasmatic area were examined by quantitative light microscopy in mature (5-6 month) and senescent (24-28 month) mice that had been ovariectomized 1 week earlier and injected with colchicine 24-48 h before sacrifice. Old mice were acyclic. As expected, B-EP immunoreactive cell bodies were restricted to the region of the arcuate nucleus. There was a 35% loss of B-EP immunopositive neurons in old, macroscopically disease-free animals. By contrast, some old animals with pituitary tumors had no loss of B-EP neurons. These results suggest that a subpopulation of B-EP neurons either die or stop synthesizing detectable concentrations of B-EP in aged mice. The basis for the absence of reduced B-EP neurons in some mice with pituitary tumors is unclear, but this observation underscores the importance of distinguishing age-related changes associated with diseases of aging from those that are independent of such diseases.
authors.affiliation: Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec Canada.
authors.forename: M M
authors.initials: MM
authors.lastname: Miller
authors.forename: D
authors.initials: D
authors.lastname: Joshi
authors.forename: R B
authors.initials: RB
authors.lastname: Billiar
authors.forename: J F
authors.initials: JF
authors.lastname: Nelson
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism; D003078:Colchicine / Q000494:pharmacology; D005260:Female; D006262:Health; D007031:Hypothalamus / Q000166:cytology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000502:physiology*; D010052:Ovariectomy; D011333:Pro-Opiomelanocortin / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D001615:beta-Endorphin / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D003078:Colchicine