title: Olfactory bulb removal does not prevent gonadotropin or prolactin responses to changing photoperiod in the ewe.
abstract: The purpose of this study was to determine if bilateral olfactory bulb removal (Bulbx) alters photoperiod-induced changes of gonadotropin and prolactin secretion in the ewe. Ovariectomized (group 1; n = 12) or ovariectomized estradiol-treated (group 2; n = 12) Suffolk ewes underwent Bulbx (7 per group) or sham operations (5 per group). All ewes subsequently were placed into photochambers and exposed to a photoregimen of alternating 16 h light/8 h dark and 10 h light/14 h dark photoperiods. Plasma concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin were determined in blood samples taken twice weekly from group 2 ewes. At the end of each 90-day photoregimen blood samples from all ewes in both groups were taken at frequent intervals for 4 h to determine LH pulse parameters. During the initial 16 h light/8 h dark photoperiod, plasma melatonin concentrations were determined for group 2 ewes during a 24-hour period. The completeness of Bulbx was determined at time of necropsy for all Bulbx ewes. In addition, the functional completeness of Bulbx was determined in group 2 ewes by exposing them to ram's wool and measuring changes in LH secretion. Bulbx did not affect either basal or photoperiod-induced changes in LH, FSH and prolactin in group 2 ewes. LH pulse parameters varied with photoperiod but were not significantly (p > 0.05) affected by Bulbx in either group 1 or group 2 ewes. The normal nocturnal elevation in plasma melatonin concentrations was unaffected by Bulbx.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois, Urbana 61801.
authors.forename: H T
authors.initials: HT
authors.lastname: Jansen
authors.forename: G L
authors.initials: GL
authors.lastname: Jackson
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D008550:Melatonin / Q000097:blood; D009830:Olfactory Bulb / Q000502:physiology* / Q000601:surgery; D010052:Ovariectomy; D017440:Photoperiod; D011388:Prolactin / Q000097:blood*; D012756:Sheep
chemical_list: D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008550:Melatonin