title: Pattern of LH and testosterone secretion of adult male fallow deer (Dama dama) during the transition into the breeding season.
abstract: Pituitary secretion of LH and testicular secretion of testosterone were investigated during the transitional period from the non-breeding to breeding season of mature male fallow deer exhibiting either normal transitional patterns or shortened transitional patterns in response to summer melatonin treatment. Melatonin implants were administered to 4 bucks for a 150-day period starting 130 days after the winter solstice. Four contemporary bucks served as controls. Melatonin treatment advanced rutting activity, testis development and neck muscle hypertrophy by 6-8 weeks. Profiles of plasma LH and testosterone, based on a 30-min sampling frequency over 24 h, were obtained from 3 treated and 3 control bucks on 4 occasions over the period spanning the transition into the breeding season. In control bucks, LH and testosterone pulse frequency were low (0-2 pulses/24 h) in January and increased (5-7 pulses/24 h) in February. By March and April (pre-rut and rut periods respectively) there was a two-fold increase in basal plasma LH concentrations, a decline in LH pulse frequency (0-1 pulse/24 h) and episodic surges in plasma testosterone concentrations. Melatonin treatment resulted in a shift in hormone profiles, with highly pulsatile patterns of LH and testosterone secretion (7 pulses/24 h) occurring earlier in January. The subsequent post-rut profiles of treated bucks were characterized by lower basal plasma LH concentrations, and reduced frequency and amplitude of plasma testosterone surges.
authors.affiliation: Ruakura Agricultural Centre, Ministry of Agriculture and Fisheries, Hamilton, New Zealand.
authors.forename: G W
authors.initials: GW
authors.lastname: Asher
authors.forename: A J
authors.initials: AJ
authors.lastname: Peterson
mesh_terms: D000818:Animals; D001835:Body Weight; D002940:Circadian Rhythm / Q000502:physiology; D003670:Deer / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000494:pharmacology; D009333:Neck / Q000033:anatomy & histology; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects; D012621:Seasons; D012636:Secretory Rate / Q000187:drug effects; D013737:Testis / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000097:blood / Q000378:metabolism*
chemical_list: D013739:Testosterone; D007986:Luteinizing Hormone; D008550:Melatonin