UNASSIGNED: The @entity2339 plays a central role in the regulation of gamete maturation, sex @entity479 production and the stimulation of reproductive behaviours in vertebrates. In seasonal breeders, the timely activation and deactivation of this control system is important to ensure successful reproduction: this process is not well understood in species which breed irregularly. Males of the viviparous blotched blue-tongued lizard, Tiliqua nigrolutea, breed annually, while females display a multiennial cycle. We investigated seasonal variation in @entity2339 responsiveness in both sexes of T. nigrolutea. We measured changes in plasma concentrations of @entity251 and @entity172 in response to a single intraperitoneal injection of a GnRH agonist, @entity1573 -II LH-RH, at three reproductively distinct times of year. Plasma @entity251 concentrations in males were significantly increased during gonadal quiescence, but not initial or final spermatogenesis. There was no @entity172 response in males at any time of year. Conversely, in females, there was an increase in plasma @entity251 , but not @entity172 , concentration, in reproductively quiescent females several months in advance of a successful pregnancy. These results indicate clear variation in @entity2270 activity with sex, season and reproductive condition in this seasonally breeding viviparous lizard. This study opens the way for further investigation into the mechanisms by which internal (body condition) and external seasonal cues (temperature and photoperiod) are coordinated to regulate reproduction in irregularly-breeding reptiles.

Response to gonadotropin-releasing hormone challenge: Seasonal variation in XXXX production in a viviparous lizard, Tiliqua nigrolutea.

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen'] @entity251 :: ('MESH:D013739', 'Chemical') :: ['testosterone'] @entity1573 :: ('9031', 'Species') :: ['chicken'] @entity2339 :: ('MESH:D007029', 'Disease') :: ['hypothalamic-pituitary-gonadal axis'] @entity2270 :: ('MESH:C566610', 'Disease') :: ['HPG axis'] @entity479 :: ('D013256', 'Chemical') :: ['steroid']
@entity479 :: (D013256,Chemical) :: ['steroid']
