Neuroendocrinology · 2008 · 16 citations · 0 references
MedicineAnimal SciencesEndocrinologyNeuroendocrinologyReproductive EndocrinologyReproductive PhysiologyAdrenal Steroid HormonesGonadal HormonesGonadal Steroid HormonesReproductive NeuroendocrinologySeasonal EndocrinologySteroid Hormone SignalingEndocrine Responses To Seasonal ChangeEstrous Cycle PhasesEstrous Cycle RegulationOvarian HormonesPineal Gland FunctionPineal Gland PhysiologySeasonal Neuroendocrine ControlSeasonal Variation
The results of a seasonal study of the regulation by steroids of ovine pineal beta-adrenoceptors are reported. The effects of ovariectomy, steroid implants and superior cervical ganglionectomy were investigated in Merino ewes. The results confirm earlier observations showing a seasonal variation in the sensitivity of the receptors to modification by gonadal steroids. A marked difference in receptor density and affinity between the follicular and luteal phases of the estrous cycle is shown for the first time, a difference which can be modified by appropriate steroid-related treatments. A season-dependent antagonism between the sympathetic innervation of the gland (presumably acting via the neurotransmitter noradrenaline) and gonadal steroids in the regulation of ovine pineal beta-adrenoceptor function is also shown.