Seasonal modification of ovine pineal function. I. Interaction of gonadal steroids and sympathetic innervation on beta-adrenoceptors.
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.
Maxwell
C A
CA
CSIRO, Divisions of Animal Production, Blacktown, Australia.
Foldes
A
A
Scaramuzzi
R J
RJ
Carter
N B
NB
Downing
J A
JA
D000818:Animals; D004958:Estradiol / Q000502:physiology; D004971:Estrus / Q000502:physiology; D005260:Female; D015171:Ganglionectomy; D010052:Ovariectomy; D010870:Pineal Gland / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012621:Seasons; D012756:Sheep
D011943:Receptors, Adrenergic, beta; D011374:Progesterone; D004958:Estradiol