alpha- and beta-adrenergic binding sites in sheep cerebral cortex: characterisation, effects of photoperiod and treatment with estrogen/progesterone.

The radioligands [3H]-dihydroergocryptine and [3H]-dihydroalprenolol were used to characterise alpha- and beta-adrenergic binding sites, respectively, in membrane fractions of sheep cerebral cortex. In terms of affinity, density and specificity these sites possess properties similar to those previously characterised in rat brain. Further, in preliminary studies, these sites also appear to be responsive to treatment with estradiol/progesterone as well as to photoperiod. Thus, estrogen treatment can elevate both alpha- and beta-adrenergic binding sites in cortical tissue of sheep kept in natural light. In contrast, artificial light either has no effect or inhibits binding in response to estrogen.