The effects of estradiol and mestranol on alpha-adrenoceptors in select regions of the rat brain.
The role of estrogens in modulating the concentration of CNS alpha-adrenoceptors has not been elucidated nor has it been determined how different estrogenic compounds affect these receptors. In this study brain alpha-1 and alpha-2-adrenoceptor binding was measured in female rats treated with estradiol and/or the synthetic estrogen mestranol. Rats treated biweekly for 12 weeks with mestranol (50 micrograms/100 g b.wt.) had a significant reduction in the apparent number of alpha-2-adrenoceptors in the frontal cortex and nucleus tractus solitarius (NTS), while apparent numbers of both alpha-1 and alpha-2-adrenoceptors were depressed in the locus coeruleus. Estradiol treatment (50 micrograms/100 g b.wt.) caused a significant elevation in apparent alpha-1-adrenoceptor numbers in the NTS relative to control. Alpha-adrenoceptor numbers in the rostral and caudal hypothalamus were not affected by either steroid treatment. These results suggest that regulation of apparent numbers of alpha-1 and alpha-2-adrenoceptors in the CNS depends on the type of estrogen used for treatment.
Shackelford
D P
DP
Department of Biology, East Carolina University, Greenville, NC 27858.
McConnaughey
M M
MM
Iams
S G
SG
D000818:Animals; D001921:Brain / Q000187:drug effects*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005625:Frontal Lobe / Q000187:drug effects; D008125:Locus Coeruleus / Q000187:drug effects; D008656:Mestranol / Q000494:pharmacology*; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
D004967:Estrogens; D011942:Receptors, Adrenergic, alpha; D008656:Mestranol