Effect of testosterone on the pressor response to common carotid occlusion in gonadectomized conscious male rats with lesion of the median eminence.
The influence of testosterone on the development of the pressor response to common carotid occlusion was investigated in control and median eminence-lesioned male rats. In control rats (N = 9), gonadectomy performed 21 days before the experiments reduced by 22% (from 51 +/- 2 to 40 +/- 2 mmHg) and treatment with testosterone (300 micrograms for 4 days before the measurements) increased the initial peak pressor response (from 51 +/- 2 to 57 +/- 2 mmHg) which depends on carotid innervation. The maintained response which is of central origin (probably ischemic) was less affected. In nongonadectomized rats (N = 6), lesions of median eminence (6 days) decreased the initial peak by 19% (from 52 +/- 2 to 42 +/- 3 mmHg) and the maintained response by 56% (from 32 +/- 2 to 14 +/- 1 mmHg). Sham-operated rats served as controls. In gonadectomized animals (N = 6) the lesion reduced only the maintained response (from 23 +/- 2 to 11 +/- 1 mmHg). Testosterone supplementation restored the maintained response but did not alter the initial peak. These results indicate that the pressor response to common carotid occlusion in male rats is modulated by testosterone and that the depression in the maintained response caused by median eminence lesion can be reversed by steroid supplementation.
Bedran-de-Castro
M T
MT
Departamento de Ciências Fisiológicas, Faculdade de Odontologia de Araçatuba, Universidade Estadual Paulista, Brasil.
Bedran-de-Castro
J C
JC
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002339:Carotid Arteries / Q000601:surgery; D003250:Constriction; D008297:Male; D008473:Median Eminence / Q000502:physiology*; D009919:Orchiectomy; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone