Hypothalamic adrenoceptors mediate sympathoadrenal activity in exercising rats.
The role of hypothalamic adrenoceptors in the exercise-induced alterations of plasma norepinephrine (NE), epinephrine (E), and corticosterone concentrations was investigated in rats. Exercise consisted of strenuous swimming against a counter-current for 15 min. Before, during, and after swimming, blood samples were withdrawn through a permanent heart catheter for determination of E, NE, and corticosterone. In control rats E, NE, and corticosterone levels were all increased during exercise. Infusion of the alpha-adrenoceptor antagonist phentolamine through permanent bilateral cannulas into the ventromedial hypothalamus (VMH) immediately before exercise reduced the exercise-induced increase in plasma E without affecting NE. Infusion of the beta-adrenoceptor antagonist timolol into the VMH enhanced plasma E and attenuated plasma NE increases. Infusion of phentolamine into the lateral hypothalamic area (LHA) led to enhanced NE and unchanged E concentrations, whereas infusion of timolol into the LHA caused a potentiation of the increase in plasma E without an effect on NE. Plasma corticosterone concentrations were not affected. The results suggest that 1) alpha- and beta-adrenoceptors in the hypothalamus influence peripheral catecholamine release, and 2) E and NE responses to exercise can be dissociated by interference of the central nervous system.
Department of Animal Physiology, State University of Groningen, Haren, The Netherlands.
A J
AJ
Scheurink
A B
AB
Steffens
R P
RP
Gaykema
D000311:Adrenal Glands / Q000502:physiology*; D000818:Animals; D002555:Cerebrospinal Fluid; D003345:Corticosterone / Q000097:blood; D004837:Epinephrine / Q000097:blood; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010646:Phentolamine / Q000494:pharmacology; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013999:Timolol / Q000494:pharmacology
D011941:Receptors, Adrenergic; D013999:Timolol; D003345:Corticosterone; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine