Effect of hypertension and age on alpha 1-adrenoceptors in rat brain: modulation of [3H] prazosin binding by chronic treatment with desipramine and AR-C239.
The influence of repeated treatment with desipramine or AR-C239 on cerebral cortex alpha 1-adrenoceptors of mature (4 months), senescent (24 months) Wistar-Kyoto and mature spontaneously hypertensive rats was measured using [3H] prazosin as a ligand. Chronic desipramine treatment had no effect on [3H] prazosin binding in mature and aged Wistar-Kyoto rats but significantly decreased it in spontaneously hypertensive rats. Repeated AR-C239 treatment did not alter [3H] prazosin binding in senescent Wistar-Kyoto and mature spontaneously hypertensive rats, but significantly increased the [3H] prazosin binding density in mature Wistar-Kyoto rats. Thus, cortical alpha 1-adrenoceptors are not up-regulated by a decreased noradrenergic activity in aged or hypertensive rats as is the case in mature normotensive rats. In addition, these receptors are down-regulated by an increased noradrenergic activity in hypertensive rats only. These results suggest that the synthesis of alpha 1-adrenoceptors is impaired with age or with genetic hypertension and their degeneration is exacerbated with genetic hypertension in response to a changing environment.
Huguet
F
F
Unité INSERM 316, Faculté de Médecine, Tours, France.
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D003891:Desipramine / Q000494:pharmacology*; D006973:Hypertension / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D010879:Piperazines; D011224:Prazosin / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D007546:Isoquinolines; D010879:Piperazines; D011942:Receptors, Adrenergic, alpha; C032994:AR-C239; D003891:Desipramine; D011224:Prazosin