Responses of adrenocorticotropin and vasopressin to hemorrhage after lesions of the caudal ventrolateral medulla in rats

Abstract

Hormonal responses to hemorrhage were examined in urethane-anesthetized rats 48 h after electrolytic lesions of the caudal ventrolateral medulla. Bilateral A 1-lesions (A 1×) inhibited the response of plasma adrenocorticotropin relative either to other lesions (X×) or to sham lesions. A 1× inhibited the response of plasma vasopressin relative to X× but not to sham lesions. A 1× and X× destroyed similar areas that were dorsal or caudal to A 1. No lesion blocked either response completely. A hemodynamic pathway controlling the release of both hormones may pass through A 1. However, other pathways may bypass this area.