Effects of passive immunization with antisomatostatin serum on plasma corticosterone concentrations in young domestic cockerels

Abstract

Young cockerels (6-8 weeks old) were injected with serum from sheep immunized against somatostatin-14 (anti-SRIF) or normal sheep serum (NSS). Blood samples were withdrawn periodically for the determination of plasma corticosterone concentration by radioimmunoassay. With frequent (every 10 min) sampling, NSS-treated control animals exhibited increased plasma corticosterone levels, presumably as a stress response to the experimental manipulation. Anti-SRIF stimulated a much greater increase in plasma corticosterone concentrations and a peak response was observed within 10 to 20 min, when the plasma corticosterone level reached more than twice that of the corresponding control value. With less frequent sampling, plasma corticosterone increased with anti-SRIF administration to as much as nine times the corresponding control value, and the peak response occurred much later. Under pentobarbitone anaesthesia, which itself increased basal corticosterone concentrations, anti-SRIF treatment promoted further increases in plasma corticosterone levels although to a smaller magnitude compared with conscious birds. The results suggest that endogenous somatostatin may play a role in the regulation of adrenocortical function in the domestic fowl. The mechanism of response may involve a central component.

Homologous and heterologous regulation of somatostatin-binding sites on chicken adenohypophysial membranes

“…The possibility that changes in endogenous SRIF secretion might participate in the physiological regu¬ lation of pituitary SRIF-binding sites was examined in birds pretreated with an antiserum to SRIF that stimulates GH secretion ), thyroid function ) and adrenocortical activity (Cheung, Harvey, Hall et al 1988). The rapid and pronounced suppression of SRIF binding to the pituitary membranes of birds injected with this anti¬ serum was, therefore, unexpected.…”

Thyrotrophin-releasing hormone-induced growth hormone (GH) secretion in anaesthetized chickens: inhibition by GH-releasing factor at central sites

“…The antiserum was adminis¬ tered i.c.v. rather than peripherally since the systemic administration of SRIF antisera not only affects pitu¬ itary GH release ) but modifies thyroid (Lam, Harvey, Hall & Spencer, 1986) and adrenal (Cheung, Harvey, Hall et al 1988) function, both of which play major roles in avian GH regulation (Harvey, 1983). The SRIF antiserum was also administered centrally since its actions on the GH responses of rats to i.c.v.…”