The Susceptibility of the Hypothalamic-Pituitary-Adrenocortical Axis to Histamine after Head X-Irradiation

Abstract

Under pentobarbital anesthesia, adult male dogs were irradiated with 1,000R of X-rays to their heads, and the adrenocortical response to histamine was investigated. The secretory activity was determined by estimating 17-hydroxycorticosteroids (17-OHCS) in adrenal venous blood. One day after irradiation, an intravenous injection of histamine (0.5mg/ kg body weight) to irradiated animals increased considerably the secretion of 17-OHCS from the adrenal, but the response was significantly less than that in non-irradiated animals. Thirty days after exposure, irradiated animals responded to the injection of histamine and secreted an appreciably large amount of 17-OHCS. However, the responsiveness was still lower than normal. It appears from these results that the corticotrophic effect of 0.5 mg histamine/kg can be dimi nished considerably by pretreatment with head X-irradiation of 1,000 R, possibly due to a disturbed activity of the hypothalamic-pituitary axis. head X-irradiation; adrenocortical response to histamine; dogs

Direct Effect of Histamine on Cortisol and Corticosterone Production by Isolated Dog Adrenal Cells

“…1967; Narita, 1971;Yamashita, Shimizu, Mieno & Kawao, 1973;Hirose, Matsumoto & Suzuki, 1976;Hirose, Matsumoto, Aikawa & Suzuki, 1977). The adrenocortical response of the dog to histamine was found to be markedly reduced, although not completely eliminated, by hypophysectomy (Hirose et al 1976.…”

Secretion of Aldosterone in Response to Histamine in Hypophysectomized-Nephrectomized Dogs

“…A number of studies have shown that systemic administration of histamine produces a marked increase in adrenocortical secretion in the dog (Suzuki, Hirai, Yoshio, Kurouji & Yamashita, 1963;Papp, Stark, Acs & Varga, 1964;Asano, 1966;Katsuki, Ito, Watanabe, lino, Yuji & Kondo, 1967;Tanigawa, 1967;Narita, 1971;Yamashita, Shimizu, Mieno & Kawao, 1973;Hirose, Matsumoto & Suzuki, 1976;Hirose et al 1977). In the study by Hirose et al (1977), significant increases in corticosterone and cortisol secretion in hypo¬ physectomized dogs in response to histamine were observed, although they were small and of short duration.…”