Central action of interleukin‐1 in altering the release of tsh, growth hormone, and prolactin in the male rat

Abstract

In order to determine the possible effects of interleukin-1 on the release of pituitary hormones by direct action on the brain, the peptide was injected into the third brain ventricle of conscious, unrestrained male rats and the effects on hormone release were compared with effects on rectal temperature. The procedure of blood sampling and intraventricular injection resulted in a significant decline in body temperature and a decrease in plasma growth hormone without alteration in the plasma level of thyroid stimulating hormone (TSH) and prolactin. Interleukin-1 injected intraventricularly at a dose of 5 ng (0.3 pmol) prevented the decline in body temperature that occurred in the saline-injected controls and resulted in a significant elevation of plasma growth hormone levels that became apparent within 15 min of injection, as well as a highly variable but significant elevation of plasma prolactin and a significant decline in plasma TSH that was observed at 30 min. The results were similar when areas under the release curves for the various hormones were calculated. On the other hand, the higher dose of 25 ng (1.5 pmole) of interleukin-1, although producing a frank pyrexia, was associated with smaller changes in hormone values, which were no longer significant for any of the three hormones. The results indicate that interleukin-1 can act in minute doses, presumably on structures near the third ventricle, to stimulate growth hormone and prolactin release and to inhibit TSH release. Apparently when frank febrile responses occur, these hormonal responses are muted for reasons that are yet to be determined. In view of the minute doses injected we favor a hypothalamic site for these effects.

Effects of endotoxin lipopolysaccharide administration on the somatotropic axis

“…However, another study showed that i.c.v. administration of IL-1 stimulated GH secretion (Rettori et al 1987). In contrast, a continuous i.v.…”

“…However, the effect of cytokines on GH secretion is not well known. IL-1 administration has been reported both to increase (Rettori et al 1987) and decrease (Peisen et al 1995) GH secretion. Similarly, tumor necrosis factor-(TNF ) has also been reported to increase (Rettori et al 1989, Elsasser et al 1991 and decrease (Walton & Cronin 1989) GH secretion.…”

Growth hormone modulates IL- and IFN- release by murine splenocytes activated by LPS or porins of Salmonella Typhimurium

“…LPS is a potent stimulus of GH secretion [5] and also of IL-1. In vivo, IL-1 causes the release of GH [34]. These findings suggest that the process of infection or inflammation and consequent immune activation can affect neuroendocrine function.…”

Influence of Uterine Inflammation on the Estrous Cycle in Rats

“…At this time, t h e v o l u m e s o f c o r p o r a l u t e a a n d p l a s m a progesterone levels were significantly increased. Furthermore, Rettori et al [19] reported the release of prolactin, which stimulates corpora lutea, by IL-1 administration into the brain ventricles of rats. There is a possibility that the endometritis might induce release of prolactin via some cytokines.…”