The role of bombesin in the mechanism of pituitary hormones release.

OBJECTIVES: Functional studies indicate that bombesin may be involved in many physiological functions, including sensory transmission, the regulation of central autonomic pathways, thermoregulation, secretion of pituitary hormones, gastric and pancreatic secretion, food intake and satiety.

MATERIAL AND METHODS: In order to evaluate the role of bombesin in the mechanism of pituitary hormones release the effects of bombesin on rGH, rTSH, rPRL, rFSH and rLH release were investigated in female Wistar-Kyoto rats. In studies 'in vitro' bombesin in a dose of 1nM, 10nM, 100nM was administered to pituitary cell culture. After 60, 120, 240 min. of incubation pituitary hormones were measured. In studies 'in vivo' bombesin was injected intraventricularly (icv) in a dose of 0.5 microg/5 microl aCSF (artificial cerebrospinal fluid) for 5 min. (experiment I). In experiment II bombesin was administered intravenously (iv) in a dose of 10 microg. After 60 min, 120 mins the animals were decapitated and serum rGH, rPRL, rTSH, rLH, rFSH concentrations were measured with RIA methods.

RESULTS: Bombesin stimulated rLH, rPRL, rTSH release from cultured pituitary cells. A slight increase of GH was also observed. After intravenous (iv) injection of bombesin an increase in serum rPRL and rGH levels was found. However, the intraventricular (icv) administration of bombesin leads to decrease of serum rGH, rPRL and rTSH concentrations.

CONCLUSION: Our studies 'in vitro' and 'in vivo' indicate that bombesin may be involved in the modulation of pituitary hormones release.