Growth hormone, prolactin and FSH release by the tachykinin dodecapeptide kassinin in the rat.

The effect of equimolar doses of kassinin, a newly discovered tachykinin dodecapeptide, and substance P on serum growth hormone, prolactin and FSH was examined in adult male Fischer 344 rats. The two peptides were injected intravenously 10 or 30 min prior to blood collection by decapitation. Kassinin in concentrations of 0.3 and 3.0 micrograms/100 g B.W., potently stimulated release of growth hormone. Both kassinin and substance P decreased prolactin at the lowest dose. An increase of serum prolactin above control values by both peptides was observed at the highest dose administered. However, this increase with the highest dose depended on the time of blood collection. Serum FSH was increased only by injection of the highest dose of kassinin or substance P. These results demonstrate that kassinin and substance P have similar effects on the secretion of these hormones. The findings provide further evidence for an involvement of peptidergic neurons in the regulation of pituitary function. Kassinin, if present in central and peripheral neurons of the mammalian central and autonomic nervous system and in the cells of the diffuse neuroendocrine system, could function as a neuropeptide.