Somatostatin-immunoreactive concentrations in human saliva and in the submandibular salivary glands of the rat. Possible sexual dependence in the human.

Many biologically active polypeptides have been detected either in the submandibular salivary glands (SSG) of the rat, and in the saliva of rats and humans. The present work has investigated the case of somatostatin (SRIF), since salivary data concerning the presence of this peptide are scarce and contradictory. In a group of healthy volunteers, SRIF-immunoreactivity (SRIF-IR) was tested in samples of mixed saliva. Not all the subjects revealed presence of SRIF-IR in saliva. For men, 5 out of 9 were positive (x = 26.40 +/- 10.03 pg/ml), whereas for women only one out of 10 was positive (x = 96.40 pg/ml). SRIF-IR was also determined in male rat submandibular glands from control animals (26.1 +/- 6.3 pg/mg protein, n = 18) and from animals injected one hour before with an alpha 1-adrenergic secretagogue, phenylephrine (27.9 +/- 7.1 pg/mg protein, n = 6). The results show that SRIF-IR is not constantly present in human saliva obtained from a young population, and that its presence apparently seems to differ between the sexes. On the other hand, the fact that SRIF-IR, unlike other peptides, is not modified when the animals are injected with phenylephrine, may simply indicate that the control mechanism of SRIF-IR release is not the same as that affecting other salivary peptides. Further studies must be carried out in order to elucidate the origin and role of salivary SRIF-IR.