ABSTRACT
The effect of in vitro stimulation of rat parotid gland with the neuropeptides substance P, calcitonin gene-related peptide and galanin has been studied by microfilament fluorescence staining and in semithin sections, and compared to control incubations and in vitro stimulation with beta-adrenergic and muscarinic agonists. Clear-cut aspects of massive granule exocytosis and cytoplasm vacuolation, indicative of protein and fluid secretion respectively, were obvious only after substance P stimulation, whereas treatment with galanin and calcitonin gene-related peptide produced little to no morphological changes. The results being in agreement with the outcome of other methodological approaches, these procedures appear reliable, may be effectively applied to the study of the functional regulation of secretory mechanisms, and may be particularly useful in human tissue analyses.
Subject(s)
Epithelial Cells/cytology , Epithelial Cells/metabolism , Neuropeptides/physiology , Parotid Gland/cytology , Parotid Gland/metabolism , Adrenergic beta-Agonists/pharmacology , Animals , Calcitonin Gene-Related Peptide/pharmacology , Calcitonin Gene-Related Peptide/physiology , Cells, Cultured , Epithelial Cells/drug effects , Exocytosis/drug effects , Exocytosis/physiology , Galanin/pharmacology , Galanin/physiology , Male , Muscarinic Agonists/pharmacology , Neuropeptides/pharmacology , Parotid Gland/drug effects , Rats , Rats, Wistar , Secretory Vesicles/drug effects , Secretory Vesicles/metabolism , Secretory Vesicles/ultrastructure , Substance P/pharmacology , Substance P/physiology , Vacuoles/drug effects , Vacuoles/metabolism , Vacuoles/ultrastructureABSTRACT
Oxytocin is a cyclic nonapeptide whose best known effects are stimulation of uterine smooth muscle cells during labor and of milk ejection during lactation. Circulating oxytocin originates from the hypothalamus, but its production has also been documented in peripheral tissues. Furthermore, seminal plasma also contains oxytocin, but its functional role is still unknown, although its secretion is generally ascribed to the prostate. In this study, we investigated the possibility that seminal oxytocin is also secreted by other exocrine glands of the human male genital tract. Intramural (Littrè's) glands isolated from bioptic specimens of normal urethrae were processed for immunogold localization of oxytocin. Immunostaining was detected in principal cells, with gold particles specifically found on secretory granules. Basal and endocrine cells were unstained. The present findings suggest that urethral glands not only produce the mucinous layer that protects and lubricates the urethral wall, but also are potential sources of other seminal components, such as oxytocin, which probably play still unclear roles in reproductive physiology.
