In a previous work on human submandibular gland treated in vitro with secretagogue drugs we were able to quantitate the response to stimulation calculating, with statistical methods, the number of microvilli per µm2 (density) in the luminal membrane observed by HRSEM from its cytoplasmic surface. With the same procedure, we have calculated also the number of microbuds, considered as the morphological aspect of membrane recycling after granule exocytosis. In fact, we demonstrated that, after stimulation with secretagogues, the density of microvilli decreased whereas that of microbuds increased. However, the two values are not inversely proportional. Recently, we have reported that, in human submandibular specimens treated in vitro with atropine before carbachol (muscarinic full agonist), secretory phenomena, evaluated according to the above cited statistical method, appeared, by HRSEM, not completely inhibited. The density of microvilli, in fact, was still significantly decreased with respect to that of control; on the other hand, the density of microbuds did not differ significantly from control values. Since atropine is a well known antagonist of muscarinic receptors and it is used at surgery to block glandular secretion, the persistence of some signs of secretion in specimens pre-treated with atropine before carbachol in the previous experiment remained without explanation. In order to better understand the effect of atropine on serous cells secretions, we treated specimens of human parotid with atropine and calculated, with the statistical method previously described, the density of microvilli and of microbuds on the cytoplasmic surfaces of secretory canaliculi seen by HRSEM, after our modified osmium maceration procedure. Biopsy specimens of human parotid glands were incubated in vitro with an inorganic oxygenated medium containing 20µM atropine. Controls were incubated in the same medium without the drug. Following treatment with atropine, most canaliculi appeared, by HRSEM, similar to controls, and their cytoplasmic side did not exhibit the protrusions characteristic of exocytotic processes described in a previous paper. To quantitate the extent of atropine inhibition with regard to secretory processes, we calculated, from HRSEM images, the density of microvilli and that of microbuds on cytoplasmic intercellular canaliculi surfaces in treated and control specimens. After atropine incubation the mean numbers of both microvilii and microbuds were similar to controls (P>0.05, Mann-Whitney D-test). These morphometric results indicate that atropine used alone does not change the basal secretion of serous cells. Even if further studied are needed to clarify the discrepancy between response to atropine alone and that to atropine/carbachol, we may ipothesize a stimulatory action of carbachol on intraglandular nerve terminals not sensitive to atropine.
A morphological study by HRSEM of human parotid glands treated in vitro with atropine
LOY, FRANCESCO;
2006-01-01
Abstract
In a previous work on human submandibular gland treated in vitro with secretagogue drugs we were able to quantitate the response to stimulation calculating, with statistical methods, the number of microvilli per µm2 (density) in the luminal membrane observed by HRSEM from its cytoplasmic surface. With the same procedure, we have calculated also the number of microbuds, considered as the morphological aspect of membrane recycling after granule exocytosis. In fact, we demonstrated that, after stimulation with secretagogues, the density of microvilli decreased whereas that of microbuds increased. However, the two values are not inversely proportional. Recently, we have reported that, in human submandibular specimens treated in vitro with atropine before carbachol (muscarinic full agonist), secretory phenomena, evaluated according to the above cited statistical method, appeared, by HRSEM, not completely inhibited. The density of microvilli, in fact, was still significantly decreased with respect to that of control; on the other hand, the density of microbuds did not differ significantly from control values. Since atropine is a well known antagonist of muscarinic receptors and it is used at surgery to block glandular secretion, the persistence of some signs of secretion in specimens pre-treated with atropine before carbachol in the previous experiment remained without explanation. In order to better understand the effect of atropine on serous cells secretions, we treated specimens of human parotid with atropine and calculated, with the statistical method previously described, the density of microvilli and of microbuds on the cytoplasmic surfaces of secretory canaliculi seen by HRSEM, after our modified osmium maceration procedure. Biopsy specimens of human parotid glands were incubated in vitro with an inorganic oxygenated medium containing 20µM atropine. Controls were incubated in the same medium without the drug. Following treatment with atropine, most canaliculi appeared, by HRSEM, similar to controls, and their cytoplasmic side did not exhibit the protrusions characteristic of exocytotic processes described in a previous paper. To quantitate the extent of atropine inhibition with regard to secretory processes, we calculated, from HRSEM images, the density of microvilli and that of microbuds on cytoplasmic intercellular canaliculi surfaces in treated and control specimens. After atropine incubation the mean numbers of both microvilii and microbuds were similar to controls (P>0.05, Mann-Whitney D-test). These morphometric results indicate that atropine used alone does not change the basal secretion of serous cells. Even if further studied are needed to clarify the discrepancy between response to atropine alone and that to atropine/carbachol, we may ipothesize a stimulatory action of carbachol on intraglandular nerve terminals not sensitive to atropine.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
