Lipid secretory mechanisms in the mammalian Harderian gland

✍ Scribed by Satoh, Yohichi; Gesase, Ainory Peter; Habara, Yoshiaki; Ono, Kazuyuki; Kanno, Tomio

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 890 KB
• Volume: 34
• Category: Article
• ISSN: 1059-910X
• DOI: 10.1002/(sici)1097-0029(19960601)34:2<104::aid-jemt2>3.0.co;2-s

✦ Synopsis

The mammalian Harderian glands are lipid-secreting glands. In an unstimulated condition, the glandular cells frequently exocytose the lipid materials; however, no intracellular calcium ion ([Ca2+l,) changes are detectable. Cholinergic (muscarinic) secretagogues induce secretory activity and increase of [Ca2+lc. A Gprotein activator, sodium fluoride, enhances the secretory activity and increase of [Ca2+Ic. Removal of extracellular calcium ions inhibits the secretion enhanced by cholinergic stimulation. Under pharmacologic stimulation, glandular cells may show an apocrine-like secretory pattern. Cholinergic stimulation also induces contraction of the myoepithelial cells covering glandular end pieces; however, the reduction in volume of glandular end pieces is not prominent. Catecholamines have no effect on the release of lipid materials. These results indicate the involvement of G-proteins linking with muscarinic receptors and Ca2+ dynamics (increase of [Ca2+l, and Ca2+ influx) in lipid secretion by glandular cells and in contraction of myoepithelial cells of mammalian Harderian glands. However, the increase of [Ca2 + I, in Harderian glands was less when compared with other cells-for instance, those which secrete protein.