Activation of intracellular signalling pathway of Helisoma duryi snail albumin gland after treatment with dopamine

ABSTRACT

The catecholamine dopamine is present in both the central nervous system and in the peripheral tissues of molluscs, where it is involved in regulating reproduction. Application of exogenous dopamine to the isolated albumin gland of the freshwater pulmonate snail Helisoma duryi [Wetherby] induces the secretion [release] of perivitelline fluid. The major protein component of the perivitelline fluid of Helisoma duryi is a native 288 kDa glycoprotein that is secreted around individual eggs and serves as an important source of nutrients for the developing embryos. The secretion of glycoprotein by the albumin gland is a highly regulated event that must be coordinated with the arrival of the fertilizedovum at the carrefour [the region where the eggs receive albumin gland secretory products]. In order to elucidate the intracellular signalling pathway[s] mediating dopamine-induced glycoprotein secretion, albumin gland cAMP production and glycoprotein secretion were measured in the presence/absence of selected dopamine receptor agonists and antagonists. Dopamine D1-selective agonists [dihydrexidine, amino-6,7-dihydroxy-1, 2, 3, 4-tetrahydronapthalene and 6-chloro-7, 8- dihydroxy-pheny1- 2, 3, 4, 5-tetrahydro- 1H-3-benzazepine hydrobromide] stimulated cAMP production and glycoprotein secretion from isolated albumin glands whereas D1-selective antagonists [7-chloro-8-hydroxy-3-methyl-1-pheny1-2, 3, 4, 5-tetrahydo-1H-3-benzazepine hydrochlovandde and 7-bromo- 8-hydroxy-3meth1-2, 3, 4, 5-tetrahydro-1H-3-benzazepine hydrochloride] suppressed dopamine-stimulated cAMP production. Dopamine D2-sclcctivc agonists and antagonists generally had no effect on cAMP production or protein secretion. The results obtained strongly suggests the presence of a dopamine D1-like receptor in the albumin gland of Helisoma duryi