Dopamine stimulates snail albumen gland glycoprotein secretion through the activation of a D1-like receptor

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 albumen 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 albumen gland is a highly regulated event that must be coordinated with the arrival of the fertilized ovum at the carrefour (the region where the eggs receive albumen gland secretory products). In order to elucidate the intracellular signalling pathway(s) mediating dopamineinduced glycoprotein secretion, albumen gland cAMP production and glycoprotein secretion were measured in the presence/absence of selected dopamine receptor agonists and antagonists. Dopamine D1-selective agonists dihydrexidine, 6,7-ADTN and SKF81297 stimulated cAMP production and glycoprotein secretion from isolated albumen glands whereas D1-selective antagonists SCH23390 and SKF83566 suppressed dopaminestimulated cAMP production. Dopamine D2-selective agonists and antagonists generally had no effect on cAMP production or protein secretion. Based on the effects of these compounds, a pharmacological profile was obtained that strongly suggests the presence of a dopamine D1-like receptor in the albumen gland of Helisoma duryi. In addition, secretion of albumen gland glycoprotein was not inhibited by protein kinase A inhibitors, suggesting that dopamine-stimulated protein secretion might occur through a protein kinase A-independent pathway.

Identification and evolutionary implications of neurotransmitter–ciliary interactions underlying the behavioral response to hypoxia inLymnaea stagnalisembryos

“…In contrast, the dopamine D2 antagonist domperidone was ineffective (Fig.8B), consistent with other studies on gastropods in which responses were typically blocked by only one of these antagonist types (Mukai et al, 2004;Dobson et al, 2006). The ability of SKF83566 to lower the rate of rotation indicates that the cilia driving embryonic rotation receive tonic dopaminergic stimulation.…”

Dopamine suppresses neuronal activity of Helisoma B5 neurons via a D2-like receptor, activating PLC and K channels

“…To rule out a potential role of D1-like receptors in mediating the effect of DA on RMP, we used a D1 receptor antagonist, SCH23390, to investigate whether the DAinduced hyperpolarization could be blocked when the D1-like receptor was inhibited (Magoski et al, 1995;Mukai et al, 2004). Whereas the pretreatment with 100 lM SCH23390, a concentration that has been demonstrated to be effective in Lymnaea, did not affect the RMP of B5 neurons (+0.4 ± 1.3 mV; n = 4, Fig.…”

Endocrine disruption in aquatic pulmonate molluscs: few evidences, many challenges

“…It also produces significant amounts of Lymnaea trypsin inhibitor (LTI), which may minimize digestion of peptides (e.g., L-EGF) and proteins in the perivitelline fluid that are important for the development of the embryos (Nagle et al 2001). Secretion of glycoproteins of the perivitelline fluid is mediated by dopamine, and recent studies strongly suggested the presence of a dopamine D1-like receptor in the albumen gland of H. duryi (Mukai et al 2004). Other molecules, such as FMRFamide, are secreted by CNS cells and affect egg laying among many other functions including heart rhythm and respiration (Saunders et al 1992).…”