Signal transduction in multifactorial neuroendocrine control of gonadotropin secretion and synthesis in teleosts—studies on the goldfish model

In teleosts, gonadotropin (GTH) secretion and synthesis is controlled by multiple neuroendocrine factors from the hypothalamus, pituitary and peripheral sources. Pituitary gonadotropes must be able to differentiate and integrate information from these regulators at the cellular and intracellular level. In this article, the intracellular signal transduction mechanisms mediating the actions of some of these regulators, including GTH-releasing hormones, pituitary adenylate cyclase-activating polypeptide, dopamine, ghrelin, sex steroids, activin, and follistatin from experiments with goldfish are reviewed and discussed in relation with recent findings. Information from other teleost models is briefly compared. Goldfish gonadotropes possess multiple pharmacologically distinct intracellular Ca2+ stores that together with voltage-sensitive Ca2+ channels, Na+/H+ exchangers, protein kinase C, arachidonic acid, NO, protein kinase A, ERK/MAPK, and Smads allows for integrated control by different neuroendocrine factors.