Enzyme cytochemical evidence for the activation of adenylate cyclase in the follicle cells of vitellogenic oocytes by the dorsal body hormone in the snail Lymnaea stagnalis.

It is unknown what cell type(s) in the gonad of the hermaphroditic snail Lymnaea stagnalis is the target(s) of the two gonadotropic hormones, dorsal body hormone (DBH) and caudo-dorsal cell neuro-hormone (CDCH). It was considered that the hormones might act by activating the adenylate cyclase (AC)-cAMP system in the targets. AC activation was determined histochemically. The CDCH (ovulation hormone) titer can be manipulated in vivo by inducing egg laying experimentally ("clean water stimulus"). The effect of the oocyte growth-stimulating DBH and also that of CDCH was studied in in vitro experiments. Only the follicle cells appeared to possess and AC-cAMP system (experiments with forskolin). This system can be activated by DBH, but not by CDCH. Activation can only be brought about in certain stages of the egg-laying process. In vivo this activation was apparent from 30-45 min until 2-3 hr after ovulation, i.e., until 0-1 hr after egg mass deposition. In vitro activation was possible 0-30 min after ovulation. Activation was only obvious in certain stages of oogenesis (not in follicle cells of younger oocyte stages). The results indicate that it is the follicle cells that are the targets for DBH. The possible role of the follicle cells is discussed. The question of what are the targets of CDCH remains unsolved. Apparently this hormone does not act via AC-cAMP, but via another second messenger.