A NEUROTRANSMITTER ROLE FOR RED-PIGMENT-CONCENTRATING HORMONE IN OVARIAN MATURATION IN THE RED SWAMP CRAYFISH PROCAMBARUS-CLARKII

The influence of red-pigment-concentrating hormone (RPCH) on ovarian m aturation in the red swamp crayfish Procambarus clarkii was studied us ing both in vivo and in vitro techniques. In vivo, RPCH stimulated ova rian maturation, However, RPCH did not affect the ovary in vitro when only RPCH, muscle and ovarian explants were used, But when RPCH, thora cic ganglia, which are known to contain gonad-stimulating hormone-like (GSH-like) activity, and ovarian explants were incubated together, si gnificant ovarian maturation ensued, The calcium ionophore A23187 mimi cked RPCH both in vivo and in vitro, These results provide evidence to support the hypothesis that RPCH has a role as a neurotransmitter in Procambarus clarkii to stimulate GSH release, with calcium acting as a second messenger for RPCH.