Demonstration of substances immunologically related to the identified arthropod neuropeptides AKH/RPCH in the CNS of several invertebrate species.

The occurrence of adipokinetic hormone (AKH) and red pigment concentrating hormone (RPCH)-like neuropeptides in the central nervous system of different invertebrate species other than insects was investigated immunocytochemically with polyclonal antisera to N- and C-terminal regions of the AKH molecule. Substances reacting with the C-terminal specific antiserum code 241 were present in neurons of the pond snail, Lymnaea stagnalis, the sowbug Porcellio scaber, the centiped Lithobius forficatus and the crayfish Astacus leptodactylus. Substances revealed by the N-terminal specific antiserum code 433 were demonstrated in the latter two species. The distribution of immunoreactive substances in neuropile areas of several ganglia suggests that these substances act as neurotransmitter/neuromodulator. Their presence in neurohemal organs such as the periphery of the pedal and visceral nerves in the pond snail and in the sinus gland of the crayfish suggests a neurohormonal role in these species.