IN-VITRO PEPTIDERGIC NEURONS FROM THE ADULT LOCUST PARS INTERCEREBRALIS - MORPHOLOGICAL AND IMMUNOCYTOLOGICAL STUDIES

Primary cell cultures were prepared from a major neurosecretory center of the: adult locust brain, the pars intercerebralis, in order to cha racterize neurosecretory cells growing in vitro. Individual pars inter cerebralis could be removed free of surrounding tissue and dissociated by mechanical treatment. Mature neurosecretory neurons of different s izes regenerate new neurites during the initial three days in vitro in serum-free medium. They show a tendency to sprout one primary neurite from which fine processes develop. By means of electron microscopy, w e observed the integrity of the cellular organelles, indicating that c ultured neurons are healthy, and we were able to distinguish three typ es of neurosecretory neurons on the basis of the ultrastructural aspec ts of the neurosecretory material. These three types have the same ult rastructural characteristics as in situ neuroparsin, ovary maturing pa rsin and locust insulin related peptide neurons. Immunogold labelling at the electron microscopic level, using the two available specific an tibodies, anti-neuroparsin and anti-ovary maturing parsin, confirms th e morphological characterization of neuroparsin and ovary maturing par sin cells. These results show for the first time that cultured locust neurosecretory neurons behave like those in vivo, in terms of their ul trastructure and immunocytochemistry. Moreover, the presence of recent ly-formed neurosecretory material both in the Golgi zone of the perika ryon and in the neuronal processes indicates that cultured neurons hav e functional capacity since they are able to synthesize de novo and to transport the neurosecretory material along the neurite. Thus our wel l-characterized culture system provides a suitable in vitro model to i nvestigate the secretory mechanism of locust neurosecretory neurons.