THE BRAIN NEUROSECRETORY-CELLS OF THE MOTH SAMIA-CYNTHIA-RICINI - IMMUNOHISTOCHEMICAL LOCALIZATION AND DEVELOPMENTAL-CHANGES OF THE SAMIA HOMOLOGS OF THE BOMBYX PROTHORACICOTROPIC HORMONE AND BOMBYXIN

We produced mouse antisera against synthetic peptides corresponding to the sequences of the Samia cynthia ricini homologues of the Bombyx mo ri PTTH and bombyxin. Immunohistochemical analyses of the Samia cephal ic neuroendocrine system using these antisera were performed to identi fy the neurosecretory cells (NSC) containing the PTTH and bombyxin hom ologues and to examine the developmental changes in their amounts in t he NSC. The results show that the PTTH and bombyxin homologues are pro duced by two pairs of dorsolateral and 16 pairs of dorsomedial NSC of Samia brain, respectively, and both are transported to, and released f rom, the corpora allata. No clear-cut correlation was found between th e fluctuation in the amount of immunoreactive substances in the brain NSC and the endocrinologically anticipated timings of PTTH secretion. From Samia brain extract, two forms of PTTH activity (similar to 30 kD a and similar to 5 kDa) were resolved through Sephadex gel filtration. The similar to 30 kDa and similar to 5 kDa PTTH seem to represent the PTTH and bombyxin homologues, respectively. We discuss that the simil ar to 30 kDa PTTH homologue is the true PTTH of Samia.