Release of neurosecretory granules within the corpus allatum in relation to the regulation of juvenile hormone synthesis in Diploptera punctata

• Published in: Insect biochemistry and molecular biology Vol. 30; no. 8; pp. 739 - 746
• Main Authors: Lloyd, Gerry T, Woodhead, Andrea P, Stay, Barbara
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-09-2000
• Subjects: Allatostatin; Animals; Brain - metabolism; Cockroach; Cockroaches - metabolism; Corpora Allata - metabolism; Diploptera punctata; ELISA; Exocytosis - physiology; Female; Hormone Antagonists - metabolism; Immunocytochemistry; Juvenile hormone synthesis; Juvenile Hormones - biosynthesis; Male; Neuropeptides - metabolism; Neurosecretion - physiology; Neurosecretory exocytosis; Cockroach; Juvenile hormone synthesis; Neurosecretory exocytosis; Immunocytochemistry; Allatostatin; ELISA
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/S0965-1748(00)00045-X

The release of neurosecretory granules within the corpora allata (CA) of the viviparous cockroach
Diploptera punctata has been compared in glands with intact nerves from the brain (Brain–CA) and those detached from the brain. Measurements of juvenile hormone (JH) synthesis in vitro, comparing these two conditions of the CA at several stages of vitellogenesis in adult females, showed lower production of hormone in Brain–CA complexes than in CA alone. Glands treated with tannic acid to trap exocytotic granules before fixation for electron microscopical examination showed, in sample sections, 10 times more exocytotic profiles in the glands with intact nerves to the brain than in the isolated glands. Sections treated with antibody against allatostatin I (Dip 7), a member of the neuropeptide family that inhibits JH synthesis by CA in vitro, showed neurosecretory granules in allatostatin immunoreactive nerves to be 75±4% of the granules in the sample of sections of CA. Because the total quantity of allatostatin in CA was found by ELISA not to vary significantly with changes in JH synthesis, it is concluded that the lower rates of JH synthesis by glands with intact nerves to the brain are most likely due to the release of small amounts of allatostatin within the CA.