Title

Protocerebral neurons inhibiting proliferation of corpus allatum cells in the cockroach, Diploptera punctata

Abstract

A mitotic wave before an increase in juvenile hormone (JH) synthesis was observed in the corpora allata during each ovarian cycle in the cockroach Diploptera punctata and was shown subsequently to be inhibited by the brain until adult females mated. Each corpus allatum (CA) was innervated by groups of neurons in the contralateral pars intercerebralis (PI) and the ipsilateral pars lateralis (PL). In this article, a third set of neurons is identified that innervates the CA located extralaterally in the contralateral PL. The topography of the brain neurons innervating the CA was reconstructed from confocal optical sections after vital staining with two fluorescent carbocyanine dyes, 1,1'-dihexadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate [DiIC (3)] and 3,3'-dioctadecyloxacarbocyanine perchlorate [DiOC (3)]. This provided information necessary to disconnect specific pathways within the brain of virgin females and to determine the effect on mitosis in the corpora allata and on the growth of oocytes. Disconnection of the CA from the PI neurons was followed by a prolonged period of moderate mitotic activity in the glands. Disconnection of the CA from PI and contralateral PL neurons was followed by a rapid wave of high mitotic activity in the CA similar to that observed after mating. The ipsilateral PL neurons did not appear to influence CA cell proliferation, because mitotic activity in glands was similar whether or not glands were connected to these neurons. Disconnection of the contralateral PI and/or ipsilateral PL neurons, but not the contralateral PL neurons, from the CA resulted in oocyte growth indicative of increased JH synthesis. The authors conclude that, whereas contralateral PI neurons inhibit both CA cell proliferation and JH synthesis, ipsilateral PL neurons affect only JH synthesis, and contralateral PL neurons modulate cell proliferation slightly only. 16 18

Document Type

Article

DOI

https://doi.org/10.1002/(SICI)1096-9861(19991101)413:4<593::AID-CNE8>3.0.CO;2-H

Keywords

1, 1'dihexadecyl- 3, 3, 3', 3'-tetramethylindocarbocyanine perchlorate, 3, 3'- dioctadecyloxacarbocyanine perchlorate, Brain, Confocal images, Corpora allata, Juvenile hormone

Publication Date

11-1-1999

Journal Title

Journal of Comparative Neurology

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