Glutamate-induced rise in cytosolic calcium concentration stimulates in vitro rates of juvenile hormone biosynthesis in corpus allatum of Diploptera punctata

We show that in a cockroach, Diploptera punctata, endocrine function of the corpus allatum may be modulated by L-glutamate, a major fast excitatory ne urotransmitter in the central nervous system of vertebrates and invertebrat es. The widely accepted concept that synthesis of juvenile hormone (JH) dep ends upon intracellular calcium concentration, is extended by the finding t hat 60 and 100 mu M L-glutamate induces both an increase in calcium concent ration in the cytosol of corpus allatum cells, and stimulates JH synthesis in vitro. We show that L-glutamate stimulates JH synthesis by inducing calc ium influx since in calcium-free medium the stimulatory effect is not obser ved. Furthermore; the non-specific glutamate-receptor antagonist, 100 mu M kynurenate, and 1.8 mM magnesium, inhibit the stimulatory effect of L-gluta mate on JH synthesis in vitro. These results suggest that functional ionotr opic glutamate receptors are present on the surface of:the cells in corpus allatum, and that rates of JH are at least in part regulated via these rece ptors. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.