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

Abstract

We show that in a cockroach, Diploptera punctata, endocrine function of the corpus allatum may be modulated by l-glutamate, a major fast excitatory neurotransmitter in the central nervous system of vertebrates and invertebrates. The widely accepted concept that synthesis of juvenile hormone (JH) depends upon intracellular calcium concentration, is extended by the finding that 60 and 100 μM l-glutamate induces both an increase in calcium concentration in the cytosol of corpus allatum cells, and stimulates JH synthesis in vitro. We show that l-glutamate stimulates JH synthesis by inducing calcium influx since in calcium-free medium the stimulatory effect is not observed. Furthermore, the non-specific glutamate-receptor antagonist, 100 μM kynurenate, and 1.8 mM magnesium, inhibit the stimulatory effect of l-glutamate on JH synthesis in vitro. These results suggest that functional ionotropic 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 receptors.