ACTIVATION OF HYPOTHALAMIC NEURONS BY INTRAOVARIAN PRESSURE SIGNALS IN A TELEOST FISH, CLARIAS-BATRACHUS - ROLE OF MECHANOSENSITIVE CHANNELS

Application of intraovarian pressure is known to trigger profound cyto morphological changes in the neurosecretory cells of nucleus preopticu s in the teleost Clarias batrachus. These findings indicate the presen ce of stretch receptors in the ovaries, perhaps equipped with mechanos ensitive channels that transduce the stretch signals to be transmitted to the brain. To test the occurrence of the mechanosensitive channels in the ovaries, we administered a range of pharmacological agents (li gnocaine, quinidine, tetraethylammonium chloride, ethylenediaminetetra acetic acid and gadolinium) known to block the mechanosensitive ion ch annels, in the ovarian lumen prior to the administration of the intrao varian pressure. Pretreatment with the above agents inhibited the resp onse by the nucleus preopticus neurosecretory cells to intraovarian pr essure. The results suggest the occurrence of the mechanosensitive cha nnels in the ovaries of teleostean fishes. In terms of function we spe culate that the stretch sensory system and the ensuing pathway connect ing the ovaries with the hypothalamus might play a role in apprising t he brain of the status of ovarian maturity and in the initiation of th e spawning reflex.