Abstract
Application of intraovarian pressure is known to trigger profound cytomorphological changes in the neurosecretory cells of nucleus preopticus in the teleost Clarias batrachus. These findings indicate the presence of stretch receptors in the ovaries, perhaps equipped with mechanosensitive 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 (lignocaine, quinidine, tetraethylammonium chloride, ethylenediaminetetraacetic acid and gadolinium) known to block the mechanosensitive ion channels, in the ovarian lumen prior to the administration of the intraovarian pressure. Pretreatment with the above agents inhibited the response by the nucleus preopticus neurosecretory cells to intraovarian pressure. The results suggest the occurrence of the mechanosensitive channels in the ovaries of teleostean fishes. In terms of function we speculate that the stretch sensory system and the ensuing pathway connecting the ovaries with the hypothalamus might play a role in apprising the brain of the status of ovarian maturity and in the initiation of the spawning reflex.