Ovarian stretch signals trigger volume increase in the magnocellular preoptic nuclear region in the brain of the catfish, Clarias batrachus (Linn.)

Intraovarian pressure of 10, 20, and 30 mm Hg magnitude was administered in the fish, Clarias batrachus, and the volume changes undergone by the magnocellular preoptic nucleus (NPO) were examined using serial brain sections of treated and sham-treated fish. The treatment consistently resulted in statistically significant (P<0.001) increase in the volume of the NPO; a rise of up to 46.48% was observed in the paraventricular subdivision of the NPO following 20 mm Hg intraovarian pressure administration. The response was abolished following transection of the spinal cord. The results suggest the occurrence of an afferent pathway from the ovary capable of transducing stretch signals and conveying action potentials to the NPO via the spinal cord. The possibility that the pathway might serve as an afferent component in the spawning reflex is examined. © 1992 Wiley-Liss, Inc.