Elevation of plasma prolactin concentrations by low temperature is the cause of spermatogonial cell death in the newt, Cynops pyrrhogaster

Temperature plays an important role in reproduction of urodeles. Spermatoge nesis in newts is arrested when the environmental temperature lowers. We fo und that transfer of newts, Cynops pyrrhogaster, to low temperature (8 and 12 degrees C) caused cell death of spermatogonia just before meiosis and el evation of prolactin concentration in the newt plasma. Injection of a dopam ine antagonist (pimozide), which is known to increase the plasma prolactin concentration, to the newt caused significant increase of spermatogonial de generation, whereas treatment with an agonist (bromocryptin), which is know n to decrease the prolactin concentration, suppressed the cell death. Final ly, injection of anti-prolactin serum into the newts which had been transfe rred to low temperature almost completely inhibited the spermatogonial dege neration for as long as 3 days. These results demonstrate that low temperat ure caused elevation of prolactin concentration in the newt blood, which in duced cell death of spermatogonia just before meiosis. (C) 1999 Academic Pr ess.