Effects of ergocornine and reserpine on metamorphosis in Bufo bufo japonicus tadpoles.

Effects of ergocornine and reserpine on tail resorption during metamorphosis in Bufo bufo japonicus tadpoles were studied. At prometamorphosis, ergocornine induced precocious tail resorption, while reserpine scarcely affected the tail size. At the climax of metamorphosis, ergocornine was almost ineffective in accelerating tail resorption, while reserpine was effective in inhibiting tail resorption. Since prolactin-like hormone is known to block the tail resorption induced by thyroid hormones, it was postulated that the release of the hormone is blocked by ergocornine during prometamorphosis and stimulated by reserpine during climax.