On the interaction of thyroxine and of oxytocin with prolactin on the growth of the tail fin in the red-spotted newt

摘要: Abstract Changes in the height of tail fin were followed over periods 3 to 4 weeks hypophysectomized or intact adult male, laboratory-conditioned red-spotted newts that injected thrice weekly with doses thyroxine (T ), ovine prolactin, T and prolactin combination, oxytocin. In groups animals, highest dose (10 μg) had a toxic effect when given alone. When combination it apparently antagonized stimulatory action growth fin. The animals receiving it, however, ate sparingly, if at all, suggesting may have been one general toxicity rather than direct inhibition. A very low (0.001 also appeared be antagonistic (0.3 U), but was shown instead below level necessary maintain survival after removal pituitary gland. Doses 1.0 0.01 μg adequate for gave no evidence antagonizing on These findings suggest among those urodeles retain as adults, typical larval antagonism (at physiological levels) somatotropic ceases once metamorphosis is complete. Oxytocin 100 μU did not alter fin, 0.3 U prolactin. It suggested interaction osmoregulatory nature.