Neonatal treatment with TRH affects development, learning, and emotionality in the rat.

Rats that received injections of TRH from Days 2-7 postnatally ran faster to a palatable food reward than controls at 33-37 days of age. Rats treated with TRH were less emotional and more active in an open field both as pups and as adults. There were few notable differences in developmental measures except that the teeth erupted earlier in control animals. Weights of glands and brain parts showed that ovaries, testes, pineal gland, and hypothalamus were heavier in treated animals. The results indicated that TRH given early in life may affect adult behavior by reducing emotionally.