thyrotropin-releasing hormone , a hypothalamic tripeptide that stimulates the secretion of pituitary thyroid-stimulating hormone in mammalian species and is widely distributed throughout the brain of vertebrates , is present in the skin of the frog ( rana pipiens ) in concentrations twice that found in the hypothalamus of this amphibian .
C0040162
thyrotropin-releasing hormone
C0032002
pituitary