PITUITARY GONADOTROPINS AND THEIR VARIABILITY - STUDIES IN EXPERIMENTAL-ANIMALS

The pituitary gonadotrophins, luteinizing hormone and follicle-stimulating hormone are not uniform molecular structures but rather an array of isoforms that are hormonally regulated. These isohormones differ from each other in their physicochemical properties, relative abundance, receptor-binding activity and biological potency. Differences in abundance may be found between sexes, after castration, throughout sexual maturation, during the oestrous cycle and after specific pharmacologic manipulations performed on experimental animals. The overall data has indicated that the sourrounding endocrine milieu, present at a given time, determines the specific types of gonadotrophin molecules to be synthetisized, processed and secreted by the pituitary gland and consequently, the potency and intensity of the gonadotrophin signal to the gonad.