Hypothalamic stimulation of prolactin release in a freshwater catfish, Heteropneustes fossilis.

Hypothalamic extract has been found to contain certain factor(s) which triggers the release of prolactin from the pituitary gland. In assay recipients, hypothalamic extract injection was as effective as perphenazine-HCl treatment in triggering the release of prolactin from pituitary gland. Rise in prolactin concentration of serum and resultant decrease in pituitary prolactin level in response to hypothalamic extract administration suggests that hypothalamus in H. fossilis has prolactin releasing factor(s). This releasing effect of hypothalamus seems to be specific since cortical extract injections were ineffective in producing the similar response.