EFFECTS OF CASTRATION AND SEX STEROIDS ON NEUROKININ-A CONCENTRATIONS IN THE ANTERIOR-PITUITARY OF MALE-RATS

The effects of acute and chronic castration and the replacement treatment with testosterone, dihydrotestosterone, or estradiol on neurokinin A (NKA) concentrations in the anterior pituitary gland were studied in male rats. Acute castration (24 hr duration) and replacement treatment with testosterone did not result in significant changes in NKA in the anterior pituitary as compared with the levels of the peptide in intact male rats. Chronic castration was followed by a decrease of anterior pituitary NKA levels, the replacement treatment with estradiol benzoate resulted in a further significant decrease and testosterone and dihydrotestosterone restored NKA in the anterior pituitary at levels similar to those found in intact rats. These results suggest that NKA levels in the anterior pituitary gland may be regulated by gonadal steroids.