Peptidylarginine deiminase in rat pituitary: sex difference, estrous cycle-related changes, and estrogen dependence.

We have found notable sex difference in peptidylarginine deiminase (EC 3.5.3.15) in rat pituitaries. Pituitaries collected from 3-week to 6-month-old male rats, and those from 3-week-old females showed negligible enzyme activities. The enzyme activity of female pituitaries increased markedly by 2 months, and even further by 6 months of age. Measurements of the enzyme activity around the estrous cycle revealed its characteristic change, being high in the proestrus and estrus, and low in the metestrus and diestrus. These changes of the enzyme activity were shown to reflect changes of the actual amount of a single type of peptidylarginine deiminase by immunoprecipitation and immunoblotting analyses using an antiserum raised to an enzyme sample purified from rat skeletal muscle. The amount of pituitary enzyme was impoverished by ovariectomy. Repeated injections of 17 beta-estradiol to ovariectomized rats substantially restored the pituitary enzyme level. The above data suggest involvement of peptidylarginine deiminase in the female pituitary function.