[Effects of testosterone and estradiol-17 beta on the secretory granules of rat submandibular gland].

Abstract

The effects of testosterone and estradiol-17 beta on the protein components, amino acid compositions and trypsin-like protease activities in the secretory granules of granular duct cells of rat submandibular glands were assayed. Male and female adult rats were divided into 4 groups, non treatment (control), castrated, testosterone injected and estradiol-17 beta injected groups. The castrated rats were received 5 injections of 5 mg/kg testosterone or 500 micrograms/kg estradiol-17 beta every other day 3 weeks after the castration. The secretory granules of submandibular gland obtained from each group were prepared using centrifugal fractionation with sucrose step gradient. The protein components of secretory granule were separated by 5-15% SDS-PAGE, and the SDS-PAGE revealed the characteristic proteins of MW 39,000 in male and MW 37,000 in female. The MW 39,000 and the MW 37,000 protein was disappeared by testectomy and ovaryectomy, respectively. The MW 39,000 protein was reappeared in the castrated male rat treated by testosterone and shown in castrated female rat treated by the same steroid. Similary the MW 37,000 protein was found in the castrated male and female rats treated by estradiol-17 beta. From the results of amino acid composition analysis, abundant Asp, Ser, Glu and Gly were revealed in the MW 39,000 protein and MW 37,000 protein. Trypsin-like protease activity located in secretory granule was reduced by castration in both male and female, however, the enzyme activities were elevated by testosterone or estradiol-17 beta injection, revealing rather higher activities than control. It was demonstrated that the secretory granule of rat submandibular gland contained the testosterone dependent protein having a MW of 39,000 and the estradiol-17 beta dependent protein having a MW of 37,000 and that the trypsin-like protease activities in the granules were sensitive to both testosterone and estradiol-17 beta.