Study on high molecular weight androgen binding protein in submandibular gland of rat

Abstract

Testosterone (T) and 5 alpha-dihydrotestosterone (DHT) binding to cytosol and nuclear extract were investigated in the submandibular gland (SMG) and ventral prostate (VP) of rat at 3 and 7 weeks of age. The concentration of T and DHT were also measured by a specific radioimmunoassay (RIA) in the cytosol and nuclei of the tissues. The androgen binding protein analyzed by Sephacryl S-200 column chromatography showed a single binding peak in the nuclei and two critical peaks in the cytosol at 7 weeks old SMG and VP. The binding proteins were recovered predominantly as the mol wt of 150-200 kDa and 14-20 kDa in the cytosol and as a mol wt of 14-20 kDa in the nuclei. The two kinds of androgen binding protein were also revealed in the cytosol of 3 weeks old rat SMG. However, the S-200 column chromatography did not reveal the 150-200 kDa protein in the prostatic cytosol from 3 weeks rat, showing one binding peak of 14-20 kDa protein. The 150-200 kDa protein was specific to T in SMG at 3rd week and to DHT at 7th week in VP. The amount of specific binding of DHT to the 150-200 kDa protein was the greatest in VP cytosol of 7th week. The specific binding to the nuclear protein was shown by T in SMG at 3rd week and by DHT in VP at 7th week. High androgen concentrations were observed in the nuclei of male SMG (T: 3.92 +/- 0.72 ng/g, DHT: 4.14 +/- 0.51 ng/g) and the values were higher than in the nuclei of VP (T: 2.69 +/- 0.70 ng/g, DHT: 2.85 +/- 0.67 ng/g) at 3 weeks old. The values in SMG decreased to the levels of 1.67 +/- 0.68 ng/g for T and 1.19 +/- 0.09 ng/g for DHT at 7 weeks. The accumulation of T and DHT in the nuclei of VP were shown at 7 weeks old, revealing 4.29 +/- 3.18 ng/g for T and 5.53 +/- 2.39 ng/g for DHT. The cytosolic androgen levels in VP rather decreased from the 3rd week (T: 2.78 +/- 1.20 ng/g, DHT: 3.57 +/- 2.31 ng/g) to the 7th week (T: 1.33 +/- 0.40 ng/g, DHT: 1.80 +/- 0.66 ng/g). The T and DHT values in male cytosol and female cytosol and nuclei of SMG did not show a distinct increase or decrease with age.(ABSTRACT TRUNCATED AT 400 WORDS)