Spermatogenesis in the vitamin A-deficient rat: possible interplay between retinoic acid receptors, androgen receptor and inhibin alpha-subunit.
In order to understand the mechanisms of retinol action on the testis, testicular retinoic acid receptor alpha, beta(RAR alpha and beta), androgen receptor (AR) and inhibin alpha-subunit were studied in normal, vitamin A-deficient (VAD) and vitamin A-supplemented rats by immunohistochemistry and immunoblotting. Compared to the normal testis, expression of 110 K AR was up-regulated by vitamin A withdrawal, whereas 51 K RAR alpha remained unchanged. An additional 55 K RAR alpha signal was observed. Readministration of retinol caused a marked decrease of AR in the VAD testis. By 24 h, AR declined to below the normal level. Although the 51 K RAR alpha signal remained unchanged, the 55 K band was slightly up-regulated at 6 h after retinol administration. A 51 K RAR beta protein was seen in the VAD but in not the normal testis. The intensity of the 51 K RAR beta band remained constant before and after the administration of retinol, but it had a slight up-shift at 6 h after retinol injection, suggesting post-translational modification of the receptor. The inhibin alpha-subunit of 18 K protein was undetectable in the VAD testis and increased to above normal level at 24 h after retinol administration. Immunohistochemically, nuclear AR immunostaining was more intense in the VAD testis than in the normal testis. The intensity of immunostaining declined in all AR-positive cells after the injection of retinol, but the decrease was more evident in Sertoli than in other cells. At 24 h after retinol the immunostaining was undetectable in most Sertoli cells. The regulation of the inhibin alpha-subunit by retinol in the cytoplasm of Sertoli cells detected by immunohistochemistry was correlated to the results in immunoblotting. These results suggest a possible interplay between retinoids, androgen and inhibin signalling systems in Sertoli cells in the regulation of spermatogenesis during retinol action.
Zhuang
Y H
YH
Department of Anatomy, Tampere University Medical School, Finland.
Bläuer
M
M
Ylikomi
T
T
Tuohimaa
P
P
D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D007265:Inhibins; D008297:Male; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011944:Receptors, Androgen / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism; D013091:Spermatogenesis / Q000187:drug effects / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology; D013737:Testis / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014162:Transfection; D014801:Vitamin A / Q000494:pharmacology; D014802:Vitamin A Deficiency / Q000378:metabolism*
D010455:Peptides; C000607073:Rara protein, rat; D011944:Receptors, Androgen; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; C094377:inhibin-alpha subunit; C082925:retinoic acid receptor beta; D014801:Vitamin A; D007265:Inhibins