Stage-specific cellular regulation of inhibin alpha-subunit mRNA expression in the rat seminiferous epithelium

: Kaipia A, Parvinen M, Shimasaki S, Ling N, Toppari J

: 1991

: Molecular and Cellular Endocrinology

: Molecular and cellular endocrinology

: Mol Cell Endocrinol

: 82

: 2-3

: 165

: 73

: 9

: 0303-7207

DOI: https://doi.org/10.1016/0303-7207(91)90028-Q

To find out the local regulation of inhibin production and its possible paracrine role in the seminiferous epithelium, inhibin alpha mRNA levels were measured in sequential 1 mm segments of rat seminiferous tubules accurately staged by transillumination technique. Highest levels were found at stages XIV-I-IV of the cycle, and lowest at stages VI-VIIb of the cycle. When dividing spermatogonia were selectively destroyed by 3 Gy of high-energy X-irradiation, stage-specific inhibin alpha mRNA levels remained unchanged until 26 and 38 days after irradiation when stages VII and VIII of the cycle showed 6- and 4-fold increases during a selective reduction of pachytene spermatocyte and round spermatid numbers, respectively. The results suggest that these cells at a strictly stage-specific fashion have a paracrine inhibitory effect on Sertoli cell inhibin alpha gene expression. Inhibin alpha mRNA level also correlates closely to the follicle-stimulating hormone-stimulated cAMP production during the cycle of the seminiferous epithelium, but does not seem to have a correlation to spermatogonial DNA synthesis.