Evidence of apoptosis in the castration-induced atrophy of the rat levator ani muscle

Apoptosis or programmed cell death has been previously reported in androgen-responsive tissue such as the prostate. We tested the hypothesis that apoptosis may also represent a component of the castration-induced atrophy of the sexually dimorphic levator ani (LA) muscle of the male rat. Gonadectomy (GDX) induced a severe decrease in the LA muscle wet weight accompanied by important modifications in cytoarchitecture including an increase in myofibrillar interspace and condensed mitochondria. These alterations were almost completely reversed after 7 days of testosterone propionate replacement therapy (GDX + TP). In GDX rats, internucleosomal DNA Fragmentation was confirmed by both agarose gel electrophoresis and electron microscopy. DNA fragmentation was no longer detected in GDX + TP rats. In GDX rats, overexpression of the trpm-2/clusterin gene, used as an early marker of apoptosis, further confirmed that an apoptotic response, typical of androgen-responsive tissues, is taking place following androgen withdrawal.