[Skeletal muscle histomorphometric study of rats in anestrus]

Castration, as well as the menopause, represents endocrine suppression that prevails the hypoestrogenism and their larger consequence on the skeletal muscle is to provoke sarcopenia.

To study the morphometric alteration of striated muscle of castrated female rats.

Twenty six female rats Wistar , distributed in two sub-groups, A and B, submitted initially to weigh-in place, vaginal cytology, ovariectomy, and biopsy of the muscle rectus femoris on the back paws, A group on right paw, and B on the left. Elapsed 20 days it was collected vaginal cytology to prove the anestrus status. After 70 days the animals went through weigh-in place, and new muscle biopsy, A group in left paw and B in right paw. The morphometric study was accomplished with the aids of a graduated lens, with reticules of 100 mm2, it was counted the myofibrils with six readings in the vertical and five in the horizontal in each sheet, being obtained a multiple number that applied on a specific formula to calculate the coefficient of muscular density.

In A the muscular density varied from 60.0 to 52.33, (p<0.05%), with variation of 14.12%, and in B from 73.5 to 54.0, (p<0.05%), with variation of 26.53%.

The castration provoked sarcopenia in the striated muscle and reduction of myofibrils number.