Proliferation of skeletal muscle satellite cells after castration and administration of testosterone propionate.
Thirty-six neonatal pigs were randomly assigned to the following treatment groups: sham implanted gonadally intact males (B), sham-implanted castrated males (C), or castrated males implanted with testosterone propionate (C + TP). Four pigs from each group were sacrificed at 7, 14, or 21 days of age after a 6-hr continuous infusion of [3H]thymidine. Myofibers isolated from the triceps brachii were prepared for satellite cell enumeration by light microscope autoradiography. A developmental decline in labeled myofiber nuclei occurred in all groups, however, the greatest decline occurred in C (P less than 0.01). A treatment-by-age interaction was observed for percentage of labeled nuclei. Castration reduced total and labeled nuclei per millimeter myofiber (P less than 0.05), and C + TP had a higher percentage of labeled nuclei than C (2.8 vs 2.2%; P less than 0.05). Since triceps brachii muscles from 21 day B and C + TP were 120% (P less than 0.05) of C, the results indicate that postnatal growth of skeletal muscle is dependent on satellite cell mitotic activity and that testosterone enhances this activity in neonatal pigs.
Mulvaney
D R
DR
Department of Animal and Dairy Sciences, Auburn University, Alabama 36849.
Marple
D N
DN
Merkel
R A
RA
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D008297:Male; D009132:Muscles / Q000166:cytology* / Q000187:drug effects; D009919:Orchiectomy; D013552:Swine; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone