Prolactin and testicular Leydig cell function: characterization of prolactin receptors in the murine MA-10 testicular Leydig cell line.

The direct role of prolactin (PRL) in testicular function is still unclear, mostly because of lack of a suitable in vitro model. To establish the suitability of the MA-10 murine tumor Leydig cell line for the study of PRL receptors (PRLR) and effects on steroidogenesis, we initially characterized PRLR on cultured MA-10 cells. The specific binding (Bs) of [125I]human growth hormone (hGH) depends on time, temperature, and Mg2+ ion and protein concentrations, with absolute specificity for the lactogenic hormones hGH and ovine PRL.

Effects of aging and physical training on the neuromuscular junction of the mouse.

The effects of age and physical exercise on synaptic function were studied in the neuromuscular junctions of three skeletal muscles of C57BL/6J mice subjected to a regimen of 10 weeks of physical training (30 min/day, 3.5 m/min). Synaptic function was found to be considerably reduced in old age, as revealed by the activity of the cholinergic enzymes choline acetyltransferase (CAT) and acetylcholinesterase (AChE).