TESTOSTERONE CONTROL OF END-PLATE AND NON-END-PLATE ACETYLCHOLINESTERASE IN THE RAT LEVATOR ANI MUSCLE

The time course of effects of castration (5-60 days) and testosterone treatment (15-60 days) of adult male rats were examined on the endplat e (+EP) and non-endplate (-EP) acetylcholinesterase (AChE) of the andr ogen-dependent levator ani (LA) muscle. The thiocholine method was use d to determine the enzyme activity. Castration caused LA muscle atroph y within 5 days but reduced the -EP and +EP AChE after 10 and 20 days, respectively. Following 30 days castration -EP and +EP AChE reached r espectively 41% and 35% of control activity. Testosterone retrieval re stored the control values of both muscle weight and total AChE after 1 5 and 60 days, respectively. Recovery of the +EP AChE preceded that of -EP AChE by 30 days. The results showed that in the rat LA muscle, +E P and -EP AChE depend on a continuous testosterone regulation that pre dominates at +EP region spreading thereafter to -EP region. Those data suggest a hormone regulation of AChE exerted indirectly through the s ynthesis and release of neurotrophic substances.