The Effect Of Resistance Training And Androgen Administration On NMJ Morphology And BDNF Expression

PURPOSE: Research examining the effect of resistance training (RT) on neuromuscular junction (NMJ) adaptation is limited, and no research is known that has examined the effect of RT and exogenous anabolic-androgen steroid (AAS) administration. AAS are often used to counteract muscle loss and improve neuromuscular strength, and function in individuals suffering from muscle wasting disease or hypogonadism. The purpose of this study was to examine the combination of RT with AAS administration on NMJ morphology. METHODS: Forty 3-month-old C57Bl/6 J mice were randomized to either a RT or sedentary (SED) group. Each group was further divided into sham (S) or AAS groups. The AAS groups were administered nandrolone decanoate (ND: 35 mg/kg/week). RT was performed using an 8-week ladder-climbing protocol. Brain-derived neurotrophic factor (BDNF) expression in the plantaris and soleus was examined via western blot analysis, while NMJ morphology was examined via immunofluorescence. RESULTS: A significant interaction for BDNF expression was noted in the plantaris (p = 0.024) and soleus (p = 0.007). BDNF expression in the plantaris was greater in RT-ND than RT-S (p = 0.019) and SED-ND (p = 0.016), while BDNF expression in the soleus was greater in RT-S compared to SED-S (p = 0.002), SED-ND (p = 0.011) and RT-ND (p = 0.022). In the plantaris, RT increased acetylcholine (ACh) receptor-stained area (p = 0.036) and ACh stained perimeter (p = 0.006), while both RT (p = 0.044) and ND (p = 0.050) increased ACh total area in the postsynaptic area. In addition, both RT and ND increased ACh vesicle-stained area (p < 0.001 and p = 0.006, respectively), ACh vesicle-stained perimeter (p < 0.001 and p = 0.02, respectively), and ACh vesicle total area (p < 0.001 and p = 0.01, respectively) in the presynaptic area. RT only increased presynaptic ACh vesicles total perimeter (p < 0.001). In the soleus, ND treatment increased ACh receptor-stained (p = 0.002) and total area (p = 0.035) in the postsynaptic area, while an interaction (p = 0.045) was noted for presynaptic vesicle total area. However, only a trend towards a difference was noted between RT-S compared to SED-S (p = 0.06). CONCLUSIONS: Resistance exercise and AAS administration appear to increase BDNF expression and NMJ morphology in both fast and slow twitch muscle groups. Supported by: This work was supported from the Israel Science Foundation (ISF grant no 1984/21).