Peripheral nerve regeneration in mice exposed to an enriched environment

Taking into account the fact that the literature contains no studies on how an enriched environment influences peripheral nerve lesions, in this study we analysed the characteristics of the sciatic nerve in mice submitted to axonotmesis and subsequent exposure to an enriched environment. Twenty-four male Wistar mice (198.66 +/- 11.61 g) were distributed into the following groups: control, lesion, enriched environment grouping (EEG) and simple environment grouping (SEG). Following lesion to the nerve, the animals were placed in different cages according to the groups they had been allocated to. The enriched cage had an exercise wheel, a ladder, a ramp, and mobile food and water compartments, which were randomly changed every day. After 24 days, the sciatic nerve was analysed quantitatively, morphometrically and functionally. The number of axons in the EEG and SEG groups was higher than that of the control group (p < 0.05). The SEG group had a higher number of axons than the lesion and EEG groups. The diameter of the axons in the experimental groups was smaller than that of the control group. The same occurred with the diameter of the nerve fibre. The thickness of the myelin sheath was inferior in the experimental groups compared to the control, and the value for the SEG group was lower than for the lesion group. The G ratio did not differ among groups. There were no differences in the values of the sciatic function index among the groups, while in the intragroup comparison there was a difference between postoperative days 7 and 14 and the preoperative values. Functioning was restored at postoperative day 21. The enriched environment did not have a negative effect on axonal regeneration and maturation, but neither did it favour the process. Functional recovery was not influenced by this form of intervention.