Research paperPattern of Mas expression in acute and post-acute stage of nerve injury in mice

- Mas receptor is differentially expressed in acute and post-acute phase after axotomy.
- Antagonist of the Mas receptor (A779) causes worse result in sciatic functional test.
- A779 affects the Schwann cell activity and the number of macrophages after axotomy.

Angiotensin-(1-7) (Ang [1-7]) and its receptor Mas are involved in a number of physiological processes, including control of arterial pressure and modulation of nervous system actions. However, the involvement of the Ang-(1-7)/Mas axis in peripheral nerve injury has not been investigated. Using a model of sciatic nerve injury in mice, we demonstrated opposing changes in Mas receptor expression at days 2 and 14 post-injury. Mas receptor expression was more intense 2 days after the nerve lesion, compared with the intensity of the intact nerve. At this time point, the sciatic nerve functional index was −20. At day 14 after the lesion, the intensity of the immunostaining labeling in longitudinal sections of the nerve was reduced (∼30%) and the functional index increased +36 (gait improvement). In the axotomized group treated with A779 (a Mas receptor antagonist), the functional recovery index decreased in relation to the untreated axotomized group. The Mas receptor inhibitor also altered the intensity of labeling of S-100, GAP43, and IBA-1 (morphological features compatible with delayed axon growth). This study demonstrated that Ang-(1-7)/Mas axis activity was differentially modulated in the acute and post-acute stages of nerve injury.