The effect of vagotomy on c-fos expression in the reticular formation areas following cystometry in cyclophosphamide-induced cystitis in rats.

Background: The involvement of the vagus nerve in the supraspinal neural circuits that control the urinary bladder function, especially during pathological conditions, became increasingly evident. However, the role of brainstem areas in these circuits is not studied yet.

Methods: In the present study, using c-fos immunohistochemistry, the roles of the vagus nerve to the responses of the reticular formation to cystometry in cyclophosphamide-treated rats were investigated.

Results: Cyclophosphamide treatment significantly increased the c-fos expression in the lateral reticular nucleus (LRt), lateral paragigantocellular nucleus (LPGi), caudal part of the ventrolateral reticular nucleus (CVL), and gigantocellular reticular nucleus (Gi) following cystometry. However, cyclophosphamide treatment didn't have significant effect on c-fos expression in ventrolateral reticular nucleus (VL), rostral part of VL (RVL), raphe pallidus nucleus (RPa), and raphe obscurus nucleus (Rob). Vagotomy significantly demolished the effect of cyclophosphamide in the LRt and LPGi areas without having any significant effect on other reticular formation areas. Whereas, in comparison to normal animals, the vagotomised animals didn't show any significant changes in c-fos expression.

Conclusion: The results of this study demonstrate the involvement of the reticular formation areas, particularly the ventral part, in processing urinary bladder function under cystitis condition. It also demonstrates the contribution of the vagus nerve in these processes.