Sensory re‐innervation of the rat uterus postpartum (1131.4)

Abstract

Sympathetic, parasympathetic and sensory nerves almost completely disappear from the pregnant rat uterus at term but return of nerves post‐partum is not well characterized. Using immunoperoxidase staining for calcitonin gene related peptide (CGRP), we assessed post‐partum (P) sensory re‐innervation of rat uterus in whole mount preparations from days P1, P3, P5, P7, P10 and P14 (n=4/group). At P1, there were few CGRP‐immunoreactive axons, mostly at the mesometrium, where a few blood vessels were lightly innervated. CGRP‐positive axons increased at P3 and P5. There were many growth cones at both times. Muscle innervation was sparse. At P7, innervation was denser, with slightly more axons in the muscle and rare CGRP‐IR axons deep in the endometrium. There were CGRP‐immunoreactive axons in the linea uteri at the ovarian end in half the rats. At P10, the pattern of CGRP innervation was similar to P7. More CGRP‐immunoreactive axons occurred in all regions but re‐innervation of the linea uteri continued to lag behind. CGRP innervation was heaviest at P14, with blood vessels moderately to heavily innervated. Nevertheless, CGRP innervation density in all uterine layers was still much less at P14 than at oestrus. These results show that sensory innervation of the uterus has begun to return at P1. Uterine CGRP innervation increases to P14 but innervation density is still lower than in the non‐pregnant state.Grant Funding Source: Supported by NHMRC Australia