Previous Adaptation Period Modulates Pregnancy Swimming Neuroprotective Effects on the Offspring Following Neonatal Hypoxic‐Ischemic Brain Injury

Abstract

Neonatal hypoxic‐ischemic encephalopathy (HI) is one the main causes of neurological damage in newborns. Pregnancy has emerging as a feasible therapeutic window for preventing central nervous system damage and has been shown to decrease early and long‐term HI consequences. However, experimental literature is conflicting and point that variables, such as a previous adaptation period to the exercise (before mating) has decisive impact on swimming consequences to the injured offspring's brain.Briefly, the adaptation period consisted of exposing female rats to 7 days (with increasing time exposure ‐ from 5 to 20 minutes) to a tank (200 cm diameter) filled with water at 32°C. After mating, from gestational day 0 to 21, pregnant rats were submitted to 20min/day of swimming or remained in the standard cages. After birth, seven‐days‐old rats were subjected to the Levine‐Rice HI model (right common carotid artery occlusion followed by 8% O2/60min). Western blotting was used to assess protein expression of GFAP (astrocytic reactivity), cytochrome c and cleaved caspase 3 (apoptotic markers) was performed in hippocampus 24h after HI. Animals were divided into 8 experimental groups, according adaptation, swimming and. Behavioral analysis was performed from PND45 and included sensorimotor and cognitive testing. Histological analysis assessed structural brain damage volumes of hemisphere and hippocampus. This study was approved by the local Institutional Animal Care and Use Committee (UFRGS #33497)Non‐parametric tests showed significant increase in astrogliosis in non‐adapted HI animals only. Swimming decreased apoptotic cell death despite adaptation period. Cylinder test evidenced HI effects (increasing the use of the ipsilateral forepaw in HI animals). No effects of swimming nor adaptation were observed in the test. In the open field testing, only HI animals whose mothers where adapted previously to the injury had increased locomotion and swimming reversed the HI effects on the test. Hemisphere and hippocampus were preserved only in the HI group whose mothers swam and were adapted before mating. In summary, the adaptation period has a major role on pregnancy swimming effects following HI and must be considered in future studies and the mechanisms involved in such modulation need to be further explored.Support or Funding InformationThis study was supported by CNPq, FAPERGS and CAPES ‐ Brazil.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.