Cyclodextrine Given Intravenously after Severe Neonatal Hypoxia, - Alone or in Combination with Progesterone, Increased Autophagy Activation and Reduced Endoplasmatic Reticulum Stress in Prefrontal Cortex

Background: Perinatal hypoxic-ischemic brain damage is a major cause of acute mortality and chronic neurologic morbidity in infants and children. Progesterone dissolved in the vehicle Cyclodextrine has shown promising results if given after traumatic brain injury. Endoplasmatic reticulum (ER) pathology may be an indicator of the severity of neuronal injuries. Therapies to attenuate ER stress applied at delayed stages, may rescue stressed neurons after neonatal hypoxia-ischemia. Together with measurements of autophagy activation, it can be used to determine effects of neuroprotective treatments.

Objective: The aim was to explore if cyclodextrine given i.v. after severe perinatal hypoxia had an equal neuroprotective effect as progesterone dissolved in cyclodextrine.

Methods: Severe global hypoxia was induced in newborn piglets. Reoxygenation with ambient air, one group(N=12) got 8mg/kg progesteron dissolved in the vehicle 2-hydroxypropyl-β-cyclodextrin i.v., another group(N=10) got 2ml/kg vehicle(Cyclodextrine) i.v. and a reference group just received 2ml/kg saline i.v.(N=11). The piglets were observed for 9.5 h after end hypoxia. Brain tissues from prefrontal cortex were sampled and the effects of progesterone and the vehicle cyclodextrine on ER stress and autophagy were measured. We assessed the molecular chaperons GRP78 and Hsp70 for ER stress and for autophagy activation of the expression of LC3(a microtubule-associated protein) and p62 in cortical tissue.

Results: The expression of GRP78 and Hsp70 were significantly reduced in both treatment groups indicating reduced ER stress. The expression of Lipidated LC3 was significantly increased and the autophagy activation confirmed by a significant reduction of p62 expression. The results are in line with reported effects of neuroptotective treatments.

Conclusions: Treatment with Progesterone dissolved in Cyclodextrine or Cyclodextrine alone after severe neonatal asphyxia increased autophagy and reduced endoplasmatic reticulum stress. The results highlight the independent therapeutic effects of a commonly used vehicle for neuroprotective drugs.