Neuroprotection by steroids after neurotrauma in organotypic spinal cord cultures: A key role for progesterone receptors and steroidal modulators of GABAA receptors

LABOMBARDA F.; GHOUMARI A.; LIERE P; DE NICOLA A.F.; SCHUMACHER M; GUENNOUN R

NEUROPHARMACOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013 vol. 71 p. 46 - 55

0028-3908

Progesterone is neuroprotective after spinal cord injury, however its mechanism of action remains unexplored.Here we used organotypic spinal cord slice cultures from 3 weeks-old mice to evaluate themechanisms of neuroprotection by progesterone and its 5a-reduced metabolites. In vitro spinal cordinjury, using a weight drop model, induced a decrease in the number of motoneurons. This was correlatedwith an increase in the number of dying cells (PIþ cells) and in LDH release. Addition of 10 mM ofprogesterone, 5a-dihydroprogesterone (5a-DHP) or allopregnanolone (3a, 5a-tetrahydroprogesterone)to the medium at the time of injury rescued the spinal cord slices from the effects of damage. Progesteroneprevented membrane cell damage, motoneuron loss and cell death. These effects were not due toits bioconversion to 5a-DHP nor to allopregnanolone, as supported by the finasteride, an inhibitor of 5areductaseenzymes, and by the absence of 5a-reduced progesterone metabolites in the slices analyzed bygas chromatographyemass spectrometry. The neuroprotective effects of progesterone required PR asthey could not be observed in slices from homozygous knockout PR/ mice. Allopregnanolone treatmentwas also neuroprotective. Its effects were not due to its bioconversion back to 5a-DHP, which canactivate gene transcription via PR, because they were still observed in slices from knockout PR/ mice.Allopregnanolone effects involved GABAA receptors, as they were inhibited by the selective GABAA receptorantagonist Gabazine, in both PRþ/þ and PR/ mice. Altogether, these findings identify both PR andGABAA receptors as important targets for neuroprotection by progestagens after spinal cord injury. 2013 Elsevier Ltd. All rights reserve