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

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• 作者：Florencia Labombarda^a ; ^b ; ^{flabo@dna.uba.ar} ; Abdel Moumen Ghoumari^a ; ^{abdel.ghoumari@inserm.fr} ; Philippe Liere^a ; ^{philippe.liere@inserm.fr} ; Alejandro F. De Nicola^b ; ^{alejandrodenicola@gmail.com} ; Michael Schumacher^a ; ^{michael.schumacher@inserm.fr} ; Rachida Guennoun^a ; ^{rguennoun@yahoo.com} ; ^{rachida.guennoun@inserm.fr}
• 关键词：Progesterone ; Allopregnanolone ; Progesterone receptor ; GABAA receptors ; Organotypic slice cultures ; Spinal cord
• 刊名：Neuropharmacology
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：71
• 期：Complete
• 页码：46-55
• 全文大小：1121 K

文摘

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 the mechanisms of neuroprotection by progesterone and its 5¦Á-reduced metabolites. In?vitro spinal cord injury, using a weight drop model, induced a decrease in the number of motoneurons. This was correlated with an increase in the number of dying cells (PI⁺ cells) and in LDH release. Addition of 10?¦ÌM of progesterone, 5¦Á-dihydroprogesterone (5¦Á-DHP) or allopregnanolone (3¦Á, 5¦Á-tetrahydroprogesterone) to the medium at the time of injury rescued the spinal cord slices from the effects of damage. Progesterone prevented membrane cell damage, motoneuron loss and cell death. These effects were not due to its bioconversion to 5¦Á-DHP nor to allopregnanolone, as supported by the finasteride, an inhibitor of 5¦Á-reductase enzymes, and by the absence of 5¦Á-reduced progesterone metabolites in the slices analyzed by gas chromatography-mass spectrometry. The neuroprotective effects of progesterone required PR as they could not be observed in slices from homozygous knockout PR^?/? mice. Allopregnanolone treatment was also neuroprotective. Its effects were not due to its bioconversion back to 5¦Á-DHP, which can activate gene transcription via PR, because they were still observed in slices from knockout PR^?/? mice. Allopregnanolone effects involved GABA_A receptors, as they were inhibited by the selective GABA_A receptor antagonist Gabazine, in both PR^+/+ and PR^?/? mice. Altogether, these findings identify both PR and GABA_A receptors as important targets for neuroprotection by progestagens after spinal cord injury.