Progesterone Effects on Neuronal Ultrastructure and Expression of Microtubule-associated Protein 2 (MAP2) in Rats with Acute Spinal Cord Injury |
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Authors: | Susana L González Juan José López-Costa Florencia Labombarda Maria Claudia González Deniselle Rachida Guennoun Michael Schumacher Alejandro F De Nicola |
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Institution: | Laboratory of Neuroendocrine Biochemistry, Instituto de Biología y Medicina Experimental, Obligado 2490, 1428, Buenos Aires, Argentina. |
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Abstract: | (1) Following acute spinal cord injury, progesterone modulates several molecules essential for motoneuron function, although
the morphological substrates for these effects are unknown. (2) The present study analyzed morphological changes in motoneurons
distal to the lesion site from rats with or without progesterone treatment. We employed electron microscopy to study changes
in nucleus and cytoplasm and immunohistochemistry for the microtubule-associated protein 2 (MAP2) for changes in cytoskeleton.
(3) After spinal cord injury, the nucleoplasm appeared more finely dispersed resulting in reduced electron opacity and the
nucleus adopted an eccentric position. Changes of perikarya included dissolution of Nissl bodies and dissociation of polyribosomes
(chromatolysis). After progesterone treatment for 3 days, the deafferented motoneurons now presented a clumped nucleoplasm,
a better-preserved rough endoplasmic reticulum and absence of chromatolysis. Progesterone partially prevented development
of nuclear eccentricity. Whereas 50% of injured motoneurons showed nuclear eccentricity, only 16% presented this phenotype
after receiving progesterone. Additionally, injured rats showed reduced immunostaining for MAP2 in dendrites, pointing to
cytoskeleton abnormalities, whereas progesterone treatment attenuated the injury-induced loss of MAP2. (4) Our data indicated
that progesterone maintained in part neuronal ultrastructure, attenuated chromatolysis, and preclude the loss of MAP2, suggesting
a protective effect during the early phases of spinal cord injury. |
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Keywords: | Chromatolysis Electron microscopy MAP2 Motoneuron Neuroprotection Progesterone Spinal cord injury |
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