Changes in myelinisation of neurons in different brain regions in progesterone-treated rats

Abstract

The influence of progesterone on myelin of the brain in adult male Wistar rats was investigated by labelling the myelin of neurons in 5 mm thick brain sections with Nile blue stain. The following nuclei were analysed hypothalamic nucleus arcuatus (ARC) and nucleus paraventricularis (NPV) claustrum (CL), nuclei of the corticomedial part of amygdala: nucleus medialis (NM), nucleus corticalis (NCO) and nucleus centralis (NCE) and in the basolateral part of amygdala, nucleus basolateralis (NBL), nucleus basomedialis (NBM) and nucleus lateralis posterior (NLP). In control male rats sacrificed at 62 days of age a great number of neurons labelled with Nile blue for myelin were detected by stereological analysis.They were observed in; ARC and NPV, in the corticomedial amygdaloid nuclei (NM, NCE NCO) as well as in the basolateral nuclei (NBL, NBM and NLP). In CL there was a smaller number of neurons with labelled myelin than in the other investigated regions. In comparison to the controls, the number of neurons labelled with Nile blue for myelin in progesterone treated male rats was significantly reduced in ARC of hypothalamus and in NCO of amygdala. A significant increase was observed in NPV of hypothalamus, and in NM, NCE NBL and NBM of amygdala. On the other hand, in CL the number of neurons labelled with Nile blue for myelin was not changed