The relationship between estrogen receptors and microtubule dynamics in post-menopausal rat brain.

Introduction: Estrogen is one of the most important regulators of neuron function. There is a broad consensus that a loss of estrogen is associated with neurodegeneration in the hippocampus which leads to cognitive impairment. Hematopoietic-Pbx-interaction-protein (HPIP) is a novel scaffolding protein which interacts with microtubules and estrogen receptors. In this study, we investigated the presence and role of HPIP in hippocampal neurons and examined the relationship between estrogen receptors and microtubule damage in post-menopausal rat brains.

Method: Eighty female Wistar albino rats, 12 weeks old, were divided into 10 groups: control, control+17-β-estradiol, control+tamoxifen, control+mitogen-activated protein kinases (MAPK) inhibitor, control+phosphoinositide 3-kinase (PI3-K) inhibitor, ovariectomized, ovariectomized+17-β-estradiol, ovariectomized+tamoxifen, ovariectomized+MAPK inhibitor, and ovariectomized+PI3-K inhibitor. Light and electron microscopic examinations were performed. Real-time polymerase chain reaction (PCR) was used to determine the expression level of HPIP in experimental groups.

Results: Light and electron microscopic examinations revealed morphological changes in hippocampal neuron axons. Axonal fluctuations and shrinkage were detected in all ovariectomized groups. HPIP was detected in all neurons with difference expression levels.

Conclusion: Proof that the HPIP protein can be found on hippocampal neurons may give rise to a new focus on neurodegeneration in post-menopausal women. Future molecular and pharmacological studies should be performed to reduce the rate of cognitive symptoms resulting from hippocampal neurodegeneration.