Hyaluronic Acid Conjugated with 17β-Estradiol Effectively Alleviates Estropause-Induced Cognitive Deficits in Rats

Area of Science:

• Neuroscience
• Pharmacology
• Endocrinology

Background:

• Women face increased risk of cognitive impairment and Alzheimer's disease (AD) post-menopause due to estrogen deficiency.
• Estradiol (E2) deficiency is a key factor in post-menopausal cognitive decline.
• Hyaluronic acid-17β-estradiol conjugate (HA-E2) is a novel drug designed for brain E2 delivery, crossing the blood-brain barrier (BBB) with sustained release and reduced side effects.

Purpose of the Study:

• To investigate the effects of HA-E2 treatment on the cholinergic septo-hippocampal system in a rat model of post-menopausal cognitive deficit.
• To evaluate HA-E2's impact on synaptic transmission in hippocampal pyramidal neurons.
• To assess HA-E2's efficacy in improving cognitive functions, specifically spatial learning and memory.

Main Methods:

• Utilized ovariohysterectomy (OHE) rats, a model simulating post-menopausal cognitive deficits.
• Administered HA-E2 (210 ng/kg body weight, twice weekly for 2 weeks).
• Assessed changes in choline acetyltransferase (ChAT) expression, dendritic spine density, and cognitive performance.

Main Results:

• HA-E2 treatment led to an 11% increase in choline acetyltransferase (ChAT) expression in the medial septal nucleus and hippocampus.
• Observed a 14-18% rise in dendritic spine density in hippocampal pyramidal neurons of HA-E2 treated rats.
• Demonstrated recovery of cognitive functions, including spatial learning and memory, in treated rats.

Conclusions:

• HA-E2 treatment effectively enhances the cholinergic septo-hippocampal system and synaptic plasticity in an estrogen-deficient rat model.
• The observed neurobiological improvements correlate with significant recovery of cognitive functions.
• HA-E2 shows promise as a therapeutic strategy for preventing and treating estrogen-deficiency-induced cognitive impairment and Alzheimer's disease.