Luteinizing hormone acts at the hippocampus to dampen spatial memory

Area of Science:

• Neuroscience
• Endocrinology
• Reproductive Biology

Background:

• Luteinizing hormone (LH) levels increase post-menopause.
• Elevated LH correlates with Alzheimer's disease and memory decline.
• The dorsal hippocampus is crucial for spatial memory formation.

Purpose of the Study:

• To investigate the direct role of LH in the dorsal hippocampus on memory function.
• To determine if LH receptor antagonism in the hippocampus can reverse memory impairments.

Main Methods:

• Ovariectomized female rats were used as a model.
• Infusions of human chorionic gonadotropin (hCG), an LH homologue, or deglycosylated-hCG (dg-hCG), an LH receptor antagonist, into the lateral ventricle or dorsal hippocampus.
• Assessment of spatial memory performance following infusions.

Main Results:

• hCG infusion into the lateral ventricle or dorsal hippocampus significantly impaired memory.
• dg-hCG infusion into the dorsal hippocampus ameliorated memory deficits.
• The gonadotropin-releasing hormone antagonist Antide did not affect memory when infused into the hippocampus.

Conclusions:

• LH directly acts within the dorsal hippocampus to cause spatial memory dysfunction.
• LH receptor antagonism in the dorsal hippocampus can restore memory function.
• These findings identify a novel mechanism for LH-mediated memory impairment.