Anticholinergic sensitivity in the aging rat septohippocampal system as assessed in a spatial memory task

Area of Science:

• Neuroscience
• Cognitive Psychology
• Pharmacology

Background:

• Aging is associated with cognitive decline, particularly in spatial memory.
• The central cholinergic system plays a critical role in learning and memory.
• The septohippocampal pathway is vital for spatial navigation.

Purpose of the Study:

• To investigate the effects of central cholinergic blockade on spatial memory in aged rats.
• To compare the effects of central cholinergic blockade in aged rats with young rats with specific brain lesions.
• To determine the role of the septohippocampal system in age-related spatial memory deficits.

Main Methods:

• Aged rats (18-21 months) and young rats with septal lesions (SL), nucleus basalis lesions (NBL), or combined lesions (SL + NBL) were used.
• The Morris Water Maze was employed to assess spatial memory performance.
• Central cholinergic blockade was induced using atropine sulfate (IP), while peripheral blockade used atropine methylbromide.

Main Results:

• Central cholinergic blockade with atropine sulfate severely impaired spatial search behavior in both impaired and non-impaired aged rats.
• Peripheral blockade with atropine methylbromide did not cause impairments, indicating central receptor involvement.
• Young rats with septal lesions (SL and SL + NBL) showed severe impairments during atropine treatment, unlike normal controls or NBL rats.

Conclusions:

• Aged rats exhibit heightened sensitivity to central cholinergic blockade, leading to severe spatial navigation deficits.
• The spatial memory deficits observed in aged rats during cholinergic blockade are comparable to those in young rats with septal lesions.
• Impaired function within the septohippocampal system likely underlies the spatial memory deficits seen in aged rats during central cholinergic blockade.