WIN55,212-2 induced deficits in spatial learning are mediated by cholinergic hypofunction

Area of Science:

• Neuroscience
• Pharmacology
• Cognitive Science

Background:

• Cannabinoids acting on CB(1) receptors are known to impair learning and memory.
• Novel non-CB(1) receptors sensitive to synthetic cannabinoids like WIN55,212-2 (WIN-2) raise questions about the mechanism of WIN-2 induced memory deficits.
• Understanding cannabinoid effects requires investigating transmitter systems modulated by these compounds, especially given the limited availability of specific antagonists.

Purpose of the Study:

• To investigate the effects of WIN-2 on the acquisition of spatial reference memory in rats.
• To determine if WIN-2 induced learning and memory deficits are mediated by CB(1) receptor activation.
• To explore the underlying neurochemical mechanisms, particularly cholinergic pathways, involved in WIN-2's effects on memory.

Main Methods:

• Spatial reference memory was assessed using the water maze task in rats.
• WIN-2 was administered intraperitoneally (i.p.) at doses of 1 mg/kg and 3 mg/kg prior to training.
• The effects of WIN-2 were evaluated in the presence of CB(1) antagonists (Rimonabant, AM281) and a cholinesterase inhibitor (rivastigmine).

Main Results:

• WIN-2 administration (1 mg/kg and 3 mg/kg) significantly impaired long-term spatial memory but not short-term memory.
• The memory deficits induced by WIN-2 were not reversed by CB(1) antagonists Rimonabant or AM281.
• Rivastigmine treatment reversed the WIN-2 induced long-term memory impairment, while not affecting MK801 induced deficits, indicating specificity.

Conclusions:

• WIN-2 impairs long-term spatial reference memory in rats through a mechanism that does not appear to involve CB(1) receptors.
• The findings suggest that WIN-2 may reduce cholinergic activation, contributing to the observed memory deficits.
• This study highlights a potential non-CB(1) mediated pathway for cannabinoid-induced memory impairment, modulated by the cholinergic system.