Cocaine exposure results in formation of dendritic varicosity in rat primary hippocampal neurons

Problem statement: It has been well documented that drugs of abuse such as cocaine can cause enhanced progression of HIV-Associated Neuropathological Disorders (HAND), the underlying mechanisms mediating these effects remain poorly understood. Approach: In present study, we explored the impact of cocaine exposure (I and 10 μM) on the dendritic beading in rat primary hippocampal neurons. Using the approach of transfection with green fluorescent protein, we observed significant dendritic swelling in hippocampal neurons exposed to 10 μM but not 1 μM of cocaine when compared with the saline treated group. Results: Cocaine exposure also resulted in decreased expression of the synaptic plasticity gene, Arc as evidenced by Western blotting. Intriguingly, cocaine exposure of primary neurons in the presence of the neurotoxin-HIV envelope protein gp 120, resulted in increased enhancement of neuronal beading as compared with exposure of neurons to either agent alone. Conclusion: Taken together these findings imply that cocaine in co-operation with HIV protein exacerbates neuronal damage in the brains of HIV-infected cocaine abusers.