Serotoninergic system in scrapie-infected hamsters

Area of Science:

• Neuroscience
• Virology
• Biochemistry

Background:

• Scrapie virus infection in hamsters leads to hypersensitivity to serotoninergic drugs.
• This hypersensitivity resembles behavioral changes seen with raphe nuclei lesions.

Purpose of the Study:

• To investigate the cause of serotonin hypersensitivity in scrapie-infected hamsters.
• To determine if scrapie virus directly targets serotoninergic neurons.

Main Methods:

• Studied pre- and postsynaptic serotoninergic sites in hamster cerebral cortices.
• Assessed [3H]imipramine binding and endogenous 5-hydroxytryptamine (5-HT) uptake in synaptosomes.
• Analyzed affinity for 5-HT1 and 5-HT2 receptors.

Main Results:

• Serotoninergic neurons remained intact; [3H]imipramine binding and 5-HT uptake were unchanged.
• Affinity for inhibitory 5-HT1 receptors decreased.
• Affinity for excitatory 5-HT2 receptors increased, creating a receptor imbalance.

Conclusions:

• The 5-HT hypersensitivity is attributed to an imbalance between 5-HT1 and 5-HT2 receptor affinities.
• Scrapie virus infection alters postsynaptic 5-HT receptor affinity, affecting cell plasma membranes.