Seratonin and Dopamine in the CNS

Dopaminergic Neurons These neurons are highly concentrated in the mid-brain with axons that project into different parts of the brain Two systems of neurons are involved: Nigrostriatal neurons are involved in motor control and Mesolimbic neurons are involved in emotional rewards

Parkinson’s disease is caused by degeneration of dopaminergic neurons of the motor pathway. Treatment with L-Dopa alleviates symptoms. D2 Dopamine receptors are implicated in alcoholism.

Cocaine blocks the reuptake of dopamine n presynptic axons, so those synapses are overstimulated. Nicotine promotes the release of dopamine in one area of the forebrain. Morphine, and amphetamines also affect dopaminergic pathways

Many drugs used to treat schizophrenia (neuroleptics) are antagonists of the D2 Dopamine receptor. Schizophrenic patients treated with these agents often develop Parkinson’s symptoms. It hypothesized that schizophrenia may be caused in part by overativity of the mesolimbic dopaminergic system.

Neurons that use seratonin are found along the midline of the brainstem. A precursor of seratonin, tryptophan, is found in turkey and milk. Seratonin is believed to regulate mood, appetite and cerebral circulation LSD mimics seratonin and causes overstimulation of seratonin receptors

MAO inhibitors increase the transmission of catecholamines and seratonin by blocking their distruction. MAO inhibitors are often used to treat depression, and one MAO inhibitor, Deprenyl has also been used to treat Parkinsons. Prozac, blocks only the reuptake of seratonin, and is somewhat more specific than some MAO inhibitors.