Question

Describe a way a drug might affect synaptic transmission.

Answer 1

Drugs interfere with neurotransmission, More specifically, drugs of abuse produce feelings of pleasure by altering neurotransmission by neuron in the reward system that releases the neurotransmitter dopamine. Thus , drugs of abuse alter communication between the neurons that is mediated by dopamine. Because the synapse is so complex, there is a variety of sites at which drugs may affect synaptic transmission.

One way to affect the synaptic transmission is to increase the amount of neurotransmitter released into the synaptic space. Drugs like alcohol, heroin and nicotine indirectly excite the dopamine containing neurons in the ventral tegmental area(VTA), so that they produce more action potentials . As the number of action potentials increases , so does the amount of dopamine released into the synapse.

Amphetamines(e.g crystals, crank ) actually cause the release of dopamine from the vesicles. This is independent of the rate of action potentials and depending on dose , can cause a relatively quick and prolonged rise of extracellular dopamine levels.

Nicotine not only act at the cell body in the VTA to increase the number of action potentials and number of vesicles released from a neuron, but it also acts by another mechanism to alter dopamine release. When nicotine binds to nicotine receptors on the dopamine-containing axon terminals in the nucleus accumbens, more dopamine is released with each action potential.