Self-Assessment 3.2

. Metabotropic receptors

are composed of multiple subunits, similar to ionotropic receptors.

work by activating a family of proteins known as G proteins.

have no effect on ion channels in the membrane.

affect the firing of the postsynaptic cell more rapidly than in the case of ionotropic receptors.

. Which of the following statements about second-messenger systems is true?

Protein kinases are enzymes that dephosphorylate (remove the phosphate group) from phosphorylated proteins.

Cyclic AMP (cAMP) stimulates a protein kinase called protein kinase G (PKG).

Second-messenger systems are the main signaling mechanism used by ionotropic receptors.

Diacylglycerol (DAG) and inositol trisphosphate (IP3) are the two second messengers used by the phosphoinositide second-messenger system.

. Drugs that can either enhance or inhibit the activity of a receptor by binding to a site on the receptor that is different from the agonist binding site are called

allosteric modulators.

partial agonists.

orthosteric modulators.

neurotrophic factors.

. Which of the following is a pharmacological approach to enhance the activity of a particular neurotransmitter system?

Administer a receptor antagonist for that transmitter.

Administer a drug that blocks the uptake/reuptake of the transmitter.

Administer a drug that blocks vesicular uptake of the transmitter.

Both b and c

. If repeatedly administering a drug produced an increased number of dendritic spines on pyramidal neurons within the prefrontal cortex, what would the experimenter most likely hypothesize regarding the meaning of this change?

There are probably more synapses on the affected neurons, although this would need to be tested experimentally by actual synapse counting.

The drug probably has an effect on synaptic plasticity, although there is no way of knowing how the pyramidal cell synapses were altered.

Synaptic plasticity has not been altered by the drug, since dendritic spine changes are not a component of synaptic plasticity.

Since dendritic spines are always associated with inhibitory synapses, the drug-induced change means that inhibitory inputs to the pyramidal neurons have increased.

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