Question

Which of the following can generate IPSPs?

a) GABA (Gamma aminobutyric acid)

b) epinephrine

c) norepinephrine

d) dopamine

e) TRH (thyroid releasing hormone)

All of the following are true neurotransmitters in the class of catecholamines Except:

a) they can increase heart rate

b) they create EPSPs

c) they may be degraded by catechol-O-methyltransferase (COMT)

d) they may bind to dopanergic receptors

e) they decrease the perception of pain

Answer 1

Question 1

Answer is option(a)GABA

IPSP(Inhibitory postsynaptic potential) is a type of synaptic potential which makes the postsynaptic neuron less likely to produce an action potential.

When inhibitory presynaptic neurons release neurotransmitters, they bind to postsynaptic receptors.And this produces some changes in the permeability of postsynaptic membrane to certain ions. As a result, postsynaptic membrane potential becomes even more negative than resting membrane potential. This is termed as hyperpolarization. In order to generate an action potential,postsynaptic membrane must depolarize. But hyperpolarisation of the postsynaptic membrane makes it less chance for depolarisation. And it is difficult to generate an action potential in the postsynaptic neuron.

GABA is a inhibitory neurotransmitter used in IPSP. Binding of GABA to its receptors keeps postsynaptic potential more negative and makes it difficult to produce action potential.

Other molecules like epinephrine,norepinephrine, dopamine and TRH are excitatory molecules which produce EPSP.

Question 2

Answer is option(d) they may bind to dopaminergic receptors.

Catecholamines exert their action by binding to adrenergic receptors,alpha and beta. They don't bind to dopaminergic receptors.

They have positive effects on heart and blood vessels which causes an increase in the heart rate. So option(a) is true.

catecholamines are excitatory molecules which generate EPSP and helps in the depolarization and creating action potential. So option(b) is true.

Catecholamines are degraded in 2 ways. One is by methylation by COMT. Another is by deamination by monoamine oxidase. So option(c)is true.

Catecholamines by increasing adrenergic transmission in the spinal cord, decreases pain sensitivity. So option (e) is also true.