Question

Dopamine synthesis is increased by activation of a. dopamine \(\beta\)-hydroxylase b. L-aromatic amino acid decarboxylase c. tyrosine hydroxylase d. monoamine oxidase e. choline acetyltransferase

Short answer

Answer: Tyrosine hydroxylase.

Step-by-step solution

Understand the role of each enzyme.

In order to determine the correct answer, let's briefly review the functions of each enzyme listed in the answer choices: a. Dopamine β-hydroxylase: It converts dopamine to norepinephrine. b. L-aromatic amino acid decarboxylase: It converts L-DOPA to dopamine. c. Tyrosine hydroxylase: It converts L-tyrosine to L-DOPA. d. Monoamine oxidase: It is involved in the degradation of dopamine. e. Choline acetyltransferase: It is involved in the synthesis of the neurotransmitter acetylcholine.

Determine the enzyme that increases dopamine synthesis.

Now that we know the functions of each enzyme, we want to identify the enzyme that specifically increases dopamine synthesis. Looking at the options, we can see that option 'c. Tyrosine hydroxylase' is responsible for the conversion of L-tyrosine to L-DOPA, which is then later converted to dopamine by L-aromatic amino acid decarboxylase. Therefore, option 'c. Tyrosine hydroxylase' is the enzyme that increases dopamine synthesis. So, the correct answer is: c. Tyrosine hydroxylase

Key concepts

Tyrosine Hydroxylase

Tyrosine hydroxylase plays a fundamental role in the chemistry of the brain, serving as the pace-setter for the production of dopamine, a key neurotransmitter involved in movement, motivation, and reward among other functions. This enzyme catalyzes the initial and rate-limiting step in dopamine synthesis, by converting the amino acid L-tyrosine into L-DOPA (levodopa). Understanding this process is vital for grasping the broader concepts of neurotransmitter metabolism.

It's also noteworthy that tyrosine hydroxylase is highly regulated by several mechanisms, including phosphorylation and feedback inhibition by neurotransmitters like dopamine itself. Thus, when learning about how dopamine synthesis is increased, one must take into account the biological controls that manage tyrosine hydroxylase activity.

Neurotransmitter Metabolism

Neurotransmitter metabolism encompasses the entire life cycle of neurotransmitters: their synthesis, release, receptor action, reuptake, and degradation. When considering dopamine, after tyrosine hydroxylase has done its part, L-DOPA is further converted into dopamine by the enzyme L-aromatic amino acid decarboxylase.

Once released into the synaptic cleft, dopamine binds to dopamine receptors on the post-synaptic neuron to exert its effects. Eventually, dopamine is metabolized by enzymes like monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). This regulatory mechanism is essential for maintaining neurotransmitter balance and preventing overstimulation of receptor sites, which can lead to toxicity or desensitization.

Pharmacology Education

Pharmacology education provides students with an understanding of how drugs interact with biological systems. It's a field that marries chemistry, biology, and medicine, and is essential for developing new therapeutics and understanding their impact on the body. An integral part of pharmacology education is studying enzymes like tyrosine hydroxylase which are often targets for drug action.

For instance, in Parkinson’s disease, the loss of dopamine-producing neurons leads to motor deficits. Pharmacological treatments often include L-DOPA, the product of tyrosine hydroxylase's catalysis, to replenish dopamine levels. Thus, a robust pharmacology education must delve deep into neurotransmitter metabolism, including synthesis and degradation enzymes, and their implications for human health and disease.