Question

An intermediate of adrenaline biosynthesis which is also a neurotransmitter is
A) Glycine
B) Gamma-aminobutyric acid
C) Dopamine
D) Glutamic acid

Answer 1

Hint:Adrenaline is a hormone and a drug, also known as epinephrine. In the medulla oblongata, adrenaline is typically released by both the adrenal glands and a small number of neurons, where it serves as a neurotransmitter to control visceral functions (e.g., respiration).

Complete answer:
Adrenaline, in chemical words, is one of a group of monoamines known as catecholamines. Adrenaline is synthesised by a metabolic pathway that transforms the amino acids phenylalanine and tyrosine into a series of metabolic intermediates and, ultimately, adrenaline into the chromaffin cells of the adrenal gland's adrenal medulla and into a small number of neurons in the brain's medulla oblongata.

Tyrosine is first oxidised by tyrosine hydroxylase into L-DOPA, which is the rate-limiting step. Then dopamine by DOPA decarboxylase is subsequently decarboxylated to give (aromatic L-amino acid decarboxylase). Via dopamine beta-hydroxylase that uses ascorbic acid (Vitamin C) and copper, dopamine is then converted to noradrenaline. In adrenaline biosynthesis, the final step is the methylation of noradrenaline's primary amine.

The enzyme phenylethanolamine N-methyltransferase (PNMT), which uses S-adenosylmethionine (SAMe) as a methyl donor, catalyses this reaction. Although PNMT is predominantly located in the cytosol of adrenal medulla endocrine cells (also known as chromaffin cells), it has been observed in the heart and brain at low levels.

Thus the correct Answer is option (C) i.e, ‘Dopamine’.

Note:Dopamine plays significant roles in executive function, motor control, motivation, arousal, reinforcement, and reward via signalling cascades that are exerted at the projections found in the substantia nigra, ventral tegmental region, and arcuate nucleus of the human brain hypothalamus through binding to dopaminergic receptors.