Which of the following is not an amine hormone?

Oxytocin

The correct answer is option 2. Oxytocin.

Let us look at each of the given options:

1. Thyroxine (T4): Thyroxine is an amine hormone derived from the amino acid tyrosine. It is produced by the thyroid gland and is important for regulating metabolism.

2. Oxytocin: Oxytocin is a peptide hormone, not an amine hormone. It is composed of nine amino acids (a nonapeptide) and is produced in the hypothalamus and released by the posterior pituitary gland. It plays a role in childbirth, lactation, and social bonding.

3. Norepinephrine (Noradrenaline): Norepinephrine is an amine hormone and a neurotransmitter. It is derived from the amino acid tyrosine and is produced by the adrenal medulla and certain neurons.

4. Adrenaline (Epinephrine): Adrenaline is an amine hormone. It is derived from the amino acid tyrosine and is produced by the adrenal medulla. It is involved in the body's fight-or-flight response.

Summary:

Thyroxine, Norepinephrine, and Adrenaline are all amine hormones derived from amino acids. Oxytocin is a peptide hormone composed of a short chain of amino acids, making it not an amine hormone.

Therefore, Oxytocin is the correct answer as it is not an amine hormone.