Which hormones are considered neurohormones?

• A. Adrenaline and cortisol
• B. Testosterone and estrogen
• C. Antidiuretic hormone (ADH) and oxytocin
• D. Thyroid hormones

Answer: (C)

Neurohormones are hormones that are produced by neuroendocrine cells, which are specialized neurons that secrete hormones directly into the blood in response to neural stimulation. Antidiuretic hormone (ADH), also known as vasopressin, and oxytocin are both synthesized in the hypothalamus and released from the posterior pituitary gland. These hormones play crucial roles in the regulation of water balance in the body and in facilitating labor and milk ejection during breastfeeding, respectively. Their release is closely linked to neural inputs, making them quintessential examples of neurohormones.

In contrast, adrenaline and cortisol are produced by the adrenal glands and are classified as stress hormones rather than neurohormones. Testosterone and estrogen are steroid hormones produced primarily by the gonads (testes and ovaries) and are involved in sexual development and reproductive functions, not stemming from neuronal activity. Thyroid hormones, which regulate metabolism, are produced by the thyroid gland and are not derived from the nervous system either. Thus, ADH and oxytocin represent key neurohormones due to their synthesis in the nervous system and their release into the bloodstream in response to neural signals.