You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Melatonin is secreted from which cells of pineal gland - and explain in detail?
Ans. is 'b' i.e., Pinealocytes o The pineal gland is a small cone shaped structure lies in the center of the brain behind the third ventricle.o It consists of two types of cells : i) Pineaiocytes, and ii) Neuroglial cell.o Pineaiocytes predominate and produce hormone melatonin (N-acetyl-5-methoxytrytamine).o The principal secretory product of the pineal gland is melatonin.o Melatonin secretion shows a circadian rhythm, the level being higher at night and lower at day.o This diurnal variation is brought about by norepinephrine secreted by postganglionic sympathetic nerves that innervate pineal gland.o In the dark norepinephrine secretion is increased which acts on b-receptors to increase intracellular cAMP and cAMP in turn produces a marked increase in N-Acetyl transferase activity, an enzyme involved in melatonin synthesis from serotonin.