Question

Which of the following hormones regulates anestrus?
A. Calcitonin
B. Melatonin
C. Estrogen
D. Progesterone

Answer 1

The phase when sexual cycle rests is termed as anestrus. This typically is a seasonal event and controlled by exposure of light through pineal gland, which releases melatonin. The stimulation of reproduction in long-day breeders may be repressed by melatonin and stimulate the reproduction in short-day breeders. Melatonin acts by regulating the hypothalamic pulse activity of gonadotropin releasing hormone.

Complete answer:
Option A Calcitonin: A hormone that is produced in humans by the parafollicular cells, which is commonly known as C-cells of the thyroid gland, is called Calcitonin. This hormone is involved in regulating the levels of calcium and phosphate in the blood and opposing the action of parathyroid hormone. Since calcitonin does not regulate anestrus.
So, option A is not correct.
Option B Melatonin: A hormone which is primarily released by the pineal gland at night, and has long been associated with control of the sleep wake cycle is known as melatonin. Anestrus is typically a seasonal event. It is controlled by light exposure through pineal gland, which releases melatonin. Since the melatonin hormone is responsible for regulating anestrus.
So, option B is the correct answer.
Option C Estrogen: Category of sex hormone that are responsible for the development and regulation of the female reproductive system and secondary sex characteristics are known as estrogen or oestrogen. In all vertebrates and some insects, estrogen is synthesized. Since Estrogen is not involved in regulating anestrus.
So, option C is not correct.
Option D Progesterone: The progesterone is an endogenous steroid and progestogen sex hormones are involved in menstrual cycle, pregnancy, and embryogenesis of humans and different species. Progesterone belongs to a group of steroid hormones called the progestogens and are the major progestogens present in the body. Progesterone does not regulate anestrus.
Hence option D is not correct.

Therefore, Option B) Melatonin is the correct answer.

Note:
The time of pregnancy, lactation, significant illness, chronic energy deficit, and possibly age are the factors which induce anestrus. A persistent anestrus due to negative feedback on the hypothalamus/pituitary/gonadal axis may be induced by chronic exposure to anabolic steroids. It is often used for the short-term treatment of insomnia such as from jet lag or shift work or as a dietary supplement and is typically taken orally.