Melatonin

What is the dominant function of melatonin in humans

- Communicate diurnal patterns to the hypothalamus - Reduce muscle activity thus reducing body temperature to induce sleep

The pineal gland regulates

Chronobiologic rhythms (also gonadal function and development in seasonal breeders)

Which structural class of hormone does melatonin belong

Amine

Pineal gland measures

Day length and adjusts melatonin secretion

Melatonin therapy for early riser

Give melatonin before bed

Melatonin therapy for a night owl

Give melatonin in early afternoon

Melatonin inhibits

Gonadotropic hormones LH/FSH via inhibition og GnRH

During spring (mating season)

Gonads become rejuvenated

During winter (non-breeding season)

High melatonin, gonads become inactive

Melatonin is stimulated by

Hypoglycemia and darkness. Duration of melatonin secretion each day is directly proportional to length of darkness

Highest density of melatonin receptors are found

Hypothalamus, Anterior Pituitary, and Retina

Why do patients with rheymatoid arthritis have worsening symptoms in the winter?

Melatonin specifically increases pro-inflammatory cytokines like TNF-alpha

Ia melatonin a major regulator of normal sleep

No, normal function is to help decrease skeletal muscle activity and body temperature to induce sleep

What secretes melatonin

Pineal gland

Animals without a pineal or lesion

Prevents pineal form receiving photoinformation and are unable to prep for breeding

Why do reast cancer patients have low serum melatonin

Studies show that melatonin inhibits growth of breast tissue