PINEAL GLAND HORMONES:
Melatonin (Synthezized from amino acid Trp)
- Age dependent (highest in children)
- Secretion is highest at night.
Synthesis:
1. Hydroxylation of trp in position 5
2. Decarboxylation from tryp to serotonin
3. Acetylation from serotonin to acetyl-serotonin
4. Methylation of acetyl-serotonin into melatonin (SAM dependent)
Biorythm:
DAY: Adrenergic neurons are inhibited by light during the day
NIGHT:
1. Norepinephrine released during night activates beta receptors, which are coupled with G proteins.
2. These increase the activity of adenylate cyclase & cAMP (secondary messengers), which activates seratonin N-
acetyl transferase (pineal gland), catalyzing the secretion of melatonin.
Melatonin (Synthezized from amino acid Trp)
- Age dependent (highest in children)
- Secretion is highest at night.
Synthesis:
1. Hydroxylation of trp in position 5
2. Decarboxylation from tryp to serotonin
3. Acetylation from serotonin to acetyl-serotonin
4. Methylation of acetyl-serotonin into melatonin (SAM dependent)
Biorythm:
DAY: Adrenergic neurons are inhibited by light during the day
NIGHT:
1. Norepinephrine released during night activates beta receptors, which are coupled with G proteins.
2. These increase the activity of adenylate cyclase & cAMP (secondary messengers), which activates seratonin N-
acetyl transferase (pineal gland), catalyzing the secretion of melatonin.
