Day/night serotonin levels in the pineal gland of male BALB/c mice with melatonin deficiency.
Studies from another laboratory have shown that several strains of laboratory mice have a genetic defect for melatonin synthesis. In non-deficient species, melatonin synthesis undergoes a typical, beta-adrenergically regulated day/night rhythm with low melatonin levels during daytime and high levels at night, the precursor serotonin showing an inverse behaviour. This study examines whether a day/night rhythm of pineal serotonin levels exists in melatonin-deficient male BALB/c mice. Mice kept under a lighting schedule of 12 h light (lights on at 07.00 h) and 12 h dark were killed at 13.00 and 01.00 h, respectively. Serotonin amounted to 12-15 ng/pineal and did not show regular day/night differences. Administration of the beta-adrenergic agonist, isoproterenol, which is known to affect melatonin synthesis in a number of species, was without effect on pineal serotonin levels. Melatonin and two of the melatonin-forming enzymes, serotonin N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) were below the detection limit in the pineal. It is concluded that in melatonin-deficient BALB/c mice, pineal serotonin synthesis is apparently intact. In BALB/c mice, serotonin synthesis and release do not appear to be directly or indirectly regulated by beta-adrenergic mechanisms.
Vollrath
L
L
Anatomisches Institut, Johannes Gutenberg-Universität, Mainz, FRG.
Huesgen
A
A
Manz
B
B
Pollow
K
K
D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D002940:Circadian Rhythm; D007545:Isoproterenol / Q000008:administration & dosage; D008297:Male; D008550:Melatonin / Q000096:biosynthesis / Q000172:deficiency*; D051379:Mice; D008807:Mice, Inbred BALB C; D010870:Pineal Gland / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; D000121:Acetylserotonin O-Methyltransferase; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin; D007545:Isoproterenol