Tryptophan loading increases daytime serum melatonin levels in intact and pinealectomized rats.
L-tryptophan (L-Trp) effects on serum and pineal melatonin were studied in fasted and non-fasted rats. Oral administration of L-Trp during the day caused serum melatonin to increase 4-fold compared to that of saline treated rats; this occurred in both fasted and non-fasted animals. In the same animals, neither NAT, HIOMT, not melatonin levels were changed. In a second study, pinealectomized rats were loaded with L-Trp. In these animals, as in those that had an intact pineal gland, L-Trp loading caused a large increase in immunoreactive serum melatonin. The results suggest that the increased melatonin in serum due to L-Trp administration is primarily derived from an extrapineal organ.
Yaga
K
K
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284-7762.
Reiter
R J
RJ
Richardson
B A
BA
D000284:Administration, Oral; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D008297:Male; D008550:Melatonin / Q000097:blood* / Q000378:metabolism; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism* / Q000601:surgery; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D014364:Tryptophan / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*
D014364:Tryptophan; D008550:Melatonin