title: Phototransduction-related circadian changes in indoleamine metabolism in the chick pineal gland in vivo.
abstract: The purpose of this study was to examine the day/night levels of pineal melatonin and its rate limiting enzyme N-acetyltransferase (NAT) in relationship to the ratio of 11-cis- to all-trans-retinal. Three-week-old chicks were placed in 12:12 light:dark (LD 12:12) cycle for one week, pineals were collected during the light phase at 1500 (i.e., after 10 hr light), during the dark phase at 1900 (i.e., 2 hr after dark), at 2100 (i.e., 4 hr after dark), and at 2300 (i.e., 6 hr after dark) and after light extension to 1900. The results show that light-sensitive 11-cis-retinal in the chick pineal has the same diurnal rhythm as NAT and melatonin; all constituents increased within 2 hr of darkness onset (at 1900) and reached their peak after 4 hr of dark. All values were lowest during the light phase at 1500. Low values for 11-cis-retinal, NAT, and melatonin were also seen in the group of chicks which experienced light extension to 1900. The data indicate that in vivo light plays a major role in triggering rhodopsin-bound 11-cis-retinal production within 2-4 hr after darkness onset; this change likely serves as the signal for the subsequent formation of the hormonal product of the pineal gland, melatonin.
authors.affiliation: Department of Anatomy, Kaohsiung Medical College, Taiwan, Republic of China.
authors.forename: J H
authors.initials: JH
authors.lastname: Sun
authors.forename: R J
authors.initials: RJ
authors.lastname: Reiter
authors.forename: A
authors.initials: A
authors.lastname: Hattori
authors.forename: K
authors.initials: K
authors.lastname: Yaga
authors.forename: D C
authors.initials: DC
authors.lastname: Herbert
authors.forename: A T
authors.initials: AT
authors.lastname: Tsin
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm / Q000502:physiology*; D007536:Isomerism; D008027:Light; D008550:Melatonin / Q000378:metabolism*; D010870:Pineal Gland / Q000378:metabolism*; D011863:Radioimmunoassay; D012172:Retinaldehyde / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000121:Acetylserotonin O-Methyltransferase; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin; D012172:Retinaldehyde