title: Ethanol consumption and pineal melatonin daily profile in rats.
abstract: It is well known that melatonin participates in the regulation of many important physiological functions such as sleep-wakefulness cycle, motor coordination and neural plasticity, and cognition. However, as there are contradictory results regarding the melatonin production diurnal profile under alcohol consumption, the aim of this paper was to study the phenomenology and mechanisms of the putative modifications on the daily profile of melatonin production in rats submitted to chronic alcohol intake. The present results show that rats receiving 10% ethanol in drinking water for 35 days display an altered daily profile of melatonin production, with a phase delay and a reduction in the nocturnal peak. This can be partially explained by a loss of the daily rhythm and the 25% reduction in tryptophan hydroxylase activity and, mainly, by a phase delay in arylalkylamine N-acetyltransferase gene expression and a 70% reduction in its peak activity. Upstream in the melatonin synthesis pathway, the results showed that noradrenergic signaling is impaired as well, with a decrease in β1 and α1 adrenergic receptors' mRNA contents and in vitro sustained loss of noradrenergic-stimulated melatonin production by glands from alcohol-treated rats. Together, these results confirm the alterations in the daily melatonin profile of alcoholic rats and suggest the possible mechanisms for the observed melatonin synthesis modification.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, Brazil.
authors.forename: Rafael
authors.initials: R
authors.lastname: Peres
authors.forename: Fernanda Gaspar
authors.initials: FG
authors.lastname: do Amaral
authors.forename: Thiago Cardoso
authors.initials: TC
authors.lastname: Madrigrano
authors.forename: Julieta Helena
authors.initials: JH
authors.lastname: Scialfa
authors.forename: Silvana
authors.initials: S
authors.lastname: Bordin
authors.forename: Solange Castro
authors.initials: SC
authors.lastname: Afeche
authors.forename: José
authors.initials: J
authors.lastname: Cipolla-Neto
mesh_terms: D000121:Acetylserotonin O-Methyltransferase / Q000235:genetics; D000437:Alcoholism / Q000503:physiopathology*; D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase; D056926:CLOCK Proteins / Q000235:genetics; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology*; D015870:Gene Expression / Q000235:genetics; D008297:Male; D008550:Melatonin / Q000097:blood*; D010870:Pineal Gland / Q000187:drug effects* / Q000503:physiopathology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics; D018342:Receptors, Adrenergic, beta-1 / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000503:physiopathology; D014365:Tryptophan Hydroxylase / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D018342:Receptors, Adrenergic, beta-1; D014365:Tryptophan Hydroxylase; D000121:Acetylserotonin O-Methyltransferase; D056926:CLOCK Proteins; C538945:Clock protein, rat; C520223:Aanat protein, rat; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin