title: Diurnal rhythm in the levels of the serotonin 5-HT1A receptors in the crayfish eyestalk.
abstract: The crayfish eyestalk (ES) has been postulated as a possible circadian clock. 5-Hydroxytryptamine (5-HT) has been shown to play the role of a neurotransmitter or a modulator in the ES. However, little is known about the 5-HT receptors in the ES. The purpose of this work is to determine the specific binding sites using [(3)H]8-hydroxy-2(di-n-propylamino)tetralin ([(3)H]8-OH-DPAT), a specific agonist of the 5-HT(1A) receptor, and to characterize the diurnal rhythm in the binding by an autoradiography procedure in the crayfish ES. Data show the presence of a circadian rhythmicity in the level of the 5-HT(1A) receptors, principally in two regions: (a) the complex retina (R)-lamina ganglionaris (LG), with the acrophase at dusk and (b) the medulla terminalis (MT), where it was in antiphase. It is suggested that (1) the expression of levels of 5-HT(1A) receptors is modulated by light-dark (LD) cycles, (2) the level of 5-HT(1A) receptors in the R-LG and MT are in antiphase during the 24-h cycle, and (3) there is a different mechanism of action of LD cycles in each of these two anatomical regions of the crayfish ES.
authors.affiliation: División de Estudios de Posgrado e Investigación, Facultad de Medicina, UNAM., Av. Universidad 3000, Circuito Interior, Unidad de Posgrado, 1er. Piso., 04510 México D. F., México.
authors.forename: Gabina
authors.initials: G
authors.lastname: Calderón-Rosete
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Flores
authors.forename: Leonardo
authors.initials: L
authors.lastname: Rodríguez-Sosa
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000493:pharmacokinetics; D000818:Animals; D003400:Astacoidea / Q000033:anatomy & histology / Q000378:metabolism*; D001345:Autoradiography / Q000379:methods; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects; D011869:Radioligand Assay / Q000379:methods; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D012160:Retina / Q000187:drug effects / Q000378:metabolism; D017366:Serotonin Receptor Agonists / Q000493:pharmacokinetics; D013997:Time Factors; D014316:Tritium / Q000493:pharmacokinetics; D014795:Visual Pathways / Q000378:metabolism*
chemical_list: D017366:Serotonin Receptor Agonists; D014316:Tritium; D044282:Receptor, Serotonin, 5-HT1A; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin