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| Titel: |
Roles of retinal and encephalic photoreceptors in the photoperiodic gonadal and locomotor activity of Japanese quail |
| Auteur: |
Ohta, Mitsuaki |
| Verschenen in: |
Biological rhythm research |
| Paginering: | Jaargang 20 (1989) nr. 2 pagina's 113-122 |
| Jaar: |
1989-05 |
| Inhoud: |
Various schedules of brain lighting with a red-light emitting diode (rLED, peak of emission at 700 nm) were repeated over periods of 2 weeks in order to assess the roles of retinal and encephalic photoreceptors and their neural interconnections in Japanese quail. The results in terms of gonadal growth showed: (1) illumination of the brains of birds held on an 8L:16D cycle (lights on at 1000 hr) for 4 additional hours was stimulatory if the 4 hrs of illumination began at the end of the standard photoperiod but not when it began 4 hrs before the onset of the standard photoperiod. However, in blinded birds, 4 hrs of brain lighting was inductive in both cases; (2) four hrs of additional illumination of the brain of hypothalamic deafferented birds was not stimulatory, but 8 hrs of such illumination was stimulatory The results in terms of the rhythm of locomotor activity showed: (1) sighted control birds synchronized their activity with the environmental 8L:16D cycle, whereas blinded and brain-illuminated birds free-ran with a long period; (2) birds that experienced brain lighting from 0600 hr had a free-running component with an initial phase determined by the timing of brain lighting, except in the case of deafferented birds; (3) all deafferented birds were arrhythmic. These results suggest that (1) the encephalic photoreceptor is involved in gonadotropin-releasing activity and in entrainment in a compensatory manner, (2) the circadian clock(s) is/are located outside the infundibular nuclear complex; (3) the neural interconnections between the photoreceptors and the circadian clock(s) are essential for complete entrainment and photoperiodic gonadal growth. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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