Interactive effect of light colours and temporal synergism of circadian neural oscillations in reproductive regulation of Japanese quail.

Avian literature reports the modulation of 'photoperiodic gonadal responses' by the temporal phase relation of serotonergic and dopaminergic oscillations in Japanese quail. But, the modulation of 'light colour responses' by the temporal synergism of neural oscillations is not yet known. Hence the present study was designed to investigate the interaction of the light colour (blue, red) and the phase relation of neural oscillations in the reproductive regulation of Japanese quail.

Light colour and intensity alters reproductive/seasonal responses in Japanese quail.

An extensive literature is available on the photoperiodic responses of avian species but studies on light colour and wavelength from light emitting diode (LED) sources on reproduction are limited. Hence, an experiment was designed to study the effect of different colours and intensities of light on the reproductive responses of Japanese quail. Three-week old quail were exposed to five different light conditions with a long photoperiod (LD 16:8): WT (white fluorescent light 100 lux as control), W LED (white light emitting diode, 30 lux), B LED (blue LED, 30 lux), G LED (green LED, 30 lux) and R-LED (red LED, 30 lux).

Interaction of specific temporal phase relations of circadian neural oscillations and long term photoperiodic responses in Japanese quail, Coturnix coturnix japonica.

Specific temporal phase relations of neural oscillations are reported to regulate gonadal activity in many avian species but their interaction with photo-sexual response are still unclear. Hence in the present study, 3week old Japanese quail maintained in short days (experiment 1) received normal saline (SD control) or serotonin precursor 5-HTP and dopamine precursor l-DOPA injections at the interval of 12h (SD 12-h) for 13days. At 37week of age, one subgroup of SD 12-h received these drugs at the interval of 8-h (SD 12-h+8-h).

Internal coincidence of serotonergic and dopaminergic oscillations modulates photo sexual responses of Japanese quail, Coturnix coturnix japonica.

Specific temporal phase relation of neural oscillations appears to be the regulator of gonadal development in many seasonally breeding species. To find out the specific phase angle of two neural oscillations that triggers gonado-inhibitory or gonado-stimulatory response, and to test the internal coincidence model, sexually immature male Japanese quail were administered with the serotonin precursor, 5-hydroxytryptophan and the dopamine precursor, L-dihydroxyphenylalanine at hourly intervals of 6, 7, 8, 9, 10, 11 and 12 h (5 mg/100 g body weight/day for 12 days under continuous condition of light, LL). Thereafter all the groups were shifted to long photoperiod (LD16:8).

Influence of temporal relationships between serotonergic and dopaminergic precursors on the regulation of gonadal development in birds.

This article is focused on the effect of specific phase relation of serotonergic and dopaminergic oscillations on the gonadal responses of different avian species. These species include (i) summer breeding birds - Red headed bunting (exhibiting post-reproductive absolute photorefractoriness) and Indian Weaver bird (which lacks absolute photorefractoriness), (ii) autumn breeding - Spotted munia and Lal munia (photoperiodic responses of which are distinctly different from that of any long day birds described thus far) and (iii) domesticated Japanese quail (which under natural day length breeds in summer, exhibits relative photorefractoriness, but breeds continuously if maintained in long photoperiod). Previous experiments have shown that daily administration of serotonin precursor 5-hydroxytryptophan and dopamine precursor L-dihydroxyphenylalanine given 8h apart during progressive phase of gonadal cycle can lead to a significant decrease in gonadal activity.