The effect of different temporal relationships of 5‐hydroxytryptophan (5‐HTP) and l‐dihydroxyphenylalanine (L‐DOPA) on reproductive and metabolic responses of migratory red‐headed bunting (Emberiza bruniceps)

TLDR: It is manifested that 12 hour relationship of these two neural oscillations may induce breeding conditions (summer), 8 hour relationship induced post reproductive regressive/photorefractory condition (late summer) and 4‐hour relationship induced...

Abstract: To study the reproductive and metabolic effects of circadian serotonergic and Dopaminergic activities, 5‐hydroxytryptophan (5‐HTP, serotonin precursor) and L‐dihydroxyphenylalanine (L‐DOPA, dopamine precursor) were administered daily in different temporal relationships in Red‐headed bunting (Emberiza bruniceps) during the preparatory phase of annual gonadal cycle. L‐DOPA given daily after 12 hours of 5‐HTP injection (12‐hr relationship) induced full gonadal development and fat deposition. But, L‐DOPA given after 4 hours of 5‐HTP administration (4‐hr relationship) stimulated only fat deposition without any gonadal effect. On the other hand, these two drugs injected 8‐hour apart led to significant decrease in gonadal growth as well as fat deposition. The findings manifested that 12 hour relationship of these two neural oscillations may induce breeding conditions (summer), 8 hour relationship induced post reproductive regressive/photorefractory condition (late summer) and 4‐hour relationship induced...