Functional maturation of neuroendocrine gonadal axis is altered by specific phase relations of circadian neurotransmitter activity in Japanese quail.
The present study was designed to ascertain the effects of temporal relationship of circadian neural oscillations on puberty attainment and reproductive growth of Japanese Quail, Coturnix coturnix japonica. Serotonin and dopamine precursors (5-hydroxytryptophan, 5-HTP and L-dihydroxyphenylalanine, L-DOPA; 5 mg/100 g body weight) were injected daily, 8 and 12 h apart in two groups of one-day old chicks, while controls received two daily injections of normal saline. Weekly/biweekly observations (body weight, cloacal gland size, testicular volume and activity, ovarian follicular diameter and rate of egg production) were made until 9 weeks of age, when the experiment was terminated. Results indicate that 8 h relationship completely suppressed gonadal growth even under long photoperiod (LD 16:8), while a 12 h relationship induced precocious sexual maturity and increased the rate of reproduction (spermatogenesis and egg production). It is concluded that circadian phase relationship of serotonergic and dopaminergic activity may not only determine the onset of reproduction in this poultry species, but may also alter the rate of reproduction possibly by affecting photoperiodic mechanism of reproductive regulation.
Phillips
D
D
Department of Zoology, Banaras Hindu University, Varanasi, India.
Chaturvedi
C M
CM
D000818:Animals; D000831:Animals, Newborn; D002940:Circadian Rhythm / Q000502:physiology*; D003370:Coturnix / Q000254:growth & development* / Q000378:metabolism; D005260:Female; D007980:Levodopa / Q000378:metabolism; D008297:Male; D009490:Neurosecretory Systems / Q000502:physiology*; D010053:Ovary / Q000254:growth & development* / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D013737:Testis / Q000254:growth & development* / Q000378:metabolism
D012701:Serotonin; D007980:Levodopa