Role of Catecholamines in Photoperiodically-Induced Gonadal Development in Coturnix Quail1

The involvement of central biogenic amines in the mechanisms controlling photoperiodically-induced testicular development in Coturnix quail were studied employing pharmacological approaches. Daily administration of alpha-methyltyrosine (MT), which blocks catecholamine (CA) biosynthesis, to 6-week-old quail exposed to long daily photoperiods markedly depleted brain dopamine (DA), norepinephrine (NE) and epinephrine (E). This was associated with a partial suppression of testicular growth 7 days after light stimulation. Combined treatment with MT and L-dihydroxyphenylalanine (L-DOPA), a precursor of DA, NE and E, elevated the monoamine levels in the brain and prevented the blocking effect of MT on testicular growth. Selective blockade of NE and E biosynthesis with diethyl-dithiocarbamate (DDC) depleted both NE and E, while it elevated DA level. Furthermore, such treatment reduced testicular weight. In DDC-treated birds, D,L-dihydroxyphenylserine (DL-DOPS) administration, which bypasses the DDC block, restored only brain NE level and reversed the blocking action of DDC on testicular weight. It is concluded that central NE plays a role in transformation of the photoperiodic information affecting gonadal development in Coturnix quail.