Aim: 

In the present study we have evaluated the effect of the oral administration of melatonin and tryptophan on humoral immune response in the ring doves (Streptopelia risoria) from different age groups.

Methods: 

Male and female ring doves of 2-3 years of age (young) and 10-12 years of age (old) were used in this study. The animals received a single capsule of 300 mg/kg b.w. of tryptophan or a single oral dose (0.25 or 2,5 mg/kg body weight/0.1 ml per animal/day, young and old animals respectively) of melatonin for 3 consecutives days 1 hr before lights off. Blood samples were performed before beginning the treatment (basal values), during the 3 days of treatment and 1 day following its termination. CH-50 activity, immunoglobulins and bactericidal activity were measured.

Results: 

Our results show that in old animals the humoral immune response was declined with respect to the young. Both melatonin and tryptophan treatment increased the immunoglobulins concentration, being the nocturnal values significantly higher than diurnal values and with major effect in old animals. The bactericidal activity of the S.risoria serum against S. aureus, after the treatment with melatonin or tryptophan, was increased at night with a higher effect in old animals. No significant differences were observed in the haemolytic activity of serum.

Conclusion: 

The oral administration of melatonin or tryptophan to young and old ring oves, produced a stimulation of the humoral immune response with an increase in serum immunoglobulins concentrations and bactericidal activity.

Supported by MEC-DGI grant 3PRO5A053. M.P. Terrón and S.D. Paredes are beneficiaries of grants by Junta de Extremadura (REI07004 and POS07012, espectively).