Influence of 5-HT1A agonist on the feeding behavior of Coturnix japonica (Galliformes: Aves)

Abstract

In this study, we investigate the effect of serotonin receptor 5-HT1A stimulation on the feeding behavior of quails (Coturnix japonica). The administration of 5-HT1A agonist, 8-OH-DPAT (0.05 to 5.0 mg/Kg) dose-dependently inhibited the food intake in normally fed quails. Greater inhibition was attained with 5.0 mg/kg (0.93 ± 0.21 g vs. 5.83 ± 0.25 g, P < 0.05, 2 h after food offer). A comparable response was obtained from previously fasted quails. At end of 2 h, a higher dose of 8-OH-DPAT induced more intense hypophagy (1.59 ± 0.41 g vs. 6.85 ± 1.04 g, P < 0.0001). Previous treatment with the antagonist 5-HT1A/β-adrenergic, propranolol, failed to block the inhibitory action of 8-OH-DPAT, but instead, intensified it (controls, 5.22 ± 1.09 g; 8-OH-DPAT, 1.41 ± 0.19 g; propranolol + 8-OH-DPAT, 0.44 ± 0.25 g, P < 0.01, for all comparisons). The administration of an isolated higher dose of propranolol induced a hypophagic action (controls, 4.5 ± 0.8 g vs. propranolol, 2.0 ± 0.2 g, P < 0.01). Current outcomes suggest a possible role of 5-HT1A receptor on the feeding behavior of quails, as opposed to mammals. On the other hand, the intensified hypophagy induced by previous administration of propranolol raises the hypothesis of a β-adrenergic excitatory mechanism that controls the feeding behavior of quails.Keywords: feeding behavior, 5-HT1A receptor, serotonergic system, quails, Coturnix japonica. 5,83 ± 0,25 g, P < 0,05, 2 h após a oferta de alimento). Resposta comparável foi alcançada nas aves previamente submetidas ao jejum alimentar. Ao final de 2 h, a dose maior de 8-OH-DPAT induziu a uma intensa resposta hipofágica (1,59 ± 0,41 g vs. 6,85 ± 1,04 g, P < 0,0001). O tratamento prévio com o antagonista 5-HT1A/β-adrenérgico, propranolol, não bloqueou a ação inibidora do 8-OH-DPAT na ingestão alimentar, ao contrário, intensificou-a (controles, 5,22 ± 1,09 g; 8-OH-DPAT, 1,41 ± 0,19 g; propranolol + 8-OH-DPAT, 0,44 ± 0,25 g, P < 0,01, para todas as comparações). A administração isolada de propranolol evidenciou uma ação hipofágica com a dose maior (controles, 4,5 ± 0,8 g vs. propranolol, 2,0 ± 0,2 g, P < 0,01). Os resultados obtidos evidenciaram um possível papel dos receptores 5-HT1A na modulação do comportamento alimentar em codornas de natureza oposta ao referido para mamíferos. Por outro lado, a potencialização da hipofagia pela prévia administração de propranolol suscita a hipótese de um mecanismo β-adrenérgico excitatório no controle do comportamento alimentar em codornas. RESUMO

Performance, Carcass Yield, Muscle Amino Acid Profile, and Levels of Brain Neurotransmitters in Aged Laying Hens Fed Diets Supplemented with Guanidinoacetic Acid

“…Considering that serotonin may exert an inhibitory action on feeding in chickens [ 47 ], GA supplementation may improve the feeding patterns and consequent carcass yield of laying hens. While some researchers have reported that an injection of a serotonin agonist reduces the food intake in the fasted–refed birds [ 48 ], others have reported an inhibitory effect on feeding patterns in fed and fasted adult quails [ 49 ].…”

Hypophagic and dipsogenic effect of the 5‐HT1A receptor agonist 8‐OH‐DPAT in broiler chickens

“…Furthermore, in the work of Kostal and Savory (1996) when female broiler breeders were injected with 40, 200 and 1000 μg/kg of the 5‐HT 1A agonist 8‐OH‐DPAT, only the highest dose of 1000 μg/kg body weight cause scratching behaviour, which is considered as part of the serotonin behaviour syndrome as described in rodents and pigeons (Kostal and Savory, 1996). Although the species’ differences cannot be disregarded, the serotonin behaviour syndrome can probably explain the inhibition of the food intake registered by Reis and Marinho (2005) in fed and fasted adult quails when doses of 500, 1000 and 5000 μg/kg of 8‐OH‐DPAT were used.…”

“…In this case, the water intake rises rapidly and significantly during the 2 h of the experiment (Saadoun and Cabrera, 2002). Recently, Reis and Marinho (2005) using the agonist 8‐OH‐DPAT showed an inhibitory effect on food intake in fed and fasted adults male quails.…”