Monochromatic light affects the development of chick embryo liver via an anti-oxidation pathway involving melatonin and the melatonin receptor Mel1cby Tuanjie Wang, Zixu Wang, Jing Cao, Yulan Dong, Yaoxing Chen

Can. J. Anim. Sci.

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Year
2014
DOI
10.4141/cjas2013-177
Subject
Food Animals / Animal Science and Zoology

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Monochromatic light affects the development of chick embryo liver via an anti-oxidation pathway involving melatonin and the melatonin receptor Mel1c

Tuanjie Wang, Zixu Wang, Jing Cao, Yulan Dong, and Yaoxing Chen1

Laboratory of Anatomy of Domestic Animals, College of Animal Medicine,

China Agricultural University, Haidian, Beijing 100193, China.

Received 8 November 2013, accepted 11 March 2014. Published on the web 31 March 2014.

Wang, T., Wang, Z., Cao, J., Dong, Y. and Chen, Y. 2014. Monochromatic light affects the development of chick embryo liver via an anti-oxidation pathway involving melatonin and the melatonin receptor Mel1c. Can. J. Anim. Sci. 94: 391400.

Monochromatic light can influence muscle development during incubation and post-hatching. This process is related to

IGF-1, which is primarily secreted by the liver. However, the effect of monochromatic light on liver development of chick embryo is unclear. In this study, 600 Arbor Acres fertile broiler eggs were randomly assigned to four incubators and exposed to continuous red light (R-group), green light (G-group), blue light (B-group), or a dark environment (D-group, control). The liver index of the G-group was higher than that of other groups (6.4715.46%) at E21, accompanied by a higher percentage of proliferating cell nuclear antigen (PCNA). The superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and total antioxidant capability (T-AOC) contents were the highest in the G-group, and this trend was positively correlated with plasma melatonin (Mel) levels and the Mel receptor Mel1c expression of liver, while the malondialdehyde (MDA) content appeared to follow an opposite trend. In vitro, the administration of exogenous melatonin (250 pg mL1) increased the proliferative activity and the antioxidant status of hepatocytes. However, this effect was significantly inhibited by Prazosin, a Mel1c inhibitor. These results suggest that green light improves the antioxidant status of the liver, which is mediated by melatonin and mel1c, and finally accelerates liver development.

Key words: Monochromatic light, chick embryo, liver, melatonin receptor, anti-oxidation

Wang, T., Wang, Z., Cao, J., Dong, Y. et Chen, Y. 2014. La lumie`re monochromatique a un effet sur le de´veloppement du foie de l’embryon de poussin par une voie d’antioxydation impliquant la me´latonine et le re´cepteur de la me´latonine Mel1c.

Can. J. Anim. Sci. 94: 391400. La lumie`re monochromatique peut influencer le de´veloppement des muscles pendant l’incubation et la pe´riode post-e´closion. Ce processus est relie´ a` l’IGF-1, qui est se´cre´te´ principalement par le foie. Par contre, les effets de la lumie`re monochromatique sur le de´veloppement du foie de l’embryon de poussin ne sont pas clairs. Dans cette e´tude, 600 oeufs de poulets de chair Arbor Acres fertiles ont e´te´ assigne´s ale´atoirement a` quatre incubateurs puis expose´s a` une lumie`re continue rouge (groupe R), verte (groupe G  « green »), bleue (groupe B), ou un environnement sombre (groupe D  « dark », te´moin). L’indice he´patique du groupe G e´tait plus e´leve´ que celui des autres groupes (6,47 % a` 15,46 %) a` E21, accompagne´ d’un plus haut pourcentage d’antige`ne nucle´aire de prolife´ration cellulaire (PCNA  « proliferating cell nuclear antigen »). Les activite´s de T-SOD, GSH-PX et T-AOC e´taient les plus e´leve´es dans le groupe G, et il y avait une corre´lation positive entre cette tendance et les niveaux plasmatiques de me´latonine (Mel) et l’expression du re´cepteur de me´latonine Mel1c dans le foie, tandis que le contenu en MDA semblait suivre une tendance inverse. In vitro, l’administration de me´latonine exoge`ne (250 pg/mL) augmentait l’activite´ prolife´rative et le statut antioxydant des he´patocytes. Par contre, cet effet e´tait inhibe´ de fac¸on significative par la Prazosin, un inhibiteur de Mel1c.

Ces re´sultats sugge`rent que la lumie`re verte ame´liore le statut antioxydant du foie, qui est me´die´ par la me´latonine et

Mel1c, et acce´le`re le de´veloppement du foie.

Mots cle´s: Lumie`re monochromatique, embryon de poussin/poulet, foie, re´cepteur a` me´latonine, voie d’antioxydation

Artificial light is widely used in poultry husbandry.

Suitable illumination regimes can increase body weight, improve the feed conversion ratio in broilers (Mahmud et al. 2011), and reduce the broiler mortality ratio (Gordon 1994). A specific light intensity range may stimulate eye development in chicks (Blatchford et al. 2012) and may affect heart muscle weight in turkeys (Yahav et al. 2000). Similarly, light stimulation during avian embryo incubation also exerts several significant effects. White light stimulus has been shown to promote embryonic development and to shorten the hatching time of chicks (Coleman and McDaniel 1975) and quails (Walter and Voitle 1973). 1Corresponding author (e-mail: yxchen@cau.edu.cn).

Abbreviations: GSH-PX, glutathione peroxidase; IOD, integrated optical density; MDA, malondialdehyde; Mel, melatonin; PCNA, proliferating cell nuclear antigen; T-AOC, total antioxidant capability; T-SOD, superoxide dismutase

Can. J. Anim. Sci. (2014) 94: 391400 doi:10.4141/CJAS2013-177 391

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Due to the superior nature of avian vision, the color of the light also affects poultry growth in addition to the light regime and intensity. Our previous studies have suggested that monochromatic light can influence the spleen index (Xie et al. 2008) and promote skeletal muscle development (Liu et al. 2010) in broilers. Several studies have demonstrated that a combination of monochromatic lights could improve the production performance of broilers (Rozenboim et al. 2004a; Cao et al. 2012).

However, there are few studies regarding the effect of monochromatic light on chick embryo development. It has been reported that green light stimuli during embryogenesis enhances both body and breast muscle weight at the embryonic stage and post-hatching (Rozenboim et al. 2004b; Zhang et al. 2012). This stimulating effect of monochromatic green light on skeletal muscle may be related to the levels of IGF-1 in the plasma and muscle of chicks (Halevy et al. 2006; Liu et al. 2010). A recent study indicated that the administration of rhIGF-1 influences muscle development in duck embryos (Liu et al. 2011) and rat (Rommel et al. 2001). IGF-1 in the circulating blood originates primarily from the liver (Sjo¨gren et al. 1999).