Effect of Monochromatic Light on Melatonin Secretion and Arylalkylamine N‐Acetyltransferase mRNA Expression in the Retina and Pineal Gland of Broilers

Abstract

The goal of this study is to investigate the effects of various monochromatic lights on plasma melatonin (MT) levels and the expression of arylalkylamine N-acetyltransferase (AANAT) mRNA in the pineal gland and retina. A total of 160 newly hatched (posthatching day 1, P1) broilers, including intact, sham-operated, and pinealectomized groups were exposed to blue light (BL), green light (GL), red light (RL), and white light (WL) by light emitting diode (LED) system for short term (24 hr) or long term (2 weeks), separately. For intact and sham-operated birds, the plasma MT level exhibited marked circadian rhythms at P7 and P14 regardless of short-term and long-term exposure to four monochromatic lights. However, WL and BL showed a faint suppression of MT secretion in contrast to GL and RL at either light or dark time points, with the following rank order: GL < RL < WL < BL. Larger circadian amplitude of MT levels was observed in GL group versus BL group (at P14: 87.70 pg/mL vs. 19.85 pg/ mL, respectively). Pinealectomy disturbed the MT rhythm under different light colors, especially in RL. Additionally, consistent with the alteration of plasma MT levels, we observed increased AANAT mRNA expression and immunoreactive cell numbers of proliferating cell nuclear antigen (PCNA) and c-Fos in the pineal gland or retina in GL than that of BL, whereas 5-HT immunoreactive cell number was significantly decreased in GL. These data suggested that GL enhanced chick pinealocytes and retinal cells to express AANAT mRNA and to secrete MT, which may be depended on promoting c-Fos expression and cell proliferation. Anat Rec, 294:1233Rec, 294: -1241Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.Key words: melatonin; AANAT mRNA; monochromatic light; broiler; pinealectomy It is well established that melatonin (MT) can regulate many different daily and seasonal cycles or rhythms in various physiological systems of vertebrates, including the cardiopulmonary, reproductive, excretory, thermoregulatory, behavioral, immune, and neuroendocrine systems (Mikami et al., 1983;Pang et al., 1996;Gwinner et al.,

Productive and Physiological Response of Broiler Chickens Exposed to Different Colored Light-Emitting Diode and Reared Under Different Stocking Densities

“…Exposure birds to LED-BL and stocked at 10 birds/m 2 are likely induce the secretion of pineal melatonin, which plays an important role in growth performance and the immune functions (Apeldoorn et al, 1999). The finding are disagree with results obtained by Jin et al (2011) indicated that the concentration of plasma melatonin under green light was the highest, followed by white light, and was the lowest in red light and blue light for broilers.…”

Role of Monochromatic Light on Development of Cecal Tonsil in Young Broilers

“…The effects of GL on the cecal tonsil disappeared after pinealectomy, indicating a close relationship between MEL and the different monochromatic lights. In addition, Jin et al () demonstrated that GL enhanced pinealocytes to secrete MEL in broilers. Collectively, the trends of development in the cecal tonsil under the different monochromatic lights were consistent with the alteration of MEL, suggesting that MEL plays a critical role in the GL‐induced promotion of development in the cecal tonsil.…”

“…Furthermore, the biosynthesis and secretion of MEL are affected by external light. For instance, green light (GL) enhances pinealocytes to secrete MEL in broilers (Jin et al, ). These studies implied that MEL might play a critical role in the monochromatic light‐induced development and immune state of the cecal tonsil in birds.…”

Melatonin Receptor Mel1b‐ and Mel1c‐mediated Green Light Induced the Secretion of Growth Hormone in Anterior Pituitary of Chicks

“…Meanwhile, the melatonin concentration in GL was the greatest and was significantly greater than those in WL, RL and BL by 6.44-22.35% (P = 0.000-0.016); the difference was not observed between RL and WL (P = 0.175). After pinealectomy, the level of plasma GH (F (3,10) = 0.376) and melatonin (F (3,11) = 0.518) in various monochromatic lights decreased significantly, especially in GL. However, the differences disappeared among the four light treatments (P > 0.05).…”