Yulan Dong

Effects of Monochromatic Light on Immune Response of Broilers

A total of 260 one-day-old Arbor Acres male broilers were exposed to red light (RL), green light (GL), blue light (BL), and white light (WL), respectively, by using a light-emitting diode system for 7 wk. There were 5 replicate pens for each light treatment and 13 birds per pen. The effects of monochromatic light on the immune response were studied. The results indicated that proliferation of peripheral blood T lymphocytes in the GL group was significantly increased (by 80.8 and 54.8%) compared with those in the RL and BL groups, respectively, at 21 d of age (P < 0.05). At 49 d of age, however, the proliferation response was significantly increased in the BL group compared with the RL group (26.9%, P< 0.05). Moreover, the GL group showed a significant elevation in the serum anti-Newcastle disease virus level as compared with that of the RL group at 28 d of age (32.9%, P < 0.05). In contrast, no significant difference in serum anti-Newcastle disease virus level was observed among the BL, RL, and WL groups at this age (P > 0.05). By 49 d of age, the antibody titer was higher in the BL group than in the RL group (62.8%, P < 0.05). However, no significant difference in antibody titer was seen among the BL, GL, and WL groups at this age. Interestingly, the BL group showed a 44.0% reduction in the level of serum interleukin-1beta as compared with that in the RL group at 49 d of age (P < 0.05). These results suggest that GL and BL enhance the immune response better than RL, and that BL may play a role in alleviating the stress response in broilers.

Effect of combinations of monochromatic lights on growth and productive performance of broilers

Our previous study suggested that green light promotes broiler growth during the early stage [posthatching day (P) 0 to P26], and blue light enhances growth during the later stage (P27 to P49). The purpose of this study was to improve broiler growth and productive performance by using a combination of monochromatic lights at critical points between the early and later stages of growth. A total of 512 male Arbor Acres broilers on P0 were reared under white light (W), red light (R), green light (G), and blue light (B) by using light-emitting diode lamps at 15 ± 0.2 lx from P0 to P26 (16 replicate pens/group, 8 birds/pen), and then switching to another color of light until P49 (4 replicate pens/group, 8 birds/pen). As compared with single monochromatic lights, broilers reared in environments under combinations of monochromatic lights, W→G, R→B, G→B, and B→G, attained heavier BW than those reared in environments under W→W (3.18 to 12.00%), R→R (1.96 to 18.14%), G→G (0.85 to 5.08%), and B→B (0.39 to 4.70%), respectively. In addition, feed conversion ratios in the W→B, R→B, and G→B combinations were lower than feed conversion ratios for W→W (15.86%, P < 0.05), R→R (18.41%, P < 0.05), and G→G (3.37%), respectively. Moreover, the eviscerated carcass weight and breast, thigh, and crus muscle weights under G→B were greater by 0.40 to 56.23% than were those for the other light groups except W→B (eviscerated carcass) and B→G (breast muscle). The results suggest that the application of the G→B and B→G exchanges can be used successfully to improve growth and productive performance in broilers.

Effect of a combination of green and blue monochromatic light on broiler immune response

Our previous study suggested that green light or blue light would enhance the broiler immune response; this study was conducted to evaluate whether a combination of green and blue monochromatic light would result in improved immune response. A total of 192 Arbor Acre male broilers were exposed to white light, red light, green light, and blue light from 0 to 26 days. From 27 to 49 days, half of the broilers in green light and blue light were switched to blue light (G-B) and green light (B-G), respectively. The levels of anti-Newcastle disease virus (NDV) and anti-bovine serum albumin (BSA) IgG in G-B group were elevated by 11.9-40.3% and 17.4-48.7%, respectively, compared to single monochromatic lights (P<0.05). Moreover, the proliferation of peripheral blood T and B lymphocytes and the IL-2 concentration in the G-B groups increased by 10.4-36.2%, 10.0-50.0% and 24.7-60.3% (P<0.05), respectively, compared with the single monochromatic light groups. However, the serum TNF-α concentration in the G-B group was reduced by 3.64-40.5% compared to other groups, and no significant difference was found between the G-B and B-G groups in any type of detection index at the end of the experiment. These results suggested that the combination of G-B and B-G monochromatic light could effectively enhance the antibody titer, the proliferation index of lymphocytes and alleviate the stress response in broilers. Therefore, the combination of green and blue monochromatic light can improve the immune function of broilers.

Melatonin plays a critical role in inducing B lymphocyte proliferation of the bursa of Fabricius in broilers via monochromatic lights

To study the role of melatonin in the monochromatic light-induced B lymphocyte proliferation of bursa, a total of 360 newly hatched broilers, including intact, sham-operated, and pinealectomized groups, were exposed to blue light (BL), green light (GL), red light (RL) and white light (WL) from a light-emitting diode system for 14d. Both in vivo and in vitro studies showed that the percentage of proliferating cell nuclear antigen (PCNA)-immunoreactive lymphocytes and the lymphocyte proliferation in response to lipopolysaccharide in the bursa of broilers in the GL intact group was the highest values among the different intact groups with altered plasma melatonin levels. Additionally, the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and total antioxidant capability (T-AOC) were the highest, whereas malondialdehyde (MDA) content and inducible nitric oxide synthase (iNOS) expression were significantly decreased in the GL intact group. After pinealectomy, the levels of SOD, GSH-Px and T-AOC decreased remarkably in the various light-treatment groups, whereas the MDA content and iNOS expression significantly increased. The administration of exogenous melatonin (250pg/mL) in vitro also significantly enhanced the bursal B lymphocyte proliferation. These findings suggest that GL illumination effectively elevates the antioxidative capacity to promote B lymphocyte proliferation of bursa in young broilers, which might depend on enhanced melatonin secretion.

Restraint stress alters immune parameters and induces oxidative stress in the mouse uterus during embryo implantation

Abstract The influence of stress on embryo implantation is not well understood. Prior studies have focused on later gestational stages and the long-term impact of stress on immune function. The objective of this study is to investigate the effects of restraint stress on the immune parameters and the oxidative states of the uterus during implantation. In this study, pregnant CD1 mice were subjected to restraint stress (4 h/d) on embryonic day 1 (E1) and sacrificed on E3, E5, and E7. Maternal plasma corticosterone (CORT) secretion and implantation sites in the uterus were examined. The uterine (excluding embryos) homogenate and uterine lymphocytes were collected to examine oxidative stress states and associated immune parameters. The results demonstrated that restraint stress increased maternal plasma CORT secretion and reduced the number of implantation sites by 15.3% on E5 and by 26.1% on E7. Moreover, restraint stress decreased the density of uterine natural killer (uNK) cells in the endometrium by 22.1–47.9% and increased the density of mast cells in the myometrium by 55.6–76.9%. Restraint stress remarkably decreased the CD3+CD4+ T/CD3+CD8+ T cell ratio (by 26.2–28.9%) and attenuated uterine lymphocyte proliferation and secretion of cytokines. In addition, restraint stress threatened the intracellular equilibrium between oxidants and antioxidants, resulting in decreased glutathione peroxidase (GSH-PX) (32.2% and 45.7%), superoxide dismutase (SOD) (15.5% and 26.1%), and total antioxidant capacity (T-AOC) (18.4% and 18.2%) activities and increased malondialdehyde (MDA) (34.4% and 43.0%) contents on E5 and E7. In conclusion, these findings demonstrate that restraint stress causes abnormal implantation and negatively impacts immune parameters in association with oxidative stress in mice.

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

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: 391-400. 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 (6.47-15.46%) 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 mL-1) 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.

Effect of monochromatic light on circadian rhythmic expression of clock genes in the hypothalamus of chick

To clarify the effect of monochromatic light on circadian clock gene expression in chick hypothalamus, a total 240 newly hatched chickens were reared under blue light (BL), green light (GL), red light (RL) and white light (WL), respectively. On the post-hatched day 14, 24-h profiles of seven core clock genes (cClock, cBmal1, cBmal2, cCry1, cCry2, cPer2 and cPer3) were measured at six time points (CT 0, CT 4, CT 8, CT 12, CT 16, CT 20, circadian time). We found all these clock genes expressed with a significant rhythmicity in different light wavelength groups. Meanwhile, cClock and cBmal1 showed a high level under GL, and followed a corresponding high expression of cCry1. However, RL decreased the expression levels of these genes. Be consistent with the mRNA level, CLOCK and BMAL1 proteins also showed a high level under GL. The CLOCK-like immunoreactive neurons were observed not only in the SCN, but also in the non-SCN brain region such as the nucleus anterior medialis hypothalami, the periventricularis nucleus, the paraventricular nucleus and the median eminence. All these results are consistent with the auto-regulatory circadian feedback loop, and indicate that GL may play an important role on the circadian time generation and development in the chick hypothalamus. Our results also suggest that the circadian clock in the chick hypothalamus such as non-SCN brain region were involved in the regulation of photo information.

Melatonin modulates monochromatic light-induced GHRH expression in the hypothalamus and GH secretion in chicks.

To study the mechanism by which monochromatic lights affect the growth of broilers, a total of 192 newly hatched broilers, including the intact, sham-operated and pinealectomy groups, were exposed to white light (WL), red light (RL), green light (GL) and blue light (BL) using a light-emitting diode (LED) system for 2 weeks. The results showed that the GHRH-ir neurons were distributed in the infundibular nucleus (IN) of the chick hypothalamus. The mRNA and protein levels of GHRH in the hypothalamus and the plasma GH concentrations in the chicks exposed to GL were increased by 6.83-31.36%, 8.71-34.52% and 6.76-9.19% compared to those in the chicks exposed to WL (P=0.022-0.001), RL (P=0.002-0.000) and BL (P=0.290-0.017) in the intact group, respectively. The plasma melatonin concentrations showed a positive correlation with the expression of GHRH (r=0.960) and the plasma GH concentrations (r=0.993) after the various monochromatic light treatments. After pinealectomy, however, these parameters decreased and there were no significant differences between GL and the other monochromatic light treatments. These findings suggest that melatonin plays a critical role in GL illumination-enhanced GHRH expression in the hypothalamus and plasma GH concentrations in young broilers.

Developmental changes of melatonin receptor expression in the spleen of the chicken, Gallus domesticus.

Melatonin plays an essential role in development and immunoregulation of the avian spleen through its receptors; however, the variations in the expression of the melatonin receptor subtypes in the developing avian spleen are still unclear. The objective of the present study was not only to investigate the distribution patterns and development changes of the expression of the melatonin receptor subtypes (Mel1a, Mel1b and Mel1c) in the chicken spleen but also to identify the correlation between the plasma melatonin concentration and the expression of the melatonin receptor subtypes. The immunohistochemical results indicated that Mel1a was mainly distributed in the red pulp and capillaries, Mel1b was predominantly distributed in the periarterial lymphatic sheath (PALS) and splenic nodule, and Mel1c was widely located in the red pulp, PALS and splenic nodule. From P0 to P21, the mRNA and protein expressions of Mel1a, Mel1b and Mel1c in the spleen were increased (P<0.05); however, a slight increase in the expression of the three melatonin receptor subtypes was observed after P21 (P>0.05). Furthermore, the mRNA levels of Mel1b and Mel1c between P0 and P14 raised more quickly than Mel1a. The plasma melatonin concentration increased in an age-dependent manner in the chicken from P0 to P42 (P<0.05), and this increasing change was linear after P14 (P<0.05). The melatonin level in the plasma is strongly correlated with the protein expressions of Mel1a (r=0.938, P=0.005), Mel1b (r=0.912, P=0.011), and Mel1c (r=0.906, P=0.012) in the chicken spleen. These results suggest the existence of age-related and region-specific changes in the expression of the melatonin receptor subtypes within the spleen of the chicken, and this characteristic pattern may be involved in the development and functional maturation of the avian spleen.

Role of sympathetic nerves on early embryonic development and immune modulation of uterus in pregnant mice

To determine the role of sympathetic nerves in the early embryonic development and the immune modulation of maternal uterus during pregnancy, a model of chemical sympathectomy in mice was established by intraperitoneal injection of 6-hydroxydopamine (6-OHDA). The embryonic development and the distribution of maternal uterine immunocytes were investigated during early pregnancy (E1-E9) with methods of histology, immunohistochemistry and ELISA. Our data showed that in the 6-OHDA-treated group, the number of implanted embryos was only 64.4% of that in the control group at E7, and the development of uterine glands and vessels was poor in pregnant mice. In addition, in uterine tissues of 6-OHDA-treated mice, the number of CD8+ T cells increased ten-fold and the concentration of IL-2 increased 3.6-fold at E5. However, no obvious changes to the number of CD4+ T cells and IL-4 were observed. Thus, the CD4+/CD8+ T cells ratio significantly decreased, while the IL-2/IL-4 ratio significantly increased. These findings indicated that the activation of sympathetic nerves might be favorable to fetal survival and development during early pregnancy through influencing on immune function and decidua formation of uterus.