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Birds' plight: Compromised cell-mediated immunity in response to ambient light pollution in redheaded buntings
Abhishek Kumar1, Khushboo Chaturvedi1, Vaibhav Vaish1
1Department of Zoology, University of Lucknow, Lucknow, India.
Abstract:
Increased exposure to artificial light at night (ALAN) has changed the scenario for natural day length over time. The impact of ALAN has been studied on reproduction, sleep, metabolism, and behavior in many species. ALAN's impact on birds' immune response is still sparsely studied. We studied the cell-mediated immunity, hematology, and reproductive phenology in redheaded bunting under short days (SD, 8L:16D), long days (LD) (LAN -, 13L:11D), and LD with ALAN (LAN +, 13L:11DLAN) illuminated with ~ 2 lx of night light. Corticosterone levels, testicular volume, heterophil count, and H/L ratio increased significantly in the LAN + group. Cell-mediated immune response (phytohemagglutinin-L challenge), total leucocyte, and lymphocyte count were significantly suppressed in the LAN + as well as LAN - group relative to the SD group of birds. ALAN treatment did not affect the total erythrocyte count, hemoglobin level, surface body temperature, and hematocrit level. Basophil, eosinophil, and monocyte count, as well as body mass and blood glucose levels, did not show any significant difference among any groups. These results suggest that ALAN exposure compromised the adaptive immune system, increased stress levels, and exaggerated the reproductive response in migratory passerine finches.
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