Role of melatonin and HSF-1\\HSP-70 in modulating cold stress-induced immunosuppression in a tropical rodent- Funambulus pennanti [Volume 87, January 2020, 102456].

Abstract

The neuroendocrine hormone melatonin and molecular chaperones (heat shock proteins) are evolutionarily conserved molecules that play an important role in protecting organisms from abiotic and biotic stressors. Environmental temperature and seasonality modulates immunity which impacts the overall health of animals. Most studies in relation to thermal stress are based on animals inhabiting temperate zones however, the substantial effect of climatic stress on tropical animals is less explored. Therefore, in this study we focused on the immunosuppressive effect of cold environment on a seasonally breeding tropical rodent and highlighted the importance of melatonin and HSF-1/Hsp-70 in regulating immunity. Animals were exposed to different temperatures with or without melatonin treatment. Our results suggest that, low temperature elicited cold-associated stress in animals marked by reduced body weight, decreased TLC/LC count in the blood and increased corticosterone production which was central to all immune alterations. Cold temperature also increased the oxidative stress which further induced apoptosis in the immune cells and activated stress response molecular chaperones HSF-1/HSP-70. Exogenous melatonin treatment not only ameliorated cold-induced immune suppression but also upregulated the expression of HSF-1 and HSP-70 in the immune cells thereby preventing protein unfolding and cell death. Thus, we conclude that melatonin and molecular chaperones synergistically alleviated immune suppression and could emerge as a promising combination therapy to target temperature stress in animals while boosting immunity.