Administration time-dependent effects of poly (I:C) on antioxidant and immune responses along the diurnal time scale in zebrafish

ABSTRACT

The circadian clock of vertebrates regulates many biological processes, including the immune system. This paper investigated whether responsiveness to poly (I:C), a synthetic analog of double-stranded RNA used as an immunostimulant, exhibits day/night differences in zebrafish. Fish were intraperitoneally (IP) injected with either phosphate-buffered saline (PBS) or poly (I:C) at two different time points: “Zeitgeber Time” (ZT) 4 (day) and ZT16 (night). Then, 6 h later, fish were euthanized, and tissue samples (skin, liver and kidney) were collected. A control group (intact fish) was also sampled at the same time points. The effect of poly (I:C) on the expression of antioxidant and immune genes was time-of-day-dependent, and the response was stronger following poly (I:C) administration in the day than at night. Time-dependent differences were observed for some genes in the PBS and control groups. However, these differences were tissue-specific. In liver, almost all the genes were affected by time of day. In kidney, poly (I:C) affected the expression of all the gene markers regardless of administration time. These findings highlight the importance of considering the time to administer poly (I:C) when evaluating the fish immune response.

GRAPHICAL ABSTRACT

KEYWORDS:

• Zebrafish
• poly (I:C)
• daily rhythm
• immune response
• antioxidant response

Acknowledgements

The authors wish to thank J.A. Oliver for caring for the fish stock and I. Rodríguez Carretero for her help during fish samplings. Funding was provided by Grant RYC-2017-21835 (“Ramón y Cajal” fellowship) awarded to L.M.V. by the Spanish MINECO/AEI/10.13039/501100011033 cofunded by “ESF Investing in your future,” Project “CHRONOHEALTH” granted by “Fundación Séneca” (19899/GERM/15) and “BLUESOLE” (AGL2017‐82582‐C3‐ 3‐R) to F.J.S.V.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All the data supporting the findings of this study are available upon request from the corresponding author.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/07420528.2022.2093735

Additional information

Funding

This work was supported by the Fundación Séneca [19899/GERM/15]; Ministry of Economy and Competitiveness [AGL2017‐82582‐C3‐ 3‐R,RYC-2017-21835].