Impact of an acute heat shock during in vitro maturation on interleukin 6 and its associated receptor component transcripts in bovine cumulus-oocyte complexes

Julia R Rowinski; Louisa A Rispoli; Rebecca R Payton; Liesel G Schneider; F Neal Schrick; Kyle J McLean; J Lannett Edwards

doi:10.1590/1984-3143-ar2020-0221

Impact of an acute heat shock during in vitro maturation on interleukin 6 and its associated receptor component transcripts in bovine cumulus-oocyte complexes

Anim Reprod. 2021 Feb 16;17(4):e20200221. doi: 10.1590/1984-3143-ar2020-0221.

Authors

Julia R Rowinski¹, Louisa A Rispoli^{1

2}, Rebecca R Payton¹, Liesel G Schneider¹, F Neal Schrick¹, Kyle J McLean¹, J Lannett Edwards¹

Affiliations

¹ Department of Animal Science, The University of Tennessee, Institute of Agriculture, AgResearch, Knoxville, TN, USA.
² Cincinnati Zoo & Botanical Garden, Cincinnati, OH, USA.

Abstract

An acute heat stress event after the LH surge increased interleukin 6 (IL6) levels in the follicular fluid of the ovulatory follicle in hyperthermic cows. To examine direct consequences of a physiologically-relevant elevated temperature (41.0°C) on the cumulus-oocyte complex (COC), IL6 transcript abundance and related receptor components were evaluated throughout in vitro maturation. Heat-induced increases in IL6 were first noted at 4 hours of in vitro maturation (hIVM); peak levels occurred at 4.67 versus 6.44 hIVM for 41.0 and 38.5°C COCs, respectively (SEM = 0.23; P < 0.001). Peak IL6ST levels occurred at 6.95 versus 8.29 hIVM for 41.0 and 38.5°C, respectively (SEM = 0.23; P < 0.01). Transcript for LIF differed over time (P < 0.0001) but was not affected by 41.0°C exposure. Blastocyst development after performing IVF was not affected by 41.0°C exposure for 4 or 6 h. When limiting analysis to when IL6 was temporally produced, progesterone levels were only impacted by time and temperature (no interaction). Heat-induced shift in the temporal production of IL6 and IL6ST along with its impact on progesterone likely cooperate in heat-induced hastening of meiotic progression described by others.

Keywords: Interleukin 6; cumulus-oocyte complex; heat shock; oocyte maturation; progesterone.

Grants and funding

Financial support: JLE received funding for this research from the Agriculture and Food Research Initiative Competitive Grant nº. 2016-67015-24899 from the USDA National Institute of Food and Agriculture, the state of Tennessee through UT AgResearch, East Tennessee Research and Education Center, the Department of Animal Science, and the USDA National Institute of Food and Agriculture, Hatch Project nº. 1015707 and 1022068.