Oral Presentation ESA-SRB 2023 in conjunction with ENSA

Coping with the cold: How does the ovine cervix respond to frozen sperm? (#5)

Jessica Rickard 1 , S. Warr 1 , S.P. de Graaf 1 , t> Pini 2
  1. Faculty of Science, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
  2. School of Veterinary Science, The University of Queensland, QLD, Australia

The fertility of frozen ram sperm is limited following cervical artificial insemination due to its inability to successfully penetrate the ewes’ cervix.  However, if deposited in the uterus, its fertility is not compromised.  The failed ability of frozen sperm to cross the ewe’s cervix is thought to be related to freezing induced changes to sperm surface characteristics previously modified by seminal plasma at ejaculation. To date, extensive work has focused on characterising proteomic sperm traits prior to and following seminal plasma exposure and in vitro processing. However, it remains unclear how cervical tissue responds to different sperm phenotypes, and whether there is a transcriptomic response impeding cervical transit.  As such, an ex vivo cell culture model was used to assess the transcriptomic response of cervical endometrial explants harvested from the reproductive tract of oestrus-synchronised ewes (n=6) to; epididymal sperm, epididymal sperm exposed to seminal plasma, frozen-thawed sperm and seminal plasma alone from rams (n=3). Explants were co-cultured under CO2 for 6h.  Analysis of differentially expressed genes by RNA sequencing revealed that sperm with exposure to seminal plasma significantly activated pathways related to integrin cell surface and extracellular matrix signalling, compared to epididymal sperm alone. Exposure of cervical explants to cryopreserved sperm activated NFKB signalling, multiple interleukin signalling pathways (IL-1, 2, 6, 8 and 15), miRNA biogenesis and estrogen receptor signalling. These results suggest that cervical gene expression is altered in response to spermatozoa and seminal plasma, and that cryopreservation may further modify this interaction. Identifying pathways of interest could highlight potential supplements for frozen sperm which could improve their ability to transit the cervix and achieve fertilisation following cervical artificial insemination.