In vivo measurement of pH and CO2 levels in the uterus of sows through the estrous cycle and after insemination

Abstract

The pH–CO2–HCO3− system is a ubiquitous biological regulator with important functional implications for reproduction. Knowledge of the physiological values of its components is relevant for reproductive biology and the optimization of Assisted Reproductive Technologies (ARTs). However, in situ measurements of these parameters in the uterus are scarce or null. This study describes a non-invasive method for in situ time-lapse recording of pH and CO2 within the uterus of non-anesthetized sows. Animals were at three different reproductive conditions, estrous with no insemination and two hours after insemination, and diestrous. From pH and CO2 data, HCO3− concentration was estimated. The non-invasive approach to the porcine uterus with novel optical probes allowed the obtaining of in situ physiological values of pH, CO2, and HCO3−. Variable oscillatory patterns of pH, CO2 and HCO3− were found independently of the estrous condition. Insemination did not immediately change the levels of uterine pH, CO2 (%) and HCO3− concentration, but all the values were affected by the estrous cycle decreasing significantly at diestrous condition. This study contributes to a better understanding of the in vivo regulation of the pH-CO2-HCO3− system in the uterus and may help to optimize the protocols of sperm treatment for in vitro fertilization.

Female reproductive fluid composition differs based on mating system in Peromyscus mice

“…We also found that the reproductive fluid pH is significantly higher in the uterus and oviduct of the polyandrous deer mouse ( P. maniculatus ) during estrus compared to its monogamous congener, P. polionotus , but that both species have a more alkaline environment in the uterus than oviduct. This result is surprising given that the opposite has been observed in other studies (López-Albors et al 2021, but see Ng et al 2018). Such alkaline environments have been shown to enhance sperm motility in birds ( Gallus domesticus, Coturnix coturnix, Meleagris gallopavo ; Holm and Wishart 1998) and humans (Saito et al 1996; Zhou et al 2015), and to activate sperm-specific CatSper channels in mice ( Mus musculus ; Kirichok et al 2006) and humans (Lishko et al 2010), thereby inducing sperm hyperactivation (Suarez et al 1993).…”

“…Our results demonstrate some important differences in the fluid collected from different regions of the female reproductive tract, however finer-scale changes in more localized areas of the reproductive tract and in response to seminal fluids will further enhance our understanding of how selection has shaped the fertilization environment in Peromyscus . Our understanding of the physiological mechanisms required for mammalian fertilization remain obscure without the ability to measure conditions in vivo in real-time (Ng et al 2018), especially in small animals, but our results suggest that even closely-related species may exhibit striking differences similar in magnitude to differences in highly divergent taxa (López-Albors et al 2021). In other mammals, evidence suggests that uterine fluid near the cervix is more viscous than more proximal regions of the uterus, and oviductal fluid in the ampullary region contains viscous compounds produced from ovulating follicles and peritoneal fluid during estrus (reviewed in Hunter et al 2011).…”

Progesterone differentially affects the transcriptomic profiles of cow endometrial cell types

“…Carbonic anhydrase 1 is a member of the large family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide and plays a pivotal role maintaining acid-base homeostasis [ 18 ] possibly impacting in the endometrium, sperm fertilization capacity, embryo transport, development and implantation [ 19 ].…”

Effect of Dexamethasone and Route of Administration on Sow Farrowing Behaviours, Piglet Delivery and Litter Performance

“…To assess vaginal permeability in vitro, simulated vaginal fluid (SPVF) was prepared using the composition reported by Owen and Katz for humans [ 15 ] and adjusted with NaOH to pH 7 [ 16 , 17 ] to simulate conditions in the sow vagina [ 18 , 19 ]. Porcine vaginal tissue was obtained from a local abattoir (Murray Bridge, SA, Australia) at slaughter and transported to the laboratory in SPVF on ice.…”