Endometrial inflammatory response to insemination in jennies

Abstract

In the jenny introduction of semen into the uterus triggers an endometrial inflammatory response characterized by polymorphonuclear (PMN) infiltration. The presence of cryoprotective agents in frozen-thawed semen may increase the inflammatory reaction. The objective of this study was to evaluate the effects of two cryoprotective agents in the induction of endometrial inflammatory response in jennies inseminated with extended semen or sham-inseminated with extender only or with deionized water. Eight Creole donkeys were inseminated or sham-inseminated in successive cycles with each one of the following treatments: DW: deionized water; B: a commercial cryopreservation extender containing glycerol (BotuCrio®, Botupharma); LDL: a cryopreservation extender that contains low density lipoproteins instead of glycerol (UNAM-extender); FS: fresh semen in a extender which contains no cryoprotective agents (INRA96, France); S-B: Semen extended in Botucrio; and S-LDL: Semen extended in UNAM-extender. The order in which jennies received each treatment was randomized. In each case, four 0.5 ml straws were used for deep insemination in the uterine horn ipsilateral to ovulation. In the case of treatments that included semen, each straw contained 200 million sperm cells. After each treatment the jennies were administered 5 mg of PGF2α at day 5 post-ovulation to induce return to estrus in order to administer the next treatment, until each jenny had received allthe treatments. Endometrial cytology samples were obtained before each treatment (time 0) and at 8, 12, 24 and 48-h after treatment. Smears were fixed and stained with Diff-Quik. Five fields were randomly chosen for microscopic observation. The total number of PMN and the total number of cells of any type were counted. The proportions of PMN in the smears were compared using the "generalized linear models" procedure of the SPSS program. Predictors were treatment, post-treatment time, treatment x time interaction. The jenny was used as a block. For multiple comparisons, the Bonferroni method was used. Extenders with cryoprotective agents and no semen resulted in higher proportion (p˂ 0.05) of PMN than the same extenders containing semen (B 43% vs S-B 26.9 % LDL 36% vs S-LDL 25.3%). The duration of significantly elevated PMN was also higher when extenders contained no semen. The extender with no cryoprotective agent (INRA96) also resulted in a higher proportion of PMN (39.6 %) than S-B and S-LDL. DW resulted in a proportion of PMN (44.8%) similar to those of the extenders containing no semen, and higher than those of the extenders containing semen. The results suggest that the presence of semen modulates and reduces the endometrial inflammatory response of jennies. The cryoprotective agents by themselves do not appear to exacerbate the inflammatory response, as a similar response was produced by an extender containing no cryoprotective agent and even by DW.