TUNEL, SCSA, SCD test and COMET assay are the current tests for detection of sperm DNA fragmentation (sDF) in clinical practice. These four tests are very different from each other for many aspects, possibly including the type of revealed damage. To verify how the same type of damage was revealed, we simultaneously detected sDF by the four tests before and after induction of sperm DNA breakage by cryopreservation and in vitro incubation. We found that all tests revealed the increase in sDF in both experimental conditions. However, when we pairwise compared the fold increases in induced sDF, we found poor (i.e., values below 0.5) Lin’s concordance correlation coefficients (CCCs) both during cryopreservation and in vitro incubation. The only exception was for SCD test/COMET assay where the CCCs were about 0.5 (cryopreservation: 0.456 (95% CI −0.071–0.784) and incubation: 0.523 (95% CI −0.018–0.827)). Bland–Altman plot analysis showed that TUNEL reveals the highest amounts of sDF during cryopreservation, whereas LiveTUNEL indicated that such damage is undergone by the viable sperm fraction. This is the first study comparing the four tests in detection of sperm DNA damage during cryopreservation and incubation.

Glucagon-like peptide-2 (GLP-2) has been reported to cause gastrointestinal relaxation by interfering with enteric inhibitory neurotransmitters, including vasoactive intestinal peptide (VIP). However, the involvement of VIP in the GLP-2’s actions on isolated ileal preparations has never been explored. In this study, we investigated whether VIP contributes to the inhibitory effects of GLP-2 on spontaneous and neurally evoked contractions in mouse ileal segments. Functional experiments showed that VIP, as well as GLP-2, depresses both spontaneous and electrically induced contractile responses. The VIP antagonist, VIP 6–28, slightly increased the amplitude of the neurally induced contractile responses. VIP 6–28 did not alter the hormone’s effects on the spontaneous activity, but reduced its inhibitory action on the neurally evoked contractions. In GLP-2-exposed specimens, immunohistochemistry showed a significant decrease in VIP-positivity in nerve fibers located in the muscle layers. These results provide the first evidence that in isolated mouse ileal preparations VIP contributes to the inhibitory effects of GLP-2 on the neurally induced contractile responses. From a physiological point of view, such depressant effects of the hormone may represent a mechanism aimed at slowing intestinal transit and optimizing nutrient absorption.