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Keiko Fujikawa, Kaoru Inoue, Reiko Yamagishi, Takae Koshiyama, Makoto Aihara; RhoGTPases activating protein Vavs-deficiency exhibits intraocular pressure variation between daytime and nighttime in mice. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
We previously described that deficiency of Vav2 and Vav2,3 (Vavs) proteins lead to an ocular phenotype in mice, that is, various levels of ocular hypertension and subsequent RGC death, and even the normal level of daytime IOP cause the significant RGC death in the CFP-expressed Vav2 and Vav2,3 (Vavs)- deficient mice (Vav2 KO, Vav2,3 KO). Here we examined IOP variation between daytime and nighttime in Vavs KO to evaluate the pressure dependent RGC death observed in Vavs KO. We expect this investigation develop to our understanding of which IOP factor may have a correlation with RGC death.
The daytime (9:00) and the nighttime (21:00) IOPs of Vavs KO at 7-10 week-age old were measured respectively for 7 days by TonoLab® rebound tonometer for rodents according to the manufacture’s recommended procedures. As a normal control, IOPs of age-matched wild-type mice (WT) were measured in the same manner. The deviation of IOPs was evaluated by the relative standard error (%) that standard error of mean was divided with the mean IOPs. Two-tailed Student’s t-test was used to compare between two groups of results. Differences between any two groups were regarded as significant when P<0.01 or P<0.05.
Examined IOPs at daytime and nighttime of Vav2 KO (n=36) were 15.9±3.1mmHg, 20.8±2.6mmHg, and IOPs of Vav2,3 KO (n=18) 17.3± 3.8mmHg, 24.3±7.7mmHg respectively, while IOPs of WT (n=24) were 14.5±1.6mmHg, 17.0±1.0mmHg. Both Vav2 KO and Vav2,3 KO showed significant elevation of IOPs at nighttime compared with those of WT (P<0.01). Especially the differences of IOPs in Vav2 KO and Vav2,3 KO between daytime and nighttime were 5.0±2.1mmHg, 7.0±7mmHg respectively , that is 2 times and 2.5 times as large as those of WT, 2.5±1.4mmHg. Furthermore the deviations of IOPs (%) at the nighttime of Vav2 KO and Vav2,3 KO , were 1.4 times (24.8±3.1%) and 1.9 times (34.4±3.1%) as large as those of WT(18.2±2.4%) (P<0.01).
We demonstrate here in Vav2 KO and Vav2,3 KO the nighttime IOPs are significant higher than those of WT, and also the gaps of IOPs between daytime and nighttime and the deviation of nighttime IOPs are larger than those of WT. These findings may imply that in Vavs KO there are some pressure-dependent insults against RGCs, even though daytime IOPs are within normal range.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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