Total Outflow Facility in Live C57BL/6 Mice of Different Age

Aleksandr Yelenskiy; MinHee K Ko; Edward R Chu; Jose M Gonzalez; Kimberly Siegmund; James C Tan

doi:10.1159/000484126

Total Outflow Facility in Live C57BL/6 Mice of Different Age

Biomed Hub. 2017 Nov 17;2(3):1-10. doi: 10.1159/000484126. eCollection 2017 Sep-Dec.

Authors

Aleksandr Yelenskiy^{1

2}, MinHee K Ko¹, Edward R Chu¹, Jose M Gonzalez¹, Kimberly Siegmund³, James C Tan¹

Affiliations

¹ Doheny Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA.
² Tulane University Department of Ophthalmology, Tulane University School of Medicine, Tulane University, New Orleans, LA, USA.
³ Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA.

Abstract

Purpose: To characterize total outflow facility across the live adult mouse lifespan as a reference for mouse glaucoma studies and the common C57BL/6 background strain.

Methods: Microperfusion was performed by single-needle cannulation and feedback-controlled coupling of pressure and flow to maintain a constant pressure in the anterior chambers of live C57BL/6NCrl mice aged 3-4 months (n = 17), 6-9 months (n = 10), and 23-27 months (n = 12). This mouse age range represented an equivalent human age range of young adult to elderly. We characterized the following across age groups in vivo: (1) outflow facility based on constant pressure perfusion in a pressure range of 15-35 mm Hg, (2) perfusion flow rates, and (3) anterior segment tissue histology after perfusion. Thirty-nine live mice underwent perfusion.

Results: Pressure-flow rate functions were consistently linear for all age groups (all R ² > 0.96). Total outflow facility in mice aged 3-4, 6-9, and 23-27 months was 0.0066, 0.0064, and 0.0077 μL/min/mm Hg, respectively. Facility was not significantly different between age groups (all p > 0.4). The groups had closely overlapping frequency distribution profiles with right-sided tails. Post hoc estimates indicated that group facility differences of at least 50% would have been detectable, with this limit set mainly by inherent variability in the strain. A trend toward higher perfusion flow rates was seen in older mice aged 23-27 months, but this was not significantly different from that of mice aged 3-4 months or 6-9 months (p > 0.2). No histological disruption or difference in iridocorneal angle or drainage tissue structure was seen following perfusion in the different age groups.

Conclusion: We did not find a significant difference in total outflow facility between different age groups across the live C57BL/6 mouse adult lifespan, agreeing with some human studies. The possibility that more subtle differences might exist ought to be judged with respect to the heterogeneity in facility at different ages. Our findings provide reference data for live perfusion studies pertaining to glaucoma involving the C57BL/6 strain.

Keywords: C57BL/6; Glaucoma; Outflow facility; Perfusion apparatus; Trabecular meshwork.

Abstract

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