HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Aihara, M. Articles by Weinreb, R. N. Search for Related Content PubMed PubMed Citation Articles by Aihara, M. Articles by Weinreb, R. N.

Effect on Diurnal Intraocular Pressure Variation of Eliminating the -2 Adrenergic Receptor Subtypes in the Mouse

¹From the Hamilton Glaucoma Center, University of California San Diego, La Jolla, California; and the ²Department of Ophthalmology, University of Tokyo, Tokyo, Japan.

PURPOSE. To investigate the effect on circadian variation of intraocular pressure (IOP) of eliminating the 2A-, 2B-, or the 2C-adrenergic receptor subtypes in the mouse.

METHODS. A microneedle method was used to measure IOP in knockout mice lacking the 2A-, 2B-, or the 2C-receptor (2A-R^–/–, 2B-R^–/–, 2C-R^–/–), in wild-type mice of the 2B knockout strain (2B-R^+/+), and in the background strain mice, C57BL/6. All mice were maintained in a 12-hour light–dark cycle commencing at 0600 hours. IOP was measured at 0900 and 2100 hours in the five groups: C57BL/6 (n = 8), 2A-R^–/– (n = 10), 2B-R^–/– (n = 8), 2B-R^+/+ (n = 8), and 2C-R^–/– (n = 10). In parallel experiments, eyes from the 2A-R^–/–, 2B-R^–/–, 2C-R^–/–, and C57BL/6 mice were embedded in epoxy resin, and semithin sections were stained with toluidine blue.

RESULTS. IOP at 0900 hours in B6, 2A-R^–/–, 2B-R^–/–, 2B-R^+/+, and 2C-R^–/– mice was 17.1 ± 1.8, 17.7 ± 1.4, 17.1 ± 2.1, 17.6 ± 1.3, and 17.3 ± 0.9 mm Hg, respectively (mean ± SD). IOP at 2100 hours in the same eyes was 19.6 ± 1.9, 19.2 ± 2.2, 20.5 ± 1.5, 19.7 ± 0.8, and 21.3 ± 2.7 mm Hg, respectively. There was no significant difference among these genotypes in IOP measured at either time point (P > 0.05, ANOVA). Within each genotype, IOP at 2100 hours was significantly higher than IOP at 0900 hours (C57BL/6, 2B-R^–/–, 2B-R^+/+, and 2C-R^–/–: P < 0.01; 2A-R^–/–: P < 0.05, paired t-test). Differences in the diurnal IOP change among the different genotypes were insignificant (P > 0.05, ANOVA). Histopathologic assessment found minimal differences in the structural organization of the anterior segment among the 2A-R^–/–, 2B-R^–/–,2C-R^–/–, or C57BL/6 mice.

CONCLUSIONS. These results indicate that IOP magnitude and circadian variation are minimally altered by the absence of the 2A-, 2B-, or 2C-receptor subtypes in transgenic mice.