Article Text
Abstract
Objective The primary aim was to determine endocannabinoid (EC) concentrations of 2-arachidonoylglycerol (2-AG), oleoylethanolamine (OEA), palmitoylethanolamine (PEA) and anandamide (AEA) in the aqueous humour of patients, and to investigate any differences in gender and diabetic or ocular disease status.
Methods and Analysis Adult participants (age >18 years) listed for a routine cataract surgery were recruited. For patients with diabetes, results from their most recent retinopathy grading were recorded. A sample of aqueous humour was removed from the anterior chamber of the patients and snap-frozen in liquid nitrogen. Levels of 2-AG, PEA, OEA and AEA were measured by liquid chromatography-tandem mass spectrometry.
Results Aqueous humour samples were taken from 93 patients (female:male=58:35), with a mean age±SD of 72.7±9.5 years. Following gender-specific analysis, the mean aqueous concentration of AEA in female patients without diabetes was significantly higher than in female patients with diabetes (0.20±0.03 nM vs 0.07±0.02 nM, p=0.001). Among female patients with diabetes, the aqueous concentration of 2-AG was higher in those with diabetic retinopathy compared with those with no retinopathy (0.30+0.16 nM vs 0.04±0.01 nM, p=0.0025). The aqueous level of the sum of EC was higher in those with ocular comorbidity (2.49±0.73 vs 1.44±0.17, p=0.0002).
Conclusion There were gender, diabetes status and comorbidity differences in aqueous humour EC levels. Since EC receptors are present in ocular tissues, including the retina (neurons, glia and endothelial cells), differential levels of ECs in the aqueous humour of patients with and without diabetes may provide a novel therapeutic target for diabetic retinopathy.
- drugs
- experimental & laboratory
- retina
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Footnotes
Contributors PR, SO’S and II: conceived the study, drafted the study proposal and applied for grant to support the analysis of the study. PR: undertook sample collection. DB and CO: analysed the ocular fluid sample for endocannabinoid concentration. All authors contributed to the writing of the manuscript and agreed on the final draft.
Funding The study was partly funded by seed grant funding from the National Eye Research Centre (grant number SAC034).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethics approval was provided by the NRES North East York (REC reference number: 15/NE/0031). Informed consent was obtained.
Provenance and peer review Not commissioned; externally peer reviewed.