PURPOSE: Kynurenines and their glycoside derivatives in the ocular lens absorb ultraviolet radiation and thus possibly help protect the retina from ultraviolet light. The current study analysed kynurenine aminotransferase I (KAT I) activity and kynurenic acid (KYNA) concentrations in human senile cataractous lenses and in experimentally induced cataracts in diabetic rats treated with streptozotocin (STZ). METHODS: KYNA levels and KAT I activity were investigated with HPLC and detected fluorimetrically in the nuclei of 91 human cataractous lenses collected during planned extracapsular extraction. The lenses were classified on the Lens Opacity Classification System III scale and compared with clear lenses regarding KYNA concentrations. Cataractous lenses from STZ-treated rats were compared with control lenses. RESULTS: KYNA concentration was 0.95 +/- 0.22 in human NC0 (nuclear color) control lenses, 0.8 +/- 0.72 in NC1, 1.18 +/- 0.88 in NC2, 1.31 +/- 0.70 in NC3, 1.78 +/- 0.92 in NC4, 8.80 +/- 8.28 (p < 0.05 vs. NC0) in NC5, and 14.0 +/- 11.1 (p < 0.05 vs. NC0) in NC6. A correlation was found between KYNA concentrations and the grade of cataract (r = 0.047, p < 0.001). KAT I activity in human cataracts was 0.44 +/- 0.16 pmol/mg protein- 1 hr- 1. Elevated KYNA concentrations in rat cataractous lenses were also observed (p < 0.05). CONCLUSIONS: KYNA levels are elevated in senile nuclear human cataracts and in cataractous lenses of rats with experimentally induced diabetes.
PURPOSE:Kynurenines and their glycoside derivatives in the ocular lens absorb ultraviolet radiation and thus possibly help protect the retina from ultraviolet light. The current study analysed kynurenine aminotransferase I (KAT I) activity and kynurenic acid (KYNA) concentrations in humansenile cataractous lenses and in experimentally induced cataracts in diabeticrats treated with streptozotocin (STZ). METHODS:KYNA levels and KAT I activity were investigated with HPLC and detected fluorimetrically in the nuclei of 91 humancataractous lenses collected during planned extracapsular extraction. The lenses were classified on the Lens Opacity Classification System III scale and compared with clear lenses regarding KYNA concentrations. Cataractous lenses from STZ-treated rats were compared with control lenses. RESULTS:KYNA concentration was 0.95 +/- 0.22 in human NC0 (nuclear color) control lenses, 0.8 +/- 0.72 in NC1, 1.18 +/- 0.88 in NC2, 1.31 +/- 0.70 in NC3, 1.78 +/- 0.92 in NC4, 8.80 +/- 8.28 (p < 0.05 vs. NC0) in NC5, and 14.0 +/- 11.1 (p < 0.05 vs. NC0) in NC6. A correlation was found between KYNA concentrations and the grade of cataract (r = 0.047, p < 0.001). KAT I activity in humancataracts was 0.44 +/- 0.16 pmol/mg protein- 1 hr- 1. Elevated KYNA concentrations in ratcataractous lenses were also observed (p < 0.05). CONCLUSIONS:KYNA levels are elevated in senile nuclear humancataracts and in cataractous lenses of rats with experimentally induced diabetes.
Authors: Michal Fiedorowicz; Tomasz Choragiewicz; Sebastian Thaler; Frank Schuettauf; Dominika Nowakowska; Kamila Wojtunik; Michele Reibaldi; Teresio Avitabile; Tomasz Kocki; Waldemar A Turski; Agnieszka Kaminska; Pawel Grieb; Eberhart Zrenner; Robert Rejdak; Mario Damiano Toro Journal: Front Physiol Date: 2019-10-01 Impact factor: 4.566
Authors: Tamera D Hughes; Osman F Güner; Emma Carine Iradukunda; Robert S Phillips; J Phillip Bowen Journal: Molecules Date: 2022-01-02 Impact factor: 4.411