Interaction of anaesthetic drugs and UV-B irradiation in the anterior segment of the rat eye.

St Erik's Eye Hospital, Karolinska Institute, Stockholm, Sweden.
Acta Ophthalmologica Scandinavica (Impact Factor: 1.85). 12/2007; 85(7):745-52. DOI: 10.1111/j.1600-0420.2006.00856.x
Source: PubMed

ABSTRACT To determine the impact of anaesthesia on acute transient cataractogenesis and ultraviolet radiation (UVR)-induced cataractogenesis.
Sprague-Dawley rats were anaesthetized with pentobarbital, which caused almost full eyelid closure, or xylazine/ketamine, which caused eyelid retraction and proptosis. The eyelids of one eye were kept open with either a suture or adhesive tape, or both. The other eye was kept closed with either a suture or tape. Cataract was graded clinically and quantified in vitro as intensity of forward light scattering. In two UVR experiments, anaesthetized rats were irradiated unilaterally with 5 kJ/m2 UVR-B 300 nm for 15 mins. The difference between the two UVR experiments was the degree of proptosis in the pentobarbital group. Corneal drying was judged clinically with a grading scale.
Within 60 mins of anaesthesia induction in the first experiment, almost all lenses in open eyes developed cataract, whereas all lenses in closed eyes remained clear. In the first UVR experiment the lens light scattering was significantly higher in the xylazine/ketamine group. In the second UVR experiment the pentobarbital group was treated to achieve proptosis similar to that in the xylazine/ketamine group, which led to a smaller difference in lens light scattering between the two anaesthesia groups. Lens light scattering in the pentobarbital groups was significantly higher with forced proptosis than without prominent proptosis.
Xylazine/ketamine anaesthesia facilitates the development of UVR-induced cataract, whereas pentobarbital anaesthesia does not. Xylazine/ketamine anaesthesia induces more proptosis and therefore leads to increased exposure of the cornea and, secondarily, the lens.

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    ABSTRACT: The purpose of the present study was to investigate cataractogenesis and recovery of lens damage after in vivo close to threshold ultraviolet (UV)-B radiation around 300 nm. Eighty six-week-old albino Sprague-Dawley rats were familiarized to a rat restrainer five days prior to exposure. Groups of non-anesthetized rats were exposed unilaterally to 8 kJ/m(2) UVR-300 nm. The animals were sacrificed at 1, 7, 48 and 336h following exposure. The lenses were extracted for imaging of dark-field lens macro anatomy and measurement of intensity of forward lens light scattering to quantify lens opacities. Three exposed lenses and one non-exposed lens from each time interval were examined with light and transmission electron microscopy (TEM). Macro anatomy and lens light scattering revealed that all contralateral non-exposed lenses were clear. The degree of lens opacity (difference in lens light scattering between exposed and non-exposed lenses) increased during the 336h, reaching a plateau towards the end of the observation period. Light microscopy and TEM demonstrated that apoptotic features appeared in the epithelium already 1h after UVR exposure, and small vacuoles were seen in the outer cortex. Epithelial damage occurs during the first 48h after exposure and is followed by regenerative repair at 336h post-exposure. Apoptotic epithelial cells were phagocytized by adjacent epithelial cells. Cortical fiber cells exhibited increasing damage throughout the observation period without any clear repair after 336h. In conclusion, acute UVR-induced cataract is partly a reversible. Lens epithelium is a primary target for UVR exposure. Damage to cortical fiber cells remained irreversible.
    Experimental Eye Research 09/2010; 91(3):369-77. · 3.03 Impact Factor
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    ABSTRACT: Purpose:  To investigate if the previously shown difference in in vivo-induced ultraviolet B radiation (UVR-B) cataractogenesis between pigmented and albino rats can be seen also with in vitro irradiation. The shielding effect of the iris and UVR absorption in the anterior segment is nullified, and inherent differences in lenticular UVR-B sensitivity between the strains may be revealed. Methods:  Lenses from albino (Fischer-344) and pigmented (Brown-Norway) rats were irradiated in vitro with 1.8 kJ/m(2) UVR-B. The lenses were cultured in standard environment in a culture incubator. Cataract was quantified daily by measuring the amount of lens forward light scattering over a period of 1 week. All lenses were photographed during the week. Results:  Two days after exposure, both strains developed significant cataract compared to control lenses, and the light scattering increased exponentially to the last day. From day 4, exposed Fischer lenses scattered more light than Brown-Norway lenses. This difference increased towards the end of the week. The type of cataract (anterior subcapsular, equatorial, and posterior cortical cataract) was similar in both strains. No anterior polar or nuclear cataract was observed. Conclusions:  Lenses from albino Fischer rats are more sensitive to in vitro UVR-B than lenses from pigmented Brown-Norway rats. Ultraviolet B radiation cataract type induced in vitro differs from in vivo cataract in pigmented rats, but not from albino rats. In vitro UVR-B exposure induces more cataract than corresponding lenticular UVR-B in vivo exposures, for both albino and pigmented rat.
    Acta ophthalmologica 06/2010; 90(2):179-83. · 2.44 Impact Factor
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    ABSTRACT: PurposeTo determine the time evolution of active caspase-3 protein expression in albino rat lens after in vivo exposure to low-dose UVR-300 nm, as detected by immunofluorescence.Methods Forty Sprague-Dawley rats were unilaterally exposed in vivo to 1 kJ/m2 UVR-300 nm for 15 min. At 0.5, 8, 16 and 24 hr after the UVR exposure, the exposed and contralateral nonexposed lenses were removed and processed for immunohistochemistry. Three mid-sagittal sections from each lens were stained. The cells labelled for active caspase-3 in each section of both the exposed and nonexposed lenses were counted and recorded three times. The difference of the proportion of labelling between the exposed and contralateral nonexposed lenses within each animal was calculated. The differences of active caspase-3 labelling at four different time-points after exposure were used to determine the time evolution of active caspase-3 expression.ResultsCaspase-3 expression was higher in the exposed than in contralateral nonexposed lenses. The mean difference between the exposed and contralateral nonexposed lenses, including all lenses from all time intervals, was 0.12 ± 0.01 (= CI 95%). The mean differences between the exposed and contralateral nonexposed lenses were 0.11 ± 0.02, 0.13 ± 0.02, 0.14 ± 0.01 and 0.09 ± 0.03 (= CI 95%) for the 0.5-, 8-, 16- and 24-hr time groups, respectively. The orthogonal comparison showed no difference in the expression of active caspase-3 between the 0.5- and the 24-hr groups (Test statistic 1.50, F1,36 = 4.11, p < 0.05) or between the 8- and the 16-hr groups (test statistic 0.05, F1,36 = 4.11, p < 0.05). There was a difference when comparing the 0.5- and 24-hr groups to the 8- and 16-hr groups (test statistic 7.01, F1,36 = 4.11, p < 0.05).Conclusion The expression of active caspase-3 in the lens epithelium increases after UVR exposure. There is a peak of expression approximately 16 hr after the exposure.
    Acta ophthalmologica 04/2014; · 2.44 Impact Factor


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