Морфометричні зміни в сітківці під впливом паклітакселу

Abstract

Досліджено патоморфогенез сітківки ока в динаміці розвитку ретинопатії (120 діб), зумовленої введенням паклітакселу в сумарній дозі 8 мг/кг маси тіла в експерименті на 42 білих рандомбредних щурах. Методи дослідження - світлова мікроскопія з використанням комп’ютерного аналізу морфоме- тричних показників (ширина шарів і товщина сітківки) сітківки ока. Встановлено, що паклітаксел індукує ретинотоксичність, яка проявляється морфологічними і морфометричними змінами.

Исследование посвящено изучению морфологических изменений сетчатки глаза в динамике развития ретинопатии, обусловленной введением паклитаксела в суммарной дозе 8 мг/кг массы тела в эксперименте. Сетчатка глаза белых рандомбредных крыс была объектом эксперимента на протяжении 120 суток и изучалась с помощью световой микроскопии с использованием компьютерного морфометрического анализа. Полученные результаты позволили установить морфометрические критерии морфологических изменений сетчатки на разных этапах развития паклитаксел-индуцированной ретинопатии.

Modern schemes of cancer treatment widely apply taxanes as highly effective anticancer medicines. Concurrently, taxanes affect not only cancer cells, but also healthy tissues. Their side effects manifest themselves in the toxicity of various parts of the eye. These effects require more thorough research, as the morphological structure of the parts affected has been little studied. The aim is to study the structure of retina in the development of paclitaxel-induced retinotoxicity at the optical level using computer morphometric analysis. Object and methods. Within the experimental research 42 randombred rats (mass 150-200 g) were given intraperitoneal injections of Paclitaxel (Actavis, Romania), dosed 2 mg/kg of body mass 1 per 2 days 4 times, which in total equals 8 mg/kg, acc. to the method introduced by R.S. Polomano et al. (2002). Samples for research were taken in 1,7, 14, 27, 60, 90, and 120 days after the last paclitaxel injection. As a fixative 10% neutral-buffered formalin was used and then the sections were embedded in paraffin according to common rules. the sections were stained in hematoxylin and eosin and meausured for the thickness of retina and its layers. Research outcomes and discussion. In 24 hours after the last paclitaxel injection we could observe the thinning of the photoreceptor layer, caused by the shortening of rod and con outer segments, and sometimes the absence of the latter. In some cases the shift of nuclei from the outer nuclear layer into photoreceptor layer was observed. The thickness of photoreceptor layer established (10,58±0,15) mkm and in control (21,52±0,26) it was diminished by 50,80% (p<0,05). The outer nuclear layer also diminished: from (41,76±0,30) mkm in control animals to (29,19±0,20) mkm, р<0,05. In this layer also diffuse homogenous areas without cells were noticed. The thickness of the outer plexiform layer has little changed. The inner nuclear layer has thinned to (14,32±0,11) mkm, р<0,05, and the inner plexiform layer has become (21,77±0,23) mkm, р<0,05. The ganglion cell layer and the nerve fiber layer, on the contrary, thickened to (8,62±0,09) mkm, р<0,05, і (4,71±0,10) mkm, р<0,05; with the manifestation of edema and lower amount of neurons. the neurons contained big vacuoles. in general the retina has become thinner. During the first 7 days the thickness of photoreceptor layer was smaller than in control animals. Also the shift of nuclei from the outer nuclear layer into photoreceptor layer was observed. the edema causes the thickening of inner and outer nuclear layers, the plexiform layers and the ganglion cell layer, the inner plexiform layer has the uneven thickness. In the neurons of ganglion neuron layer neurons with pyknotic nuclei and vacuolized neuroplasm were identified. There were fewer neurons in the ganglion neuron layer. The retina thickness significantly rises. After 15 days in the photoreceptor layer the shortening of rod and cone outer segments continued. Generally, the layer thinned to (8,32±0,10) mkm, p<0,05. The outer nuclear and plexiform layers lost some of their thickness, while the inner nuclear layer did not differ from that of the control animals. The total thickness of retina decreased. In 27 days after the last injection of paclitaxel the following changes were registered: the photoreceptor, inner and outer nuclear layers and the nerve fiber layer thickened, and the ganglion neuron layer became thinner comparing to the previous term of research. The retina thickness remained larger than in control animals. In 60 days after the last paclitaxel injection the photoreceptor and outer nuclear layers remained thinned (11,24±0,16) mkm, p<0,05, and (33,74±0,49) mkm, p<0,05, correspondingly). Meanwhile, we observed the thickening of the inner nuclear (p<0,05), the inner plexiform (p<0,05), the ganglion neuron (p<0,05) and nerve fiber (p<0,05) layers. On the 90th day the photoreceptor layer remained thinner than in control animals (13,27±0,18) mkm, p<0,05. The other layers thickened: the outer nuclear - (50,47±1,19) mkm, p<0,05; the inner nuclear layer - (30,54±0,67) mkm, p<0,05; the inner plexiform layer - (48,91±1,03) mkm, p<0,05; the ganglion neuron layer - (15,73±0,42) mkm, p<0,05. These layers are swollen. The retina thickness reached (170,47±3,18) mkm, p<0,05. On the 120th day the retina layers became thinner, the morphometric indexes approached the 90-day term. The photoreceptor and outer nuclear layers are steadily thinner than those in the control animals. The deep retina layers - from the inner nuclear to the nerve fiber one - are still somewhat thicker than in the control animals, and in total the thickness of retina approaches the normal index - (121,68±1,33) mkm, p<0,05.