Differential neuronal expression of receptor interacting protein 3 in rat retina: involvement in ischemic stress response.

BACKGROUND: Receptor-interacting protein 3 (RIP3), a member of RIP family proteins, has been shown to participate in programmed necrosis or necroptosis in cell biology studies. Evidence suggests that necroptosis may be a mode of neuronal death in the retina. RESULTS: In the present study we determined the expression of RIP3 in normal rat retina and its changes following acute high intraocular pressure (aHIOP). RIP3 immunoreactivity (IR) was largely present in the inner retinal layers, localized to subsets of cells expressing neuron-specific nuclear antigen (NeuN), parvalbumin and calbindin in the ganglion cell layer (GCL) and inner nuclear layer (INL). No double labeling was detected for RIP3 with PKC-α or rhodopsin. RIP3 immunoreactivity was increased in the GCL at 6 hr and 12 hr, but reduced at 24 hr in the retina, without apparent alteration in laminar or cellular distribution pattern. Western blot analysis confirmed the above time-dependent alteration in RIP3 protein expression. RIP3 expressing cells frequently co-localized with propidium iodide (PI). A few co-localized cells were observed between RIP3 and Bax or cleaved caspase-3 in the GCL in 12 hr following aHIOP. CONCLUSIONS: The results indicate that RIP3 is expressed differentially in retinal neurons in adult rats, including subsets of ganglion cells, amacrine and horizontal cells. RIP3 protein levels are elevated rapidly following aHIOP. RIP3 labeling co-localized with PI, Bax or cleaved caspase-3 among cells in the ganglion cell layer following aHIOP, which suggest its involvement of RIP3 in neuronal responses to acute ischemic insults.

[A novel mutation of CYP1B1 gene in primary congenital glaucoma].

OBJECTIVE: To investigate the distribution of the CYP1B1 (Cytochrome P450, family 1, subfamily B, polypeptide 1) gene mutations in primary congenital glaucoma (PCG) in Hunan Province. METHODS: Case-control study. Thirteen cases of PCG from different districts of Hunan province were collected in this study. Direct sequencing was used to evaluate the coding and the promoter regions of the CYP1B1 gene in PCG patients. RESULTS: A novel pathogenic mutation (c.C319G, L107V) was identified in a PCG patient in our study and it was a missense mutation in exon 2. Additionally, four single nucleotide polymorphisms(SNPs) were found in PCG patients, including R48G, A119S, V432L and D449D. CONCLUSION: A novel CYP1B1 gene mutation (L107V) may be the cause for primary congenital glaucoma in Hunan Province.

BACE1 in the retina: a sensitive biomarker for monitoring early pathological changes in Alzheimer's disease.

Because of a lack of sensitive biomarkers, the diagnosis of Alzheimer's disease (AD) cannot be made prior to symptom manifestation. Therefore, it is crucial to identify novel biomarkers for the presymptomatic diagnosis of AD. While brain lesions are a major feature of AD, retinal pathological changes also occur in patients. In this study, we investigated the temporal changes in ß-site APP-cleaving enzyme 1 (BACE1) expression in the retina and brain to determine whether it could serve as a suitable biomarker for early monitoring of AD. APP/PS-1 transgenic mice, 3, 6 and 8 months of age, were used as an experimental group, and age-matched C57/BL6 wild-type mice served as the control group. In the Morris water maze test, there were no significant differences in escape latency or in the number of crossings in the target area among mice of different ages. Compared with wild-type mice, no changes in learning or memory abilities were detected in transgenic mice at 3 months of age. However, compared with wild-type mice, the escape latency was significantly increased in transgenic mice at 6 months, starting on day 3, and at 8 months, starting on day 2, during Morris water maze training. In addition, the number of crossings of the target area was significantly decreased in transgenic mice. The learning and memory abilities of transgenic mice were further worsened at 8 months of age. Immunohistochemical staining revealed no BACE1 plaques in wild-type mice at 3, 6 or 8 months or in transgenic mice at 3 months, but they were clearly found in the entorhinal cortex, hippocampus and prefrontal cortex of transgenic mice at 6 and 8 months. BACE1 expression was not detected in the retina of wild-type mice at 3 months, but weak BACE1 expression was detected in the ganglion cell layer, inner plexiform layer and outer plexiform layer at 6 and 8 months. In transgenic mice, BACE1 expression in the ganglion cell layer was increased at 3 months, and BACE1 expression in the ganglion cell layer, inner plexiform layer and outer plexiform layer was significantly increased at 6 and 8 months, compared with age-matched wild-type mice. Taken together, these results indicate that changes in BACE1 expression appear earlier in the retina than in the brain and precede behavioral deficits. Our findings suggest that abnormal expression of BACE1 in the retina is an early pathological change in APP/PS-1 transgenic mice, and that BACE1 might have potential as a biomarker for the early diagnosis of AD in humans.

The correlation between rat retinal nerve fiber layer thickness around optic disc by using optical coherence tomography and histological measurements.

AIM: To explore the correlation between the retinal nerve fiber layer (RNFL) thickness by using optical coherence tomography (OCT) and by histological measurements in normal adult rats and optic nerve transected rats. METHODS: The RNFL thickness of 36 rats was scanned in a circle 3.46mm far from the optic disc by OCT. The two experimental groups were the normal group (n=20 rats) and the optic nerve transected group (n=16 rats). The latter group included 4 groups (n=4/group) surviving for 1 day, 3, 5 and 7 days. Then the RNFL thickness of the same retina area was also measured by NF-200 immunohistochemical staining method. Linear regression was used to analyze the correlation between the data obtained from these two methods. RESULTS: The RNFL thickness of normal right eyes around optic disc by OCT was 72.35±5.71µm and that of the left eyes was 72.65±5.88µm (P=0.074). The RNFL thickness of the corresponding histological section by immunohistochemistry was 37.54±4.05µm (right eyes) and 37.38±4.23µm (left eyes) (P=0.059). There was a good correlation between the RNFL thickness measured by OCT and that measured by histology (R(2)=0.8131). After optic nerve transection, the trend of the RNFL thickness was thinner with the prolonged survival time. The correlation of the thickness detected by the above two methods was approximately (R(2)=0.8265). Value of the RNFL thickness in rats around optic disc measured by OCT was obviously higher than that measured by common histological measurement in normal adult rats and optic nerve transected rats. CONCLUSION: The RNFL thickness measured by OCT has a strong correlation with that measured by histological method. Through OCT scanning, we found that the thickness of RNFL gradually becomes thinner in a time-dependent manner.

Differential changes of local blood supply in rat retinae are involved in the selective loss of retinal ganglion cells following the acute high intraocular pressure.

PURPOSE: To detect changes in local blood supply to central, middle, and peripheral retina following acute high intraocular pressure and to investigate the effects of changes in local retinal blood supply on the selective loss of retinal ganglion cells. METHODS: The acute high intraocular pressure model of Sprague-Dawley rats was established by increasing the anterior chamber pressure to 110 mmHg via a normal saline perfusion system. Blood supply to the central, middle, and peripheral retina at 3, 6, and 12 h, and 1, 3, 7, and 14 d following induction of acute high intraocular pressure was detected by using gelatin-ink perfusion and fluorescent microsphere injection. Retinal ganglion cell loss following acute high intraocular pressure was detected by fluorogold retrograde labeling. Finally, the relationship between changes in local retinal blood supply and loss of retinal ganglion cells was investigated. RESULTS: The increased ratio of blood supply of peripheral retina was less than that of the central and middle retina at 3 h to 14 d following acute high intraocular pressure. The percent of retinal ganglion cell loss in the peripheral retina was clearly greater than that in the central and middle retina during the first 3 d following induction of acute high intraocular pressure (p < 0.05). Using either the gelatin-ink infusion method or the microsphere injection method (p < 0.05), a significantly negative correlation between the percent of retinal ganglion cell loss and the corresponding increased local blood supply after induction of acute high intraocular pressure (r = -0.57 or -0.72) was found. Moreover, a significant negative correlation in the peripheral retina (r = -0.80 or -0.91; p < 0.05) was observed. CONCLUSION: A disparity exists between changes in local blood supply to the central and middle retina, and the peripheral retina following induction of acute high intraocular pressure in rats. This inequality of changes in local blood supply in rat retina is related to the selective loss of retinal ganglion cells.