In vivo TSPO and cannabinoid receptor type 2 availability early in post-stroke neuroinflammation in rats: a positron emission tomography study

Abstract Background Upregulated levels of 18-kDa translocator proteins (TSPO) and type 2 endocannabinoid receptors (CB2) are considered to reflect different aspects of microglia-related neuroinflammatory responses in the brain. Relative to the increase in the TSPO expression that occurs slightly later during neuroinflammation in a proinflammatory fashion, CB2 activation is considered to relate to the neuroprotective responses that occurs predominantly at an early stage of brain disorders. These findings, however, were deduced from studies with different animal samples under different experimental settings. Here, we aimed to examined the differences in TSPO binding and CB2 availability at an early stage of stroke in the same animal using positron emission tomography (PET). Methods We used a total of eight Sprague-Dawley rats that underwent photothrombotic stroke surgery. The binding levels of a TSPO tracer [11C](R)PK11195 and a CB2 tracer [11C]NE40 were measured at 24 h after the surgery in the same animal using PET in combination with immunohistochemistry for CB2 and several other markers. A morphological inspection was also performed with X-ray computed tomography for small animals. Results The levels of [11C]NE40 binding potential (BPND) were significantly higher in the cerebral cortical region on the lesion side than those on the non-lesion side, whereas no difference was found in the levels of [11C](R)PK11195 BPND between hemispheres. The tracer influx index (R1) data were all reduced on the lesion side irrespective of tracers. This increase in [11C]NE40 BPND was concomitant with an elevation in CB2 expression mainly within the microglia in the peri-infarct area, as shown by immunohistochemical examinations with Iba-1, CD11b/c+, and NG2+ staining. Conclusions The present results provide in vivo evidence of different responses of microglia occurring in the acute state of stroke. The use of the CB2 tracer [11C]NE40 allows us to evaluate the roles played by the neuroprotective aspect of microglia in acute neuroinflammatory processes

Vitrectomy for Tractional Retinal Detachment with Twin Retinal Capillary Hemangiomas in a Patient with Von Hippel-Lindau Disease: A Case Report

Purpose: The purpose of this study was to report a case of Von Hippel-Lindau disease (VHL) with twin retinal capillary hemangiomas that was successfully treated by vitreous surgery for tractional retinal detachment following laser photocoagulation. Case: A 44-year-old male presented at our university hospital after noticing decreased visual acuity in his right eye. The patient had previously undergone multiple operations for cerebellar, thoracic, and lumbar spine hemangioblastomas when he was approximately 19 years old. Upon initial examination, ocular findings revealed twin connected retinal capillary hemangiomas around the temporal upper area of the patient’s right eye. The patient was subsequently diagnosed with VHL based on his medical history and current observations of the ocular fundus. Tractional retinal detachment had occurred as the result of the formation of proliferative membranes following laser photocoagulation. The patient underwent vitreous surgery to treat the tractional retinal detachment, resulting in a successful postoperative outcome. Conclusion: The findings of this study show the possibility that proliferative changes and tractional retinal detachment can arise following photocoagulation for retinal capillary hemangiomas in patients with VHL

Additional file 3: Figure S3. of In vivo TSPO and cannabinoid receptor type 2 availability early in post-stroke neuroinflammation in rats: a positron emission tomography study

Immunohistochemical results one day after photochemically induced thrombosis (PIT). Iba-1- and GFAP-positive regions are scattered around the infarct core. (JPG 248 kb

Additional file 1: Figure S1. of In vivo TSPO and cannabinoid receptor type 2 availability early in post-stroke neuroinflammation in rats: a positron emission tomography study

CT images and regions of interest. Frontal, −2 mm from the olfactory-frontal cortex junction (nearly 3 mm from the bregma). Parietal, −6 mm from the junction (nearly −1 mm from the bregma). Blue, lesion side; light blue, contralateral (non-lesion) side. (JPG 68 kb

Additional file 2: Figure S2. of In vivo TSPO and cannabinoid receptor type 2 availability early in post-stroke neuroinflammation in rats: a positron emission tomography study

The levels of SUV in each brain region. No significant difference was found in either [11C]NE40 or [11C](R)PK11195 SUV levels. (JPG 100 kb