Weiyan Zhou1, Weiqi Bao1, Donglang Jiang1, Yanyan Kong1, Fengchun Hua1, Xiuhong Lu2, Yihui Guan3. 1. PET Center, Huashan Hospital, Fudan University, No. 518, East Wuzhong Road, Xuhui District, Shanghai 200235, China. 2. PET Center, Huashan Hospital, Fudan University, No. 518, East Wuzhong Road, Xuhui District, Shanghai 200235, China. Electronic address: xiuhonglu@fudan.edu.cn. 3. PET Center, Huashan Hospital, Fudan University, No. 518, East Wuzhong Road, Xuhui District, Shanghai 200235, China; Institute of Integrative Medicine, Fudan University, No. 12, Middle Urumqi Road, Jing'an District, Shanghai 200040, China. Electronic address: guanyihui@hotmail.com.
Abstract
INTRODUCTION: The objective of this study was to synthesize an N-methyl-d-aspartate receptor (NMDAR) radiotracer [18F]-GE-179 in one-pot and evaluate its in vivo binding for NMDAR activation after brain ischemia reperfusion injury. METHODS: [18F]-GE-179 was auto-synthesized using a quick one-pot method from a stable disulfide precursor and purified using semi-preparative high-performance liquid chromatography (HPLC) with ethanol/aqueous NaH2PO4 as the eluent. Dynamic micro-positron emission tomography (PET)/computed tomography (CT) study of [18F]-GE-179 was successfully performed using a rat model of middle cerebral artery occlusion (MCAO, induced by transient occlusion into the left MCA). A simplified reference tissue model method was used to calculate the [18F]-GE-179 non-displaceable binding potential (BPND) for intracranial NMDAR activation assessment. Immunofluorescence staining of NMDAR NR1 subunit in brain slices containing lesion was also performed. RESULTS: [18F]-GE-179 was successfully prepared in a yield of 23-30% in a formulation that could be injected directly after dilution. Localized radioactivity accumulation was observed in the animal model of MCAO. Significantly higher (p = 0.0003-0.0404) BPND relative to equivalent contralateral was found in the ipsilateral caudate putamen, Acb core/shell, cortex cingulate, amygdala, hypothalamus, and superior colliculus. Immunofluorescence staining showed elevated NMDAR expression in the affected hemisphere. CONCLUSIONS: [18F]-GE-179 was synthesized using a one-pot process with a markedly improved yield. Preliminary in vivo micro-PET study visualized excessive NMDAR stimulation successfully in a rodent model of MCAO, which was consistent with results of in vitro immunofluorescence staining. The study demonstrates that [18F]-GE-179 is a promising PET probe for the detection of functional NMDAR alterations.
INTRODUCTION: The objective of this study was to synthesize an N-methyl-d-aspartate receptor (NMDAR) radiotracer [18F]-GE-179 in one-pot and evaluate its in vivo binding for NMDAR activation after brain ischemia reperfusion injury. METHODS: [18F]-GE-179 was auto-synthesized using a quick one-pot method from a stable disulfide precursor and purified using semi-preparative high-performance liquid chromatography (HPLC) with ethanol/aqueous NaH2PO4 as the eluent. Dynamic micro-positron emission tomography (PET)/computed tomography (CT) study of [18F]-GE-179 was successfully performed using a rat model of middle cerebral artery occlusion (MCAO, induced by transient occlusion into the left MCA). A simplified reference tissue model method was used to calculate the [18F]-GE-179 non-displaceable binding potential (BPND) for intracranial NMDAR activation assessment. Immunofluorescence staining of NMDAR NR1 subunit in brain slices containing lesion was also performed. RESULTS: [18F]-GE-179 was successfully prepared in a yield of 23-30% in a formulation that could be injected directly after dilution. Localized radioactivity accumulation was observed in the animal model of MCAO. Significantly higher (p = 0.0003-0.0404) BPND relative to equivalent contralateral was found in the ipsilateral caudate putamen, Acb core/shell, cortex cingulate, amygdala, hypothalamus, and superior colliculus. Immunofluorescence staining showed elevated NMDAR expression in the affected hemisphere. CONCLUSIONS: [18F]-GE-179 was synthesized using a one-pot process with a markedly improved yield. Preliminary in vivo micro-PET study visualized excessive NMDAR stimulation successfully in a rodent model of MCAO, which was consistent with results of in vitro immunofluorescence staining. The study demonstrates that [18F]-GE-179 is a promising PET probe for the detection of functional NMDAR alterations.