Genetically targeted reporter imaging of deep neuronal network in the mammalian brain

Abstract

Positron Emission Tomography (PET) allows biomolecular tracking, while PET monitoring of brain networks has been hampered by the lack of a suitable reporter. Here, we describe invivo brain reporters utilizing bacterial dihydrofolate reductase, ecDHFR, and its antagonist, TMP. In mice, peripheral administration of radiofluorinated and fluorescent TMP analogs enabled PET and intravital microscopy, respectively, of neuronal ecDHFR expressions. This technique was applicable to the visualization of chemogenetically provoked neuronal ensemble activities in the hippocampus. Notably, ecDHFR-PET captured neuronal projections in non-human primate brains, indicating the availability of ecDHFR-based techniques for network monitoring. Finally, we demonstrated PET assays of turnover and self-assembly of proteins tagged with ecDHFR mutants. Collectively, the current reporter technology offers diverse in-vivo molecular analyses of a brain circuit.

Dynamic alterations in the central glutamatergic status following food and glucose intake: in vivo multimodal assessments in humans and animal models

“…AAV particles were purified with HiTrap heparin column (GE Healthcare) and virus titer was determined by AAVpro V R Titration kit (for Real Time PCR) ver2 (TaKaRa) as described previously. 33 A total of 12 male C57BL/6 J mice (20-30 g, 7-11 weeks; Japan SLC, Inc., Hamamatsu) were used in experiments with glucose (2 g/kg; n ¼ 6) and saline injection (n ¼ 6). For the surgical procedure, the animals were anesthetized with a mixture of air, oxygen, and isoflurane (3-4% for induction and 2% for surgery) via a facemask, and a cranial window (3-4 mm in diameter) was attached over the left somatosensory cortex, centered at 1.8 mm caudal and 2.5 mm lateral from the bregma, according to the 'Seylaz-Tomita method'.…”

“…AAV particles were purified with HiTrap heparin column (GE Healthcare) and virus titer was determined by AAVpro® Titration kit (for Real Time PCR) ver2 (TaKaRa) as described previously. 33 …”

Letting the little light of mind shine: Advances and future directions in neurochemical detection

“…Though fluorescence imaging provides high spatiotemporal resolution, it is not compatible with human applications. Positron emission tomography (PET) and magnetic resonance imaging (MRI) using nuclear medicine or genetically encoded probes provide information at the whole-brain level and have been broadly used for diagnosis in humans, albeit with poor spatial and temporal resolution (Finnema et al, 2015;Li and Jasanoff, 2020;Shimojo et al, 2020). The development of cell-based neurotransmitter fluorescent engineered receptors (CNiFERs) is another detection method for dopamine, norepinephrine and neuropeptides (Muller et al, 2014).…”