TY - JOUR
T1 - In vitro characterization of [3H]VAT in cells, animal and human brain tissues for vesicular acetylcholine transporter
AU - Liang, Qianwa
AU - Joshi, Sumit
AU - Liu, Hui
AU - Yu, Yanbo
AU - Zhao, Haiyang
AU - Benzinger, Tammie L.S.
AU - Perlmutter, Joel S.
AU - Tu, Zhude
N1 - Funding Information:
The authors thank the Cyclotron Facility of Washington University School of Medicine. This work was supported by the USA National Institutes of Health (NIH) through the National Institute of Neurological Disorders and Stroke , the National Institute on Aging [ NS075527 , NS103988 and NS103957 ].
Funding Information:
The authors thank the Cyclotron Facility of Washington University School of Medicine. This work was supported by the USA National Institutes of Health (NIH) through the National Institute of Neurological Disorders and Stroke, the National Institute on Aging [NS075527, NS103988 and NS103957].
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/11/15
Y1 - 2021/11/15
N2 - Vesicular acetylcholine transporter plays a crucial role in the cholinergic system, and its alterations is implicated in several neurodegenerative disorders. We recently developed a PET imaging tracer [18F]VAT to target VAChT in vivo with high affinity and selectivity. Here we report in vitro characterization of [3H]VAT, a tritiated counterpart of [18F]VAT. Using human VAChT-rich cell membrane extracts, a saturated binding curve was obtained for [3H]VAT with Kd = 6.5 nM and Bmax = 22.89 pmol/mg protein. In the [3H]VAT competition-binding assay with a panel of CNS ligands, binding inhibition of [3H]VAT was observed using VAChT ligands, the Ki values ranged from 5.41 to 33.3 nM. No inhibition was detected using a panel of other CNS ligands. In vitro [3H]VAT autoradiography of rat brain sections showed strong signals in the striatum, moderate to high signals in vermis, thalamus, cortex, and hippocampus, and weak signals in cerebellum. Strong [3H]VAT ARG signals were also observed from striatal sections of normal nonhuman primates and human brains. Competitive ARG study with human striatal sections demonstrated strong ARG signals of [3H]VAT in caudate and putamen were blocked significantly by either VAChT ligand TZ659 or (−)-vesamicol, but not by the σ1 receptor ligand Yun-122. ARG study also indicated that signal in the striatal sections from PSP human brains was lower than normal human brains. These data provide solid evidence supporting [18F]VAT as a suitable PET radiotracer for quantitative assessment of VAChT levels in vivo.
AB - Vesicular acetylcholine transporter plays a crucial role in the cholinergic system, and its alterations is implicated in several neurodegenerative disorders. We recently developed a PET imaging tracer [18F]VAT to target VAChT in vivo with high affinity and selectivity. Here we report in vitro characterization of [3H]VAT, a tritiated counterpart of [18F]VAT. Using human VAChT-rich cell membrane extracts, a saturated binding curve was obtained for [3H]VAT with Kd = 6.5 nM and Bmax = 22.89 pmol/mg protein. In the [3H]VAT competition-binding assay with a panel of CNS ligands, binding inhibition of [3H]VAT was observed using VAChT ligands, the Ki values ranged from 5.41 to 33.3 nM. No inhibition was detected using a panel of other CNS ligands. In vitro [3H]VAT autoradiography of rat brain sections showed strong signals in the striatum, moderate to high signals in vermis, thalamus, cortex, and hippocampus, and weak signals in cerebellum. Strong [3H]VAT ARG signals were also observed from striatal sections of normal nonhuman primates and human brains. Competitive ARG study with human striatal sections demonstrated strong ARG signals of [3H]VAT in caudate and putamen were blocked significantly by either VAChT ligand TZ659 or (−)-vesamicol, but not by the σ1 receptor ligand Yun-122. ARG study also indicated that signal in the striatal sections from PSP human brains was lower than normal human brains. These data provide solid evidence supporting [18F]VAT as a suitable PET radiotracer for quantitative assessment of VAChT levels in vivo.
KW - Autoradiography
KW - Binding assay
KW - Progressive supranuclear palsy
KW - Radioligand
KW - Striatum
KW - Vesicular acetylcholine transporter
UR - http://www.scopus.com/inward/record.url?scp=85116834515&partnerID=8YFLogxK
U2 - 10.1016/j.ejphar.2021.174556
DO - 10.1016/j.ejphar.2021.174556
M3 - Article
C2 - 34627806
AN - SCOPUS:85116834515
SN - 0014-2999
VL - 911
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
M1 - 174556
ER -