RT Journal Article
SR Electronic
T1 Longitudinal Small-Animal PET Imaging of the zQ175 Mouse Model of Huntington Disease Shows In Vivo Changes of Molecular Targets in the Striatum and Cerebral Cortex
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 617
OP 622
DO 10.2967/jnumed.116.180497
VO 58
IS 4
A1 Häggkvist, Jenny
A1 Tóth, Miklós
A1 Tari, Lenke
A1 Varnäs, Katarina
A1 Svedberg, Marie
A1 Forsberg, Anton
A1 Nag, Sangram
A1 Dominguez, Celia
A1 Munoz-Sanjuan, Ignacio
A1 Bard, Jonathan
A1 Wityak, John
A1 Varrone, Andrea
A1 Halldin, Christer
A1 Mrzljak, Ladislav
YR 2017
UL http://jnm.snmjournals.org/content/58/4/617.abstract
AB Since the discovery of the HTT gene in 1993, numerous animal models have been developed to study the progression of Huntington disease (HD) and to evaluate potential new therapeutics. In the present study, we used small-animal PET to characterize the expression of molecular targets in the recently reported HD animal model, the zQ175 mouse model. Methods: Male heterozygous zQ175 (Htttm1Mfc/190JChdi, CHDI-81003003) and wild-type (WT, C57BL/6J) animals were imaged with the dopamine D2 receptor radioligand 11C-raclopride, the PDE10A radioligand 18F-MNI-659, the dopamine D1 receptor radioligand 11C-NNC 112, and the 5-HT2A radioligand 11C-MDL 100907 at 6 and 9 mo of age. The outcome measure was the binding potential (BPND), using the cerebellum as the reference region. Selected regions of interest were the striatum for all radioligands and additionally the striatum, rostral cortex, caudal cortex, and hippocampus for 11C-NNC 112 and 11C-MDL 100907. Results: At 6 mo of age, the BPND in the striatum was lower in zQ175 than WT animals by 40% for 11C-raclopride, by 52% for 18F-MNI-659, by 28% for 11C-NNC, and by 11% for 11C-MDL 100907. In the rostral cortex, D1 receptor binding was 22% lower in zQ175 than WT animals. We found an overall reduction in D1 and 5-HT2A binding in the hippocampus of zQ175 compared with WT animals. The BPND of 11C-MDL 100907 in the caudal cortex was also lower in zQ175 WT animals. At 9 mo, there was a slight further reduction of D1, D2, and 5-HT2A BPND in the striatum, whereas PDE10A reached a plateau. Cortical markers were also slightly further decreased at 9 mo in zQ175 animals. Conclusion: Our study indicates a marked reduction of ligand binding to D1 and D2 and 5-HT2A receptors as well as loss of PDE10A enzyme in the striatum of zQ175 mice as compared with WT animals, in agreement with data obtained in clinical PET studies of patients with HD. The zQ175 mouse model recapitulates the expression pattern seen in humans with HD and may have value in further elucidating pathophysiologic events and therapeutic strategies.