Circuit-selective striatal synaptic dysfunction in the Sapap3 knockout mouse model of obsessive-compulsive disorder.

Biol Psychiatry

BACKGROUND: Synapse-associated protein 90/postsynaptic density protein 95-associated protein 3 (SAPAP3) is an excitatory postsynaptic protein implicated in the pathogenesis of obsessive-compulsive behaviors. In mice, genetic deletion of Sapap3 causes obsessive-compulsive disorder (OCD)-like behaviors that are rescued by striatal expression of Sapap3, demonstrating the importance of striatal neurotransmission for the OCD-like behaviors. In the striatum, there are two main excitatory synaptic circuits, corticostriatal and thalamostriatal. Neurotransmission defects in either or both of these circuits could potentially contribute to the OCD-like behaviors of Sapap3 knockout (KO) mice. Previously, we reported that Sapap3 deletion reduces corticostriatal alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid-type glutamate receptor-mediated synaptic transmission.

METHODS: Whole-cell electrophysiological recording techniques in acute brain slices were used to measure synaptic transmission in the corticostriatal and thalamostriatal circuits of Sapap3 KO mice and littermate control animals. Transgenic fluorescent reporters identified striatopallidal and striatonigral projection neurons. SAPAP isoforms at corticostriatal and thalamostriatal synapses were detected using immunostaining techniques.

RESULTS: In contrast to corticostriatal synapses, thalamostriatal synaptic activity is unaffected by Sapap3 deletion. At the molecular level, we find that another SAPAP family member, SAPAP4, is present at thalamostriatal, but not corticostriatal, synapses. This finding provides a molecular rationale for the functional divergence we observe between thalamic and cortical striatal circuits in Sapap3 KO mice.

CONCLUSIONS: These findings define the circuit-level neurotransmission defects in a genetic mouse model for OCD-related behaviors, focusing attention on the corticostriatal circuit for mediating the behavioral abnormalities. Our results also provide the first evidence that SAPAP isoforms may be localized to synapses according to circuit-selective principles.

Year of Publication
Biol Psychiatry
Date Published
2014 Apr 15
PubMed ID
PubMed Central ID
Grant list
T32NS051156 / NS / NINDS NIH HHS / United States
K02 NS054840 / NS / NINDS NIH HHS / United States
R01 MH097104 / MH / NIMH NIH HHS / United States
NS064577 / NS / NINDS NIH HHS / United States
DA031833 / DA / NIDA NIH HHS / United States
MH081201 / MH / NIMH NIH HHS / United States
NS054840 / NS / NINDS NIH HHS / United States
T32 NS051156 / NS / NINDS NIH HHS / United States
R01 DA031833 / DA / NIDA NIH HHS / United States
R01 MH081201 / MH / NIMH NIH HHS / United States
R01 NS064577 / NS / NINDS NIH HHS / United States