Mice expressing constitutively active Gsalpha exhibit stimulus encoding deficits similar to those observed in schizophrenia patients.
People with schizophrenia display sensory encoding deficits across a broad range of electrophysiological and behavioral measures, suggesting fundamental impairments in the ability to transduce the external environment into coherent neural representations. This inability to create basic components of complex stimuli interferes with a high fidelity representation of the world and likely contributes to cognitive deficits. The current study evaluates the effects of constitutive forebrain activation of the G(s)alpha G-protein subunit on auditory threshold and gain using acoustic brainstem responses and cortically generated N40 event-related potentials to assess the role of cyclic AMP signaling in sensory encoding. Additionally, we examine the ability of pharmacological treatments that mimic (amphetamine) or ameliorate (haloperidol) positive symptoms of schizophrenia to test the hypothesis that the encoding deficits observed in G(s)alpha transgenic mice can be normalized with treatment. We find that G(s)alpha transgenic mice have decreased amplitude of cortically generated N40 but normal acoustic brainstem response amplitude, consistent with forebrain transgene expression and a schizophrenia endophenotype. Transgenic mice also display decreased stimulus intensity response (gain) in both acoustic brainstem response and N40, indicating corticofugal influence on regions that lack transgene expression. N40 deficits in transgenic animals were ameliorated with low dose haloperidol and reversed with higher dose, suggesting dopamine D2 receptor-linked Gi activity contributes to the impairment. Consistent with this hypothesis, we recreated the G(s)alpha transgenic deficit in wild type animals using the indirect dopamine agonist amphetamine. This transgenic model of sensory encoding deficits provides a foundation for identifying biochemical contributions to sensory processing impairments associated with schizophrenia.
Maxwell
C R
CR
Division of Neuropsychiatry, Department of Psychiatry, University of Pennsylvania, Translational Research Laboratories, Room 2223, 125 South 31st Street, Philadelphia, PA 19104, USA.
Liang
Y
Y
Kelly
M P
MP
Kanes
S J
SJ
Abel
T
T
Siegel
S J
SJ
D000161:Acoustic Stimulation / Q000379:methods; D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001309:Auditory Threshold / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D001933:Brain Stem / Q000187:drug effects / Q000503:physiopathology* / Q000528:radiation effects; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D004195:Disease Models, Animal; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004569:Electroencephalography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000187:drug effects / Q000235:genetics*; D005260:Female; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics / Q000378:metabolism*; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D012559:Schizophrenia / Q000235:genetics / Q000503:physiopathology*
D000697:Central Nervous System Stimulants; D018492:Dopamine Antagonists; D000661:Amphetamine; D019205:GTP-Binding Protein alpha Subunits, Gs; D006220:Haloperidol