Startle and sensorimotor correlates of ventral thalamic dopamine and GABA in rodents

Recent studies have implicated the thalamus as a possible site for neuroanatomical and neurochemical changes in schizophrenia. In the present study, we investigated thalamic neurochemical correlates of behaviors potentially linked to schizophrenia. Whole thalamic DOPAC levels were elevated in rats that had poor extinction of the acoustic startle response. The dopamine agonist apomorphine microinjected into the ventromedial thalamus (VmT) disrupted prepulse inhibition of startle. Catalepsy was induced by VmT microinjections of the GABA-A agonist muscimol. A previous study revealed attentional disturbances and suppression of frontal cortical metabolic activity after muscimol microinjections into the mediodorsal thalamic nucleus. Together with recent findings of neuron cell loss and elevated DA levels in the thalamus of schizophrenics, these data suggest the involvement of disturbances of thalamic neurotransmission in schizophrenia.