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Axons of dopaminergic neurons innervate the striatum where they contribute to movement and reinforcement learning. Past work has shown that striatal GABA tonically inhibits dopamine release, but whether GABA-A receptors directly modulate transmission or act indirectly through circuit elements is unresolved. Here, we use whole-cell and perforated-patch recordings to test for GABA-A receptors on the main dopaminergic neuron axons and branching processes within the striatum of adult mice. Application of GABA depolarized axons, but also decreased the amplitude of axonal spikes, limited propagation and reduced striatal dopamine release. The mechanism of inhibition involved sodium channel inactivation and shunting. Lastly, we show the positive allosteric modulator diazepam enhanced GABA-A currents on dopaminergic axons and directly inhibited release, but also likely acts by reducing excitation from cholinergic interneurons. Thus, we reveal the mechanisms of GABA-A receptor modulation of dopamine release and provide new insights into the actions of benzodiazepines within the striatum.

A insônia é um dos distúrbios do sono caracterizado pela dificuldade em iniciar ou manter o sono. Isso se reflete em um sono de baixa qualidade que pode causar problemas ao longo do dia, como cansaço e falta de energia. Sob essa condição, estão associados alguns fatores genéticos, entre eles os genes ABCC9, 5-HTT e Clock. A presente revisão de literatura tem por objetivo a explanação acerca dos fatores genéticos relacionados com o distúrbio da insônia. Trata-se de uma revisão de literatura de forma sistemática, realizada por meio de um levantamento bibliográfico que procura reunir os conhecimentos sobre as características da insônia e sua herança gênica. Encontrou-se uma relevância de achados autorais valiosos para a síntese dessa pesquisa. Portanto, a partir do estudo abordado nessa revisão, torna-se evidente a importância do conhecimento das causas genéticas do distúrbio da insônia para a melhor abordagem clínica, haja vista a relevância desse mecanismo biológico.

Characteristic changes in brain activity accompany the paradoxical increase in alertness observed in some patients with severe brain injury when they are treated with the sleeping pill zolpidem.

Zolpidem produces paradoxical recovery of speech, cognitive and motor functions in select subjects with severe brain injury but underlying mechanisms remain unknown. In three diverse patients with known zolpidem responses we identify a distinctive pattern of EEG dynamics that suggests a mechanistic model. In the absence of zolpidem, all subjects show a strong low frequency oscillatory peak ∼6–10 Hz in the EEG power spectrum most prominent over frontocentral regions and with high coherence (∼0.7–0.8) within and between hemispheres. Zolpidem administration sharply reduces EEG power and coherence at these low frequencies. The ∼6–10 Hz activity is proposed to arise from intrinsic membrane properties of pyramidal neurons that are passively entrained across the cortex by locally-generated spontaneous activity. Activation by zolpidem is proposed to arise from a combination of initial direct drug effects on cortical, striatal, and thalamic populations and further activation of underactive brain regions induced by restoration of cognitively-mediated behaviors.