Characterization of proteins in the rat striatum following acute cocaine administration

Cocaine self-administration induces sex-dependent protein expression in the nucleus accumbens

Substance use disorder (SUD) is a chronic neuropsychiatric condition characterized by long-lasting alterations in the neural circuitry regulating reward and motivation. Substantial work has focused on characterizing the molecular substrates that underlie these persistent changes in neural function and behavior. However, this work has overwhelmingly focused on male subjects, despite mounting clinical and preclinical evidence that females demonstrate dissimilar progression to SUD and responsivity to stimulant drugs of abuse, such as cocaine. Here, we show that sex is a critical biological variable that defines drug-induced plasticity in the nucleus accumbens (NAc). Using quantitative mass spectrometry, we assessed the protein expression patterns induced by cocaine self-administration and demonstrated unique molecular profiles between males and females. We show that 1. Cocaine self-administration induces non-overlapping protein expression patterns in significantly regulated proteins in males and females and 2. Critically, cocaine-induced protein regulation differentially interacts with sex to eliminate basal sexual dimorphisms in the proteome. Finally, eliminating these baseline differences in the proteome is concomitant with the elimination of sex differences in behavior for non-drug rewards. Together, these data suggest that cocaine administration is capable of rewriting basal proteomic function and reward-associated behaviors.

Protein kinase G regulates β-synuclein in response to repeated exposure to cocaine in the rat dorsal striatum in a Ca²⁺-dependent manner

Protein kinase G (PKG) activation plays a crucial role in neuronal plasticity after repeated exposure to cocaine in the dorsal striatum. The present study investigated the characteristics of β-synuclein expression by PKG activation after repeated cocaine administration in the rat dorsal striatum. The results demonstrated that repeated, but not acute, exposure to cocaine (20mg/kg) once a day for 7 consecutive days significantly upregulated expression of β-synuclein. Furthermore, this upregulation was decreased by the depletion of Ca(2+), but not blockade of Na(+) influx. Blockade of N-methyl-d-aspartate (NMDA) receptors and ryanodine-sensitive Ca(2+) channels also decreased the elevation of β-synuclein expression by repeated cocaine administration. Inhibition of neuronal nitric oxide synthase, which can activate PKG, did not alter the expression of β-synuclein elevated by repeated cocaine administration. These findings suggest that the expression of β-synuclein can be regulated by Ca(2+)-dependent PKG activation via stimulation of NMDA receptors and voltage-operated Ca(2+) channels in the endoplasmic reticulum in the dorsal striatum.