A cocaine analog, 2beta-propanoyl-3beta-(4-tolyl)-tropane (PTT), reduces tyrosine hydroxylase in the mesolimbic dopamine pathway

Transcriptomic profiling of the ventral tegmental area and nucleus accumbens in rhesus macaques following long-term cocaine self-administration

BACKGROUND

The behavioral consequences associated with addiction are thought to arise from drug-induced neuroadaptation. The mesolimbic system plays an important initial role in this process, and while the dopaminergic system specifically has been strongly interrogated, a complete understanding of the broad transcriptomic effects associated with cocaine use remains elusive.

METHODS

Using next generation sequencing approaches, we performed a comprehensive evaluation of gene expression differences in the ventral tegmental area and nucleus accumbens of rhesus macaques that had self-administered cocaine for roughly 100days and saline-yoked controls. During self-administration, the monkeys increased daily consumption of cocaine until almost the maximum number of injections were taken within the first 15min of the one hour session for a total intake of 3mg/kg/day.

RESULTS

We confirm the centrality of dopaminergic differences in the ventral tegmental area, but in the nucleus accumbens we see the strongest evidence for an inflammatory response and large scale chromatin remodeling.

CONCLUSIONS

These findings suggest an expanded understanding of the pathology of cocaine addiction with the potential to lead to the development of alternative treatment strategies.

Monoamine transporters: from genes to behavior

Modulation of fast neurotransmission by monoamines is critically involved in numerous physiological functions and pathological conditions. Plasma membrane monoamine transporters provide one of the most efficient mechanisms controlling functional extracellular monoamine concentrations. These transporters for dopamine (DAT), serotonin (SERT), and norepinephrine (NET), which are expressed selectively on the corresponding neurons, are established targets of many psychostimulants, antidepressants, and neurotoxins. Recently, genetic animal models with targeted disruption of these transporters have become available. These mice have provided opportunities to investigate the functional importance of transporters in homeostatic control of monoaminergic transmission and to evaluate, in an in vivo model system, their roles in physiology and pathology. The use of these mice as test subjects has been helpful in resolving several important issues on specificity and mechanisms of action of certain pharmacological agents. In the present review, we summarize recent advances in understanding the physiology and pharmacology of monoamine transporters gained in mice with targeted genetic deletion of DAT, SERT, and NET.