Ifenprodil attenuates the acquisition and expression of methamphetamine-induced behavioral sensitization and activation of Ras-ERK1/2 cascade in the caudate putamen

Identification of the circRNA-miRNA-mRNA network for treating methamphetamine-induced relapse and behavioral sensitization with cannabidiol

AIMS

This study aims to investigate the pharmacological effects and the underlying mechanism of cannabidiol (CBD) on methamphetamine (METH)-induced relapse and behavioral sensitization in male mice.

METHODS

The conditioned place preference (CPP) test with a biased paradigm and open-field test were used to assess the effects of CBD on METH-induced relapse and behavioral sensitization in male mice. RNA sequencing and bioinformatics analysis was employed to identify differential expressed (DE) circRNAs, miRNAs, and mRNAs in the nucleus accumbens (NAc) of mice, and the interaction among them was predicted using competing endogenous RNAs (ceRNAs) network analysis.

RESULTS

Chronic administration of CBD (40 mg/kg) during the METH withdrawal phase alleviated METH (2 mg/kg)-induced CPP reinstatement and behavioral sensitization in mice, as well as mood and cognitive impairments following behavioral sensitization. Furthermore, 42 DEcircRNAs, 11 DEmiRNAs, and 40 DEmRNAs were identified in the NAc of mice. The circMeis2-miR-183-5p-Kcnj5 network in the NAc of mice is involved in the effects of CBD on METH-induced CPP reinstatement and behavioral sensitization.

CONCLUSIONS

This study constructed the ceRNAs network for the first time, revealing the potential mechanism of CBD in treating METH-induced CPP reinstatement and behavioral sensitization, thus advancing the application of CBD in METH use disorders.

Effects of the GluN2B-selective antagonist Ro 63-1908 on acquisition and expression of methamphetamine conditioned place preference in male and female rats

BACKGROUND

Methamphetamine abuse has increased significantly in recent years. Currently, there are no FDA-approved pharmacotherapies for the treatment of methamphetamine use disorder. The goal of the current study was to determine if the N-methyl-d-aspartate (NMDA) GluN2B-selective antagonist Ro 63-1908 can block the conditioned rewarding effects of methamphetamine as assessed in conditioned place preference (CPP).

METHODS

Two main experiments were conducted. In the first experiment, male (n = 24) and female (n = 24) rats received either vehicle or Ro 63-1908 (1.0-10.0 mg/kg) 30 min prior to the posttest to determine if blocking the GluN2B subunit attenuates expression of methamphetamine CPP. In the second experiment, male (n = 18) and female (n = 18) rats received either vehicle or Ro 63-1908 (1.0 or 3.0 mg/kg) 30 min prior to each conditioning session to determine if blocking the GluN2B subunit attenuates acquisition of methamphetamine CPP.

RESULTS

Ro 63-1908 (3.0 mg/kg) blocked acquisition of methamphetamine CPP in male rats, but only attenuated CPP in female rats. Ro 63-1908 did not alter expression of CPP in either sex. Increasing the dose of Ro 63-1908 (10.0 mg/kg) failed to block acquisition of CPP in an additional group of female rats (n = 6). A control experiment showed that Ro 63-1908 (3.0 mg/kg) did not produce CPP or conditioned place aversion in male rats (n = 6) or in female rats (n = 6).

CONCLUSIONS

The results of this study show that Ro 63-1908 is able to decrease the conditioned rewarding effects of methamphetamine.

Phosphorylation of GluN2B subunits of N-methyl-d-aspartate receptors in the frontal association cortex involved in morphine-induced conditioned place preference in mice

Morphine is one of the most abused drugs in the world, which has resulted in serious social problems. The frontal association cortex (FrA) has been shown to play a key role in memory formation and drug addiction. N-Methyl-d-aspartate receptors (NMDARs) are abundant in the prefrontal cortex (PFc) and much evidence indicates that GluN2B-containing NMDARs are involved in morphine-induced conditioned place preference (CPP). However, the function of GluN2B in the FrA during morphine-induced CPP has yet to be fully investigated. In the present work, a CPP animal model was employed to measure the expression of phosphorylated (p-) GluN2B (Serine; Ser 1303) in the FrA and NAc in different phases of morphine-induced CPP. We found that p-GluN2B (Ser 1303) was increased in the FrA during the development and reinstatement phases but unchanged in the extinction phase. The use of ifenprodil, a GluN2B-specific antagonist, to block the activity of GluN2B in the two phases attenuated morphine-induced CPP and reinstatement. Furthermore, ifenprodil also blocked morphine-induced upregulation of p-GluN2B (Ser 1303) in the FrA in both phases. These results indicate that GluN2B-containing NMDARs in the FrA may be involved in the regulation of morphine-induced CPP and reinstatement.

Molecular hydrogen attenuates methamphetamine-induced behavioral sensitization and activation of ERK-ΔFosB signaling in the mouse nucleus accumbens

Methamphetamine (METH) is one of the most prevalently used illegal psychostimulants in many countries. Continuous exposure to METH leads to behavioral sensitization in animals, which can be used as a behavioral model with many mechanisms in common with relapse in humans. Molecular hydrogen has recently gained attention for its potential as a novel healthcare product with preventive and therapeutic applicability to a wide range of pathological conditions. However, it remains unclear whether and, if so, how hydrogen regulates METH-induced behavioral abnormalities. In the present study, we investigated the roles of molecular hydrogen on the acquisition and transfer of METH-induced behavioral sensitization and the accompanying changes in ERK phosphorylation and ΔFosB activation in the nucleus accumbens (NAc) of mice. To this end, male C57BL/6 mice received METH (0.1, 0.5 and 1.0 mg/kg, i.p.) injections for 7 days followed by a METH challenge (0.1, 0.5 and 1.0 mg/kg, i.p.) after a 7-day transfer period. Molecular hydrogen, delivered through a hydrogen-rich saline (HRS) injection (10 mL/kg, i.p., 3-h interval), was administered during the acquisition and transfer periods. We found that HRS administration was able to inhibit the acquisition and transfer of 0.1 and 0.5 mg/kg METH-induced behavioral sensitization to a certain extent, thereby attenuating the expression of behavioral sensitization. The HRS injections alone did not induce any obvious changes in locomotor activity in mice. Intriguingly, the increases in pERK and ΔFosB in the NAc, which accompanied the METH-induced behavioral sensitization, were also attenuated by the HRS treatments. Due to the anti-oxidative function of molecular hydrogen, the HRS injections reduced METH-induced reactive oxygen species and malondialdehyde generation in the NAc. These results suggest that molecular hydrogen serves as an anti-oxidative agent with potentially therapeutic applicability to the treatment of METH addicts.

HIV-1 TAT protein enhances sensitization to methamphetamine by affecting dopaminergic function

Methamphetamine abuse is common among humans with immunodeficiency virus (HIV). The HIV-1 regulatory protein TAT induces dysfunction of mesolimbic dopaminergic systems which may result in impaired reward processes and contribute to methamphetamine abuse. These studies investigated the impact of TAT expression on methamphetamine-induced locomotor sensitization, underlying changes in dopamine function and adenosine receptors in mesolimbic brain areas and neuroinflammation (microgliosis). Transgenic mice with doxycycline-induced TAT protein expression in the brain were tested for locomotor activity in response to repeated methamphetamine injections and methamphetamine challenge after a 7-day abstinence period. Dopamine function in the nucleus accumbens (Acb) was determined using high performance liquid chromatography. Expression of dopamine and/or adenosine A receptors (ADORA) in the Acb and caudate putamen (CPu) was assessed using RT-PCR and immunohistochemistry analyses. Microarrays with pathway analyses assessed dopamine and adenosine signaling in the CPu. Activity-dependent neurotransmitter switching of a reserve pool of non-dopaminergic neurons to a dopaminergic phenotype in the ventral tegmental area (VTA) was determined by immunohistochemistry and quantified with stereology. TAT expression enhanced methamphetamine-induced sensitization. TAT expression alone decreased striatal dopamine (D1, D2, D4, D5) and ADORA1A receptor expression, while increasing ADORA2A receptors expression. Moreover, TAT expression combined with methamphetamine exposure was associated with increased adenosine A receptors (ADORA1A) expression and increased recruitment of dopamine neurons in the VTA. TAT expression and methamphetamine exposure induced microglia activation with the largest effect after combined exposure. Our findings suggest that dopamine-adenosine receptor interactions and reserve pool neuronal recruitment may represent potential targets to develop new treatments for methamphetamine abuse in individuals with HIV.

Methamphetamine and Ovarian Steroid Responsive Cells in the Posteriodorsal Medial Amygdala are Required for Methamphetamine-enhanced Proceptive Behaviors

Methamphetamine (Meth) is a psychomotor stimulant strongly associated with increases in sexual drive and impulse in both men and women. These changes in sexual motivation have a greater impact on women due to their likelihood of facing the greater burden of unplanned pregnancies, as well as increased risk for psychiatric co-morbidities such as depression. We have previously established a rodent model of Meth-induced increases in sexual motivation. Using this model, we have identified the posteriodorsal medial amygdala (MePD) via excitotoxic lesion studies as a necessary nucleus in Meth-facilitated female sexual motivation. While lesion studies give us insight into key nuclei that may be targets of Meth action, such an approach does not give insight into the identity of the specific MePD neurons or neural circuitry involved in Meth-induced increases in proceptive behaviors. Using the DAUN02 inactivation method, a recently established technique for removing behaviorally relevant cell populations, we present evidence that the ovarian steroid/Meth responsive cells in the MePD are necessary for Meth-induced facilitation of proceptive behaviors. These findings form the basis for future work that will allow for the classification of neuronal subtypes involved in the MePD’s modulation of proceptive behavior as well as a stronger understanding of the neurocircuitry of female sexual motivation.