Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
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Neuropsychopharmacology · Feb 2007
Smoking modulation of mu-opioid and dopamine D2 receptor-mediated neurotransmission in humans.
This is a pilot examination of the hypothesis that some of the effects of smoking cigarettes in humans are mediated through nicotine activation of opioid and dopamine (DA) neurotransmission. Neuroimaging was performed using positron emission tomography and the radiotracers [11C]carfentanil and [11C]raclopride, labeling mu-opioid and DA D2 receptors, respectively. Six healthy male smokers were abstinent overnight. ⋯ Lower mu-opioid receptor BP was also detected during the denicotinized smoking condition in the smoker group, compared to baseline scans in non-smokers, in the cingulate cortex, thalamus, ventral basal ganglia, and amygdala. These reductions were reversed during the average nicotine condition in the thalamus, ventral basal ganglia and amygdala. These data point to both the feasibility of simultaneously examining opioid and DA neurotransmission responses to smoking in humans, as well as to the need to examine non-nicotine aspects of smoking to more fully understand the behavioral effects of this drug.
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Neuropsychopharmacology · Feb 2007
Effects of opiate drugs on Fas-associated protein with death domain (FADD) and effector caspases in the rat brain: regulation by the ERK1/2 MAP kinase pathway.
This study was designed to assess the effects of opiate treatment on the expression of Fas-associated protein with death domain (FADD) in the rat brain. FADD is involved in the transmission of Fas-death signals that have been suggested to contribute to the development of opiate tolerance and addiction. Acute treatments with high doses of sufentanil and morphine (mu-agonists), SNC-80 (delta-agonist), and U50488H (kappa-agonist) induced significant decreases (30-60%) in FADD immunodensity in the cerebral cortex, through specific opioid receptor mechanisms (effects antagonized by naloxone, naltrindole, or nor-binaltorphimine). ⋯ Pretreatment of rats with SL 327 (a selective MEK1/2 inhibitor that blocks ERK activation) fully prevented the reduction of FADD content induced by SNC-80 in the cerebral cortex (43%) and corpus striatum (29%), demonstrating the direct involvement of ERK1/2 signaling in the regulation of FADD by the opiate agonist. The results indicate that mu- and delta-opioid receptors have a prominent role in the modulation of FADD (opposite to that of Fas) shortly after initiating treatment. Opiate drugs (and specifically the delta-agonists) could promote survival signals in the brain through inhibition of FADD, which in turn is dependent on the activation of the antiapoptotic ERK1/2 signaling pathway.
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Neuropsychopharmacology · Nov 2006
Comparative StudyGenetic inactivation of the NMDA receptor NR2A subunit has anxiolytic- and antidepressant-like effects in mice.
There is growing evidence implicating the glutamate system in the pathophysiology and treatment of mood and anxiety disorders. Glutamatergic neurotransmission is mediated by several receptor subfamilies including multiple NMDA receptor subunits (NR2A-D). However, little is currently understood about the specific roles of NMDA subunits in the mediation of emotional behavior due to a lack of subunit-specific ligands. ⋯ Locomotor activity in the nonaversive environments of the home cage or a familiar open field were normal in the NR2A KO mice, as were gross neurological and sensory functions, including prepulse inhibition of startle. Taken together, these data demonstrate a selective and robust reduction in anxiety- and depression-related behavior in NMDA receptor NR2A subunit KO mice. Present results support a role for the NR2A subunit in the modulation of emotional behaviors in rodents and provide insight into the role of glutamate in the pathophysiology and treatment of mood and anxiety disorders.
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Neuropsychopharmacology · Nov 2006
Multicenter Study Comparative Study Clinical TrialThree-year outcomes in deep brain stimulation for highly resistant obsessive-compulsive disorder.
Deep brain stimulation (DBS) of the anterior limb of the internal capsule has been shown to be beneficial in the short term for obsessive-compulsive disorder (OCD) patients who exhaust conventional therapies. Nuttin et al, who published the first DBS for OCD series, found promising results using a capsule target immediately rostral to the anterior commissure extending into adjacent ventral capsule/ventral striatum (VC/VS). Published long-term outcome data are limited to four patients. ⋯ Surgical adverse effects included an asymptomatic hemorrhage, a single seizure, and a superficial infection. Psychiatric adverse effects included transient hypomanic symptoms, and worsened depression and OCD when DBS was interrupted by stimulator battery depletion. This open study found promising long-term effects of DBS in highly treatment-resistant OCD.
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Neuropsychopharmacology · Oct 2006
Comparative StudyActivation of adenosine A1 receptors reduces anxiety-like behavior during acute ethanol withdrawal (hangover) in mice.
Elevated signs of anxiety are observed in both humans and rodents during withdrawal from chronic as well as acute ethanol exposure, and it represents an important motivational factor for ethanol relapse. Several reports have suggested the involvement of brain adenosine receptors in different actions produced by ethanol such as motor incoordination and hypnotic effects. In addition, we have recently demonstrated that adenosine A1 receptors modulate the anxiolytic-like effect induced by ethanol in mice. ⋯ The acute administration of 'nonanxiolytic' doses of adenosine and the selective adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA), but not the adenosine A2A receptor agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA), at the onset of peak withdrawal (18 h), reduced this anxiogenic-like response. In addition, the effect of CCPA on the anxiety-like behavior of ethanol hangover was reversed by pretreatment with the selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). These results reinforce the notion of the involvement of adenosine receptors in the anxiety-like responses and indicate the potential of adenosine A1 receptor agonists to reduce the anxiogenic effects during ethanol withdrawal.