Pharmacology, biochemistry, and behavior
-
Pharmacol. Biochem. Behav. · Oct 2013
Transdermal delivery of cannabidiol attenuates binge alcohol-induced neurodegeneration in a rodent model of an alcohol use disorder.
Excessive alcohol consumption, characteristic of alcohol use disorders, results in neurodegeneration and behavioral and cognitive impairments that are hypothesized to contribute to the chronic and relapsing nature of alcoholism. Therefore, the current study aimed to advance the preclinical development of transdermal delivery of cannabidiol (CBD) for the treatment of alcohol-induced neurodegeneration. In Experiment 1, 1.0%, 2.5% and 5.0% CBD gels were evaluated for neuroprotection. ⋯ Experiment 2 tested a next generation 2.5% CBD gel formulation, which was compared to CBD administration by intraperitoneal injection (IP; 40.0 mg/kg/day). This experiment found similar magnitudes of neuroprotection following both routes of administration; transdermal CBD decreased FJB+ cells in the entorhinal cortex by 56.1% (p<0.05), while IP CBD resulted in a 50.6% (p<0.05) reduction in FJB+ cells. These results demonstrate the feasibility of using CBD transdermal delivery systems for the treatment of alcohol-induced neurodegeneration.
-
Pharmacol. Biochem. Behav. · Oct 2013
Activation of mTOR in the spinal cord is required for pain hypersensitivity induced by chronic constriction injury in mice.
The mammalian target of rapamycin (mTOR) is known to regulate cell growth, and it also participates in pain transmission as has been recently verified in inflammatory and neuropathic pain models. The targeting of mTOR represents a new strategy for the control of chronic pain. In the present study, we investigated the effect of mTOR in the expression of PSD95 and NR2B-PSD95 or GluA2-PSD95 interaction ratio in a chronic constriction injury (CCI) mice model. ⋯ These data suggest that the mTOR pathway is activated in the spinal dorsal horn in CCI-induced neuropathic pain, and the intrathecal injection of rapamycin can reduce mechanical allodynia. Our findings indicate that spinal mTOR is an important component of CCI-induced neuropathic pain, and mTOR may be a potential target for chronic pain therapy.
-
Pharmacol. Biochem. Behav. · Oct 2013
Spinal D-amino acid oxidase contributes to mechanical pain hypersensitivity induced by sleep deprivation in the rat.
We studied the hypothesis that spinal d-amino acid oxidase (DAAO) that is expressed in astrocytes and that has been reported to promote tonic pain in various pathophysiological conditions plays a role in 'physiological' pain hypersensitivity induced by rapid eye movement sleep deprivation (REMSD). The experiments were performed in healthy rats with a chronic intrathecal (i.t.) catheter. Pain behavior was assessed by determining limb withdrawal response to repetitive stimulation of the hind paw with a calibrated series of monofilaments. ⋯ CBIO (1-3 μg), sodium benzoate (30-100 μg) and AS-057278 (3-10 μg) produced dose-related antihypersensitivity effects in sleep-deprived animals. In control animals (with no sleep deprivation), the currently used doses of DAAO inhibitors failed to produce significant changes in mechanically evoked pain behavior. The results indicate that among spinal pain facilitatory mechanisms that contribute to the sleep deprivation-induced mechanical pain hypersensitivity is DAAO, presumably due to production of reactive oxygen species, such as hydrogen peroxide, an endogenous agonist of the pronociceptive TRPA1 ion channel.
-
Pharmacol. Biochem. Behav. · Oct 2013
Food deprivation increases the low-dose locomotor stimulant response to ethanol in Drosophila melanogaster.
Acute and chronic states of food deprivation result in increased sensitivity to a variety of natural reinforcers as well as to drugs of abuse. Food deprived animals show increased locomotor activity during periods of food deprivation, as well as increased locomotor stimulant responses to drugs of abuse, including cocaine, amphetamine, morphine, and ethanol, implying that drugs of abuse act in part on neural systems that underlie responses towards food. To determine whether this effect extends to an invertebrate, highly genetically tractable animal, the locomotor stimulant effects of low dose ethanol were assessed under a variety of feeding conditions in the fruit fly, Drosophila melanogaster. ⋯ Life-span extending dietary depletion procedures or previous periods of food deprivation did not affect the response to ethanol, indicating that only animals in an acutely food deprived state are more sensitive to the stimulant effects of ethanol. These results suggest that increased sensitivity to the stimulant effects of some drugs of abuse might reflect an evolutionarily conserved neural mechanism that underlies behavioral responses to natural reinforcers and drugs of abuse. The identification of this mechanism, and the genes that underlie its development and function, will constitute a novel approach towards the study of alcohol abuse and dependence.