The possible interactions between Δ9‐tetrahydrocannabinol (Δ9‐THC) and nicotine remain unclear in... more The possible interactions between Δ9‐tetrahydrocannabinol (Δ9‐THC) and nicotine remain unclear in spite of the current association of cannabis and tobacco in humans. The aim of the present study was to explore the interactions between these two drugs of abuse by evaluating the consequences of Δ9‐THC administration on the somatic manifestations and the aversive motivational state associated with nicotine withdrawal in mice. Acute Δ9‐THC administration significantly decreased the incidence of several nicotine withdrawal signs precipitated by mecamylamine or naloxone, such as wet‐dog‐shakes, paw tremor and scratches. In both experimental conditions, the global withdrawal score was also significantly attenuated by acute Δ9‐THC administration. This effect of Δ9‐THC was not due to possible adaptive changes induced by chronic nicotine on CB1 cannabinoid receptors, as the density and functional activity of these receptors were not modified by chronic nicotine administration in the different...
The CB1 cannabinoid receptors modulate the addictive processes associated with different drugs of... more The CB1 cannabinoid receptors modulate the addictive processes associated with different drugs of abuse, including psychostimulants. Mice lacking CB1 receptors exhibit an important attenuation of the reinforcing responses produced by cocaine in an operant self-administration paradigm. We have investigated the effect of chronic cocaine treatment on dendrite structure and spine density of the principal cortical neuron, the pyramidal neuron, in CB1 knockout mice and wild type littermates. Layer III pyramidal cells of the motor cortex were injected intracellularly in fixed cortical slices and their morphometric parameters analyzed. Under basal conditions, the field area of the dendritic arbors was more extensive and dendritic spine density was higher in wild type mice than in CB1 knockout mice. Chronic treatment of cocaine diminished the size and length of the basal dendrites and spine density on pyramidal cells from wild type mice. However, the total number of spines in the pyramidal cells of CB1 knockout mice augmented slightly following chronic cocaine treatment, although no changes in the morphology of the dendritic arbor were observed. Our data demonstrate that microanatomy and synaptic connectivity are affected by cocaine, the magnitude and nature of these changes depend on the presence of CB1 receptors.
The possible interactions between Δ9‐tetrahydrocannabinol (Δ9‐THC) and nicotine remain unclear in... more The possible interactions between Δ9‐tetrahydrocannabinol (Δ9‐THC) and nicotine remain unclear in spite of the current association of cannabis and tobacco in humans. The aim of the present study was to explore the interactions between these two drugs of abuse by evaluating the consequences of Δ9‐THC administration on the somatic manifestations and the aversive motivational state associated with nicotine withdrawal in mice. Acute Δ9‐THC administration significantly decreased the incidence of several nicotine withdrawal signs precipitated by mecamylamine or naloxone, such as wet‐dog‐shakes, paw tremor and scratches. In both experimental conditions, the global withdrawal score was also significantly attenuated by acute Δ9‐THC administration. This effect of Δ9‐THC was not due to possible adaptive changes induced by chronic nicotine on CB1 cannabinoid receptors, as the density and functional activity of these receptors were not modified by chronic nicotine administration in the different...
The CB1 cannabinoid receptors modulate the addictive processes associated with different drugs of... more The CB1 cannabinoid receptors modulate the addictive processes associated with different drugs of abuse, including psychostimulants. Mice lacking CB1 receptors exhibit an important attenuation of the reinforcing responses produced by cocaine in an operant self-administration paradigm. We have investigated the effect of chronic cocaine treatment on dendrite structure and spine density of the principal cortical neuron, the pyramidal neuron, in CB1 knockout mice and wild type littermates. Layer III pyramidal cells of the motor cortex were injected intracellularly in fixed cortical slices and their morphometric parameters analyzed. Under basal conditions, the field area of the dendritic arbors was more extensive and dendritic spine density was higher in wild type mice than in CB1 knockout mice. Chronic treatment of cocaine diminished the size and length of the basal dendrites and spine density on pyramidal cells from wild type mice. However, the total number of spines in the pyramidal cells of CB1 knockout mice augmented slightly following chronic cocaine treatment, although no changes in the morphology of the dendritic arbor were observed. Our data demonstrate that microanatomy and synaptic connectivity are affected by cocaine, the magnitude and nature of these changes depend on the presence of CB1 receptors.
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Papers by R. Maldonado