Individual differences in behavioral characteristics or initial responses to abused drugs had been recently demonstrated to have predictive value in the propensity of later abuse. The research described here was initi...Individual differences in behavioral characteristics or initial responses to abused drugs had been recently demonstrated to have predictive value in the propensity of later abuse. The research described here was initiated to determine the initial response of rats to administration of morphine if the physiological response has predictive value for the propensity of the animals to later self-administration. The initial response of extracellular fluid levels of the biogenic monoamine neurotransmitters in the anterior cingulate cortex (aCC) was assessed in drug rats with in vivo microdialysis following administration of morphine. Rats that did not acquire morphine self-administration (NSA) had higher baseline levels of aCC extracellular fluid levels of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) than animals that developed stable morphine self-administration (SA). However, the response independent administration of morphine resulted in a dramatic increase in (DA) in aCC in the SA group, while the morphine injection in the NSA rats increased extracellular fluid levels of noradrenaline (NA). It is possible that these differences might be related to the development of physical dependence. Therefore, the development of physical dependence was observed in these animals. There was no relationship between the propensity to self-administration morphine and the development of physical dependence. Rats that showed the highest withdrawal scores had lower extracellular fluid levels of serotonin (5-HT) compared to rats showing low withdrawal scores. Thus, monoamine neuronal innervations of the aCC respond to an initial dose of morphine that is predictive of the later propensity to self-administration and the resistance and predisposition to the formation of opiate dependence, but there is no relationship between these two indices in individual animals. These data add to a growing body of evidence for the involvement of neuronal systems in the aCC in the actions of opiates.展开更多
The objective of these experiments was to study the effects of ethanol on the anxiety level, activity, metabolic rate, and feeding and drinking behaviors of rats that were chronically treated with nicotine. The chroni...The objective of these experiments was to study the effects of ethanol on the anxiety level, activity, metabolic rate, and feeding and drinking behaviors of rats that were chronically treated with nicotine. The chronic intake of nicotine changed the effects of the acute administration of ethanol. Thus, the nicotine-dependent rats demonstrated a significantly decreased anxiolytic-like effect in response to ethanol than did the control rats. This decrease may lead to a decrease in the sensitivity of animals to the positive reinforcing effects of ethanol and an increase in their consumption to achieve the desired effect. The negative action of ethanol on the metabolism, motor activity and drinking behavior of rats that chronically consumed nicotine was increased. Chronic nicotine intake can be assumed to lead to cross-tolerance of the effects of ethanol. On the contrary, the sensitivity to the action of ethanol increased.展开更多
文摘Individual differences in behavioral characteristics or initial responses to abused drugs had been recently demonstrated to have predictive value in the propensity of later abuse. The research described here was initiated to determine the initial response of rats to administration of morphine if the physiological response has predictive value for the propensity of the animals to later self-administration. The initial response of extracellular fluid levels of the biogenic monoamine neurotransmitters in the anterior cingulate cortex (aCC) was assessed in drug rats with in vivo microdialysis following administration of morphine. Rats that did not acquire morphine self-administration (NSA) had higher baseline levels of aCC extracellular fluid levels of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) than animals that developed stable morphine self-administration (SA). However, the response independent administration of morphine resulted in a dramatic increase in (DA) in aCC in the SA group, while the morphine injection in the NSA rats increased extracellular fluid levels of noradrenaline (NA). It is possible that these differences might be related to the development of physical dependence. Therefore, the development of physical dependence was observed in these animals. There was no relationship between the propensity to self-administration morphine and the development of physical dependence. Rats that showed the highest withdrawal scores had lower extracellular fluid levels of serotonin (5-HT) compared to rats showing low withdrawal scores. Thus, monoamine neuronal innervations of the aCC respond to an initial dose of morphine that is predictive of the later propensity to self-administration and the resistance and predisposition to the formation of opiate dependence, but there is no relationship between these two indices in individual animals. These data add to a growing body of evidence for the involvement of neuronal systems in the aCC in the actions of opiates.
文摘The objective of these experiments was to study the effects of ethanol on the anxiety level, activity, metabolic rate, and feeding and drinking behaviors of rats that were chronically treated with nicotine. The chronic intake of nicotine changed the effects of the acute administration of ethanol. Thus, the nicotine-dependent rats demonstrated a significantly decreased anxiolytic-like effect in response to ethanol than did the control rats. This decrease may lead to a decrease in the sensitivity of animals to the positive reinforcing effects of ethanol and an increase in their consumption to achieve the desired effect. The negative action of ethanol on the metabolism, motor activity and drinking behavior of rats that chronically consumed nicotine was increased. Chronic nicotine intake can be assumed to lead to cross-tolerance of the effects of ethanol. On the contrary, the sensitivity to the action of ethanol increased.
