Effects of 9 -tetrahydrocannabinol and ethyl alcohol on adjunctive behavior and the lateral hypothalamus |
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Authors: | M J Wayner I Greenberg S Fraley S Fisher |
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Affiliation: | Brain Research Laboratory, Syracuse University, 601 University Avenue, Syracuse, New York 13210 USA |
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Abstract: | The fact that electrical stimulation of the lateral hypothalamus (LH) can be substituted for the delivery of a food pellet in typical schedule induced polydipsia was established and demonstrated the role of this part of the brain in the mediation of adjunctive behavior. The assumption that Δ9-tetrahydrocannabinol (Δ9-THC) and ethyl alcohol affect behavior because of a differential effect on the same LH mechanism was supported by the following evidence. Relatively small doses of Δ9-THC, 0.25, 0.375, and 0.50 mg/kg, enhanced adjunctive drinking; whereas, larger quantities of 0.625 and 0.75 mg/kg had no appreciable effects. The effect is somewhat specific, as it did not occur with strychnine sulfate, and rate dependent within limits as it was most pronounced in animals with low rates of responding or in animals when responding at a low rate. The effect of rate dependency was also apparent with fixed interval schedules of 2 and 4 min and a multiple schedule of a fixed interval and a signalled timed out period of nonreinforcement. Low rates of responding were enhanced by all doses of Δ9-THC, 1.0, 1.5, 2.0, 2,5, and 3.0 mg/kg, and there was an obvious dose related decrease in high rates. A similar effect was observed with low and high rates of electrical self-stimulation through implanted LH electrodes. The hypothesis that some drugs such as Δ9-THC and ethyl alcohol can enhance the positive feedback in an LH mediated motor control system by the facilitation of the same mechanism which initially generated the behavior was confirmed. Oral self administration of ethyl alcohol in a saccharin sweetened fluid enhanced recovered adjunctive drinking of the solution in quantities which should be sufficient to produce physical dependence if continued for relatively long periods. Recovered adjunctive drinking occurs in animals without food or water deprivation and it is an intense and persistent phenomenon. |
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Keywords: | Adjunctive behavior Adjunctive drinking Hypothalamus Lateral hypothalamus Ethyl alcohol Alcoholism Self stimulation Drinking Behavioral addiction Drug addiction Addiction |
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