Marvin Nachman

Learned taste aversions in rats as a function of dosage, concentration, and route of administration of LiCl

Abstract Rats drank a 15% sucrose solution for 10 min and were then injected intraperitoneally with various volumes of 0.15 M LiCl to produce a learned taste aversion to the sucrose. A dose response curve was obtained between the volume of 0.15 M LiCl injected and the degree of aversion. With additional groups, the LiCl concentration was varied inversely with volume injected and it was found that the aversion was dependent on the absolute quantity of LiCl and not on the concentration or volume of solution. LiCl was also found to be equally effective in producing learned aversions whether administered intraperitoneally, subcutaneously, or by stomach tube. The dose-response curve indicated that a very strong aversion occurs at a dose of 3.0 mEq/kg and that the threshold dose for producing an aversion is approximately 0.15 mEq/kg. The threshold dose was discussed in relation to the amount normally given to human patients as a therapeutic dose. It was concluded that the rat is highly sensitive to learning a taste aversion with LiCl.

Alcohol Aversion in the Rat: Behavioral Assessment of Noxious Drug Effects

Injections of p-chlorophenylalanine or n-butyraldoxime given after rats were first given a 10-minute drinking test with saccharin or ethanol solutions produced a learned aversion to these solutions. These findings suggest that the reduced self-selection of alcohol (preference) resulting from the administration of these drugs, reported by others, is not specifically alcohol-related. The technique described offers a sensitive procedure for the assessment of unpleasant effects of drugs.

The role of olfactory and orosensory factors in the alcohol preference of inbred strains of mice.

Abstract Removal of the olfactory bulbs eliminated the aversion to alcohol which is seen in normal BALB/c mice but did not abolish the preference for alcohol seen in normal C57BL mice. This result, along with the fact that BALB/c mice appear to avoid alcohol immediately, without prior experience, led to the hypothesis that BALB/c mice are more responsive than are C57BL mice to alcohol as a sensory stimulus. To test this hypothesis, a conditioning procedure was used in which normal animals of both strains drank alcohol in a single bottle test and were then injected with toxic lithium chloride. It was found that BALB/c mice learned aversions to alcohol, saccharin, and sucrose, whereas C57BL mice learned aversions to saccharin and sucrose but were deficient in learning an alcohol aversion. It was concluded that BALB/c mice normally avoid alcohol because of its odor but that for C57BL mice, other sensory cues or post-ingestional factors play an important role in their preference for alcohol.

Lateralization of learned taste aversion by cortical spreading depression.

Abstract Male Sprague-Dawley rats which were taught a strong aversion to ingestion of lithium chloride under unilateral cortical spreading depression failed to show this aversion when spreading depression was changed to the opposite hemisphere. Control rats which learned the aversion with both hemispheres functional show a very strong aversion to LiCl in subsequent tests with either both hemispheres functional or one hemisphere under spreading depression. These results indicate that cortical participation is important for learning of a taste aversion.

Aversion to strychnine sulfate by Norway rats, roof rats, and pocket gophers

Abstract Sprague-Dawley and wild Norway rats ( Rattus norvegicus ), roof rats ( R. rattus ), and pocket gophers ( Thomomys bottae ) were employed in drinking trials of distilled water and 0.01, 0.05, and 0.5% strychnine sulfate solutions for periods of 10 minutes (rats), 20 minutes (pocket gophers), and 24 and 48 hours for all species. Both the wild Norway and the Sprague-Dawley rats apparently found strychnine highly unpalatable, especially the 0.5 and 0.05% concentrations. They were able readily to discriminate even the weakest strength and acquired a marked aversion to all the strychnine solutions, whereas the roof rats developed an aversion only for the 0.05 and 0.5% concentrations and pocket gophers never learned to avoid completely even the 0.5% strength, though they were made ill. These tests suggest that strychnine sulfate may be usable as a rodenticide for R. rattus , if it is prepared at the proper concentration. Twelve of 15 pocket gophers and 1 of 5 roof rats drank lethal amounts of the solutions, whereas none of the 27 laboratory and wild Rattus norvegicus did.