Strain differences in eating and drinking evoked by electrical stimulation of the hypothalamus

Abstract

Strain differences in eating and drinking evoked by electrical stimulation of the hypothalamus. PHYSIOL. BEHAV. 26(3) 371-378, 1981.-Electrical stimulation of the lateral hypothalamus (ESLH) has been shown to produce individual response differences that cannot be attributed to the neuroanatomical locus of the electrode. The purpose of the present experiment was to investigate strain differences in the incidence of eating and drinking evoked by ESLH. The responses of 49 Long-Evans and 51 Spragne-Dawley male rats implanted with bilateral hypothalamic electrodes were studied. Animals from these two strains do not differ in their normal food or water consumption. Analysis of the responses to ESI~H demonstrated that a significantly greater number of Long-Evans rats ate food and/or drank water during ESLH than did the Spragne-Dawley rats. These results could not be attributed to differences in electrode placements, or rearing conditions. In addition to strain differences, the importance of individual differences within each strain was demonstrated by the fact that both electrodes in a given animal commonly evoked the same behavior. Hypotheses to explain these results are discussed. Electrical stimulation Lateral hypothalamus Strain differences Evoked eating and drinking Stimulus-bound behavior Long-Evans Sprague-Dawley

Relation between eating evoked by lateral hypothalamic stimulation and tail pinch in different rat strains

“…To determine whether this relationship could be generalized to other populations with more random genetic combinations than the selected lines, we studied the readiness to display tail-pinch eating by male rats from two other strains that were known to differ in ESLH-evoked eating. As already noted, Mittleman and Valenstein (1981) have reported that L-E rats exhibit significantly more ESLH-evoked eating than do S-D rats during tests identical to those used in Experiment 1.…”

“…Other behavioral and physiological differences between the Hi and Lo lines of the LC1 and LC2 animals have been established (Ganchrow, Lieblich, & Cohen, 1981;Inbal et al, 1980;Lieblich, Cohen, Marom, & Dymshitz, 1980), but prior to the present experiment they had not been tested for either ESLH-or tail-pinch-induced eating. L-E rats display significantly more ESLH-induced eating than do the S-D animals (Mittleman & Valenstein, 1981), but their behavior in response to tail pinch has not been compared.…”

“…There is now convincing evidence that animals differ in the likelihood that they will eat or drink in response to ESLH, and this difference cannot be explained by electrode placement. For example, rats with two electrodes in different locations within the hypothalamus are more likely to eat or drink in response to stimulation via a second electrode if they had shown these behaviors when stimulated with the first electrode (Mittleman & Valenstein, 1981;Valenstein, Cox, & Kakolewski, 1970). Rats with moveable electrodes continue to eat and drink after the electrode position has been changed several times within the hypothalamus while other animals do not exhibit those behaviors at any electrode placement (Wise, 1971).…”

“…These studies all argue strongly for individual differences in the probability that ESLH will evoke eating and drinking. Recently, it has been shown that there are also significant strain differences in the probability of obtaining ESLH-induced eating and drinking that similarly cannot be explained by electrode placement (Mittleman & Valenstein, 1981).…”

The propensity for nonregulatory ingestive behavior is related to differences in dopamine systems: Behavioral and biochemical evidence.

“…Of particular interest here are individual differences in the predisposition to show nonregulatory ingestive behavior. Not all animals display nonregulatory ingestive behavior when activated, or they do not display it to the same degree (Bachus & Valenstein, 1979; Koob, Fray, & Iversen, 1976; Mittleman & Valenstein, 1981, 1984; Valenstein, 1969; Valenstein, Cox, & Kakolewski, 1970; Valenstein, Lieblich, Divar, Cohen, & Bachus, 1982; Wise, 1971). In exploring what factors might-predispose animals to display nonregulatory ingestive behavior, animals that do eat and drink during electrical stimulation of the lateral hypothalamus ( ESLH -pos) and those that do not ( ESLH -neg) have been compared in a variety of different experimental paradigms; for example, ESLH -pos rats exhibit significantly more drinking during SIP tests than ESLH -neg rats, results indicating a consistency across two experimental paradigms (Mittleman & Valenstein, 1984).…”