Sweet Success, Bitter Defeat: A Taste Phenotype Predicts Social Status in Selectively Bred Rats

Abstract

For social omnivores such as rats and humans, taste is far more than a chemical sense activated by food. By virtue of evolutionary and epigenetic elaboration, taste is associated with negative affect, stress vulnerability, responses to psychoactive substances, pain, and social judgment. A crucial gap in this literature, which spans behavior genetics, affective and social neuroscience, and embodied cognition, concerns links between taste and social behavior in rats. Here we show that rats selectively bred for low saccharin intake are subordinate to high-saccharin-consuming rats when they compete in weight-matched dyads for food, a task used to model depression. Statistical and experimental controls suggest that differential resource utilization within dyads is not an artifact of individual-level processes such as apparatus habituation or ingestive motivation. Tail skin temperature measurements showed that LoS rats display larger hyperthermic responses to social interaction after status is established, evidence linking taste, social stress, autonomic reactivity, and depression-like symptoms. Based on regression using early- and late-competition predictors to predict dyadic disparity in final competition scores, we tentatively suggest that HiS rats emerge as dominant both because of an “early surge” on their part and because LoS acquiesce later. These findings should invigorate the comparative study of individual differences in social status and its relationship to mental and physical health.

Cocaine self-administration punished by i.v. histamine in rat models of high and low drug abuse vulnerability: Effects of saccharin preference, impulsivity, and sex

“…For instance, LoS rats show greater measures of ethanol [34] and glucose [35] withdrawal compared to HiS rats. LoS (vs. HiS) rats also display greater acoustic startle response [36], social subordination [37], latency of emergence and increased defection in the novel open field, as well as heightened stress-induced anorexia [38] and analgesia [36]. The present results may offer a direct link between such variance in emotional reactivity and resilience of drug consumption despite aversive consequences.…”

Intracranial self-stimulation reward thresholds during morphine withdrawal in rats bred for high (HiS) and low (LoS) saccharin intake

“…For example, in previous studies, LoS rats showed greater ethanol withdrawal-induced anxiety and heightened withdrawal effects from discontinuation of a glucose solution, as well as greater latency of emergence and increased defecation in the novel open field (Dess et al, 2005; Yakovenko et al, 2011). Dess and co-workers have also noted more stress-induced anorexia and analgesia (Dess and Minor, 1996) than HiS rats (Dess et al, 2000b), and LoS rats also exhibited more emotional reactivity (e.g., subordination, hyperthermia) than HiS rats when competing with weight-matched HiS rats for food (Eaton et al, 2012). Recently, we found that i.v.…”

Similarities and Differences Between "Proactive" and "Passive" Stress-Coping Rats in Responses to Sucrose, NaCl, Citric Acid, and Quinine

“…Given that passive and proactive stress-coping styles are more beneficial in migratory and territorial environments, respectively, we hypothesized that different coping styles would be associated with altered responsivity to taste stimuli. There are reports in the literature that have found associations between affective measures such as "fearfulness" and social subordination with increased gustatory responsivity to bitter stimuli (e.g., Dess and Minor 1996;Eaton et al 2012). Furthermore, there is some evidence suggesting differences in preference of taste compounds including saccharin, NaCl, and citric acid between wild and domestic guinea pigs (Jacobs 1978).…”

“…Furthermore, it would follow that there are associations between affective responsiveness and gustatory sensitivity to taste stimuli. Indeed, rats that were bred for sensitivity to the bitter component of saccharin and low consumption of saccharin took longer to emerge in an open field test, used to infer "fearfulness" (Dess and Minor 1996), and were prone to social subordination in a social procedure (Eaton et al 2012) compared with rats selectively bred for high consumption of saccharin. Rats that underwent a chronic intermittent stress paradigm for several weeks subsequently showed significantly lower intake of saccharin and sucrose solutions compared with controls (Katz 1982;Willner et al 1987).…”