Choice of Lard, But Not Total Lard Calories, Damps Adrenocorticotropin Responses to Restraint

Abstract

Although rats given the choice of eating high-density calories as concentrated sucrose solutions or lard exhibit reduced responsivity in the hypothalamo-pituitary-adrenal axis, rats fed high-fat diets have normal or augmented responses to stressors. To resolve this apparent discrepancy, we compared in adult male rats the effects of 7-d feeding with lard + chow (choice) to feeding a 50% lard-chow mixture (no-choice) and to chow only. Rats with choice composed diets with 50-60% total calories from lard. Rats were exposed to 30 min of restraint on d 7. In the choice group, there was a robust inhibition of ACTH and corticosterone responses to restraint compared with chow or no-choice groups. Total caloric intake was less with choice than no-choice. Fat depot weights and body weight gain were similar in the high-fat groups. Leptin concentrations were equal but insulin was higher in the choice group. We conclude the following: 1) choice of eating high-density calories strongly damps hypothalamo-pituitary-adrenal responses to stress; without choice, high-density diet is ineffective; and 2) insulin may signal metabolic well-being, and may act through hypothalamic sites to reduce caloric intake but through forebrain sites to damp stress responses.

Food-intake regulation during stress by the hypothalamo-pituitary-adrenal axis

“…Anorexia induced by acute and repeated restraint stress was followed by increased proportion of comfort food eating (with high fat/sugar contents) (Dallman, 2010;Dallman et al, 2005;Foster et al, 2009;la Fleur et al, 2005;Pecoraro et al, 2004). In contrast to normal diet, when sweet food was presented to the stressed animals repeated mild pinch resulted in hyperphagia and considerable gain in body weight (Rowland and Antelman, 1976) (Table 1).…”

“…Food intake Anorexia (Bazhan et al, 2007;De Souza et al, 2000;Fryer et al, 1997;Harris et al, 2001;Krahn et al, 1990;Rybkin et al, 1997) Hyperphagia (Dallman, 2010;Dallman et al, 2005;Foster et al, 2009;la Fleur et al, 2005;Pecoraro et al, 2004) Mechanisms Stress induces anorexia due to decreased signaling of: AgRP (Chagra et al, 2011;Kas et al, 2005) NPY (Tempel and Leibowitz, 1994;White, 1993) due to increased signaling of: insulin? (Chavez et al, 1997;Warne, 2009) leptin?…”

“…(Dagogo-Jack et al, 1997;Miell et al, 1996;Newcomer et al, 1998;Slieker et al, 1996;York, 1996) CRH and Ucn 3 (Bernier, 2006;Ohata and Shibasaki, 2011;Smagin et al, 1998) CART (Kask et al, 2000;Xu et al, 2010) Nesfatin-1 (Goebel et al, 2009;Stengel et al, 2011) NPW (Beck et al, 2010) Melanocortins (Liu et al, 2007;Yamano et al, 2004) central monoaminergic systems (Gibson, 2006) autonomous nervous system (Seematter et al, 2004) Stress induces hyperphagia due to reduction of: sensor specific satiety (Ahn and Phillips, 2012;Ortolani et al, 2011) stressor aversiveness (Piazza and Le Moal, 1997) CRH signaling? (Foster et al, 2009;la Fleur et al, 2005;Pecoraro et al, 2004) due to activation of central reward pathways (Piazza and Le Moal, 1997), due to alterations in gut microbiota (Tehrani et al, 2012) Glucocorticoids induce hyperphagia (Dallman, 1993;Drapeau et al, 2003;Epel et al, 2000;Tataranni et al, 1996) due to increased signaling of: NPY (Gyengesi et al, 2010;Krysiak et al, 1999;McKibbin et al, 1992;White et al, 1994;Wilding et al, 1993), AgRP (Coll et al, 2005;Savontaus et al, 2002), Nociceptin (Green and Devine, 2009;Nativio et al, 2011;…”

Dynamic body weight and body composition changes in response to subordination stress

“…There are conflicting reports about the stress responsiveness of rats maintained on HF diet [65][66][67][68] and the differences may be accounted for by the variety of animal models and stress paradigms used. HF animals in our pilot study had an enhanced corticosterone response to 1-hour restraint stress prior to colony formation, but they subsequently had typical behavioral responses to VBS.…”

“…It may be possible that SUB behavior will change if they are presented with diets composed of different macronutrients to consume, such as a high fat (HF) diet, or if they are provided with a choice of macronutrients. It has been suggested that having a choice of which macronutrient to consume can play a significant role in macronutrient influences on the negative effects of stress [68]. These are interesting considerations that warrants future study.…”