Differential effects of heat in the phases of the light–dark cycle in the activity‐based anorexia model

Abstract

Background: This research builds on the studies on ambient temperature as a key influence in the recovery of rodents exposed to the activity-based anorexia (ABA) model. The ABA model is an experimental paradigm in which rodents under a restricted feeding schedule and with free access to an activity wheel show signs that parallel those of anorexia nervosa in humans. Objective: The present study focuses on the effects of applying heat during the different phases of the dark-light cycle in the activity levels, body weight, food intake, body temperature, and recovery rates of 30 male rats submitted to ABA. Method: After reaching a 20% weight loss criterion, animals were randomly assigned to three experimental conditions: (a) continuous warming, (b) warming exclusively during the light phase, or (c) warming exclusively during the dark phase. Results: Differential effects were found depending on the modalities of warming: in comparison with either light or dark warming, continuous warming significatively decreased activity, facilitated weight gain, and maintained body temperature. Transient effects of warming were found both in the groups warmed either during light or dark periods exclusively. Discussion: The results suggest that both light and dark warming did not promote recovery in animals exposed to ABA. Evidence about the beneficial effects of continuous warming are in line with previous research and reinforces adding external heat as a useful tool in the treatment of anorexia nervosa.

Activity-Based Anorexia Induces Browning of Adipose Tissue Independent of Hypothalamic AMPK

“…In addition, it is well-established that ABA-induced hyperactivity is an adaptative behavioral response to compensate for hypothermia ( 9 ). Our data are in line with previous studies reporting the beneficial effect of increased ambient temperature to 32°C on the recovery of rats subjected to the ABA model, even after 20% weight loss has occurred ( 10 – 13 , 15 , 58 ). Although our data confirm former evidence, the use of temperature recording by telemetry allows a constant monitoring of the body temperature throughout the experiment, which constitutes a big advantage when compared to previous reports.…”

“…AN-associated hyperactivity has been proposed as an adaptative behavioral response to compensate for hypothermia (9). Previous research has shown that exposure to a high ambient temperature (AT) prevents and reverses the hyperactivity and improves feeding patterns, allowing body weight recovery in both male and female rats under ABA conditions (10)(11)(12)(13)(14)(15). These beneficial effects of temperature have been also found in the semi-starvation induced hyperactivity model (SIH) (16).…”

Similarities and differences regarding acute anorexia nervosa and semi-starvation: does behavioral thermoregulation play a central role?

“…Using a well-established rodent model, the activity-based anorexia model (ABA), it has been demonstrated that providing heat to the "anorexic" ABA-rodent reduces activity and weight loss (Routtenberg and Kuznesof, 1967;Epling and Pierce, 1996;Hillebrand et al, 2005;Gutierrez et al, 2006;Vazquez et al, 2006;Roura et al, 2020).…”

Activity-based anorexia animal model: a review of the main neurobiological findings

“…Drug therapies designed to antagonize MC receptors could be combined with a temperature adjustment. It is well known that a continuous warming is beneficial to ABA animals [169] and that rising temperature from 21 to 32 °C can block ABA induction and reduces its related behavior by increasing food intake and reducing RWA [170][171][172]. In this context, a parallelism between the ABA model and AN patients should be evidenced: in fact, warming at 32 °C also showed a fivefold reduction in corticosterone levels in ABA rats if compared to a 21 °C housing [173], and this anxiolytic effect was also present in AN patients when exposed to a heated environment [174].…”