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Rationale A recent review paper by Cooper (Appetite 44:133-150, 2005) has pointed out that a role for benzodiazepines as appetite stimulants has been largely overlooked. Cooper's review cited several studies that suggested the putative mechanism of enhancement of food intake after benzodiazepine administration might involve increasing the perceived pleasantness of food (palatability). Objectives The present study examined the behavioral mechanism of increased food intake after benzodiazepine administration. Materials and methods The cyclic-ratio operant schedule has been proposed as a useful behavioral assay for differentiating palatability from regulatory effects on food intake (Ettinger and Staddon, Physiol Behav 29:455-458, 1982 and Behav Neurosci 97:639-653, 1983). The current study employed the cyclic-ratio schedule to determine whether the effects on food intake of chlordiazepoxide (CDP) (5.0 mg/kg), sodium pentobarbital (5.0 mg/kg), and picrotoxin (1.0 mg/kg) were mediated through palatability or regulatory processes. Results The results of this study show that both the benzodiazepine CDP and the barbiturate sodium pentobarbital increased food intake in a manner similar to increasing the palatability of the ingestant, and picrotoxin decreased food intake in a manner similar to decreasing the palatability of the ingestant. Conclusions These results suggest that the food intake enhancement properties of benzodiazepines are mediated through a mechanism affecting perceived palatability. [ABSTRACT FROM AUTHOR]

Controversies regarding the mental health consequences of disasters are rooted both in disciplinary orientations and in the widely varied research strategies that have been employed in disaster mental health studies. However, despite a history of dissensus, there are also key issues on which researchers agree. Disasters constitute stressful and traumatic experiences. However, vulnerability to such experiences, as well as to more chronic stressors, is socially structured, reflecting the influence of socio-economic status and other axes of stratification, including gender, race, and ethnicity. Disaster events differ in the extent to which they generate stress for victims. A holistic perspective on disaster mental health would take into account not only disaster event characteristics, but also social-systemic sources of both acute and chronic stress, secondary and cumulative stressors, and victims internal and external coping capacities.

Four male Wistar rats, 180 days old at the start of the experiment, at 85% of their free-feeding body weight were trained to respond on a geometric cyclic-ratio schedule comprised of the following ratio values: 2, 4, 8, 16, 32 and 64, for 0.1 ml of 5% sucrose reinforcement. The response functions (response rates plotted against reinforcement rates) were linear and of negative slope over the range of ratio values from 2 to 16. IP administration of 1.0 mg/kg 5-MeODMT reduced the x- and y-intercepts of the linear portion of the response function without altering the slope relative to 2.0 ml/kg 0.85% saline IP. This was interpreted as a perceived palatability effect. IP administration of 100 mg/kg pCPA elevated the reinforcement rate intercept but also decreased the slope of the response function. This finding was interpreted as an increase in the perceived palatability of the reinforcer, coupled with a decrease in motivation at higher schedule conditions, possibly due to peripheral effects of pCPA.

Rats deprived of food for 23 hr were given unconstrained access to food for 1 hr following the completion of a lever-press requirement. Four experimental subjects were each tested for 7 sessions in each of a series of lever-press requirement conditions (1, 5, 10, 20, 50, 100, 150, 200) with a free access condition before and after this series, and with a final return to the 100 lever-press condition. To each experimental subject was yoked an equally deprived control subject which received access to food independently of its own responding, at the same time as its experimental partner. The food consumption of the experimental subjects, but not that of the controls, increased systematically as the lever-press requirement increased. It is argued that the results suggest that the way the procurement cost of food is related to both the frequency and size of meals is due to a direct but independent effect of the cost on both meal size and latency to initiate eating.

Four non-deprived rats received daily sessions of 20 min access to a saccharin-and-sucrose solution following various prior activities, in an attempt to disentangle the normally confounded roles of time spent, amount and rate of procurement responding in causing an increase in consumption once access is gained. After the normal rate of running (approx 35 m/min) was established, six conditions were run in random order, involving waiting zero and 2.5 min in an immobilised running-wheel, and running, with the wheel rotated by a motor, in four conditions formed by combining two speeds (12 and 30 m/min) with two distances (12 and 30 m), prior to access to the solution. Drinking increased with the speed of prior running, and to a lesser extent with the distance run, but was not related systematically to the time spent running. It is suggested that information from the animal's own behavior in gaining access to a commodity, particularly the rate of energy expenditure, may influence its utilisation of the commodity by affecting the rate of subsequent consummatory responding.

Four non-deprived female rats were required to run in a wheel to obtain 20 min unconstrained access to a saccharin and sucrose solution. Each was run in a series of conditions in which the requirement was a proportion (0.25, 0.5, 1.0, 1.25 and 1.5) of the amount of running performed in a condition in which the wheel alone was available. A condition in which no running was required to gain access to the solution and one in which the subject was locked in the stationary wheel for the time taken to complete the highest requirement before being allowed access to the solution were also included. The results showed that as the requirement increased the amount of solution consumed also increased, and this relationship did not depend on the time taken to perform the requirement.

Four rats, 22.5 hr deprived of water, were tested in 3 conditions, in which they were required to run zero, 5 or 300 one-sixth revolutions in a wheel to gain 30 min access to water in a drinking tube. The number of licks performed in the 30 min increased monotonically with the procurement cost, and was 20% greater following the larger cost than when there was no cost. However, examination of the rates of drinking throughout the 30 min revealed that differences occurred between the conditions only at the beginning of the period. In the first 3 min there was a monotonic relationship between the proportion of time spent drinking and the procurement cost, but no effect of the cost on the rate could be detected after the first 6 min. The results are consistent with the hypothesis that the effect is mediated by a transient elevation of the subject's arousal level.

Three groups of five male and five female students were exposed to different levels of auditory stimulation (no music or music played at 70 dB or 90dB) under naturalistic conditions and were permitted to avail themselves freely of a supply of soft drinks. Increasing auditory stimulation produced an increase in total consumption. Reported prior frequencies of soft drink consumption and of exposure to loud music had no bearing on the result of the experimental manipulation, suggesting that the effect was not due to previous history.