The effects of continuous naltrexone infusions on diet preferences are modulated by adaptation to the diets

Two groups of male rats were placed on a feeding regimen in which a fat/protein diet and a carbohydrate/protein diet were available ad lib. Naltrexone was infused via osmotic minipumps either at the time the diets were introduced or after one week of adaptation to the diets. In rats adapted to the diets, naltrexone caused a decrease in the intakes of fat/protein and carbohydrate/protein diets. Relative preferences for the two diets were generally unchanged. In contrast, when naltrexone was infused at the time of introduction of the diets, a polarization phenomenon was observed: rats tended to consume nearly all of their daily calories from either one diet or the other. Six rats (out of 10) showed a stronger preference for the carbohydrate/protein diet than did any of the saline-treated rats, while 3 showed a stronger preference for the fat/protein diet than did any of the saline-treated rats. Thus, the effect was not diet- or macronutrient-specific. These preferences became significantly less extreme after termination of naltrexone infusions. Conditioned aversions and naltrexone-induced reductions in exploratory behavior are discussed as potential explanations for this polarization effect. These results indicate that naltrexone has differential effects on the development versus the maintenance of diet preferences. Further, they emphasize the importance of examining individual differences as well as baseline preferences in studies on the control of intake and diet selection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30229/1/0000622.pd

The relationship between saccharin and alcohol intake in rats

Male rats were given daily sessions during which a palatable saccharin solution was available. Based on intakes averaged over 3 days, groups with low, intermediate, or high intake of saccharin were formed. These rats were then given daily sessions in which alcohol (2-8%) or water were available. Initially, sessions were conducted with rats on a food restriction schedule; in later sessions, food was available ad lib. When rats were food restricted, there were no differences among the groups in terms of alcohol or water intake. When the food restriction schedule was discontinued, alcohol intake in the intermediate and high saccharin intake groups was generally higher than that of the low saccharin group. On the final series of alcohol sessions, the high saccharin group consumed significantly more 2% and 6% alcohol than the low saccharin group. These results are consistent with reports which have found that rats selected for high or low alcohol intake have corresponding high and low intakes of saccharin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30072/1/0000442.pd

Fat-preferring rats consume more alcohol than carbohydrate-preferring rats

Rats with a genetic preference for alcohol (ETOH) have been found to consume more dietary fat then ETOH nonpreferring rats. We therefore hypothesized that rats selected on the basis of fat and carbohydrate (CHO) preferences would differ in ETOH intake. Patterns of macronutrient self-selection were determined by allowing rats to select diets from separate source of CHO, fat and protein. Subsequently, CHO- and fat-preferring groups were formed. All rats were then returned to a lab chow diet and trained to drink ETOH (4-14%) during one hour of access per day. Food restriction was used only in the first three weeks of the procedure. On the final drinking session, water and ETOH were alternated on a daily basis. Fat-preferring rats consumed significantly more ETOH than water, CHO-preferring rats consumed approximately equal amounts of ETOH and water. Futhermore, fat-preferring rats consumed more ETOH than CHO-preferring rats. This study suggests that there may be a common mechanism underlying diet preference and oral intake of ETOH.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29255/1/0000312.pd

Feasibility of self-structured current accessed bubble devices in spacecraft recording systems

The self-structured, current aperture approach to magnetic bubble memory is described. Key results include: (1) demonstration that self-structured bubbles (a lattice of strongly interacting bubbles) will slip by one another in a storage loop at spacings of 2.5 bubble diameters, (2) the ability of self-structured bubbles to move past international fabrication defects (missing apertures) in the propagation conductors (defeat tolerance), and (3) moving bubbles at mobility limited speeds. Milled barriers in the epitaxial garnet are discussed for containment of the bubble lattice. Experimental work on input/output tracks, storage loops, gates, generators, and magneto-resistive detectors for a prototype device are discussed. Potential final device architectures are described with modeling of power consumption, data rates, and access times. Appendices compare the self-structured bubble memory from the device and system perspectives with other non-volatile memory technologies

Alcohol Use and Cognition at Mid-Life: The Importance of Adjusting for Baseline Cognitive Ability and Educational Attainment

The nature of the relationship between cognition and alcohol consumption remains controversial. Studies have reported negative, positive, and nonsignificant effects of alcohol consumption on cognition. Problematic throughout the literature is that baseline cognitive ability has not been adequately controlled in previous studies, and even educational attainment is only sometimes controlled. Because such variables may be associated with both alcohol intake and later-life cognition, we hypothesize that the observed relationship between alcohol intake and cognition may change when these variables or other conditions in early life have been controlled. Methods : We examined the relationship of alcohol intake and cognition at age 53 using the Wisconsin Longitudinal Study, which has followed Wisconsin high school graduates from 1957 to 1992. Our measures include cognitive ability test scores from the freshman and junior years of high school, educational attainment, an abstract reasoning test score at age 53, alcohol intake at age 53, and other measures. Results : When no controls were used, both men and women with low levels of alcohol consumption at 53 (i.e., 0–1 drink per day) had better scores on the abstract reasoning subtest of the Wechsler Adult Intelligence Scale (WAIS-R) at age 53 than subjects who never drank or currently did not drink. However, after adjusting for adolescent-measured cognitive ability and educational attainment, men with low levels of consumption no longer had higher abstract reasoning scores than nondrinking men, but they still did have higher abstract reasoning scores than men who drank more than one drink per day. For women, adjusting for cognitive ability and educational attainment eliminated all significant effects of alcohol on cognition, and reversed the nonsignificant result that women with higher consumption had the highest cognition scores. These results demonstrate the importance of adjusting for baseline cognitive ability when attempting to study the effect of long-term alcohol use patterns on cognition, and that educational attainment cannot be considered a valid substitute for baseline cognition scores. Conclusions : Much of the apparent benefit of moderate alcohol intake on cognition in our society may well be explained by differential rates of alcohol consumption among subjects with differing baseline cognitive ability scores. Neither is there evidence that moderate alcohol intake reduces cognitive functioning.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65631/1/01.ALC.0000078060.18662.C1.pd

Effects of fluoxetine on the oral environment of bulimics

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73809/1/j.1399-302X.1993.tb00545.x.pd

The anorectic effects of CRH and restraint stress decrease with repeated exposures

Intracerebroventricular (icv) administration of corticotropin-releasing hormone (CRH) or exposure to a restraint stressor causes acute anorexia in rats. However, the effects on food intake of repeated injections of CRH or repeated exposures to restraint stress have not been previously reported. As the effects of these more chronic CRH and stress treatments may be of greater relevance to emerging hypotheses of the pathogenesis of human eating and affective disorders, we measured the changes in food intake and body weight of rats after repeated central injections of CRH. In two experiments using two different daily dosages of CRH and two different schedules of administration, we found that the anorectic effect of CRH decreased over repeated injections. Weight gain was slowed significantly only in the high-dose experiment. Rats may become tolerant to the anorectic effects of CRH delivered by repeated icv injections. These findings have important implications for hypothesized mechanisms of anorexia nervosa and/or depression.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28570/1/0000373.pd

Effects of preferential delta and kappa opioid receptor agonists on the intake of hypotonic saline

A previous study has implicated central mu opioid receptors in the preference for salt solutions. Because mu, kappa and delta receptors are all thought to play a role in food intake and/or the mediation of palatability, we performed a series of experiments to determine whether preferential agonists at kappa and delta receptors might also stimulate the intake of salt solutions. When injected centrally into nondeprived rats, two selective agonists at delta receptors caused increases in the intake of 0.6% saline; the intake of concurrently available water was either unchanged or slightly increased. The selective kappa agonist U-50, 488H had no effect on water or saline intake, whereas the preferential kappa agonist DAFPHEDYN caused a delayed increase in saline intake. These results indicate a role for central delta receptors in the preference for salt solutions, and are consistent with the suggestion that opioids play a role in the mediation of palatability.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28718/1/0000539.pd

The relationship of dieting severity and bulimic behaviors to alcohol and other drug use in young women

Patients with bulimia nervosa frequently have problems with alcoholism and other substance abuse. The goal of this study was to assess whether this relationship between eating abnormalities and substance abuse extends to subthreshold levels of dieting and substance use. A self-administered questionnaire assessing dieting and substance use (alcohol, cigarettes, and marijuana) was completed by 1,796 women prior to their freshman year in college. Using a scale derived from DSM-III-R criteria for bulimia nervosa and previous research in this population, subjects were categorized as nondieters, casual, intense, severe, at-risk, or bulimic dieters. The relationship between the dieting-severity category and frequency and intensity of alcohol use and frequency of marijuana and cigarette use was assessed. DSM-III-R criteria for bulimia nervosa were met by 1.6% of the women. Only 13.8% of these women were nondieters. Increasing dieting severity was positively associated with increasing prevalence of alcohol, cigarette, and marijuana use and with increasing frequency and intensity of alcohol use. The bulimic and at-risk dieters were similar in their alcohol and drug use. The relationship between eating disorders and alcoholism and other substance abuse noted in clinical populations extends in a continuous, graded manner to subthreshold levels of dieting and substance use behaviors. Dieting-related attitudes and behaviors in young women may be related to increased susceptibility to alcohol and drug abuse.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30340/1/0000742.pd

Behavioral effects of corticotropin-releasing factor: localization and characterization of central effects

Corticotropin-releasing factor (CRF) has potent behavioral effects when administered intracerebroventricularly to rats. CRF and its receptors are found in an uneven distribution in the brain. In an effort to localize the site of the anorectic effect of CRF, exogenous CRF or saline was injected into cannulas directed toward the paraventricular hypothalamic nucleus (PVN), lateral hypothalamus, ventromedial hypothalamus, globus pallidus, or striatum of rats. CRF decreased food intake only when injected into the PVN. In subsequent experiments PVN injections of CRF were shown to (1) increase grooming and movement; (2) not induce a conditioned taste aversion to saccharin in a single bottle test; and (3) inhibit the increase in feeding induced by injections of norepinephrine into the PVN. These results suggest that CRF induces not only anorexia, but also increased movement and grooming by action in the PVN.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27370/1/0000396.pd