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PubMed2005

Centrally administered orexin A increases motivation for sweet pellets in rats.

RATIONALE: Centrally administered orexin A induces both feeding and locomotion in rats. Thus, the feeding response following orexin A administration may be secondary to general increases in activity rather than a specific motivation to eat. OBJECTIVE: The aim of the study is to determine whether orexin A increases the motivation to eat. METHODS: The effect of orexin A (0, 31.25, 62.5, 125, 250, and 500 pmol) on breakpoint was determined in male Sprague-Dawley rats with rostro-lateral hypothalamic cannulae under a progressive ratio of five schedule (PR5). The effect of orexin A (0, 31.25, 125, and 500 pmol) on pressing rate under a fixed ratio (20) schedule was obtained to analyze the time course of orexin-A-induced pressing. The effect of 24-h food deprivation on breakpoint under PR5 and the effect of orexin A (125 pmol) on free feeding (sweet pellets) and on open-field locomotor activity (0, 100, 500, and 1,000 pmol) were also tested. RESULTS: Orexin A significantly augmented free feeding of sweet pellets, open-field locomotor activity, rate of pressing (FR20 schedule), and breakpoint (PR5 schedule), although compared to 24-h deprivation, the effect of orexin A on breakpoint was mild. However, there was a differential dose response relationship and time course of stimulation between orexin A's effects on locomotion and lever pressing. CONCLUSION: These data indicate that infusion of orexin A enhances free feeding by enhancing and possibly prolonging motivation to eat.

Animals↗
PubMed1997

GABAergic drugs and sexual motivation, receptivity and exploratory behaviors in the female rat.

Female rats were allowed to pace sexual interactions in a bilevel chamber, where a sexually vigorous male was tethered to the bottom level. Exploratory behaviors (sniffing, rearing), locomotor activity (expressed as number of level changes and periods of inactivity) as well as items of sexual motivation (latency to descend to the male's level, approaches towards the male and genital exploration) were recorded. In addition, sexual receptivity was evaluated in a non-paced situation. A test for motor impairment was also performed. The GABA transaminase inhibitor gamma-acetylene GABA reduced exploratory behaviors at doses much lower than those needed to reduce receptivity. The GABA reuptake inhibitor SKF 100330A did not affect any behavior category at doses of 15 and 30 mg/kg, but had a sedative action at 60 mg/kg. This was shown as impaired motor coordination and an almost total absence of activity in the bilevel chamber. Receptivity was not impaired, however. The mixed GABAA/ GABAB agonist progabide reduced exploratory behaviors and receptivity without producing motor impairment at a dose of 400 mg/kg. The GABAA agonist THIP impaired motor coordination and reduced receptivity and exploratory behaviors at a dose of 10 mg/kg. A larger dose, 20 mg/kg, had a strong sedative action. Only a small proportion of the animals descended to the males level. The GABAB agonist baclofen reduced receptivity at a dose that had no effect on motor coordination or exploratory behaviors. None of the drugs had a specific effect on sexual motivation. Whenever behaviors reflecting motivation were reduced, there were also other behavioral effects indicative of sedation. These data show that GABA receptor agonists, particularly the GABAB agonist baclofen, reduce sexual receptivity at doses that have only slight effect on motor functions or exploratory behaviors. In contrast, non-specific enhancement of GABAergic activity by a transaminase or reuptake inhibitor have effects on motor functions and exploratory behaviors at doses much lower than those needed to reduce receptivity.

Animals↗
PubMed2006

I can use a condom, i just don't: the importance of motivation to prevent HIV in adolescent seeking psychiatric care.

Youth continue to show high HIV infection rates, and adolescents with mental health problems are especially at risk. We used longitudinal data to test a cognitive-behavioral model of risky sexual behavior among 175, ethnically diverse urban adolescents seeking mental health services. Path analyses of the cross-sectional data revealed that Motivation was a strong predictor of Behavioral Skills and Sexual Risk Taking. The model explained 42% of the variance in Sexual Risk Taking with age included-29% without age. In the longitudinal path analyses, Motivation had a significant negative effect on levels of Sexual Risk Taking 6 months later, controlling for Information, Behavioral Skills, age, and baseline levels of Sexual Risk Taking. These longitudinal effects explained 60% of the variance in Sexual Risk Taking. These results underscore the need to address motivational factors in HIV prevention programs designed for adolescents with mental health problems.

Adolescent↗
PubMed2006

Motives and methods of under-age casino gamblers.

Numerous studies have documented that under-age gambling is quite common. The present study employs interviews of 48 university students who gambled under-age to determine the motives and methods associated with casino gambling by minors. The information gathered in these interviews indicates that access to casinos is easily attained, that the risk of exposure once gambling is minimal, and the motivations of under-age gamblers differ in important ways from that of adults, as access to alcohol, accompanying parents, and the desire to experience the "forbidden fruit" of casino gambling are commonly mentioned motivations by under-age gamblers.

Adolescent↗
PubMed1980

Energy charge, phosphorylation potential and proton motive force in chloroplasts.

Adenylate concentrations were measured in intact chloroplasts under a variety of conditions. Energy charge was significant in the dark and increased in the light, but remained far below values expected from observed phosphorylation potentials in broken chloroplasts, which were 80 000 M-1 or more in the light. With nitrite as electron acceptor, phosphorylation potentials in intact chloroplasts were about 80 M-1 in the dark and only 300 M-1 in the light. Similar phosphorylation potentials were observed, when oxaloacetate, phosphoglycerate or bicarbonate were used as substrates. delta G'ATP was -42 kJ/mol in darkened intact chloroplasts, -46 kJ/mol in illuminated intact chloroplasts and -60 kJ/mol in illuminated broken chloroplasts. Uncoupling by NH4Cl, which stimulated electron transport to nitrite or oxaloacetate and decreased the proton gradient, failed to decrease the phosphorylation potential of intact chloroplasts. Also, it did not increase the quantum requirement of CO2 reduction. It is concluded that the proton motive force as conventionally measured and phosphorylation potentials are far from equilibrium in intact chloroplasts. The insensitivity of CO2 reduction and of the phosphorylation potential to a decrease in the proton motive force suggests that intact chloroplasts are over-energized even under low intensity illumination. However, such a conclusion is at variance with available data on the magnitude of the proton motive force.

Adenosine Diphosphate↗
PubMed1981

Influence of different energy drains on the interrelationship between the rate of respiration, proton-motive force and adenine nucleotide patterns in isolated mitochondria.

The respiration of rat liver mitochondria was stimulated by three different ways of energy drain: (a) partial uncoupling (equivalent to direct collapse of the proton-motive force), (b) intramitochondrial utilization of ATP for citrulline synthesis, and (c) extramitochondrial utilization of ATP for glucose phosphorylation. At identical rates of respiration, the intramitochondrial ATP : ADP ratios were the same in all three systems. Furthermore, the proton-motive force was the same in partially uncoupled mitochondria and in the presence of hexokinase plus glucose up to a respiration rate amounting to about 60% of that of the fully active state. However, external ATP : ADP ratios were considerably different in various systems at comparable rates of oxygen uptake, being the lowest under conditions when ATP was being utilized externally. On this basis, it is concluded that the respiratory rate is controlled directly by the proton-motive force and the mitochondrial ATP-synthesizing system operates under near-equilibrium conditions with respect to the membrane energy state parameters. However, a disequilibrium exists at the step of the transport of ATP from mitochondria to the external (cytoplasmic) compartment.

Adenosine Diphosphate↗
PubMed1982

Estimation of H+-translation stoicheiometry of mitochondrial ATPase by comparison of proton-motive forces with clamped phosphorylation potentials in submitochondrial particles.

The proton-motive forces generated in submitochondrial particles by both hydrolysis of ATP and oxidation of succinate have been measured by flow dialysis and compared with the ambient phosphorylation potentials. It is concluded that three H+ are translocated for each ATP molecule hydrolysed or synthesised. By utilising rat liver mitochondria respiring with beta-hydroxybutyrate as a new system for regeneration of ATP from ADP and Pi, phosphorylation potentials were clamped at a range of values by using mixtures of particles and mitochondria in various ratios. As the rate of ATP hydrolysis by the particles was lowered, the proton-motive force decreased only slightly except at the very lowest rates, these results paralleling earlier studies on the relation between rate of respiration-driven proton translocation and proton-motive force.

Adenosine Triphosphatases↗
PubMed1987

Neuronal activity in the ventral tegmental area (VTA) during motivated bar press feeding in the monkey.

Neuronal activity of 58 dopaminergic (DA) and 200 non-dopaminergic (non-DA) neurons in the ventral tegmental area (VTA) of female monkeys was recorded, and correlation to bar press feeding, sensory stimulation and change in motivation was investigated. DA neurons, judged by duration of action potentials (more than 2.5 ms) and responsiveness to apomorphine, had lower firing rates (0-8 impulses/s); non-DA neurons had intermediate firing rates (10-30 impulses/s). Two-thirds of the DA and non-DA neurons responded in bar press feeding; the former with mostly tonic and the latter with phasic responses. Fifteen neurons (5%) responded phasically to arm extension toward the bar, 124 (excitation 88, inhibition 36, 45%) during bar press (BP), and 91 (excitation 32, inhibition 59, 33%) during ingestion reward (RW). Most BP responses (84/124, 68%) continued tonically throughout the BP period with no correlation to each BP movement. In 14 neurons (14/124, 11%), firing showed a specific variation: transient early BP responses shifted to tonic steady ones in palatable food trials, and the shifts correlated well with BP speed. In 20 other neurons, firing increased during BP hip lifting, and at specific vocalization to ask for food; it decreased during food ingestion, drinking and inguino-crural stimulation. Apomorphine administration decreased firing for the first 5-15 min, then increased it with frequent lip smacking, nausea, involuntary movement and vocalization. Thus VTA neurons showed mostly steady tonic responses but some specific phasic responses. They responded not only to motor events but also in close relation to changes of motivational aspects. Neuronal responses were excitation during procurement of reward and inhibition during or after perception of reward. This modulation in firing, might be important in the initiation and execution of movement and/or motivated behavior.

Action Potentials↗
PubMed1985

Partial uncoupling, or inhibition of electron transport rate, have equivalent effects on the relationship between the rate of ATP synthesis and proton-motive force in submitochondrial particles.

The rates of electron transport and of ATP synthesis have been measured in bovine heart Mg-ATP submitochondrial particles oxidising succinate under conditions of partial attenuation of the proton-motive force by malonate or FCCP. This paper reports evidence that the relationship between the rate of ATP synthesis and the magnitude of the proton motive force is independent of the mode by which the decrease of the proton motive force is achieved.

Adenosine Triphosphate↗
PubMed1996

Effects of beta-CCE on retention of aversively- and appetitively-motivated tasks in rats.

Beta-carboline-3-carboxylic acid ethyl ester (beta-CCE; 1.0 or 5.0 mg/kg, i.p.) or vehicle control was administered to male Sprague-Dawley rats immediately after training in an aversively- or appetitively-motivated task. Aversively-motivated training consisted of a one-trial step-though inhibitory (passive) avoidance task with a 0.6 mA, 1.0 s foot shock. Retention was tested 21 days after training. The 5.0 mg/kg dose of beta-CCE significantly enhanced retention performance in the inhibitory avoidance task compared to the vehicle control. For appetitive training, the animals learned a T-maze for water reward. Retention was tested 48 h later, and neither dose of beta-CCE was found to affect retention performance. These results suggest that beta-CCE, when administered immediately after training, may alter retention performance of an aversively-motivated task but not an appetitive task.

Animals↗
PubMed1991

NMDA receptor channel antagonism by dizocilpine (MK-801) impairs performance of rats in aversively motivated complex maze tasks.

To determine the involvement of the N-methyl-D-aspartate (NMDA) receptor in shock-motivated complex maze performance, the drug dizocilpine (DIZO; a.k.a. MK-801) was administered a) to naive, 3-month-old male F-344 rats prior to acquisition (AQ) in the 14-unit T-maze (Experiment 1), and b) to well-trained 11-month-old male F-344 rats prior to testing in a delayed-matching-to-sample (DMTS) task in the detour maze (Experiment 2). For Experiment 1, rats first were pretrained in a straight runway on one-way active avoidance (13/15 correct avoidances) for a maximum of 30 trials. On the following day, either DIZO 0.025 (n = 8), 0.05 (n = 8), 0.1 (n = 8), mg/kg, or saline (SAL; n = 15) was administered subcutaneously (SC) 20 min prior to 15 AQ trials in the shock-motivated 14-unit T-maze. The highest dose disrupted all measures of maze performance including errors, alternation errors, runtime, shock duration and frequency, but also produced marked motor ataxia. The 0.05-mg/kg group displayed significant impairment in AQ of this task but only on the cognitive measures, errors and alternation errors, and the 0.025-mg/kg group was impaired on the alternation measure only. One week later, the 15 SAL rats were divided into 2 groups and tested on retention with either SAL or 0.05 mg/kg DIZO. No effects on maze performance were observed. For Experiment 2, after receiving extensive pretraining in the shock-motivated detour maze, 7 rats were exposed to a novel sequence of 4 problems (P) during each of 7 daily sessions. Performance was evaluated 20 min after SC injection of either DIZO--0.025, 0.05, 0.125 mg/kg, or SAL. The 0.125-mg/kg dose caused extreme motor ataxia which precluded testing during that session. The 0.05-mg/kg but not the 0.025-mg/kg dose significantly disrupted performance on both error and trials to criterion measures. Both problem and interaction effects were significant. Disruption was most evident on two specific problems, those involving a side change from the first to second detour. Also, rats had more difficulty switching sides from problem to problem (few errors on P-1 and most on P-4), suggesting proactive interference effects. In sum, DIZO was observed to significantly disrupt performance in both mazes in a dose-related manner similar to effects observed in previous studies following administration of the anticholinergic drug scopolamine. For the 14-unit T-maze, the present results simulate age-related deficits previously found in acquisition of that task.

Aging↗
PubMedDate not supplied

An experimental test of affect, subjective craving, and alcohol outcome expectancies as motivators of young adult drinking.

Research on motivations for alcohol use suggests that both positive and negative affect, craving, and outcome expectancies are good predictors of alcohol consumption. The present study tested the utility of these variables in predicting laboratory measures of alcohol consumption among young social drinkers. Two conditioning models of alcohol procurement guided analyses: the conditioned withdrawal model (represented by negative affect and craving) and the appetitive-motivational model (represented by positive outcome expectancies and subjective evaluations). Results showed that negative affect and craving did not significantly influence either subjects' latencies to begin drinking or speed of consuming one placebo beverage. Positive outcome expectancies and evaluations, however, had a marked impact on speed of drinking. Thus, the appetitive-motivational model appears to better characterize the drinking patterns of young social drinkers than does the conditioned withdrawal model.

Adult↗
PubMed2004

Suppressing effect of the cannabinoid CB1 receptor antagonist, SR 141716, on alcohol's motivational properties in alcohol-preferring rats.

Administration of the cannabinoid CB(1) receptor antagonist, SR 141716 [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-carboxamide], has been reported to reduce alcohol intake and alcohol self-administration in different models of excessive alcohol consumption, including the selectively bred Sardinian alcohol-preferring (sP) rats. The present study investigated whether SR 141716 was also capable of decreasing, in this rat line, alcohol's motivational properties. Extinction responding for alcohol, defined as the maximal number of lever responses reached in the absence of alcohol in rats trained to lever-press for alcohol, was used as index of alcohol's motivational properties. Rats were initially trained to lever-press for oral alcohol (15%, v/v) under a fixed ratio (FR) schedule of FR4. Once self-administration behavior was established, extinction sessions were conducted. SR 141716 (0, 0.3, 1 and 3 mg/kg; i.p.) was acutely administered before extinction sessions. In order to assess the specificity of SR 141716 action on extinction responding for alcohol, a separate group of sP rats was trained to lever-press for a 3% (w/v) sucrose solution under an FR4 schedule. SR 141716 administration produced a dose-dependent, virtually complete suppression of extinction responding for alcohol. In contrast, extinction responding for sucrose was not significantly altered by treatment with SR 141716. Further to the consummatory aspects, these results also extend the suppressing effect of SR 141716 to the appetitive aspects of alcohol drinking behavior in sP rats. The results also implicate the cannabinoid CB1 receptor in the neural substrate mediating alcohol's motivational properties in this rat line.

Alcohol Drinking↗
PubMed2005

Cannabinoid CB1 receptor is dispensable for memory extinction in an appetitively-motivated learning task.

The interaction of the cannabinoid CB1 receptor with its endogenous ligands plays an essential role in extinction of aversive memories (Marsicano, G., Wotjak, C.T., Azad, S.C., Bisogno, T., Rammes, G., Cascio, M.G., Hermann, H., Tang, J., Hofmann, C., Zieglgansberger, W., Di, M., V, Lutz, B., 2002. The endogenous cannabinoid system controls extinction of aversive memories. Nature 418, 530-534). The present study tested the generality of this observation in respect to positively-reinforced memories. To this end, male cannabinoid CB1 receptor deficient mice (CB1R-/-) and their wild-type littermate controls (CB1R+/+) were trained in an appetitively-motivated operant conditioning task, in which food-deprived animals received a food reward on nose-poking into an illuminated hole. During training, CB1R-/- turned out to be less motivated to participate in the task. After further restriction of daily food consumption, however, CB1R-/- reached the same level of performance as CB1R+/+ as far as number of correct responses and errors of omission are concerned. The accuracy of performance served as a measure for the memory of the light-reward association and was stable at similarly high levels over a retention period of 9 days without additional training (97.6+/-0.5% vs. 97.0+/-0.9% correct responses). During subsequent extinction training, the positive reinforcement was omitted. As a consequence, both CB1R-/- and CB1R+/+ showed a similar decline in accuracy of performance and total number of correct responses, accompanied by an increase in errors of omission. These data demonstrate that the cannabinoid CB1 receptor is not essential for extinction of the stimulus-response association in an appetitively-motivated learning task.

Animals↗
PubMed2006

Effects of energy-content labels and motivational posters on sales of sugar-sweetened beverages: stimulating sales of diet drinks among adults study.

This study examined the effects of an environmental intervention promoting more non-energy-containing beverage consumption compared to sugar-sweetened soft drink consumption through vending machines in an urban college setting. Eight soft drink vending machines were randomly selected and assigned to one of three conditions over a 9-week period: energy-content labels on non-energy-containing beverage selection panels (intervention I), labels plus motivational posters (intervention II), or control. The totals of all beverages sold and machine revenue were recorded at baseline (2 weeks), intervention (5 weeks), and postintervention (2 weeks) periods. Use of energy-content labels and motivational posters, compared with control group, resulted in a significantly lower growth rate of sugar-sweetened beverage sales (P<0.05). Total revenue for all beverages increased during the intervention period. It is estimated that the non-energy-containing beverages combined accounted for 70.52% of the increased revenue. Results of this study suggest that energy-content labels and motivational posters on beverage vending machines may be an effective way to influence beverage sales.

Beverages↗
PubMed2006

Exogenous cortisol shifts a motivated bias from fear to anger in spatial working memory for facial expressions.

Studies assessing processing of facial expressions have established that cortisol levels, emotional traits, and affective disorders predict selective responding to these motivationally relevant stimuli in expression specific manners. For instance, increased attentional processing of fearful faces (attentional bias for fearful faces) is associated with fear and anxiety and diminishes after administration of the anxiolytic hormone testosterone. Conversely, attentional bias for angry faces has been associated with higher levels of approach motivation (e.g. anger) and testosterone, but lower levels of cortisol. This negative relation between cortisol levels and bias for angry faces was also seen in a test of biased working memory performance. However, previous research suggests that exogenous glucocorticoids acutely decrease fearful and inhibited behavior and increase aggressiveness. Hypothesizing from these findings, the present study tested this spatial working memory for faces of various emotional expressions (neutral, happy, fearful, and angry) after double-blind, placebo-controlled administration of 40 mg cortisol in 18 healthy young men. It was predicted that cortisol would acutely attenuate memory bias for fearful expressions while increasing memory bias for angry expressions, in effect creating a shift in biased motivated memory from fear to anger. Results largely confirmed the hypotheses. This is the first causal evidence that cortisol differentially regulates spatial working memory for different facial expressions. Possible biological mechanisms are discussed.

Adolescent↗
PubMed1997

Community motivators promote use of emergency obstetric services in rural Sierra Leone. The Freetown/Makeni PMM Team.

PRELIMINARY STUDIES: An appraisal of government health facilities documented generally poor conditions, a shortage of drugs and supplies, and inadequate skills among staff. Focus group discussions in the community revealed a lack of knowledge about obstetric complications and difficulty in reaching health facilities. INTERVENTIONS: Improvements were made in services at primary health units (PHUs) through May 1993. Community motivators were trained in June and provided with bicycles and raingear in September 1993. Among their duties were community education, formation of village action groups for emergency transport and facilitation of referral for women with obstetric complications. RESULTS: Between August 1992 and December 1995, women with major complications seen at the PHUs increased from nine to 16 per month, with fluctuations due to disruptions in services and civil strife. The proportion of women with complications who were referred by the community motivators diminished over time, dropping from 24% to 1% over the first two years (1993-1994) and then recovering somewhat to 10% in the final period of observation. COSTS: The cost of this intervention was approximately US$5082, with about half coming from the project and the rest from the government (44%) and the community (8%). CONCLUSIONS: The project improved utilization of the PHUs by women with complications, indicating that once services are of acceptable quality, many women will use them. The contribution of the motivators was positive, though smaller than expected.

Community Health Services↗
PubMed2002

The effect of first aid training on Australian construction workers' occupational health and safety motivation and risk control behavior.

METHOD: A 24-week experiment was conducted to assess how first aid training affects the motivation of small business construction industry employees in avoiding occupational injuries and illnesses and its effect on their occupational health and safety behavior. A simplified multiple baseline design across workplace settings was used to evaluate the effects of first aid training. Participants' motivation to control occupational safety and health risks was explored during in-depth interviews before and after receipt of first aid training. Objective measurement of occupational safety and health behavior was conducted by a researcher directly observing the workplace before and after participants received first aid training. RESULTS: The observations at participants' worksites suggested that, for the most part, the first aid training had a positive effect on the occupational safety and health behavior of participants. First aid training appeared to reduce participants' "self--other" bias, making them more aware that their own experience of occupational safety and health risks is not beyond their control but that their own behavior is an important factor in the avoidance of occupational injury and illness. First aid training also appeared to reduce participants' willingness to accept prevailing levels of occupational safety and health risk and increase the perceived probability that they would suffer a work-related injury or illness. Participants expressed greater concern about taking risks at work after receiving first aid training. IMPACT ON INDUSTRY: It appears that first aid training enhances participants' motivation to avoid occupational injuries and illnesses and improves their risk control behavior. The implications of this are that first aid training can have a positive preventive effect and could complement traditional occupational health and safety training programs. As such, there may be benefit in providing first aid training to all employees rather than limiting this training to a small number of designated "first aiders."

Accident Prevention↗