PubMed Health⌕ Search

Biomedical subjects

A R Caggiula

Publications and source records attributed to A R Caggiula.

At least 19 recordsLinked to original sources
PubMed1992

Amphetamine or haloperidol 2 weeks earlier antagonized the plasma corticosterone response to amphetamine; evidence for the stressful/foreign nature of drugs.

We inquired whether a single exposure to amphetamine (AM) or haloperidol (HALO) could modify the plasma corticosterone (CORT) response to a second injection of AM 2 weeks later. Male rats were injected with 4 mg/kg d-AM sulfate and tested for water intake for 5 h before sacrifice. Overall, AM induced water intake but none of the pretreatments altered this effect. By contrast, preexposure to AM, HALO or its vehicle 2 weeks earlier prevented the elevation of plasma CORT obtained when AM was administered without pretreatment. A combined pretreatment of HALO or its vehicle with AM produced an even greater blockade of AM-induced CORT elevation. Manipulations which prevented AM-induced drinking reduced the effectiveness of AM pretreatment in attenuating AM-induced elevation in CORT, suggesting that the pretreatment may have been sensitizing the effectiveness of a coping response--drinking--in reducing the CORT effect. Our findings also indicate that a dopamine agonist (AM), a dopamine antagonist (HALO) and a nonspecific stressor (acidic vehicle) can all induce the same, long-lasting action on CORT. This strongly suggests that the effects of AM and HALO in this instance cannot be explained in terms of their pharmacological actions, which are opposite to one another, but instead relate to their properties as stressful/foreign agents to the organism.

Amphetamine↗
PubMed1992

One brief exposure to a psychological stressor induces long-lasting, time-dependent sensitization of both the cataleptic and neurochemical responses to haloperidol.

Rats were exposed for 10 minutes to one of several enclosures graded in novelty. In one experiment they were then simply sacrificed and plasma corticosterone determinations made in order to obtain an index of the relative stressfulness of these enclosures. In a second experiment the animals received haloperidol and were tested for catalepsy, 2 hours or two weeks following the novel experience. The most novel experience, exposure to a black box, resulted in the highest corticosterone levels and was the only one of our pre-treatments to induce significant enhancement of catalepsy as well as alteration of nucleus accumbens dopamine levels, 2 weeks--but not 2 hours--later. These findings indicate that brief exposure of adult animals to a psychological stressor can induce a long-term alteration in both behavioral and neurochemical responses to a drug and that this effect requires a minimum level of stress to get started and once triggered gets stronger with the passage of time.

Animals↗
PubMed1992

Habituation and dishabituation of human salivary response.

Habituation may be relevant for understanding how sensory stimuli influence factors related to ingestive behavior. In the first of three experiments in humans we showed that salivation and hedonic ratings to lemon or lime juice habituated within 10 presentations, and dishabituation of the salivation and hedonic ratings to the original juice were observed after a new juice was presented. Experiment 2 replicated the habituation and decrease in hedonics to lemon juice, and showed both dishabituation and a relative increase in hedonics when chocolate taste, rather than another juice, served as the dishabituating stimulus. In a third experiment we showed a video game, a nontaste stimulus, could serve as a distractor to prevent the development of habituation, as well as a dishabituator after habituation had occurred.

Adolescent↗
PubMed1992

Abstinence from smoking decreases habituation to food cues.

Smokers typically gain weight after cessation due, in part, to increased caloric intake. This increase may be due to enhanced responding to sensory characteristics of foods resulting from a failure to habituate to food cues. To test this possibility, salivation to eight presentations of strawberry yogurt was assessed in male smokers and nonsmokers in two sessions. To test stimulus specificity, on the ninth trial, subjects were presented either more strawberry yogurt or lemon yogurt. Smokers were studied under nonabstinent or abstinent conditions. Salivation for nonabstinent smokers and nonsmokers decreased over presentations, while abstinent smokers showed little change. Nonabstinent smokers and nonsmokers recovered salivation when the new flavor yogurt was presented, and showed greater consumption on the final trial for the different versus same flavor yogurt. Nonabstinent smokers participated in additional within-session smoking sessions to control for withdrawal. Nonabstinent subjects were not different across smoking or not smoking sessions, suggesting the effects are not due to the acute effects of withdrawal.

Adolescent↗
PubMed1992

Effect of food change on consumption, hedonics, and salivation.

This study assessed the influence of introducing a new food after repeated presentations of one food on food consumption, hedonics, and salivation. Male subjects were provided repeated 150-calorie courses of pizza or cheeseburger until satiety. Hedonics and salivation were measured before each course. Subject were then provided an additional 450 calorie course of the same or the new food. During the development of satiety, subjects showed reliable increases in fullness and decreases in hunger and hedonics. Salivation briefly increased to maximal salivation, followed by reliable decreases. No differences in pattern of change for fullness, hunger, hedonics or salivation were noted across foods. Presentation of the new food resulted in significantly greater caloric consumption than another serving of the same food (130 vs. 44.5 kcal), an increase in hedonics and salivation relative to presentation of the same food, with no influence on hunger or fullness. These results suggest that after satiety develops, response recovery for subjective, physiological, and behavioral components of eating can be observed when new, palatable foods are presented.

Adolescent↗
PubMed1992

Effects of nicotine on subjective arousal may be dependent on baseline subjective state.

The often disparate and contrasting effects of nicotine on subjective arousal in smokers may be due in part to differences in presmoking subjective state. In Study 1, on each of 2 days, 10 male smokers were divided into high- and low-baseline subgroups on the basis of median split of resting predrug baseline subjective arousal. Then, subjects received intermittent nicotine (15 mu/kg) or placebo via measured-dose nasal spray, with drug conditions counterbalanced between days. In Study 2, 32 male and female smokers were similarly divided into high- and low-baseline subgroups on subjective arousal prior to either smoking or sham-smoking (n = 16 each) during a single session. Results were virtually identical between studies in showing that subjective arousal responses to nicotine (Study 1) or smoking (Study 2) were significantly inversely related to baseline arousal level; those initially low in arousal showed large increases following nicotine or smoking whereas those high in arousal showed little change. No such baseline dependency of responses was seen following placebo or sham smoking. Baseline dependency of cardiovascular responses to nicotine or smoking was also evaluated in similar fashion to determine generalizability of these effects to nonsubjective responses. In each study, systolic blood pressure response was related to baseline level but there was no effect of baseline level on heart rate and diastolic blood pressure responses. Implications of these results for explaining differential rewarding effects of smoking are discussed.

Administration, Intranasal↗
PubMed1991

One experience with 'lower' or 'higher' intensity stressors, respectively enhances or diminishes responsiveness to haloperidol weeks later: implications for understanding drug variability.

This laboratory has previously shown that acute exposure to a variety of brief stressful events can have a very long-lasting influence on subsequent responsiveness to pharmacological and non-pharmacological stressors. In some cases the response to these agents is enhanced, while in others it is diminished: the common denominator being that in each instance the influence of the initial stressor grows stronger with the passage of time. Here, we identify one factor that determines which time-dependent effect is manifest. In 3 separate experiments, male rats were subjected to a single exposure to stressors of either lower or higher intensity and their effects on haloperidol-induced catalepsy and dopamine and dihydroxyphenylacetic acid levels in the nucleus accumbens and medial frontal cortex, measured either 1-2 h or 2 weeks later. The stressors were either environmental (needle jab or 1 h of immobilization), metabolic (200 or 750 mg/kg, i.p. of 2-deoxy-D-glucose), or no effect on haloperidol-induced catalepsy when stressors preceded such behavioral testing by 1-2 h. By contrast, when the interval was 2 weeks, the lower-intensity stressors all increased haloperidol catalepsy, whereas the higher-intensity stressors decreased the same response. In other words, a process that progressed with the passage of time was observed regardless of whether sensitization or diminution of haloperidol's action occurred. In contrast to the uniform bipolar behavioral effects observed, depending on the intensity of the prestressor, the neurochemical findings failed to show any evidence of bipolarity whatever.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Behavioral economic analysis of smoking: money and food as alternatives.

The relative reinforcing value of smoking versus two nonpharmacological reinforcers, money and food, was evaluated in young female smokers in two experiments. In Experiment 1 eight smokers worked for access to smoking or money on concurrent progressive variable ratio schedules of reinforcement (VR4 to VR50) across two days of Smoking Deprivation or No Deprivation. During No Deprivation money was reliably chosen over smoking. During Deprivation subjects initially (VR4) chose smoking over money, but at subsequent comparisons allocated equal time to work for smoking or money. In Experiment 2 eight smokers were provided access to smoking or food across four conditions: No Deprivation, Smoking Deprivation, Food Deprivation and Smoking + Food Deprivation, using the same progressive variable ratio schedules as in Experiment 1. Results showed an increase in the reinforcing value of food after Food Deprivation and smoking after Smoking Deprivation. On the dual deprivation day, subjects initially (VR4) chose to work for food, showed equal preferences over the next three schedule comparisons (VR8-VR20), and from VR25-VR50 shifted their choice to smoking. An increase in percent of calories as fat was observed during all deprivation conditions. The results demonstrate the use of the concurrent schedule paradigm for assessing choice among pharmacological and nonpharmacological reinforcers, and shows the relative reinforcing value of smoking depends on recent deprivation, response demands to obtain the reinforcer and availability of alternative reinforcers.

Adolescent↗
PubMed1991

Conditioned tolerance to the anorectic and corticosterone-elevating effects of nicotine.

We have shown that tolerance to the behavioral effects of nicotine is partially dependent on conditioned environmental cues that predict drug delivery. The present research extends this finding to physiological effects of nicotine by assessing both the appetite-suppressing and adrenocortical-activating effects of nicotine, as measured by plasma corticosterone (CORT). In the first study, male rats on a 22-h food deprivation schedule were injected daily with 0.33 or 0.66 mg/kg (free base) of nicotine bitartrate or saline in a distinctive environment and tested for milk intake. Nicotine initially suppressed milk intake and tolerance developed over 10 days. Changing cues associated with drug administration partially reversed tolerance since injection of nicotine in a new environment reduced milk intake of tolerant animals. Similarly, animals who repeatedly received nicotine in one environment exhibited CORT levels lower than rats injected for the first time, and this tolerance also was partially reversed when administration occurred in the new environment. The second experiment indicated that the increased CORT of Experiment 1 was not a stress response associated with injecting animals in a different environment. These results indicate that tolerance to both behavioral and neuroendocrine effects of nicotine is influenced by conditioning.

Animals↗
PubMed1991

Conditioned tolerance to the heart rate effects of smoking.

This study extended our findings that behavioral tolerance to nicotine in animals can be influenced by conditioning to cardiovascular tolerance in humans. Subjects smoked one-half a cigarette during each of five trials. In the ten-minute intersmoking interval the contexts that preceded smoking were varied. Smokers in the Changing group attended to a different five-minute segment of a Sherlock Holmes radio mystery before each trial, while those in the Repeated group listened to the same segment of the tape. Presmoking heart rates were stable across the groups from trials 1 to 5. As predicted, heart rate for subjects who smoked in the same context showed tolerance to smoking from trials 1 to 5 (84.5 to 78 bpm), while subjects who smoked in in the same context showed tolerance to 83.9 bpm). COa levels increased equally for both groups over the five trials. The results of this study suggest tolerance to smoking can be influenced by learning.

Adult↗
PubMed1991

Does the gender relevance of the stressor influence sex differences in psychophysiological responses?

Sex differences in psychophysiological responses to stress may be important to understanding sex differences in risk for coronary heart disease. This investigation tested the hypothesis that the gender relevance of the stressor influences the extent of sex differences in cardiovascular, neuroendocrine, and lipid responses during stress. Participants performed two tasks that were described as masculine oriented, feminine oriented, or not gender relevant. Although these descriptions influenced the participants' perceptions of the tasks, they did not influence the extent of sex differences in physiological responses in a manner consistent with the study hypothesis. Future directions for research are discussed regarding sex differences in psychophysiological responses.

Achievement↗
PubMed1991

Correlation between locomotor stimulation and the electrophysiological effects of low doses of morphine on substantia nigra dopamine neurons. I. Acute drug administration.

Parallel experiments were done to determine whether the behavioral effects of low doses of morphine correlated with changes in the electrophysiological activity of two subpopulations of mesencephalic dopamine neurons in rats. Acute administration of morphine sulfate (0.01 or 0.20 mg/kg i.v.) produced a naloxone antagonizable increase in locomotion and a corresponding increase in the discharge rates of Type A dopamine neurons. Morphine sulfate led to a relatively long-latency (120-200 sec) loss of spontaneous discharge activity in the majority of Type B dopamine neurons and this was blocked by a high dose of naloxone (5.0 mg/kg). Naloxone (0.10 or 5.0 mg/kg i.v.), combined with morphine, led to a paradoxical behavioral suppression. These data suggest that morphine produces opposite effects on two functionally distinct subtypes of neurons in the substantia nigra pars compacta and that behavioral output may reflect an interaction between these changes in discharge activity in mesencephalic dopamine pathways.

Animals↗
PubMed1990

T-lymphocyte reactivity during the menstrual cycle in women.

Reactivity of blood lymphocytes to nonspecific mitogenic stimulation with phytohemagglutinin (PHA) was measured in nine healthy, regularly cycling women at three phases of their menstrual cycles corresponding to peak levels of estradiol (midfollicular phase), peak levels of progesterone (midluteal phase), and the lowest levels of both hormones (menstrual phase). Sampling points were verified by radioimmunoassay of estrogen, progesterone, luteinizing hormone, and follicle-stimulating hormone. There were significant increases in reactivity associated with an increasing concentration of PHA and with autologous plasma vs AB plasma. However, no differences were found in reactivity to PHA over the three menstrual cycle phases and correlational analyses indicated no relationship between counts and any of the hormones measured.

Adolescent↗
PubMed1990

Immobilization 12 days (but not one hour) earlier enhanced 2-deoxy-D-glucose-induced immunosuppression: evidence for stressor-induced time-dependent sensitization of the immune system.

1. Prior exposure to a stressor can either increase or decrease subsequent behavioral, neurochemical, and endocrine reactivity to stress, depending on the pattern of stress exposure. 2. Massed or frequent exposures typically induce a reduction in reactivity whereas intermittent or widely spaced exposures increase subsequent reactivity. 3. In the present study, the authors examined whether a single presentation of a temporally remote stressor would increase the immunosuppressive effects of a subsequent stressor. Specifically, the authors investigated the effectiveness of 2-deoxy-D-glucose (2-DG) in suppressing the responsiveness of splenic lymphocytes in male, Sprague-Dawley rats that received either no prior treatment, or immobilization either one hour or 12 days earlier. 4. Splenic lymphocyte responsiveness to the T-cell mitogens, Concanavalin A (Con-A) and phytohemagglutinin (PHA) was suppressed following a single injection of 2-DG. 5. The group exposed to the stress of immobilization one hour prior to 2-DG demonstrated a comparable level of immune suppression. 6. In contrast, animals immobilized 12 days prior to the administration of 2-DG showed a more pronounced suppression of immune responsiveness which was significantly greater than the other groups injected with 2-DG. 7. Neither the stress-induced elevation in corticosterone, nor the suppression of blood lymphocyte reactivity to Con-A and PHA was enhanced by prior immobilization. 8. The results indicate that the immunosuppressive effects of an acute stressor can sensitize with the passage of time.

Animals↗
PubMed1989

Environment-specific tolerance to nicotine.

Research has shown that tolerance to the behavioral effects of numerous drugs is mediated by learning. The present study was designed to test whether animals develop tolerance to the antinociceptive effects of nicotine, and whether these effects are also learned. Rats were given dally injections of nicotine in the same environment. After each injection, the latency of tail withdrawal from a hot water bath was measured. This was continued until they were tolerant to the drug: i.e., their response latencies did not differ from animals repeatedly given saline. The role of learning in nicotine tolerance was assessed by changing the environment in which they received nicotine on the day after tolerance was achieved. When the drug environment was changed, the animals recovered the full dose effect of nicotine on tail-flick latencies. These results show that tolerance develops to nicotine's antinociceptive effects, and that this tolerance also may be influenced by learning.

Analgesics↗
PubMed1989

Prior stress attenuates the analgesic response but sensitizes the corticosterone and cortical dopamine responses to stress 10 days later.

This study demonstrates that pre-exposure to stress influences subsequent effects of stress on pain sensitivity (stress-induced analgesia) and on plasma corticosterone and brain catecholamine activity. Animals exposed to a 30 min shock session (S1 = 8, 5.0 s shocks) 10 days earlier showed a significant attenuation of shock-induced analgesia, as measured by increased latency of tail withdrawal from a hot water bath immediately after a 40 s, 1.6 mA footshock (S2). Animals exposed to shock 10 days before testing also exhibited a higher plasma corticosterone response to testing than did all other groups. Norepinephrine (NE) levels in the frontal cortex and dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) levels in the frontal cortex and nucleus accumbens were not altered in any group. However, the DOPAC/DA ratio in the frontal cortex was increased by analgesia testing, and this increase was enhanced only by the combination of shock 10 days before testing and shock immediately before the test (S1 + S2). These results are consistent with previous reports from this laboratory which indicate that an animal's acute response to stress is strongly influenced by its past history of stress.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Changing environmental cues reduces tolerance to nicotine-induced anorexia.

Male rats on a 22-h food deprivation schedule were injected daily with a low dose of nicotine and allowed to drink sweetened milk for 10 min in a test cage in the colony room. Nicotine initially suppressed milk intake but complete tolerance developed within 10 days so that the amount of intake did not differ from saline controls. The role of temporal cues was tested on the next day by changing the timing of cues, and omitting others that normally preceded nicotine injection while keeping constant the physical environment within which injection and testing took place and the drug-test interval. Changing the timing of injection significantly suppressed milk intake. These results show that tolerance to the anorectic effects of a low dose of nicotine is partially dependent on the presence and timing of cues associated with tolerance acquisition.

Animals↗