Effects of response-dependent and independent electric shock on schedule-induced polydipsia

In Experiment I, lever pressing by rats was maintained by the delivery of food pellets under a 45-sec fixed-interval schedule. Fixed-time 180-sec and fixed-interval 180-sec schedules of shock delivery were systematically superimposed on the baseline food schedule to study effects on schedule-induced water intake. Response-dependent shock had little, if any, effect on water intake, whereas shocks independent of lever pressing attenuated fluid intake. In Experiment 2, rats received food pellets under a fixed-time 60-sec schedule. Electric shock delivered concurrently under a variable-time 180-sec schedule, but never while the animal was licking or within 5 sec after licking terminated, led to similar attenuation of water intake. These findings suggest that schedule-induced polydipsia is sensitive to differences in the functional properties of response-independent and dependent electric shock.

Comparisons between variable-interval and fixed-interval schedules of electric shock delivery

Responding maintained in rats under a variable-interval 35-sec food schedule was suppressed more by 60-sec and 240-sec fixed-interval schedules of shock delivery than by 60-sec and 240-sec variable-interval schedules of shock delivery. When the delivery of shock was preceded by a 5-sec visual stimulus, little overall response suppression was found with either fixed-interval or variable-interval schedules. In a third experiment, the percentage of occasions on which a cue preceded each shock delivery was varied from 0% to 100%. For the fixed-interval shock condition, the most suppression occurred with the 0% treatment, the least with 100%, and an intermediate amount with the 50% treatment. For the variable-interval groups, the most suppression occurred in the 50% condition, the least in the 100% group, and an intermediate amount with 0%.

Effects of signaled and unsignaled shock on schedule-controlled lever pressing and schedule-induced licking: Shock intensity and body weight

Schedule-controlled lever pressing and schedule-induced licking were studied in rats under a multiple fixed-interval fixed-interval schedule of food reinforcement. Following acquisition of stable rates of pressing and licking, a multiple variable-time variable-time schedule of electric-shock delivery was superimposed upon the baseline schedule. In only one component of the multiple schedule, a 5-sec stimulus preceded each shock (signaled shock). In the other component shock was unsignaled. Several shock intensities (Experiment 1) and body weights (Experiment 2) were studied. Lever pressing and licking were affected similarly by experimental manipulations, although with parametric differences. Depending upon shock intensity and body weight, rates of lever pressing and licking were hardly suppressed, suppressed primarily in the unsignaled shock component (differential suppression), or markedly suppressed in both components. Differential suppression during components with signaled and unsignaled shock and conditioned suppression of responding during the preshock stimulus appeared not to be functionally related. Differential suppression depended more on the discriminability of shock-free time, and on shock intensity, body weight, and the type of response than on the "preparatory" behavior preceding shock.

Effects on responding of mixed and multiple schedules of signalled and unsignalled response-dependent electric-shock delivery

Responding in two rats was maintained under mixed and multiple variable-interval 35-sec variable-interval 35-sec food delivery schedules. Similar rates and patterns of responding occurred in each component of the two schedules. Mixed and multiple variable-interval 65-sec variable-interval 65-sec schedules of response-dependent shock delivery were super-imposed on the mixed and multiple baseline food schedules, respectively. In one component, a 5-sec stimulus was presented on the average of once every 65 sec. Offset of the stimulus arranged that the next response would produce shock. In the other component, no stimulus was presented during the 5-sec period. The mixed schedule of signalled and unsignalled dependent shock delivery yielded similar degrees of response suppression in each component, but the multiple schedule of shock delivery revealed differential degrees of response suppression. Considerably more suppression occurred in the component not associated with the preshock stimulus, thus implicating the discriminative functions of the correlated stimulus.

Pediatric residency training on tobacco: training director tobacco survey

BACKGROUND

Statements from the American Academy of Pediatrics encourage pediatricians to address tobacco. However, most fail to do so and little is known about the preparation to intervene on tobacco they receive during residency training.

METHODS

The Pediatric Residency Training Director Tobacco Survey was mailed to all pediatric residency training directors in the United States. The survey assessed the nature of training and supervision on tobacco, barriers to training, and factors that influence the inclusion of tobacco in the residency training curriculum.

RESULTS

Seventy percent of the training directors returned the surveys. Relatively few offered training/supervision on tobacco on a formal basis. Training directors were reluctant to treat parents who smoke, were skeptical about third party payer reimbursement, and did not believe that office-based interventions for treating tobacco use among patients were effective. Key barriers to training were competing priorities, lack of training resources, and lack of faculty with expertise on tobacco.

CONCLUSION

Residency training is an excellent time to train future pediatricians to intervene on tobacco, but too few pediatric training programs have taken up this charge. Much needs to be done to correct this situation and to prepare future pediatricians to meet the tobacco challenge.

Pediatric residency training on tobacco

OBJECTIVE

Pediatricians have a unique role to play in the antismoking arena. However, few pediatric residency training programs prepare residents to meet the tobacco challenge. This study evaluates the effects of a comprehensive pediatric residency training program on tobacco on resident tobacco intervention behaviors, as well as on changes in the behavior of patients and their parents/guardians.

METHODS

Pediatric residents were exposed to a comprehensive training program on tobacco. Baseline and follow-up surveys of residents, parents/guardians, and patients were used to assess the effects of the training program. A quasi-experimental design permitted unambiguous evaluation of the program's effects on resident intervention behaviors.

RESULTS

The comprehensive training program on tobacco led to marked and significant changes in resident intervention on tobacco. Many of these changes were supported by parents' and patients' reports. In turn, resident intervention on tobacco led to a significant increase in the likelihood that parents would maintain a "smoke-free household." Significant changes in the prevalence of parental smoking were not found, although the trend during 3 years of follow-up was in the desired direction. A high proportion of residents reported that they intervened on tobacco in patients at baseline and follow-up, but too few patients were sampled to permit analysis of the impact on changes in smoking.

CONCLUSIONS

Comprehensive training on tobacco had a positive and powerful effect on the tobacco intervention behavior of pediatric residents. In turn, intervention on tobacco by pediatric residents may have a significant impact on patients and their parents. These findings underscore the efficacy of pediatric residency training on tobacco, and it is hoped that they will serve as an impetus for other pediatric residency programs to introduce training on tobacco.

The pediatrician's role in reducing tobacco exposure in children

OBJECTIVE

Pediatricians have a unique and important role to play in the prevention and treatment of childhood and adolescent tobacco use, the protection of patients from the harmful effects of environmental tobacco smoke, and the encouragement of smoking cessation among parents. However, because recent research indicates that physician training in tobacco dependence is woefully weak and lacks a model for training, this article constructs a useful approach to this problem.

METHODOLOGY

A comprehensive review of the literature served as the basis for the development of a new model for pediatrician training in tobacco dependence.

RESULTS

A comprehensive model is presented for training pediatricians in the areas of reducing infant and child exposure to environmental tobacco smoke, preventing youth smoking initiation, and providing smoking cessation assistance for adolescents and parents.

CONCLUSIONS

Pediatricians have been called on to play an active role in the antitobacco arena. Because of their unique opportunity to interact with children, adolescents, and parents, pediatricians can and should be antitobacco interventionists. For this to occur, however, additional guidance should be provided to pediatricians during their training to better prepare them to carry out effective assessment and intervention practices. smoking initiation, smoking prevention, smoking cessation, environmental tobacco smoke, pediatricians.

Tobacco control activities of primary-care physicians in the Community Intervention Trial for Smoking Cessation. COMMIT Research Group

OBJECTIVE

To compare tobacco control practices of physicians and their staff in Intervention communities with those in Comparison communities of the Community Intervention Trial for Smoking Cessation (COMMIT).

DESIGN

COMMIT was a randomised trial testing community-based intervention for smoking cessation carried out over four years.

SETTING

Eleven matched pairs of communities assigned randomly to Intervention and Comparison conditions.

PARTICIPANTS AND INTERVENTIONS

Physicians in the Intervention communities participated in continuing medical education (CME). Training for office staff focused on tobacco control and office intervention "systems".

OUTCOME MEASURES

Smoking control attitudes and practices reported by primary-care physicians in the 22 communities, smoking policies, and practices of 30 randomly selected medical offices in each community, and patient reports of physician intervention activities.

RESULTS

Response rates to the physicians' mail survey were 45% and 42% in Intervention and Comparison communities, respectively. Telephone interviews of office staff had response rates of 84% in both conditions. Physicians in Intervention communities were more likely to attend training than those in Comparison communities (53% and 26%, respectively (P<0.0005)). In both conditions, training attendees perceived themselves as being better prepared to counsel smokers than non-attendees (P < or = 0.01) and reported more activity in smoking intervention. Intervention communities carried out more office-based tobacco control activities (P = 0.002). Smokers in Intervention communities were more likely to report receiving reading material about smoking from their physicians (P = 0.026). No other differences in physician intervention activities were reported by smokers between the Intervention and Comparison communities.

CONCLUSIONS

The COMMIT intervention had a significant effect on some reported physician behaviours, office practices, and policies. However, most physicians still did not use state-of-the-art smoking intervention practices with their patients and there was little, or no, difference between patient reports of intervention activities of physicians in the Intervention and Comparison communities. Better systems and incentives are needed to attract physicians and their staff to CME and to encourage them to follow through on what they learn. The recently released Agency for Health Care Policy and Research clinical practice guideline for smoking cessation and other standards and policies outline these systems and offer suggestions for incentives to facilitate adoption of these practices by physicians.

Use of the nicotine skin patch by smokers in 20 communities in the United States, 1992-1993

OBJECTIVE

To measure the characteristics of smokers associated with the use of the nicotine skin patch in the general population and to evaluate whether use of the patch is associated with successful smoking cessation.

DESIGN

Data from two surveys conducted in 20 communities in the United States as part of the National Cancer Institute's Community Intervention Trial for Smoking Cessation (COMMIT) study. Nicotine patch prevalence was estimated using data from a 1993 cross-sectional survey of 13691 current and former smokers. The effectiveness of the nicotine skin patch as a smoking cessation aid was evaluated adjusting for other covariants using data from a cohort tracking study of 9809 smokers who were followed between 1988 and 1993. As the nicotine patch was not available to consumers until January 1992, analyses were restricted to respondents who reported themselves to be current smokers in 1993 or former smokers who reported quitting after January 1992.

OUTCOME MEASURES

Current and former smokers who reported having made a serious effort to stop smoking in the past five years were asked to indicate whether they had used the nicotine skin patch to help them stop smoking. Those answering "Yes", were classified as nicotine patch users. Smoking cessation was based on self-report. A "quitter" was defined as someone who had been a smoker as of January 1992 who reported in 1993 not smoking any cigarettes for the preceding six months or longer.

RESULTS

The prevalence of nicotine patch use by smokers averaged across the 20 study communities was 12.8%, making the patch one of the most popular cessation methods used by smokers. Compared with non-users, patch users were more likely to be female, white, have higher annual household incomes, be more motivated to stop smoking, and to smoke more heavily. Among low-income smokers (annual household income below US$10000), nicotine patch use was significantly higher among those who lived in a state where the public insurance programme (Medicaid or Medi-Cal) included the patch as a benefit (12.1% vs 7.7%). Among those who made an attempt to quit smoking, the likelihood of successful quitting was more than twice as high among patch users compared with non-users. Among patch users, the highest quit rates were observed among those who used the patch for between one and three months.

CONCLUSIONS

The nicotine skin patch is a popular and effective means of smoking cessation. Use of the nicotine patch, especially by low-income smokers, could be increased by reducing the out-of-pocket expenditure required for smokers to get the product.

Cigarette smoking among patients with mental retardation and mental illness

Among 136 adults with mental illness and mental retardation who were consecutively treated at a developmental disabilities clinic, 25 reported that they currently smoked cigarettes. Among those with mild and borderline retardation, smoking rates were 30 and 37 percent, respectively. Smokers were significantly more likely than nonsmokers to drink alcohol, use other drugs, and be sexually active. Multiple regression analysis found that a mild or borderline level of retardation and a diagnosis of schizophrenia were significant predictors of smoking. Mentally retarded persons with mental illness are at risk of tobacco-related disease and may benefit from prevention and smoking cessation interventions.

Predictors of smoking cessation in a cohort of adult smokers followed for five years

OBJECTIVE

To identify variables predictive of smoking cessation in a cohort of cigarette smokers followed for five years.

DESIGN

Data analysed in this paper come from a cohort tracking telephone survey of 13415 cigarette smokers aged 25-64 years from 20 American and two Canadian communities who were interviewed in 1988 and re-interviewed in 1993 as part of the National Cancer Institute's Community Intervention Trial for Smoking Cessation. Predictors of smoking cessation evaluated in this study included measures of past and current smoking behaviour, past quit attempts, stated desire to quit smoking, and demographic characteristics.

OUTCOME MEASURES

Smoking cessation was based on self report. A "quitter" was defined as a cohort member who, at the final annual contact in 1993, reported not smoking any cigarettes for the preceding six months or longer. Any smoker who reported having made a serious quit attempt between 1988 and 1993 was asked to indicate reasons that contributed to their decision to try to stop smoking.

RESULTS

67% of smokers reported making at least one serious attempt to stop smoking between 1988 and 1993 and, of these, 33% were classified as having quit smoking in 1993. The most common reasons given for quitting smoking were concern over health (91%), expense (60%), concern about exposing others to secondhand smoke (56%), and wanting to set a good example for others (55%). Statistically significant predictors of smoking cessation included male gender, older age, higher income, less frequent alcohol intake, lower levels of daily cigarette consumption, longer time to first cigarette in the morning, the use of premium cigarettes, initiation of smoking after age 20, history of past quit attempts, a strong desire to stop smoking, and the absence of other smokers in the household. Predictor variations with the largest relative risks for smoking cessation were those associated with nicotine dependence such as amount smoked daily and time to first cigarette in the morning.

CONCLUSIONS

Despite the fact that most smokers expressed a strong desire to stop smoking in 1988, the majority, especially the most dependent heavy smokers (>25 cigarettes/day), struggled unsuccessfully to achieve this goal.

Effects of a 2.5-mg silver acetate lozenge on initial and long-term smoking cessation

BACKGROUND

Silver acetate over-the-counter products, such as gum, lozenge, and spray, produce an aversive metallic taste when combined with cigarette smoke. Hence, they hold promise of serving as an effective smoking deterrent, one that may be used on a self-help basis.

PROCEDURE

Five hundred adult smokers, male and female, were assigned randomly to one of two experimental conditions, 2.5-mg silver acetate lozenge and placebo lozenge. A double-blind study of the effects of a 2.5-mg silver acetate lozenge on initial (3 weeks) and long-term (12 months) smoking cessation was carried out.

RESULTS

About 90% of the subjects (n = 500) reported using the lozenge (silver acetate or placebo) for smoking cessation, and they used about five lozenges per day. Over 70% of the quitters (n = 70) reported using the lozenge on an as-needed basis for relapse prevention. The overall objectively verified quit rates for subjects assigned to the silver acetate and placebo conditions at Visit 3 (3 weeks) were 17% (n = 42) and 11% (n = 28), respectively, a difference which approached statistical significance (P = 0.071). When the analysis was restricted to subjects who used the product, a statistically significant difference (P < 0.05) in initial smoking cessation emerged (26%, n = 37 vs 16%, n = 23) for subjects assigned to the silver acetate and placebo conditions. At 12 months follow-up, 26% (n = 11) of initial quitters in the silver acetate condition and 32% (n = 9) of the quitters in the placebo condition were abstinent. This difference was not statistically significant.

CONCLUSIONS

The study demonstrated modest efficacy for the effect of the 2.5-mg silver acetate lozenge on initial smoking cessation for the subset of subjects who used the product as recommended. We failed to demonstrate efficacy of the lozenge for long-term relapse prevention. Additional research on the efficacy of the 2.5-mg silver acetate lozenge and long-term abstinence in general appears warranted.

Past quit smoking assistance and doctors' advice for white and African-American smokers

Data for 473 African-American and white smokers showed that whites were more likely than African Americans to use formal cessation programs to quit smoking, to report that their doctor told them to stop smoking, and to use nicotine replacement therapy. While physicians advised a high proportion of smokers of each race group to quit smoking and were quite aggressive in prescribing nicotine replacement therapy, they were deficient in providing necessary behavioral support to their patients.

A survey of pediatric office-based interventions on smoking

A mail survey of pediatrician practices and procedures for the modification of environmental tobacco smoke (ETS) and cigarette smoking in patients and parents was mailed to pediatricians. Results indicated that a large proportion of pediatricians address the issue of ETS and cigarette smoking.

Smokers' baseline characteristics in the COMMIT trial

BACKGROUND

Baseline telephone survey data from 10 COMMIT sites were submitted to statistical analyses to compare the smoking characteristics of non-Hispanic white (white), non-Hispanic black (black), Mexican-origin (Mexican), and Puerto Rican-origin (Puerto Rican) smokers.

RESULTS

White men and women were more likely to be classified as "heavy smokers" than members of other racial/ethnic groups, although black and Puerto Rican smokers were more likely than whites to increase their smoking rates on weekends. Whites were less likely to report stopping smoking in the past. White and Mexican smokers were most likely to smoke light or ultralight brands and least likely to smoke menthol cigarettes. Blacks were most likely to report smoking their first cigarette of the day within 10 min of waking.

CONCLUSION

The differences and similarities among different groups of smokers may have important implications for understanding patterns of tobacco-related disease in smokers from different racial/ethnic and sex groups.

Paterson COMMIT: a smoke-free community initiative

Paterson COMMIT is an effort to combat cigarette smoking. The theme for 1994 was "The Smoke-Free Household," and programs were aimed at altering community norms and helping smokers quit. Paterson COMMIT is a successful demonstration of what a community can accomplish.

Physicians and smoking cessation. A survey of office procedures and practices in the Community Intervention Trial for Smoking Cessation

OBJECTIVE

To obtain a baseline measure of tobacco control activities carried out by physicians and of tobacco control policies and practices in physician offices.

DESIGN

All primary care physicians in 11 communities were asked through a mail survey about their tobacco control practices. Thirty offices in each community were randomly selected and interviewed by telephone to determine office policies and practices.

SETTING

Both surveys assessed primary care settings in the 11 intervention communities.

RESULTS

The physicians' survey (response rate, 48%) indicated that physicians report intervention with smokers more than 70% of the time, but the interventions rarely include key behavioral elements necessary for smoking modification. Physicians who received formal training in smoking cessation reported that they believed themselves to be more prepared and that they spent more time counseling patients than physicians who were not trained. The office survey (response rate, 83.2%) indicated that smoke-free policies are in place in most clinics and offices and that many offices provide printed materials on smoking cessation. However, few offices had staff to coordinate smoking cessation activities. These surveys will be repeated following the intervention phase of the Community Intervention Trial for Smoking Cessation to assess changes in counseling practices and office policies.

CONCLUSION

There is a positive relationship between attending training and intervening with more cessation activities. Physicians perceive themselves as prepared to help smokers, but few are providing more than advice to stop smoking.

Tobacco control in New Jersey: a public forum on smoking and youth

The New Jersey State Commission on Smoking OR Health held a public forum on tobacco control. The public provided a strong mandate for action, and recommendations to the Commission were made concerning smoking, youth, and environmental tobacco smoke.

Smoking cessation factors among African Americans and whites. COMMIT Research Group

OBJECTIVES

This study was undertaken to explore smoking patterns and attitudes that influence smoking cessation and relapse among African Americans.

METHODS

Baseline data from eight Community Intervention Trial for Smoking Cessation (COMMIT) sites were analyzed.

RESULTS

Compared with Whites, African Americans who smoke less than 25 cigarettes per day were 1.6 times more likely to smoke within 10 minutes of awakening (a behavioral indicator of nicotine dependence), adjusting for education, age, and gender (OR = 1.2 for heavier smokers). African Americans reported a stronger desire to quit smoking and reported serious quit attempts in the past year. African Americans favored tobacco restrictions (they were 1.8 times more likely than Whites to view smoking as a serious community problem, 1.7 times more likely to favor restrictions on cigarette vending machines, and 2.1 times more likely to prohibit smoking in their car). African Americans were lighter/moderate, menthol smokers.

CONCLUSIONS

African Americans find smoking socially unacceptable and are strongly motivated to quit, but their "wake-up" smoking may indicate high nicotine dependence, making abstinence difficult even for lighter smokers.

Baseline factors associated with smoking cessation and relapse. MRFIT Research Group

BACKGROUND

Data on smoking cessation and relapse for 6 yers of the Multiple Risk Factor Intervention Trial were evaluated in univariate and multivariate analyses to determine the relationship between variables measured at the beginning of the trial and smoking cessation and relapse for special intervention and usual care participants.

RESULTS

The variables positively associated with smoking cessation in both the SI and the UC groups included age, education, and past success in quitting; there was a negative association with the number of cigarettes smoked per day. The expectation of quitting was positively associated with cessation in the special intervention group only, while life events, alcohol, and the presence of a wife who smokes were significant predictors of reduced cessation for the usual care group. The special intervention program may have overcome obstacles which interfered with cessation among the usual care participants. Associations with relapse were generally stronger in the usual care group than in the special intervention group. For usual care participants, multivariate analyses showed that education, past success in quitting smoking, alcohol, and life events were associated with relapse rates. For special intervention participants, only alcohol emerged as a significant predictor. Conclusion. The data are relevant in terms of factors that govern smoking cessation and relapse for adult smokers who take part in formal intervention programs and for those who are left to modify their behavior on their own.

Comparison of smoking behavior change for SI and UC study groups. MRFIT Research Group

BACKGROUND

The results of MRFIT smoking intervention program are presented for the 4,103 special intervention and 4,091 usual care men who reported smoking cigarettes at the first screening visit.

RESULTS

Among the special intervention men, the reported cessation rate increased from 43.1% at 12 months to 48.9% at 72 months. The reported cessation rate among the usual care men increased from 13.5% at 12 months to 28.8% at 72 months. Among smokers who reported cessation at 72 months, 51.3% of special intervention men and 22.7% of usual care men had quit smoking within the first year and remained abstinent thereafter. Average thiocyanate and expired-air carbon monoxide served as objective measures of smoking and were significantly lower among the special intervention men than among the usual care men over the entire follow-up period. The reported cessation rates at 72 months varied according to initial levels of smoking. Smokers reporting 1-19 cigarettes per day at entry were more likely to quit than heavier smokers. For each category of smoking at entry (1-19, 20-39, and 40 or more cigarettes per day) significantly more special intervention than usual care smokers reported cessation.

CONCLUSION

These results indicate that the MRFIT smoking intervention program was successful in promoting early cigarette smoking cessation and maintaining cessation over the entire trial for a large percentage of cigarette smokers.

The making of a smoke-free hospital may not be as easy as you think

Literature describing experiences in the implementation of a smoke-free policy in a hospital suggests that, with careful preparation and close monitoring, a smoke-free policy can be successfully instituted. Despite this pervasive viewpoint, any hospital personnel considering the adoption of a smoke-free policy should be aware that the institution of such a policy may be quite difficult. The experience at University Hospital suggests that a strong policy statement, administrative support, and a comprehensive implementation plan have helped to achieve widespread compliance with the smoke-free policy among hospital employees. Unfortunately, the smoke-free policy has been less successful changing the smoking activities of the patients. Although others have not reported this compliance problem, we believe it is a real problem that many institutions will face. We present methods used to identify, combat, and monitor this compliance problem.

Long-term smoking intervention at the worksite: Effects of quit-smoking groups and an "enriched milieu" on smoking cessation in adult white-collar employees

Maximizing the potential of worksites for smoking intervention remains elusive. We hypothesized that long-term effectiveness of group intervention would be enhanced when offered within an "enriched milieu" (full program) compared with relative isolation (group only). The data failed to support the hypothesis. Although sustained abstinence rates were higher at full-program sites (50%) than at group-only sites (44%), the difference did not achieve statistical significance. Initial (35% vs. 47%) and 12-month (18% vs. 22%) quit rates at full-program and group-only sites also failed to demonstrate the "benefit" of the "enriched milieu."

Effects of repeated administration of soman on schedule-controlled behavior and brain in the rat

The effects of repeated SC administration of soman on schedule-controlled performance and brain pathology were studied in the rat. Soman suppressed response rates in both components of a multiple fixed interval 50-sec fixed-ratio 25 (mult. FI 50-sec FR 25) schedule of reinforcement, although all animals revealed marked tolerance to repeated drug administration. Response rates generally recovered to baseline levels within 1-3 sessions. Three of the six animals studied, however, demonstrated marked deterioration of steady state schedule performance, particularly during the FI 50-sec component of the multiple schedule. Compared to untreated controls, all soman-treated animals exhibited pathological changes in brain. The most salient finding was glial cell proliferation in layer 4 and deep parts of layer 3 of the cerebral cortex. Glial cell proliferation was most marked in animals that exhibited deterioration of steady state schedule performance.

Effect of soman on schedule-controlled behavior and brain acetylcholinesterase in rats

Rats were trained to press a lever under a multiple fixed-ratio 25 fixed-interval 50-second (FR25 FI50-sec) schedule of food reinforcement. Soman, 70-90 micrograms/kg, s.c., suppressed response rates in both components, with a slightly greater effect in the FI schedule. The pattern of responding under the FI schedule, however, was maintained until lever-pressing was nearly completely suppressed. At the highest doses, soman occasionally caused tremors or mild tonic seizures with hindlimb abduction. The suppression of response rate was correlated with inhibition of acetylcholinesterase (AChE) in all brain regions examined: cortex, striatum, hippocampus, hypothalamus and brainstem. Cortical AChE was inhibited to the highest degree, while striatal AChE was most resistant to inhibition by soman.

Inhibition of acetylcholinesterase in the gut inhibits schedule-controlled behavior in the rat

Rats were trained to press a lever under a multiple Fixed-Ratio 25 Fixed-Interval 50-second schedule of food reinforcement. Subcutaneous injection of soman, 80 micrograms/kg, suppressed responding under both schedules and inhibited acetylcholinesterase (AChE) in the brain. AChE activity in the gastrointestinal tract was not significantly inhibited. In contrast, i.p. injection of either soman (10-40 micrograms/kg), neostigmine (75 micrograms/kg) or DFP (350 micrograms/kg) caused marked suppression of behavior and AChE activity of the gut, without affecting brain AChE. These doses caused marked increases in peristaltic activity and likely caused gastrointestinal spasm. Injection of DFP, 500 micrograms/kg, s.c., inhibited AChE in both the brain and gut. The results indicate that inhibition of AChE in the gastrointestinal tract by certain anticholinesterase agents may be involved in the behavioral effects attributed to these drugs.

Effect of repeated intraperitoneal injections of soman on schedule-controlled behavior in the rat

Intraperitoneal (IP) administration of the acetylcholinesterase inhibitor, soman (10-40 micrograms/kg), suppressed in a dose-related manner response rates in rats maintained under a multiple fixed-interval 50-s fixed-ratio 25 schedule of food delivery. Chronic administration of soman at weekly intervals resulted in tolerance to the response. When soman administration was separated by 2-5 weeks in individual rats, the suppressive effects of the agent again became apparent. Analysis of acetylcholinesterase activity revealed that enzyme inhibition was limited to gastrointestinal areas near the site of injection. There was no significant effect on brain acetylcholinesterase even following IP injection of doses which completely suppressed responding. The IP route may be useful for studying tolerance and other chronic effects of soman without producing generalized toxicity.

Effects of selective central muscarinic blockade on schedule-controlled behavior and on the rate-decreasing effects of physostigmine

N-(4-diethylamino-2-butynyl)-succinimide, or DKJ-21, is a muscarinic receptor antagonist with a high degree of selectivity for the central nervous system. In the present study of 6 rats maintained under a fixed-interval 50-sec schedule of food reinforcement, atropine and methylatropine reduced responding in a dose dependent manner, while DKJ-21 had little or no effect. Our findings suggest that the suppression caused by atropine and methylatropine may be the result of the dry mouth induced by these agents. Doses of DKJ-21 which had no effect on schedule performance antagonized the rate-lowering effects of physostigmine in all of the animals. Neither atropine nor methylatropine consistently antagonized the inhibitory effects of physostigmine. Some antagonism may be inferred, however, from the findings that response rates were suppressed less by combinations of atropine and physostigmine than by either drug alone.

Effects of diazepam on responding suppressed by response-dependent and independent electric-shock delivery

While the effects of benzodiazepines on punished responding (response-dependent shock) are straightforward and unambiguous, their effects on behavior suppressed by response-independent shock are conflicting and inconsistent. Some investigators reported that benzodiazepines either have no effect on, or suppress further, responding during response-independent shock, while others reported that benzodiazepines enhance response rates during independent shock delivery in the same manner as during dependent shock. The present study compared the effects of diazepam on rates of lever pressing maintained by a variable-interval 35-sec schedule of food delivery in rats exposed alternately to fixed-interval 180 sec (response-dependent) and fixed-time 180 sec (response-independent) schedules of shock delivery. Diazepam increased punished responding in a dose-dependent manner for each animal. "Rate-dependency," degree of suppression and presence of external stimuli influenced rate-enhancement by the drug. Effects of diazepam on responding suppressed by response-independent shock were inconsistent, with two animals revealing rate enhancement comparable to punished responding, and two others revealing further increases in response suppression. Reasons for the differential effects of diazepam on response-rates suppressed by the two forms of shock delivery remain obscure, although the basic phenomenon seems to be real and not merely an artifact of "rate-dependency."

Effects of diazepam on schedule-controlled and schedule-induced behavior under signaled and unsignaled shock

Schedule-controlled lever pressing and schedule-induced licking were studied in rats under a multiple fixed-interval fixed-interval schedule of food reinforcement upon which was superimposed a multiple variable-time variable-time schedule of electric-shock delivery. Shocks were signaled in one component of the multiple schedule and unsignaled in the other. The effects of diazepam upon the suppression of behavior during the signal (conditioned suppression) and during signaled and unsignaled shock (differential suppression) were studied under several shock intensities (Experiment 1) and at increased body weight (Experiment 2). In each study, diazepam led to dose-dependent increases in the rate of pressing and licking during signaled and unsignaled shock, but had little effect on conditioned suppression. the rate-enhancing effects of diazepam depended upon the intensity of shock, nature of the response, and whether or not shocks were signaled. The data was discussed in terms of (1) implications for understanding the effects of signaled and unsignaled shock on behavior, (2) the effects of diazepam on behavior suppressed by response-independent shock, and (3) comparison between operant and schedule-induced behavior.

Effects of salsolinol, a tetrahydroisoquinolone alkaloid, on multiple schedule performance in rats

Rats were trained to lever press under a multiple fixed-ratio fixed-interval schedule of food reinforcement. Intracerebroventricular injections of salsolinol (1-methyl-6,7-dihydroxytetrahydroisoquinoline), a condensation product of dopamine and acetaldehyde, caused a dose-related decrease in fixed-ratio responding over a dosage range of 15-120 microgram. In contrast, fixed-interval responding was only reduced at the 120 microgram dose and was increased in two of the animals after injection of 15-30 microgram of salsolinol.

Effects of electric-shock delivery on schedule-induced water intake: delay of shock, shock intensity, and body-weight loss

In each of four experiments, schedule-induced water intake in the rat was studied under fixed-time 40-sec food delivery. Experiments I and II studied the temporal relationship between response-independent electric-shock delivery and licking. Shock was delivered under a variable-time 60-sec schedule. A lick-dependent delay was imposed so that licking and shock delivery were systematically separated in time by a minimum of 1 to 15 sec. Over a wide range of shock intensities the data failed to reveal a consistent delay-of-shock effect. Similar shock intensities led to similar reduction of water intake at each delay of shock interval. Experiments III and IV studied the effects of body-weight loss on water intake during independent shock delivery. In Experiment III, shock was delivered under variable-time 60-sec with a minimum separation between shock and licking of 5 sec. In Experiment IV, shock was delivered under variable-time 180-sec. The minimum separation between shock and licking was 10 sec. In each study, the resistance of water intake to suppression by shock delivery increased as the degree of body-weight loss increased. Schedule-induced water intake was affected more by shock when the animal was maintained at 90% of free-feeding weight than at 70%.

Effects of response-independent electric shock on schedule-induced alcohol and water intake

In 3 experiments, food-deprived rats either lever-pressing for intermittent food pellets or obtaining them on free-fixed interval schedules displayed schedule-induced water and alcohol polydipsia. Concurrent response-independent electric shock attenuated water intake, shock intensities producing reductions in polydipsic water consumption had little effect upon alcohol intake, but shocks of sufficient intensity did attenuate post-pellet alcohol drinking. Possible explanations for the differential effect of response-independent electric shock on schedule-induced water and alcohol intake are discussed.

Effects of schedule, percent body weight, and magnitude of reinforcer on acquisition of schedule-induced polydipsia

Two experiments with 43 Charles River (cd) male rats investigated the effects of schedule, percent body weight, and magnitude of reinforcer on the acquisition of schedule-induced polydipsia. A leaner reinforcement schedule induced greater polydipsia as did two non-schedule variables, reduced body weight and small magnitude of reinforcer. These findings, related to contemporary theories of schedule-induced polydipsia, emphasize the role of non-schedule variables in this behavior.

Acquisition and extinction of schedule-induced polydipsic consumption of alcohol and water

16 Charles River (cd) rats were trained to bar-press on an FI 60 schedule for varying number of days, half with water present and half with alcohol. Predictably, schedule-induced fluid consumption resulted. 10 days of extinction of bar-pressing followed. During FI 60 both groups bar-pressed approximately equally often but greater fluid consumption occurred in the group on water. During extinction, both groups showed reduced bar-pressing behavior. Whereas water consumption was extinguished in two days, alcohol consumption remained high and quite variable after bar-pressing had stopped. Results suggest that bar-pressing and fluid consumption are independent behaviors which finding argues against explanations of schedule-induced polydipsia based on adventitious reinforcement. For some rats, the termination of alcohol intake prior to the end of an FI 60 session without an associated cessation of bar-pressing suggested that schedule-induced polydipsia may have been a function of the aversiveness of the reinforcement schedule.

A fortuitous observation regarding "psychogenic" polydipsia

Observations are reported of 5 rats, which had developed schedule-induced polydipsia and essentially stopped drinking, but not bar pressing, when they manipulated or chewed cellulose material from the excreta tray under the conditioning chamber. Polydipsia reappeared with removal of cellulose. This suggested that drinking was one of a number of inter-pellet behaviors depending upon available stimuli.

Long-term smoking intervention at the worksite: effects of quit-smoking groups and an "enriched milieu" on smoking cessation in adult white-collar employees

Maximizing the potential of worksites for smoking intervention remains elusive. We hypothesized that long-term effectiveness of group intervention would be enhanced when offered within an "enriched milieu" (full program) compared with relative isolation (group only). The data failed to support the hypothesis. Although sustained abstinence rates were higher at full-program sites (50%) than at group-only sites (44%), the difference did not achieve statistical significance. Initial (35% vs. 47%) and 12-month (18% vs. 22%) quit rates at full-program and group-only sites also failed to demonstrate the "benefit" of the "enriched milieu."