Biomedical subjects

J H Porter

Publications and source records attributed to J H Porter.

At least 37 records · Page 2Linked to original sources

PubMed1990

Differential effects of haloperidol and clozapine on the reinforcing efficacy of food reward in an alleyway reacquisition paradigm.

Using the alleyway reacquisition procedure developed by Horvitz and Ettenberg, the present study compared the effects of a typical neuroleptic haloperidol (0.15 and 0.30 mg/kg) to those of an atypical neuroleptic clozapine (5.0 and 10 mg/kg) on running times 24 hours after a single food-rewarded trial administered during an extinction regimen. Rats that received food reward plus an injection of vehicle or 0.15 mg/kg haloperidol ran faster on the subsequent test day than did nonrewarded rats. The 0.30 mg/kg dose of haloperidol blocked this reacquisition effect, yielding results consistent with the anhedonia hypothesis. Clozapine (5.0 and 10 mg/kg), however, failed to block the reacquisition of alleyway running. Thus, unlike haloperidol, clozapine did not produce anhedonic effects in this reacquisition paradigm. These results suggest that neither motor nor anhedonic properties of neuroleptics appear to be crucial to the clinical efficacy of neuroleptics.

Animals↗

PubMed1989

Effects of phencyclidine-like drugs on punished behavior in rats.

The effects of phencyclidine (PCP) and a number of PCP-like drugs on punished responding in rats were compared to those of chlordiazepoxide and morphine. Twenty rats, trained to lever-press for food reinforcement, were tested under a modified Geller-Seifter procedure using a multiple schedule with responding in one component reinforced under a fixed-interval 60-sec schedule while each response in the other component resulted in both food and brief electric shock presentation. Chlordiazepoxide, PCP, etoxadrol, (+)-N-allylnormetazocine and (-)-beta-cyclazocine all resulted in selective increases in rates of responding during the punishment component. Two drugs with predominant opiate-agonist actions in vivo, (-)-alpha-cyclazocine and morphine, did not increase punished responding at any dose tested. These results confirm previous research using pigeons that had shown antipunishment effects of PCP and provide further evidence for an overlap in the pharmacology of PCP-like drugs and depressant drugs such as barbiturates and benzodiazepines. The concordance between the discriminative stimulus properties and antipunishment effects of PCP-like drugs and actions at the PCP receptor suggests that the PCP receptor may play a role in both behavioral actions of this group of drugs.

Animals↗

PubMed1988

Rats that acquire a THC discrimination more rapidly are more sensitive to THC and faster in reaching operant criteria.

Male Sprague-Dawley rats were trained to discriminate delta-9-tetrahydrocannabinol (THC) from saline in a two-lever operant task using successive training criteria. Untreated animals were first shaped to barpress for a milk reward with one lever available. As each animal reached criterion the second lever was installed, the first lever was removed, and the animal was treated with 3.0 mg/kg THC 30 min prior to barpress training. When criterion on the second lever was reached the rats were trained to discriminate THC from vehicle injections with both levers available. Following acquisition of the discrimination, test doses of THC at 0.00, 0.375, 0.75, 1.5 and 3.0 mg/kg revealed that the half of the 24 rats who reached criterion (STC) more rapidly exhibited significantly greater sensitivity to THC at the 0.75 mg/kg test dose than did the 12 slow-learner rats; the former group generated an ED50 of 0.77 mg/kg, whereas the ED50 for the later group was 1.63 mg/kg. The fast learners acquired both the initial barpress response and the discrimination more rapidly than did slow-learners. Results suggest that some animals are inherently more sensitive to THC and faster in meeting learning criteria.

Animals↗

PubMed1988

Assessment of pimozide's motor and hedonic effects on operant behavior in rats.

The present study examined the effects of the neuroleptic pimozide on several measures of motor capacity and reinforcement efficacy in rats trained to respond according to a multiple random interval (RI) food reinforcement schedule (mean interreinforcement intervals of 10, 20, 40, 80, and 160 sec). Pimozide (0.125, 0.25, 0.5, and 1.0 mg/kg) produced a dose-dependent suppression of response rates for all five RI schedules and a dose-dependent increase in response duration. An independent measure of motor activity in photocell activity chambers also was decreased by pimozide in a dose-dependent manner. Photocell activity was significantly correlated with response duration and with the Matching Equation parameter k. Thus, all three measures of motor performance revealed similar decreases in motor capacity at the high dose of pimozide. Reinforcement efficacy also was reduced by the 1.0 mg/kg dose of pimozide as indicated by an increase in the Matching Equation parameter Re. The parameters k and Re were not significantly correlated, suggesting that these two Matching Equation parameters do provide independent measures of motor capacity and reinforcement efficacy, respectively. The present results demonstrate the importance of obtaining measures other than simple response rates in order to assess drug effects on operant behavior.

Analysis of Variance↗

PubMed1988

Situational anxiety and blood pressure lability in the physician's office.

In order to evaluate the association between situational anxiety levels and blood pressure variability during physician's office visits, 19 patients were assessed at the beginning of the visit and before and after being examined by the physician. Assessment included blood pressure measurement as well as self-report of current anxiety level. Previous findings that systolic readings do significantly diminish over the course of the visit were replicated for both hypertensive and normotensive patients, accompanied by correlative decreases in state anxiety. Diastolic blood pressure readings were more stable and less associated with fluctuations in state anxiety, except in patients with initially higher diastolic readings. Results were interpreted as indicating the importance of using more than one blood pressure measurement in diagnosing hypertension and monitoring its management. In particular, patients' anxiety responses upon entering the examining room may produce artificial elevations.

Adult↗

PubMed1987

Exposure to magnetic resonance imaging does not produce taste aversion in rats.

A taste aversion test was used to evaluate possible toxic effects of magnetic resonance imaging (MRI). Thirty male Sprague-Dawley rats were randomly assigned to four groups: Group One (n = 10) received 30 minutes exposure inside the MRI scanner; Group Two (n = 10) received a sham exposure to the MRI scanner; Group Three (n = 5) was injected with 0.15 M lithium chloride; and Group Four (n = 5) was injected with vehicle. All groups were given 10 minutes access to a 0.1% saccharin solution immediately prior to their respective treatment. The rats treated with lithium chloride displayed a taste aversion to the saccharin solution upon subsequent testing over an eight day period. The two control groups (Two and Four) and the rats exposed to MRI did not display any aversion to the saccharin solution. These results are compared to other studies that have shown that magnetic fields can influence biological systems.

Animals↗

PubMed1987

Differential effects of pimozide and clozapine on schedule-controlled and scheduled-induced behaviors after acute and chronic administration.

The present study reports the comparative effects of pimozide (PMZ; 0.1, 0.3 and 1.0 mg/kg) and clozapine (CZP; 1.0, 3.0 and 10.0 mg/kg) on fixed-interval 60-sec responding after acute and chronic administration and on the acquisition of schedule-induced drinking (SID) during a chronic dosing procedure. Both the 0.3 and the 1.0 mg/kg of PMZ groups responded significantly less than vehicle controls after acute dosing without disrupting the operant response patterns as measured by index of curvature (IOC), and these effects persisted for 38 days of treatment. Acute treatment with 3.0 and 10.0 mg/kg of CZP significantly suppressed operant response rates and disrupted the pattern of operant responding, in that the IOC was significantly lower for these subjects than for vehicle controls. The CZP-treated animals gradually developed tolerance to the drug effects and were performing at vehicle control levels after Day 7 of treatment. SID was assessed from Day 19 through Day 38 of neuroleptic treatment. PMZ suppressed the acquisition of SID. Animals treated with 1.0 and 0.3 mg/kg of PMZ consumed less water than controls and did not develop the postpellet drinking pattern characteristic of SID. Both the vehicle and 0.1 mg/kg of PMZ groups increased the amount of water they consumed across the 10 blocks of sessions. A dose-related suppression of SID also was noted for CZP-treated rats. Vehicle controls and three of the subjects treated with 10.0 mg/kg of CZP acquired the SID behavior. These animals gradually increased the amount of water they consumed across sessions and drank in a temporal pattern consistent with SID.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

Schedule-induced polydipsia: another look at water-intake volume regulation.

Experiment 1 found that rats regulated the number of drinks per session during schedule-induced polydipsia, rather than volume intake when water was obtained from different sized water dipper cups. However, when water availability was manipulated during polydipsia sessions by changing the aperture size of the water bottle tube (Experiment 2), the rats regulated total water-intake volume per session. Experiment 3 demonstrated that this volume regulation was more precise during schedule-induced drinking than during water deprivation induced drinking. Also, it was shown that the different sized apertures were effective in manipulating the rates of water availability and ingestion. These experiments demonstrated that volume regulation during schedule-induced polydipsia occurs only when water is freely available via drinking tubes.

Animals↗

PubMed1985

Intravenous self-administration of pentobarbital and ethanol in rats.

Rats provided with unlimited access to intravenous doses of ethanol (30, 60, 90, 180, and 360 mg/kg/infusion) failed to initiate and maintain lever pressing that resulted in ethanol delivery. When pentobarbital (0.5 mg/kg/infusion) was substituted for ethanol, lever pressing increased. There were three indications of the positive reinforcing effects of pentobarbital: (1) a greater number of lever presses occurred when pentobarbital was response-contingent than when saline was available; (2) a greater number of responses were made on the pentobarbital lever than on a control "activity" lever; and (3) systematic changes in lever pressing were a function of pentobarbital dose (0.125, 0.25, 0.5, 1.0, and 2.0 mg/kg/infusion). Sequential substitution of ethanol (30, 90, 360 mg/kg/infusion) for pentobarbital failed to maintain lever pressing. However, access to combinations of ethanol (1, 3, 10, 30, 60 mg/kg/infusion) and a nonreinforcing dose of pentobarbital (0.125 or 0.25 mg/kg/infusion) did maintain lever pressing. As the dose of ethanol increased, the daily number of infusions first increased then decreased. Following a history of self-administration of ethanol-pentobarbital combinations, a retest of ethanol alone (10 or 30 mg/kg/infusions) followed by pentobarbital alone (0.125 or 0.25 mg/kg/infusion) failed to maintain lever pressing.

Animals↗

PubMed1985

Effects of glucose-saccharin preloads on schedule- and deprivation-induced drinking in rats.

The present series of experiments found that high volumes of a glucose-saccharin solution consumed by rats prior to testing (i.e., a preload) produced a small, but significant suppression of established schedule-induced drinking (Experiment 2). This reduction in polydipsic drinking did not appear to be due to the caloric value of the preload (Experiment 1) or to any changes in food motivation, since Experiment 2 showed that there were no changes in lever pressing on a fixed-interval 1-min food schedule. In Experiment 3, the glucose-saccharin preloads produced a complete suppression of water deprivation-induced drinking. While schedule-induced drinking does appear to be a nonhomeostatic form of drinking, under certain testing conditions, it is sensitive to manipulations which affect homeostatic thirst mechanisms.

Animals↗

PubMed1985

Suppression of schedule-induced drinking and food-reinforced bar pressing by tail-pinch is not reversed by naloxone.

In Experiment 1 eleven food-deprived rats were tested in a schedule-induced drinking paradigm under both tail-pinch and non-tail-pinch conditions. Tail-pinch produced a strong suppression of schedule-induced drinking, licking, licks per milliliter, bar presses, and number of reinforcers received during 30-min test sessions. Experiment 2 showed that the narcotic antagonist naloxone (2 and 4 mg/kg) did not reverse the tail-pinch suppression of schedule-induced drinking and food-reinforced bar pressing. Experiment 3 demonstrated that the suppression of schedule-induced drinking by tail-pinch could not be attributed to a suppression of drinking behavior in general, as tail-pinch had no effect on deprivation-induced drinking. The failure of naloxone to reverse this blockade suggests that endogenous opiate systems do not play a very important role in the suppression of schedule-induced polydipsia by tail-pinch. It was suggested that the combination of both the schedule-induction paradigm and the tail-pinch procedure increased arousal levels to such a high level that all behaviors were suppressed.

Animals↗

PubMed1984

Schedule-induced behavior in children as a function of interreinforcement interval length.

Two four year old twin female children were tested on fixed interval (FI) 30-, 60-, 90- and 120-sec food schedules with M&M candy reinforcers. Both subjects displayed increased drinking, gross and fine body movement, and grooming on the FI schedules as compared to Baseline conditions. Bitonic functions were noted for drinking, fine body movements and grooming for Subject J and for drinking and fine movement for Subject K, similar to those which have previously been reported in animal studies. These preliminary results demonstrated that certain behaviors may be induced by intermittent food reinforcement schedules in humans and are excessive when appropriate baselines are used for comparison. Also, these data further strengthen the species generality of schedule-induced behaviors to human subjects.

Animals↗

PubMed1984

Latent inhibition in the aversion to oral methadone.

Fourteen adult Sprague-Dawley rats received daily 3 mg/kg naltrexone (Group One, n = 7) or saline (Group Two, n = 7) injections for 24 days. During this time they underwent forced choice testing with 0.125 mg/ml methadone (the unconditioned stimulus, UCS) versus taste-balanced 0.04 mg/ml quinine placebo solutions. The handling, injection ritual, and taste cues served as a conditioned stimulus (CS)-complex. While Group Two (CS-UCS paired) animals showed pronounced pharmacological methadone aversions, those in Group One (CS pre-exposed rats in which the effects of methadone were blocked by the naltrexone) maintained a moderate intake of the opiate solution. When the injection conditions were reversed for 10 days, no change in percent methadone solution occurred for either group; thus, Group One displayed a latent inhibition effect after the CS pre-exposure, while Group Two maintained its previously acquired aversion. Testing after a 3-month drug free period, however, revealed the acquisition of a comparable methadone aversion by Group One (hence, recovery from the latent inhibition observed in the first reversal phase). Parallels with latent inhibition and retention in conditioned taste aversion studies were drawn, and further support for generality in the laws of learning, suggested.

Animals↗

PubMed1983

Schedule-induced polydipsia as a function of percent of body weight in the Mongolian gerbil.

Three male Mongolian gerbils displayed schedule-induced polydipsia on a fixed-time 3-min food reinforcement schedule at 85% body weight (BW). When the gerbils' body weights were gradually increased to ad lib levels, the polydipsia disappeared. When the gerbils were subsequently reduced to 85% BW again, the previous polydipsia levels of water intake were recaptured. These data replicate previous findings with rats, and suggest that schedule-induced polydipsia may be as robust in gerbils and other species, as it is with rats, once the optimal generating conditions are established.

Animals↗

PubMed1982

Lungworms of feral swine in Florida.

Metastrongylus apri, M salmi, and M pudendotectus were found in 94%, 76%, and 64%, respectively, of 90 feral swine from a study area in southern Florida. The mean number of worms per infected animal was 155, with a range of 1-1,980 (1 or more species). Metastrongylus apri was found singly or in combination with 1 or both of the other species. Single or concurrent infections of M salmi and M pudendotectus were not found. Male hogs had significantly (P less than 0.05) higher intensities of M apri infection. Juvenile animals were infected with M apri only, but subadults and adults were infected with all 3 species. Hogs examined during October, November, and December had significantly (P less than 0.05) higher intensities of infection of all 3 species, compared with hogs examined at other times of the year. There were significant (P less than 0.05) interactions between host sex, host age, and season for intensities of infection with M pudendotectus.

Animals↗

PubMed1982

Adjunctive behavior in children on fixed interval food reinforcement schedules.

Four female children (4 to 6 years of age) were tested on fixed interval (FI) 30-sec and 60-sec food schedule with M & M candy reinforcers. All four subjects displayed increased movement on the FI schedules as compared to appropriate FR 1 baseline conditions. Increased drinking was shown by three subjects, and increased vocalization by two subjects. These results clearly demonstrated schedule-induced behaviors in children with food reinforcement schedules which are typically used in animal experiments.U

Child↗

PubMed1982

Intraperitoneal preloads of water, but not isotonic saline, suppress schedule-induced polydipsia in rats.

In Experiment 1, 10 ml intraperitoneal preloads of water completely suppressed the acquisition of schedule-induced polydipsia in four of six rats. Preloads of 10 ml of isotonic saline retarded the acquisition of polydipsia slightly, but there were no significant differences in asymptotic levels of water intake between Saline Preload and Sham Preload groups. Experiments 2 and 3 demonstrated that established polydipsia was suppressed by about 10 ml when 10 ml water preloads were given; whereas, 10 ml saline preloads had no significant effect on established polydipsia. These results demonstrate that schedule-induced polydipsia is sensitive to internal states of water balance.

Animals↗

PubMed1982

Effects of bilateral and unilateral neocortical lesions on schedule-induced polydipsia in rats.

Fifteen adult female rats were subjected to one of the following surgical procedures: (1) bilateral neocortical ablation; (2) unilateral neocortical ablation; or (3) sham surgery. Following recovery, all rats were tested on a fixed-time 1-min food schedule for acquisition of schedule-induced polydipsia. Contrary to a previous report by Bigler, Fleming and Shearer [1], no attenuation of polydipsia was seen in either group of rats with neocortical damage.

Animals↗