These experiments were undertaken to determine if local injection of pilocarpine in the neostriatum of the rat produces oral motor activities that are similar to those produced by systemic administration. In the first experiment, IP administration of 2.0–8.0 mg/kg pilocarpine increased chewing movements and tongue protrusions. In the second experiment, chronic guide cannulae were implanted bilaterally in ventromedial or ventrolateral striatum, and rats were injected with saline, 30, and 60 µg pilocarpine (per side). A dose-related increase in vaculous chewing was induced by injections of pilocarpine in the ventrolateral but not the ventromedial striatum. Tongue protrusions were induced by injections of pilocarpine into the ventromedial and the ventrolateral striatum. A third experiment demonstrated that this response was blocked completely by 10 µg scopolamine co-administered via the same cannulae, but the response was not reduced significantly by 10 µg haloperidol. These results indicate that ventrolateral striatal cholinergic mechanisms are involved in oral motor activities in the rat. This syndrome may provide a model for human clinical phenomena such as parkinsonian tremor.
The effects of acute administration of the selective 5-hydroxytrypamine (5-HT; serotonin) uptake inhibitor, paroxetine, and the potent 5-HT(2A) receptor antagonist, N-ethyl-4-[4',4'-bis(rho-flourophenyl)butyl]-1-piperazinecarboxamide (amperozide) on social cohesion was determined by using a tether paradigm, in which the movement of one of a pair of rats was restricted to one-half of an observation chamber. Administration of 0.1mg/kg paroxetine, 1.0, 3.0, and 5.0mg/kg amperozide but neither 1.0 nor 10.0mg/kg paroxetine increased time spent in contact with the untreated, tethered rat. Whereas only the lowest dose of paroxetine (0.1mg/kg) promoted social cohesion, all doses of amperozide (1.0, 3.0, and 5.0mg/kg) promoted social cohesion. The amperozide-induced increases in time spent in contact were greater than the paroxetine-induced increases in seconds spent in contact, regardless of dose. Acute administration of amperozide is more effective than acute administration of paroxetine in promoting social cohesion between pairs of male conspecifics. Amperozide may be an effective alternative treatment for patients with social anxiety disorder suffering from adverse side effects of paroxetine. Amperozide may prove to be a more effective treatment for social anxiety disorder than paroxetine, which is supported by our results.
The purpose of this study was to determine if gender plays a role in the quality and quantity of the advice given to undergraduates about applying to graduate school. Four hundred male and female psychologists who listed a university address and e-mail address in the 1997 Directory of the American Psychological Association were sent an e-mail inquiry from a pseudostudent (either Theresa or Brian Miller). In the first e-mail, the pseudostudent asked if the subjects would be willing to look at his or her GRE scores and grade point average (GPA) for the purpose of providing advice about his or her chances of getting into the graduate program at the subject's school. Two hundred forty subjects consented to examine the figures, nearly equally split between males and females. Subjects were then sent the GPA and scores of an outstanding, average, or poor applicant. The results indicated that female faculty were significantly more likely to consent to examine the data of a female pseudostudent and male faculty were significantly more likely to consent to examine the data of a male pseudostudent. However, once the faculty member agreed to offer advice, gender had no impact on the length or quality of advice given to the pseudostudent, and advice became a function of the pseudostudent's academic credentials. Furthermore, while male and female subjects were equally likely to encourage, discourage, or recant on their offer to give feedback, male subjects were more likely to refuse to review the data and female subjects were more likely to offer a neutral response to the data. The results are discussed in terms of the difficulty students face in finding adequate information about pursuing a graduate education. These problems may be magnified for female students because there are fewer female faculty available to serve as mentors.
The purpose of this study was to determine someof the factors that influence outside reviewers andsearch committee members when they are reviewingcurricula vitae, particularly with respect to the gender of the name on the vitae. The participants inthis study were 238 male and female academicpsychologists who listed a university address in the1997 Directory of the American PsychologicalAssociation. They were each sent one of four versions of acurriculum vitae (i.e., female job applicant, male jobapplicant, female tenure candidate, and male tenurecandidate), along with a questionnaire and aself-addressed stamped envelope. All the curricula vitaeactually came from a real-life scientist at twodifferent stages in her career, but the names werechanged to traditional male and female names. Althoughan exclusively between-groups design was used to avoidsparking genderconscious responding, the resultsindicate that the participants were clearly able todistinguish between the qualifications of the jobapplicants versus the tenure candidates, as evidenced bysuggesting higher starting salaries, increasedlikelihood of offering the tenure candidates a job,granting them tenure, and greater respect for theirteaching, research, and service records. Both men andwomen were more likely to vote to hire a male jobapplicant than a female job applicant with an identicalrecord. Similarly, both sexes reported that the male job applicant had done adequate teaching,research, and service experience compared to the femalejob applicant with an identical record. In contrast,when men and women examined the highly competitive curriculum vitae of the real-life scientist whohad gotten early tenure, they were equally likely totenure the male and female tenure candidates and therewas no difference in their ratings of their teaching, research, and service experience. There was nosignificant main effect for the quality of theinstitution or professional rank on selectivity inhiring and tenuring decisions. The results of this study indicate a gender bias for both men and womenin preference for male job applicants.
Classic neuroleptic drugs produce a syndrome of vacuous jaw movements in rats, and this syndrome has been offered as an animal model of early onset extrapyramidal side effects. The atypical antipsychotics do not produce elevations in vacuous jaw movements, or do so only at very high doses. The purpose of the present study was to determine the impact of the putative antipsychotic, amperozide, on vacuous jaw movements in rats. Groups of rats received daily injections of haloperidol (0.2, 0.4, or 0.8 mg/kg), clozapine (2.0, 4.0, 8.0 mg/kg), amperozide (2.0, 4.0, 8.0 mg/kg) or vehicle for 4 weeks. Once per week, rats were observed for the presence of vacuous jaw movements. Haloperidol increased vacuous jaw movements with increasing doses. Clozapine only produced elevations in vacuous jaw movements at the highest dose. In contrast, increasing doses of amperozide resulted in decreasing vacuous jaw movements for this portion of the dose-response curve. This is the first report of the effect of amperozide on vacuous jaw movements and results are discussed in terms of a potentially unique behavioral profile with respect to this behavior.
The present series of experiments was conducted to investigate the vacuous jaw movements induced by sub-chronic administration of haloperidol (HP). In the first experiment, daily injection of 0.4 mg/kg H P for 10 days increased vacuous jaw movements and decreased rearing behavior. The second and third experiments investigated the interaction between the effects of HP and the anticholinergic drug scopolamine. Co-administration of 0.5 mg/kg scopolamine with 0.4 mg/kg HP for 9 days reduced vacuous jaw movements and increased rearing responses relative to rats that received HP alone. Co-administration of HP with 0.25 mg/kg scopolamine for 9 days increased rearing relative to rats that received HP alone, but there was no effect of the lower dose of scopolamine on vacuous jaw movements. Administration of 0.5 mg/kg scopolamine plus 0.4 mg/kg HP on days 11-14 to rats that had received HP alone for 10 days reversed the effect of HP on rearing, but not on vacuous jaw movements. Rats that had received HP plus scopolamine for 10 days showed dramatic increases in vacuous jaw movements when scopolamine was withdrawn. Because vacuous jaw movements are produced within the first few days of administration, reduced by administration of scopolamine, and exacerbated by withdrawal of scopolamine, the pharmacological characteristics of these movements do not appear to bear a close relation to those of tardive dyskinesia in humans. The present results are consistent with the hypothesis that vacuous jaw movements, in rats share some characteristics with Parkinsonian symptoms.
A series of experiments were conducted in order to characterize the role of nucleus accumbens dopamine (DA) in the neurochemical and behavioral effects of phencyclidine (PCP). In the first study, microdialysis probes were implanted in nucleus accumbens to determine the effects of 4.0 and 8.0 mg/kg PCP on extracellular levels of DA and its metabolites, dihydroxyphenyl-acetic acid (DOPAC) and homovanillic acid (HVA) in behaving rats. PCP increased extracellular DA, DOPAC and HVA in the same dose range that produced increases in locomotor activity, stereotypy and ataxia. The increases in extracellular DA that were induced by 4.0 mg/kg PCP were significantly correlated with the increases in locomotor activity. In the second study, rats received bilateral injections of 6-hydroxydopamine in order to deplete DA in nucleus accumbens. DA-depleted and control rats received injections of saline and 4.0 mg/kg PCP and were tested in an ‘intruder’ paradigm. In this procedure, saline- and PCP-treated rats were placed in a stable colony of three other rats and social behavior was observed for 30 min. PCP reduced the frequencies of various social behaviors, but accumbens DA depletion did not reverse the effects of PCP on social behavior. Subsequently, all rats received 8.0 mg/kg PCP and were assessed for locomotor activity, stereotypy and ataxia. Depletion of DA in nucleus accumbens attenuated PCP-induced locomotion, but did not alter the effects of the drug on stereotypy or ataxia. These results indicate that DA in nucleus accumbens is related to the locomotor effects of PCP, but that the effects of PCP on social behavior, stereotypy and ataxia are dependent upon DA in other brain regions or on neurotransmitters other than DA.
An important aspect of motivated behavior is that organisms will perform complex instrumental behaviors to gain access to stimuli such as food. In the present study, food-deprived rats were tested in an operant chamber in which the animals had a choice between pressing a lever to obtain a more-preferred food (Bioserve pellets), or free feeding on a less-preferred food (lab chow). Typically, rats pressed the lever to obtain the preferred food pellets, and ate little of the less-preferred food even though it was freely available. Pre-fed rats showed suppression of both lever pressing and feeding. Systemic administration of 0.1 mg/kg haloperidol (HP) led to a dramatic shift in the behavior of these rats, such that the number of lever presses was substantially reduced, but the amount of less-preferred food consumed showed a significant increase. This result occurred if the rats pressed a lever on either a CRF or FR5 schedule. Injection of 3.5–7.0 µg HP directly into the nucleus accumbens, or intra-accumbens injections of 6-hydroxy-dopamine, also decreased lever pressing for food and increased feeding on laboratory chow. Thus, interference with brain dopamine suppressed a highly active instrumental response for food, although the behavior of the animal was still directed towards food acquisition and consumption.
Although nicotine is a drug of abuse for millions of smokers, it has been difficult to demonstrate clearly the motivational properties of nicotine with rats using the conditioned place preference (CPP) paradigm. The first experiment attempted to replicate CPPs reported by other researchers using nicotine doses of 0.4, 0.8, and 1.2 mg/kg. There was a trend for all three doses to produce aversions, but it was significant only for the 0.8 mg/kg dose. Exposures to the CS alone extinguished aversions, but a "priming" dose (0.2 mg/kg) of nicotine given after extinction produced aversions only in animals exposed to 1.2 mg/kg. Experiment 2 tested whether preexposure to morphine or nicotine would sensitize animals to nicotine's reinforcing effects. In this experiment, rats were exposed to either six nicotine (0.6 mg/kg) or morphine (1.0 mg/kg) dosings prior to preference conditioning. Neither preferences nor aversions were observed in any group following subsequent conditioning with 0.6 mg/kg nicotine. The results suggest that previous observations of preference effects may have been due to specific procedural factors or may have depended on negative reinforcement due to stress reduction.