Some behavioral effects of repeated d-amphetamine administrations

Effects of daily administrations of d-amphetamine were studied on key peck responses of pigeons maintained under a multiple fixed-interval 2-min, fixed-ratio 30-responseschedule. Under the fixed-interval schedule, a pause was followed by a transition to increasing rates of responding until food presentation. Under the fixed-ratio schedule, higher sustained rates of responding were maintained. Low to intermediate doses (0.3-1.0 mg/kg) of d-amphetamine changed the temporal patterns and occasionally increased rates of responding under the fixed-interval schedule. Higher doses decreased rates of responding under bothschedules. With daily injections of 1.0 mg/kg d-amphetamine prior to experimental sessions, the effects of this dose on rates and patterns of responding were attenuated, and d-anphetamine dose-effect curves were shifted to the right, primarily under the fixed-ratio schedule. Similar results were obtained with daily presession injections of 5.6 mg/kg d-amphetamine in a second group of pigeons, except that rates of responding under both schedules were decreased by this daily dose, and did not return completely to control values with repeated injections. In a third group of pigeons, 1.0 mg/kg d-amphetamine administered daily, after experimental sessions, did not alter dose-effect functions for d-amphetamine. In a second experiment, pigeons were trained to peck one response key when given 1.0 mg/kg d-amphetamine and a different key when given presession water injections. Increasing doses of d-amphetamine produced incresing percentages of d-amphetamine-key responses. Repeated administration of 5.6 mg/kg d-amphetamine shifted these dose-effect functions to the right one-half log unit. Results suggested that decreases in reinforcement frequency are not a necessary condition for the development of behavioral tolerance to d-amphetamine.     

Intrastriatal injection of endothelin evokes dopaminergic turning behaviour in rats through activation of the ETB receptor

Contralateral intrastriatal injection of 0.1 pmol or 1 pmol of endothelin-1 produced ipsilateral turning behaviour in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal pathway. This effect could be abolished by pretreatment with either the endothelinET_A/B receptor antagonist bosentan (1 nmol, intrastriatally) or the dopamine D₂ receptor antagonist raclopride (0.1 mg/kg, s.c.) suggesting that endothelin is acting at endothelin receptors to evoke ipsilateral turning behaviour and that this response is mediated by dopamine. Similar ipsilateral turning behaviour was observed upon intrastriatal injection of 1 pmol of endothelin-3 or the specific ET_B receptor agonist, [Ala^1,3,11,15]endothelin-1 when compared to endothelin-1. Pretreatment with the specific ET_B receptor antagonist BQ788 blocked the ipsilateral turning response to intrastriatal injection of endothelin-1 while pretreatment with the specific ET_A receptor antagonist BQ123 did not significantly change the response to injection of endothelin-1. This indicates that endothelin-1, which has affinity for both ET_A and ET_B receptors, is most likely acting at the ET_B receptor to elicit its effect. These results suggest that low doses of endothelin may act at ET_B receptors to evoke the release of dopamine from the striatum in vivo.     

Neuronal responses in monkey anterior putamen during operant bar-press behavior

Single neuron activity was recorded in the monkey anterior putamen to compare visuomotor-related responses during operant bar-press behavior with visual discrimination of objects. Of 615 neurons recorded 9.8% ( ) responded to the presentation of food during forced delay of access to the bar. Of these 60 neurons, 38 were also tested with nonfood, and 19 of these responded to the nonfood objects regardless of the following movement. The amplitude of the visual-related responses of some differential neurons was graded for different objects to reflect the relative degree of preference for the food presented. However, these responses disappeared in reaction time tasks in which the bar could be accessed for pressing immediately upon presentation of an object. The visual response latency of differential neurons ranged from 50 to 700 ms (mean ± SD, 386 ±211 ms), which was longer than that of the nondifferential responses (207 ± 204 ms). These results suggest that anterior putamen neurons might participate in estimation of visual information that could be related to forecasting movement.     

Synergism between buprenorphine and cocaine on the rotational behavior of the nigrally-lesioned rat

 Buprenorphine, a partial mu-opioid receptor agonist, has been proposed as a treatment for cocaine abuse. However, studies in animals have produced conflicting results on the nature of the interaction between buprenorphine and cocaine. In some studies, buprenorphine attenuated the effects of cocaine and in others it enhanced them. The purpose of the present study was to evaluate the interaction of buprenorphine and cocaine on the rotational behavior of the nigrally-lesioned rat. Both buprenorphine (0.003–0.1 mg/kg) and cocaine (1.0– 30 mg/kg) alone produced dose-dependent increases in rotational behavior. Buprenorphine produced long-lasting turning with a peak at 60 min after administration, while cocaine produced turning that peaked immediately after administration and lasted for about 2 h. To distinguish simple additivity from other possible outcomes, we determined the relative potency of each drug alone, using a defined level of effect: 150 turns above the saline control in 4 h. This effect was produced by 10.0 mg/kg cocaine alone and by 0.0175 mg/kg buprenorphine alone. Based on these results, fixed ratio combinations were tested and the experimentally derived effects were compared to the theoretically additive values, using an isobolographic analysis. The fixed ratio combinations of the two drugs tested produced turning greater than predicted from simple additivity. This finding provides statistically-supported evidence for synergism between the actions of buprenorphine and cocaine. Received: 28 January 1997 / Final version: 7 June 1997     

Abnormal behavior of elderly people residing in institutions of medical and social welfare systems

Abstract We investigated factors correlated with abnormal behavior in the elderly residing in a special nursing home (group A) and a psychiatric hospital (group B) using the dementia behavior disturbance scale, the mini mental state examination, the Japanese version of the Philadelphia Geriatric Center morale scale, and the ADL assessment scale. The cognitive function of group B was decreased compared with that of group A, but most activities of daily living (ADL) in the latter group were disrupted compared with those in the former. Only a few categories of ADL correlated with abnormal behavior in group A, whereas cognitive function, quality of life, and most categories of ADL correlated with abnormal behavior in group B. These results suggest that factors correlated with abnormal behavior in the elderly differ within institutions of medical and social welfare systems.     

Sexual behavior and attitudes of University students in Northern Ireland

Two surveys of a Northern Ireland student sample were conducted in 1987 and 1988. A total of 419 female and 201 male subjects completed self-administered anonymous questionnaires concerning their behavior, knowledge, and attitudes towards sex, AIDS, homosexuality, contraception, and relationships. Results indicated a relatively low level of sexual experience, and for those with experience, relatively few partners. The possible influences of gender and religiosity on sexual behavior and attitudes, in the context of Northern Ireland, are discussed. Subjects reported considerable variation in the amount of sex education, but the majority received little or none. This student sample held relatively conservative attitudes towards love, sex, and marriage and this was particularly true for females and for regular churchgoers. In addition, attitudes towards homosexuality were negative (particularly among regular churchgoers). Attitudes towards contraception were more positive than expected among Catholic subjects, and few indicated that they would refuse to use contraceptives on principle. Responses to items about AIDS were highly uniform, suggesting that much of the information made available to the public has been absorbed. However, the lack of uniformity of response to more general items about sex, relationships, and contraception may indicate that fundamental changes in sexual behavior are unlikely to be brought about by influencing a rather narrowly defined set of attitudes about AIDS.     

Female sexual receptivity is defective in juvenile hormone-deficient mutants of theapterous gene ofDrosophila melanogaster

During reproductive maturation of female insects, the acquisition of sexual receptivity is coordinated with ovarian development. Juvenile homone regulates vitellogenesis in the ovaries, but the action of this hormone in the development of sexual behavior is less well-understood. A strain ofDrosophila melanogaster carrying a mutation in theapterous gene(ap ⁴) was known to exhibit arrested vitellogenesis (rescuable by applying exogenous juvenile hormone), sterility of both sexes, and a deficiency of juvenile hormone. In this study, we examined the effects of mutations ofap on female receptivity and its relationship to juvenile hormone. We observed abnormally low female receptivity in homozygousap strains, and heteroallelic combinations ofap mutations exhibited low receptivity. For female receptivity,ap showed no dominance (i.e.,ap/ap ⁺ was intermediate betweenap/ap andap ⁺/ap ⁺). Low receptivity mapped genetically to theap locus. The reduction in female receptivity in these mutants is positively correlated with levels of juvenile hormone synthesized by their corpora allata.This work was supported in part by The Scheinfeld Center for Humans Genetics in the Social Sciences (J.R.), The National Science Foundation (BNS-882 1339 to J.R.), BARD (No. IS-1664-89R to D.S.), The Israel Cancer Research Fund (grant to D.S.), The Rekanati Foundation of Tel Aviv University (grant to D.S.), and The Israeli Fruit Council (award to M.A.)     

Risk-Taking among Adolescents Who Say They Can Get a Handgun

In a survey of 5657 community-residing adolescents, those who said they could get a handgun in two days reported similar and those who said they could not get a handgun reported fewer risk behaviors and less violence perpetration and victimization than adolescents who have their own handgun. Adolescents who said they could get a handgun reported more exposure to and experience with firearms than those who said they could not get a handgun. Risk reduction efforts regarding adolescents should be expanded to include adolescents who say they can get a handgun.