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Biomedical subjects

G R King

Publications and source records attributed to G R King.

31 records · Page 2Linked to original sources
PubMed1993

Dopamine efflux during withdrawal from continuous or intermittent cocaine.

Daily, intermittent, subcutaneous cocaine injections produce sensitization, while the continuous administration of cocaine produces tolerance to the behavioral effects of subsequent cocaine injections. The present experiments examined whether these behavioral differences are related to differences in the ability of cocaine to increase extracellular dopamine. Increases in perfusate DA, in response to different concentrations of cocaine, were measured in caudate-putamen slices obtained from rats withdrawn for 7 days from a 14-day treatment of either continuous or daily subcutaneous cocaine injections. Compared to saline controls, cocaine-induced DA efflux was increased in subjects receiving daily injections and markedly decreased in subjects receiving continuous cocaine. Thus, different temporal patterns of cocaine administration produce dramatically different alterations in DA neurotransmission. Such changes in dopamine release may be related to the withdrawal symptoms experienced by human cocaine abusers.

Animals↗
PubMed1993

Withdrawal from continuous or intermittent cocaine: effects of NAN-190 on cocaine-induced locomotion.

Rats were pretreated with 40 mg/kg/day cocaine for 14 days by either SC injections or osmotic minipumps. Rats were then withdrawn from the pretreatment regimen for 7 days. In Experiment 1, rats received 0- to 2.0-mg/kg IP injections of 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine (NAN-190), a putative 5-hydroxytryptamine1A (5-HT1A) receptor antagonist. In Experiment 2, rats received the same doses of NAN-190 in combination with a 15-mg/kg IP injection of cocaine. The results of Experiment 1 indicate that the continuous-infusion group demonstrated a dose-dependent suppression of locomotor behavior by single doses of NAN-190. NAN-190 had no consistent dose-dependent effect on the locomotor behavior of subjects in the other pretreatment groups. The results of Experiment 2 indicate that rats receiving intermittent, daily injections tended to exhibit behavior consistent with 5-HT1A receptor supersensitivity. In contrast, rats receiving continuous cocaine tended to exhibit behavior consistent with 5-HT1A receptor subsensitivity. Changes in 5-HT1A receptor sensitivity may contribute to some of the anxiety and depressive symptoms exhibited by human cocaine abusers.

Analysis of Variance↗
PubMed1993

Withdrawal from continuous or intermittent cocaine: behavioral responsivity to 5-HT1 receptor agonists.

Research on chronic cocaine administration indicates that both the dose and route of administration influences the effects of chronic cocaine. Rats were pretreated with 40 mg/kg/day cocaine for 14 days by either SC injections or osmotic minipumps. Rats were then withdrawn from the pretreatment regimen for 7 days and their behavior rated following injections of 5-hydroxytryptamine1A (5-HT1A) or 5-HT1B agonists. In Experiment 1, rats received 0- to 4.0-mg/kg IP injections of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a selective 5-HT1A receptor agonist. In Experiment 2, rats received 0- to 16.0-mg/kg IP injections of 7-trifluoromethyl-4(4-methyl-1-piperazinyl)- pyrrolo[1,2a]quinoxaline (CGS 12066B), a selective 5-HT1B receptor agonist. The results of Experiment 1 indicated that rats receiving cocaine via osmotic minipumps exhibited marked 5-HT1A receptor subsensitivity. In contrast, rats receiving daily cocaine injections sometimes demonstrated evidence of 5-HT1A supersensitivity and sometimes demonstrated evidence of 5-HT1A normosensitivity. The results of Experiment 2 indicated there were no consistent differences between the pretreatment groups in the behavioral response to CGS 12066B, although there were significant differences at single, isolated time points. Overall, the results indicate that, at least in the present behavioral paradigm, the effects of chronic cocaine administration are mediated by changes in 5-HT1A receptor sensitivity but not by changes in 5-HT1B receptor sensitivity.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1992

Oral cocaine self-administration: relation of locomotor activity to pharmacokinetics.

Rats were exposed to daily schedule-induced polydipsia sessions in which solutions of cocaine HCl were available. Both cocaine solution concentration (0.08-0.32 mg/ml) and session duration (0.25-3 h) were varied to determine their effects on locomotor activity rate. Additional animals were used to determine the effect of session length on serum cocaine and metabolite levels when drinking 0.32 mg/ml cocaine solution. Changes in locomotor activity rate were related to serum cocaine concentration by a linear concentration-effect model. By estimation from the linear model, the serum cocaine concentration threshold for increasing locomotor activity was about 0.01 microgram/ml. Under these schedule-induction conditions, there was no evidence for the development of acute tolerance to the locomotor-stimulating activity of cocaine.

Animals↗
PubMed1992

Intermittent and continuous cocaine administration: residual behavioral states during withdrawal.

Rats were pretreated with 40 mg/kg/day cocaine for 14 days by either subcutaneous injections or osmotic minipumps. Rats were then withdrawn from the pretreatment regime for 1 or 7 days and given a 20-mg/kg IP cocaine challenge (day 1) or a 0-, 10-, 20-, or 40-mg/kg IP cocaine challenge (day 7). The results indicate that rats receiving intermittent, daily injections exhibited sensitization to the behavioral effects of a cocaine challenge on days 1 and 7 of withdrawal. In contrast, rats receiving continuous cocaine exhibited tolerance to the behavioral effects of a cocaine challenge on days 1 and 7 of withdrawal. The present results support and extend previous research that indicates that the route and temporal pattern of administration influences the effects of chronic cocaine. Furthermore, the present results indicate that the continuous infusion paradigm may represent an alternative animal model of some aspects of high-dose cocaine abuse, as compared to the typical procedure of single, or multiple, daily cocaine injections.

Animals↗
PubMed1991

Self-control and impulsiveness in adult humans when food is the reinforcer.

Moderately food- and water-deprived women repeatedly chose between longer access to juice after a long delay (the self-control alternative), and shorter access to juice after a short delay (the impulsive alternative). In contrast to previous experiments using points exchangeable for money as the reinforcer, which have found consistent self-control across subjects, behavior of the present subjects varied between complete self-control and complete impulsiveness. Individual subjects' degree of self-control was not related to their majors, to their past or present degree of reported actual food deprivation, to their ratings of desire for the juice, or to their latency to respond. However, subjects who reported that they were currently dieting were significantly more impulsive; they obtained juice earlier within individual trials but had smaller total juice access time. The operant conditioning laboratory paradigm developed for the present research can be useful in investigating general determinants of self-control and impulsiveness for food reinforcers, as well as in investigating the origins of individual differences in food choice.

Adolescent↗
PubMed1990

Humans' sensitivity to variation in reinforcer amount: Effects of the method of reinforcer delivery.

Two experiments examined human subjects' sensitivity to variation in reinforcer amount under different methods of reinforcer delivery. Subjects chose between schedules varying in terms of amount and/or delay of reinforcement, the reinforcer being points exchangeable for money. In Experiment 1, reinforcer amount was manipulated by varying the monetary value of the points across conditions while the number of seconds of access to a consummatory response remained constant. Choice was strongly sensitive to reinforcer amount and indicative of self-control, as in previous experiments. In Experiment 2, reinforcer amount was manipulated by automatically delivering different numbers of points during the amount period, and the consummatory response was eliminated. Sensitivity to variation in reinforcer amount was significantly lower than in Experiment 1. Furthermore, the subjects in Experiment 2 exhibited significantly less self-control than did the subjects in Experiment 1. Humans' sensitivity to variation in reinforcer amount appears to be affected by factors that enhance the discrimi-nability of the consequences of responding.

Journal Article↗
PubMedDate not supplied

Union elections and the NLRB. The healthcare industry continues to challenge bargaining unit determinations.

In the healthcare industry today, unions and management must cope with a confused, contradictory, and often changeable body of law and National Labor Relations Board (NLRB) policy when unions attempt to establish themselves at a particular institution. More than 15 years ago, Congress amended the National Labor Relations Act to grant labor unions the right to organize employees of not-for-profit hospitals and other healthcare organizations. An election to form a union cannot be held, however, until the NLRB determines which employee classifications constitute an "appropriate" collective bargaining unit. Since 1974, labor and management have fought over this basic question before Congress, the NLRB, and the federal courts. One paragraph of congressional instruction to the NLRB, which stipulates that the board prevent "proliferation of bargaining units in the health care industry," has over the years been construed in widely varying ways by the board and the courts. Management has argued that two units should be the maximum number allowed as appropriate whereas unions have argued for more. Last April the NLRB established a rule allowing for as many as eight bargaining units at a particular institution, but three months later a federal district court issued a permanent injunction against the rule. The board has appealed the injunction, and as both sides await a ruling, dozens of pending hospital union election cases have mounted up. Nor does a decision by a court of appeals promise to resolve the issue.

Collective Bargaining↗