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H Rigter

Publications and source records attributed to H Rigter.

At least 55 records · Page 3Linked to original sources
PubMed1981

A comparison of the ability of opioid peptides and opiates to affect active avoidance conditioning in rats.

Enkephalins reduce acquisition of an active avoidance response when administered intraperitoneally shortly before training. The present study examined whether microgram or delta opiate receptors are involved in this enkephalin effect. This was done by comparing the efficacy of micro- and delta-receptor agonists; by attempting to block the enkephalin effect with micro- and delta-receptor antagonists; and by comparing the characteristics of the effects of Met-enkephalin and Leu-enkephalin. In addition, the efficacy of kappa-agonists in reducing acquisition was assessed. It was found that micro-agonists are inactive in this assay; several delta- and kappa-agonists are active. However, not all of the data are consistent with the adequacy of this receptor classification. The micro-receptor antagonist naloxone did not readily block the effect of Met- or Leu-enkephalin but neither did the micro/delta-antagonist, diprenorphine. An additional complexity is the emergence of differences in behavioral activity of Met- snd Leu-enkephalin.

Adrenocorticotropic Hormone↗
PubMed1980

Attenuation of amphetamine-induced enhancement of learning by adrenal demedullation.

These experiments investigated the effect of immediate posttrial administration of peripherally acting DL-4-hydroxyamphetamine on retention of a one-trial inhibitory avoidance response in intact, adrenal medullectomized, sympathectomized, and medullectomized and sympathectomized rats. In intact rats, 0.82 mg/kg of DL-4-OH-amphetamine enhanced retention performance. In rats sympathectomized by peripheral 6-hydroxydopamine, 24 h prior to training, a lower dose of 4-OH-amphetamine (0.21 mg/kg) was most effective in enhancing retention. Adrenal demedullation abolished the memory enhancing effects of DL-4-OH-amphetamine and also D-amphetamine. These findings suggest that the memory enhancing effects of DL-4-OH-amphetamine and D-amphetamine involve adrenal medullary catecholamines.

Adrenal Medulla↗
PubMed1980

Tolerance to ethanol and severity of withdrawal in mice are enhanced by a vasopressin fragment.

Mice were rendered physically dependent on ethanol by inhalation of ethanol vapour and treatment with pyrazole for 3 days. On Day 4, withdrawal convulsions were measured and on Day 5 or later, residual tolerance to the hypothermic effect of an i.p. challenge dose of 3 g/kg ethanol was assessed. Mice continuously infused with the vasopressin fragment des-Gly9-[Arg8]-vasopressin dicitrate (DGAVP) throughout the periods of dependence induction and withdrawal testing exhibited exacerbated withdrawal convulsions. DGAVP also tended to exacerbate withdrawal when injected s.c. repeatedly (10 micrograms/injection/mouse) during testing for withdrawal. The data indicate that these effects were not likely to have been due to subconvulsive activity of DGAVP by itself or to changes in blood levels of ethanol. Continuous infusion of DGAVP enhanced residual tolerance on Day 5 but did not maintain tolerance when the time interval between withdrawal and testing for tolerance was increased. Restricting treatment with DGAVP to the period of induction of dependence (Days 1-3) also enhanced tolerance on Day 5. The data indicate that the vasopressin fragment modulates the development and/or the decay of tolerance to ethanol. In addition it exacerbates withdrawal convulsions, an effect that may be due to modulation of physical dependence.

Animals↗
PubMed1980

Genetic analysis of tolerance to ethanol hypothermia in recombinant inbred mice: effect of desglycinamide(9)-Arginine(8)-vasopressin.

The hypothermic effect of ethanol, tolerance to ethanol hypothermia, and the effect of desglycinamide(9)-Arginine(8)-vasopressin dicitrate (DGAVP) on ethanol hypothermic tolerance were investigated in Bailey's Recombinant Inbred strains of mice. Strains differed markedly in baseline temperatures and initial sensitivity to ethanol. There were no significant strain differences in tolerance. DGAVP attenuated the strain differences in initial sensitivity to ethanol and blocked tolerance development. These effects were accompanied by changes in the pattern of genetic control.

Animals↗
PubMed1980

Endorphins alter acquisition and consolidation of an inhibitory avoidance response in rats.

Peripheral i.p. administration of 1.0 microgram/kg gamma-endorphin to rats, 30 min prior to training in a 1-trial inhibitory avoidance task, enhanced retention performance measured 72 h later. A much smaller dose of 0.1 microgram/kg beta-endorphin administered immediately following training produced a retention deficit. Both of these endorphin effects were time dependent, since gamma-endorphin given 90 min prior to, and beta-endorphin given 90 min after training produced no effect on retention performance. A wide dose range of either gamma-endorphin (0.1-10 micrograms/kg) administered after training or beta-endorphin (0.1-10 micrograms/kg) administered before training had no effect. These results suggest that the behavioral actions of beta-endorphin and smaller beta-lipotropin sequences such as gamma-endorphin, are distinct. We also found that 0.1-100 micrograms/kg of either alpha-endorphin or Met-enkephalin given before or after training was without effect on retention of the response.

Animals↗
PubMed1980

Effects of peptides related to neurohypophyseal hormones on ethanol tolerance.

Mice were rendered tolerant to the hypothermic effect of ethanol by forcing them to inhale ethanol vapor for 3 days. One day after withdrawal, tolerance was assessed by determining the response of the mice to an acute 3 g/kg IP challenge dose of ethanol. Thirty minutes before the injection of ethanol, saline or peptide solution was SC injected. The peptides studied were des-Gly9-Arg8-vasopressin (a peptide with reduced peripheral endocrine activities), oxytocin, and analogs and fragments of these peptides. None of the peptides, with the possible exception of oxytocin, affected body temperature in naive animals or the acute hypothermic response to ethanol in non-tolerant mice. Des-Gly9-Arg8-vasopressin enhanced the expression of tolerance to ethanol hypothermia; shorter fragments of vasopressin did not share this effect. Oxytocin attenuated the expression of tolerance but this may been due to an interaction with the acute effects of ethanol.

Animals↗
PubMed1980

Enkephalin and fear-motivated behavior.

Leu[Enkephalin (400.0 micrograms/kg) and the enkephalin analog [DAla,DLeu]enkephalin (0.4, 4.0, and 40.0 micrograms/kg) were intraperitoneally administered to rats 5 min before they were trained on aversively motivated tasks. The peptides impaired acquisition of a one-way active avoidance response, facilitated acquisition of an inhibitory avoidance response, and had no effect on acquisition of a swim-escape response. The data indicate that the enkephalin effects are not mediated through actions on locomotor activity, pain perception or reactivity, or light sensitivity. Rather, we suggest that [Leu]enkephalin and its analog strengthen the tendency of rats to suppress behavior in the presence of cues previously associated with aversive stimulation. This effect may be due to an enkephalin-induced increase in fear or arousal. The enkephalin effect on behavior was obtained at low doses and was observed within a few minutes after administration. These findings are consistent with the interpretation that enkephalin effects may be initiated at a peripheral site.

Animals↗