EFFECTS OF D-AMPHETAMINE ON BLOOD GLUCOSE AND TISSUE GLYCOGEN LEVELS OF ISOLATED AND AGGREGATED MICE

Hypoglycemia and presumptive rhabdomyolysis secondary to lisdexamfetamine toxicosis in 3 cats

OBJECTIVE

To describe the clinical course and novel biochemical changes in 3 cats with lisdexamfetamine (LDX) toxicosis.

SERIES SUMMARY

Three cats presented with LDX exposure and initially displayed typical clinical signs of amphetamine toxicosis. However, over the course of hospitalization, hypoglycemia and markedly elevated creatine kinase levels consistent with rhabdomyolysis ensued. All cats were treated with sedatives including phenothiazines and dexmedetomidine. Two cats were hospitalized for 4 days and 1 for 5 days. All cats survived.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first case series in cats that reports the novel biochemical changes of delayed hypoglycemia and elevated creatine kinase several days into hospitalization for the treatment of LDX toxicity. The development of delayed clinical signs suggests reconsideration of established hospitalization guidelines for amphetamine ingestion in cats.

Effect of methamphetamine on the fasting blood glucose in methamphetamine abusers

Methamphetamine is a popular psychostimulant worldwide which causes neurotoxicity and neuroinflammation. Although previous studies have characterized potential associations between addictive drugs and fasting blood glucose, the influence of methamphetamine on the blood glucose is still largely unknown. The present study was designed to investigate the change of fasting blood glucose of methamphetamine abusers and to confirm the impairment of liver and kidney. Fasting blood glucose was significantly decreased in methamphetamine abusers and in a high-fat diet mouse model with methamphetamine treatment discontinuation. Serum level of ALT, creatine kinase and creatinine were increased in methamphetamine abusers. Serum level of ALT and AST were increased in a high-fat diet mouse model after methamphetamine injection, but there was no significant difference in the anatomy of the liver and kidney in high-fat diet treated mice with or without methamphetamine. The levels of ALT and creatinine were also increased in the methamphetamine abusers. This study demonstrated that the level of glucose was decreased in methamphetamine abusers and in high-fat diet-fed mice after methamphetamine treatment discontinuation. The effect of methamphetamine on the levels of blood glucose may provide the evidence that methamphetamine abusers should be keep energy balance due to the low blood glucose.

MDMA: a social drug in a social context

RATIONALE

The drug ±3,4-methylenedioxymethamphetamine (MDMA, "ecstasy," "molly") is thought to produce prosocial effects and enhance social interaction. However, in most laboratory studies to date, the participants have been tested under nonsocial conditions, which may not simulate the effects the drug produces in more naturalistic social settings.

METHODS

Healthy experienced MDMA users participated in three laboratory sessions in which they received MDMA (0.5 or 1.0 mg/kg or placebo, double blind). They were randomly assigned to one of three social conditions, in which they were tested alone (solitary (SOL); N = 10), in the presence of a research assistant (research assistant present (RAP); N = 11) or in the presence of another participant who also received the drug (other participant present (OPP); N = 11).

RESULTS

As expected, MDMA increased heart rate and blood pressure and produced positive subjective effects in all the three groups. It also increased ratings of attractiveness of another person and increased social interaction in RAP and OPP. The social context affected certain responses to the drug. The effects of MDMA were greater in the OPP condition, compared to the SOL or RAP conditions, on measures of "feel drug," "dizzy," and on cardiovascular. But responses to the drug on other measures, including social behavior, did not differ across the conditions.

CONCLUSIONS

These findings provide some support for the idea that drugs produce greater effects when they are used in the presence of other drug users. However, the influence of the social context was modest, and it remains to be determined whether other variables related to social context would substantially alter the effects of MDMA or other drugs.

Effects of d-amphetamine in grouped versus isolated humans

This study was designed to determine whether the subjective, behavioral or physiological effects of a stimulant drug in humans depend on whether subjects are tested under isolated or social conditions. Forty-two subjects were randomly assigned to either the Social (SOC) or Isolated (ISO) condition. SOC subjects participated in 4 h laboratory sessions in groups of 3 or 4, whereas ISO subjects participated in the sessions alone. All subjects participated in three sessions, during which they received capsules containing d-amphetamine (10 or 20 mg) or placebo, in mixed order under double blind conditions. Subjective, physiological and behavioral measures were obtained at regular intervals, d-amphetamine produced dose-related, prototypic stimulant effects on many measures, including self-reported mood states, behavioral indices and physiological measures. Most of these effects were unaffected by the setting in which subjects were tested (SOC vs ISO). However, body temperature was overall higher in the SOC group, and there was a trend for d-amphetamine to produce greater hyperthermic effects in the SOC group. In addition, 10 mg d-amphetamine increased heart rate in the SOC group but not in the ISO group. The results suggest that, like in laboratory animals, some of the effects of stimulants in humans are greater under aggregated conditions. However, unlike in the animal studies, this observed enhancement of the drug's effects under aggregated conditions was limited to physiological measures and did not apply to other subjective or behavioral measures.

The Effect of Stress on Spontaneous Nest Leaving Behavior in the Mouse: An Improved Model of Stress-Induced Behavioral Pathology

The present experiments were conducted to develop a more sensitive and reliable model of stress-induced behavioral pathology in the mouse. Male mice were housed singly in nest cages connected to either a circular tunnel, a recreational cage or a large box with food foraging apparatus. Spontaneous nocturnal out of nest activity or food foraging behavior in these environments was continuously monitored for a two week period during which time the effects of stress were examined. It was found that both repeated restraint and aggression stress markedly and persistently reduced out of nest nocturnal activity or food foraging behavior in all 3 environments but did not alter activity in a novel open field or plus maze or food or saccharin intake in the nest cage. In a preliminary experiment the reduction in out of nest activity by stress was attenuated by prior chronic treatment with the antidepressant, desmethylimipramine. Plasma corticosterone was elevated immediately after aggression stress but reduced 5 hr after chronic aggression stress. The reduction in activity did not appear the result of increased anxiety as measured by spontaneous risk assessment behavior in the nest. It is concluded that the decrease in out of nest activity after stress in the present studies models a withdrawn behavioral state and may be due to either or both a decrease in appetitive motivation to leave the nest or an increased aversion to the external environment which does not apparently involve anxiety.

Blockade of effect of stress on risk assessment behavior in mice by a beta-1 adrenoceptor antagonist

Previous studies have shown that acute stress impairs risk assessment behavior in mice. The present study was undertaken to determine the role of beta adrenoceptors, which are known to be stimulated by stress, in this effect. Mice were treated with either a beta-1 antagonist, betaxolol, a beta-2 antagonist, ICI 118551, an alpha-1 antagonist, prazosin, or an alpha-2 antagonist, yohimbine, and 30 min later were subjected to a 1-h session of restraint stress. Thirty minutes after the stress the animals were tested for the entry latency, number of headpokes prior to entry, and the path of entry into a white open field from a small dark box. In agreement with previous findings, stress was found to markedly reduce risk assessment behaviors as reflected by a reduced entry latency, a reduced number of headpokes and a changed entry path from wall hugging to central entry. Betaxolol was found to prevent all of the above effects of stress dose dependently, whereas ICI 118551, prazosin, and yohimbine had no reversal effects. It is concluded that beta-1 receptor activation and possibly brain glycogen depletion is involved in the effects of stress on risk assessment behavior.

Delayed arousal from anesthesia: a further similarity between stress and beta-1 adrenoceptor blockade

The present studies investigated the role of beta adrenergic receptors in mediating arousal from anesthesia and the effects of stress on this process. In support of previous findings by others, it was found that blockade of beta-1 and beta-2 receptors by propranolol delayed arousal from halothane anesthesia and that this effect was attributable to blockade of beta-1 receptors because it was duplicated by betaxolol but not by ICI 118,551. Restraint stress also produced a delay in arousal from both halothane and hexobarbital anesthesia. This effect, which was observed at 0.5 but not 24 h after the stress, could not be explained by a stress-induced alteration in the metabolism of the anesthetic, as no difference in brain concentration of hexobarbital was found between stressed and control mice. The parallel effects of beta-1 blockade and stress further supports the hypothesis that stress produces an impairment in function at either the beta-1 receptor or some process coupled to this receptor.

Motilities of isolated and aggregated mice; a difference in ultradian rhythmicity

Isolated mice display higher locomotor activity and greater sensitivity to d-amphetamine than aggregated mice. Ultradian motility rhythms can be shown to differ both quantitatively and qualitatively between isolated and aggregated mice.

Methamphetamine-induced insulin release

Administration of methamphetamine or amphetamine to rats and mice produces a rapid increase in the level of immunoassayable plasma insulin not attributable to hyperglycemia. While in the mouse this release of insulin is followed consistently by a profound hypoglycemia, in the rat this response is variable. Studies in vitro demonstrate that insulin is released by a direct effect of methamphetamine on the pancreas.

Physiological and drug-induced changes in the glycogen content of mouse brain

1. The effect of the method of killing on the concentration of glycogen in mouse brain was determined. The cerebral glycogen content of mice killed by immersion in liquid nitrogen did not differe significantly from that of animals decapitated and the heads immediately frozen. A delay before freezing led to the rapid loss of brain glycogen, with a 17% fall at 10 s and an 82% loss after 5 min.2. Hyperglycaemia, induced by the administration of D-glucose, resulted in an 8.3% loss of brain glycogen after 120 min. Insulin hypoglycaemia produced a 10.7% fall in glycogen at 60 min followed by an 11.2% increase at 120 min.3. Exposure to either high (32 degrees C) or low (10 degrees C) ambient temperatures caused a depletion of brain glycogen.4. A circadian rhythm of brain glycogen concentration was found, with a nadir which was coincident with the peak of locomotor activity and body temperature.5. Drugs from several pharmacological classes were studied for their in vivo effect on the concentration of glycogen in mouse brain.6. Brain glycogen was increased by all the depressant drugs tested, and by some drugs which had little effect on behaviour (diphenhydramine, phenytoin and propranolol), or which caused excitation (caffeine and nialamide).7. Glycogen was depleted only by amphetamine-like compounds or by bemegride-induced convulsions.8. The results are discussed with particular reference to the possible relation between catecholamines and glycogen metabolism in the brain.