Narcotic analgesics and aggression

Aggression and increased glutamate in the mPFC during withdrawal from intermittent alcohol in outbred mice

RATIONALE

Disrupted social behavior, including occasional aggressive outbursts, is characteristic of withdrawal from long-term alcohol (EtOH) use. Heavy EtOH use and exaggerated responses during withdrawal may be treated using glutamatergic N-methyl-D-aspartate receptor (NMDAR) antagonists.

OBJECTIVES

The current experiments explore aggression and medial prefrontal cortex (mPFC) glutamate as consequences of withdrawal from intermittent access to EtOH and changes in aggression and mPFC glutamate caused by NMDAR antagonists memantine and ketamine.

METHODS

Swiss male mice underwent withdrawal following 1-8 weeks of intermittent access to 20 % EtOH. Aggressive and nonaggressive behaviors with a conspecific were measured 6-8 h into EtOH withdrawal after memantine or ketamine (0-30 mg/kg, i.p.) administration. In separate mice, extracellular mPFC glutamate after memantine was measured during withdrawal using in vivo microdialysis.

RESULTS

At 6-8 h withdrawal from EtOH, mice exhibited more convulsions and aggression and decreased social contact compared to age-matched water controls. Memantine, but not ketamine, increased withdrawal aggression at the 5-mg/kg dose in mice with a history of 8 weeks of EtOH but not 1 or 4 weeks of EtOH or in water drinkers. Tonic mPFC glutamate was higher during withdrawal after 8 weeks of EtOH compared to 1 week of EtOH or 8 weeks of water. Five milligrams per kilogram of memantine increased glutamate in 8-week EtOH mice, but also in 1-week EtOH and water drinkers.

CONCLUSIONS

These studies reveal aggressive behavior as a novel symptom of EtOH withdrawal in outbred mice and confirm a role of NMDARs during withdrawal aggression and for disrupted social behavior.

Effects of SCH 23390, raclopride, and haloperidol on morphine withdrawal-induced aggression in male mice

Dopamine seems to play a very important role in aggressive behavior observed in morphine withdrawal. The effect of SCH 23390 (0.5 mg/kg), raclopride (0.3 mg/kg), and haloperidol (0.1 mg/kg) on morphine withdrawal-induced aggression has been studied in this work. Mice were rendered dependent by a daily injection of morphine (2.5 mg/kg) for 14 days. Three different experiments were carried out with the objective to evaluate the antiaggressive effect of the dopamine antagonists on: first, spontaneous morphine withdrawal; second, naloxone-induced withdrawal; and third, naloxone-induced withdrawal after previous administration of the neuroleptics. Thirty minutes after injection of the dopamine antagonists, experimental animals were confronted in a neutral area with anosmic, group-housed conspecifics (standard opponents), and aggression was evaluated by estimation of times allocated to 11 different behavioral categories. Morphine withdrawal produced an increase in aggressive behavior and a decrease in social and nonsocial behaviors. The three neuroleptics counteracted this aggression, but when SCH 23390 (selective D1 antagonist) and haloperidol (mixed D1/D2 antagonist) were administered in naloxone-induced withdrawal, the effect was greater in comparison to the spontaneous withdrawal. However, no changes were observed after raclopride administration (selective D2 antagonist). In conclusion, the alterations in the dopaminergic system produced by opiate withdrawal depend on the type of withdrawal produced, and this produces a change in the antiaggressive potency of the dopamine antagonists.

Interaction of morphine and haloperidol on agonistic and motor behaviors of male mice

To further clarify the interaction between opioid and dopaminergic systems, the effects of simultaneous administration of morphine hydrochloride (1.25 or 2.5 mg/kg) and haloperidol (0.1 mg/kg) on aggressive behavior of male mice were explored. Isolated male mice (experimental animals) were confronted in a neutral area with anosmic, group-housed consepecifics (standard opponents) 30 min after injection of both compounds, and aggression was evaluated by estimation of times allocated to 11 different behavioral categories. In the first experiment (which functioned as a pilot study), the two doses of morphine were explored. In the second one, incorporating a more complete experimental design, only the lowest morphine dose was used and the animals were preselected by a previous aggression test. In attack behavior, morphine added to haloperidol counteracted, at least partially, the antiaggressive effect of the neuroleptic. In contrast, the impairing effects of haloperidol on motor activity were increased by the addition of morphine. These results show that the behavioral effects of dopaminergic antagonists are modulated by opioid influences and that opiates and dopaminergic agents interact in a different manner on motor and on aggressive behaviors.

Behavioral profile of raclopride in agonistic encounters between male mice

Raclopride is a substituted benzamide with high selectivity as an antagonist of central dopaminergic D2 receptors and potential antipsychotic effects. In comparison with a classic DA receptor blocking agent like haloperidol, raclopride displays an atypical profile in preclinical tests for extrapyramidal side effects. Antiaggressive properties of raclopride on agonistic behavior have not yet been fully explored. In this work the effects of raclopride (0.1, 0.3, or 0.6 mg/kg) on aggressive and motor behaviors in male mice were studied. Aggression tests were performed 30 min after injections. Encounters were videotaped and behavior was evaluated, measuring the time spent in 11 broad categories of behavior. The results show a clear antiaggressive effect of raclopride, with very little motor impairment and some increase in exploratory behavior. This behavioral profile is very similar to the one observed with other atypical neuroleptics and differs somewhat from that found in the classic compounds.

Antiaggressive and motor effects of haloperidol show different temporal patterns in the development of tolerance

The study of the temporal course of tolerance development was used as a means to separate different aspects of the action of haloperidol on social behavior. Agonistic behavior was studied in isolated male mice that confronted standard opponents (anosmic and grouped conspecifics) in a neutral area. The aggressive and motor behaviors of the experimental animals were evaluated 30 min or 24 h either after a single injection of haloperidol (0.4 mg/kg) or following the last of a series of 15 or 30 injections. When animals were evaluated 30 min after the haloperidol injection, no tolerance to the antiaggressive effects was evident. The action on immobility, on the contrary, showed a clear tolerance development with repeated drug administration, both with 15 and 30 injections. When evaluated 24 h after the last injection, tolerance to the antiaggressive effects developed with repeated injections. Increased immobility was never found in the tests carried out after 24 h, not even in the single injection group. The clear divergence found in the temporal courses of tolerance to haloperidol in its antiaggressive and motor effects suggests that these actions are mediated through different neurophysiological mechanisms. A parallel with extrapyramidal and therapeutic effects is discussed.

Neuropeptide levels in premenstrual syndrome

To determine whether changes in circulating levels of neuropeptides are associated with symptoms of premenstrual syndrome (PMS), 20 women with the diagnosis of PMS and 20 asymptomatic subjects were studied. The premenstrual beta-endorphin levels were significantly lower in PMS patients (P = 0.0001). The decrease in beta-endorphin levels during the luteal phase, compared with the follicular phase, in PMS patients was also significant (P = 0.0002). Neurotensin, human pancreatic peptide, vasoactive intestinal polypeptide, gastrin, and bombesin-like immunoreactivity levels did not reveal significant changes between days 7 and 25 in patients with PMS.

Irritable aggression induced by delta 9-tetrahydrocannabinol in rats pretreated with 6-hydroxydopamine

Administration of delta 9-tetrahydrocannabinol (THC) to grouped rats injected intraventricularly with 6-hydroxydopamine (6-OHDA) produced violent fighting accompanied by remarkable hyperirritability. This behavior was induced reproducibly from the 10th to 100th postoperative days. It was shown that this irritable aggression could be measured continuously and quantitatively in terms of degree of activity and/or vocalization using a newly designed analyzer. The effect of THC differed markedly from the action of apomorphine and methamphetamine in 6-OHDA pretreated rats. Apomorphine induced irritable aggression but not vigorous vocalization. On the other hand, methamphetamine induced much less irritable aggression than apomorphine-induced aggression. It is assumed that a THC-invoked imbalance in catecholamine agonistic and serotonin antagonistic action brought about by activation of supersensitized catecholaminergic receptor was operating to produce the aggression. Specifically, hypoactivity of serotonergic neurons might play a key role in the occurrence of THC-induced irritable aggression.

Naloxone inhibits intermale aggression in isolated mice

Aggression and thermal pain thresholds were measured in separate groups of isolated male mice following 0.2-5.0 mg/kg SC injections of the opiate antagonist naloxone. The drug inhibited aggressive behaviors dose-dependently, but had no effect on pain. These results suggest that endogenous opioid systems may be activated during repeated intermale aggressive encounters.

Premenstrual syndrome

The premenstrual syndrome (PMS) is a major clinical entity afflicting a large segment of the female population. Available information are descriptive in nature and the etiology of this syndrome remains unclear. In this review, both biochemical and psychosocial elements of the syndrome have been explored in an effort to redefine the pathophysiology of this seemingly multifactorial psychoneuroendocrine dysfunction. We propose that luteal phase sensitivity to and subsequent withdrawal from the central effects of the neuropeptides beta-endorphin and alpha-melanocyte-stimulating hormone result in a cascade of neuroendocrine changes within the brain-hypothalamus-pituitary complex. Modulation of neurotransmitter function by these peptides may produce alterations in mood and behavior as well as enhance pituitary release of prolactin and vasopressin. Variable gonadal steroid modulation of these responses from subject to subject likely accounts for the heterogeneous clinical manifestations of the PMS.

Acute heroin abstinence in man: II. Alterations in rapid eye movement (REM) sleep

The purpose of this study was to examine the effects of withdrawal from heroin upon rapid eye movement (REM) sleep. Subjects included both heroin-dependent patients and drug-free controls. The drug users were young males who had an average daily intake of approximately 973 mg of 92 - 98% pure heroin before entering the study. All electrophysiological data were obtained via a telemetry system on a 24-hour per day basis for 5 to 7 consecutive days. EEG records were scored into the standard awake and sleep states. Results showed a marked decrease in total amount of REM sleep during heroin withdrawal. This total decrease was associated with a decrease in duration of individual REM episodes and a large decrease in the number of occurrences of REM sleep. The heroin-dependent patients during withdrawal also showed a prolonged latency from sleep onset to first REM episode and a reduced number of REM shifts per 24-hour period. No significant difference in REM sleep interval was observed between the control subjects and drug users. Some of the overt behavioral characteristics associated with heroin withdrawal may be indirectly related to the concurrent loss in REM sleep as observed in this study.

Acute heroin abstinence in man: I. Changes in behavior and sleep

The purpose of this study was to examine overt behavioral characteristics and sleep during acute heroin abstinence in man. Both heroine-dependent patients and drug-free control subjects were observed and monitored on a 24-hour per day basis for 5 to 7 days. Observational data were analyzed for frequency of occurrence of various behaviors including the signs and symptoms of withdrawal. Electroencephalographic (EEG) data were scored into awake and sleep stages according to standard techniques. The heroin-dependent subjects generally displayed a higher number of observations across all recording days as compared to the controls. In addition, the signs and symptoms of withdrawal for these patients peaked on day 1 or day 2 and then declined over the remaining recording days. The EEG state data showed an increase in waking and decrease in both slow wave and REM sleep during acute heroin withdrawal. Total sleep was maximally suppressed on withdrawal days 2 and 3 and was still below normal control values on withdrawal days 5 - 7. REM sleep was more disrupted than slow-wave sleep during withdrawal from heroin. Results of this study indicate that heroin withdrawal produces a differential action upon central nervous system structures responsible for the various states of sleep, waking and related behaviors.