The hyperkinetic syndrome following long-term haloperidol treatment: involvement of dopamine and noradrenaline

Differential behavioural effect of quinpirole in neuroleptic-pretreated rats - role of alpha(1)-adrenoceptor

This paper presents the effect of 14-day intraperitoneal (i.p.) neuroleptic treatment on the behavioural response of Wistar rats to (-)-quinpirole hydrochloride (3 mg/kg, i.p.) administered 24 h after the last neuroleptic dose. Chlorpromazine hydrochloride (10 mg/kg), haloperidol (2 mg/kg) or (+/-)-sulpiride (100 mg/kg) increased the effect of quinpirole; however, there were qualitative and quantitative differences between the neuroleptics. Chlorpromazine and haloperidol, but not sulpiride, pretreatment enhanced quinpirole-induced locomotor hyperactivity. Prazosin (0.5 mg/kg, i.p. ) given to chlorpromazine-treated rats 1 h before quinpirole attenuated the quinpirole-induced hyperlocomotion. In chlorpromazine-pretreated rats, quinpirole elicited defensive aggressive behaviour with vocalization, copulatory attempts, intense rearing and head-down sniffing. When prazosin was given before quinpirole, head-down sniffing and object-directed oral activity were mainly observed. In haloperidol-pretreated rats, quinpirole induced intense head-down sniffing, rearing, grooming and object-directed oral activity. In sulpiride-pretreated rats, quinpirole induced intense head-down sniffing, grooming and object-directed oral activity. The results of the study suggest that differences in the behavioural expression of dopamine D(2) receptor supersensitivity induced by neuroleptics may be, at least in part, caused by concurrent stimulation of alpha(1)-adrenoceptors.

Etiology of alcoholism: relevance of prenatal hormonal influences on the brain, anomalous dominance, and neurochemical and pharmacological brain asymmetry

Because of possible prenatal hormonal influences on the brain, leading to anomalous dominance, pharmacological and neurochemical asymmetry, and consequent antisocial personality and phobic anxiety, the subject ingests ethanol for its tension-reducing properties via endorphinergic activation and the dopaminergic reward system. Due to presence of stress, and effects of anomalous dominance on ethanol metabolizing enzymes, ethanol-oxidizing systems are activated leading to high rates of ethanol elimination from the blood, and thus the decreased intensity of reaction to ethanol, leading to tolerance. Since stress can cause a decrease in the number of opiate receptors, a vicious cycle of ingesting more and more ethanol may be instituted.

Inhibiting noradrenergic overactivity by inhibition of thromboxane and concomitant activation of opiate receptors via dietary means

A yin-yang hypothesis is presented linking noradrenergic activity, thromboxane, melatonin, left hemisphere functioning, and cyclic AMP on the one hand, and dopamine, beta-endorphin, calcium, right hemisphere functioning, and cyclic GMP on the other. It is further suggested that there is a yoking of NA, TXA2, serotonin and melatonin in the left hemisphere, and a similar yoking of DA, BE, calcium and cGMP in the right. Evidence is presented to support the hypothesis that each element (NA, TXA2, etc.) on one side can modulate or balance a corresponding element (DA, BE, etc.) on the other. It is suggested that thromboxane is the key element in noradrenergic overactivity and that not taking this into consideration has confounded much prior research. This theory takes into account information processing models as well as pharmacological data and neurochemical theory on coupling of adenylate cyclase to its hormone receptors. Inhibiting noradrenergic overactivity can be obtained by inhibiting thromboxane and concomitantly activating opiate receptors. This protocol may have clinical utility in treating a wide range of disorders such as: anxiety, depression, schizophrenia, sleeplessness, withdrawal states, enuresis, Gilles de la Tourette syndrome, Parkinsonism, Alzheimers, dementia, anorexia, infant ruminations, essential tremor, spasticity of spinal cord injury, diarrhoea, ulcerative colitis, extrapyramidal symptoms, akathisia, neuroleptic malignant syndrome, attention deficit disorder, hyperhidrosis, and possibly AIDS.

Carbon dioxide inhalation therapy for anxiety: effectiveness due to increased prostacyclin and decreased thromboxane biosynthesis? Re-evaluation of a neglected technique

CO2 inhalation has been used for many years in the treatment of various psychiatric and medical disorders and different rationales for its effect have been offered. Since it has been recently found that CO2 inhibits thromboxane biosynthesis and raises levels of prostacyclin, a new rationale for the effect of CO2 inhalation, based on its inhibition of thromboxane biosynthesis, is offered.

Catecholamine metabolism in the attention deficit disorder: implications for the use of amino acid precursor therapy

The use of catecholamine precursors and agonists in the attention deficit disorder and various biochemical studies have implicated deficient catecholamine metabolism in the pathogenesis of this illness. The amino acid L-tyrosine, a catecholamine precursor, is capable of augmenting central dopamine norepinephrine. Study of its use in the treatment of the attention deficit disorder as a safer alternative to stimulant therapy is thus warranted.

Spontaneous and apomorphine-induced locomotor changes parallel dopamine receptor differences in two rat strains

Two inbred strains of rats (F344 and Buffalo) were tested for differences in spontaneous and apomorphine-induced inhibition of locomotor activity. F344 rats showed greater percentage decreases in locomotion after apomorphine (0.25, 1.0 and 2.5 mg/kg) compared to the Buffalo strain. F344 rats also showed higher levels and slower habituation of spontaneous locomotor activity. F344 rats had previously been shown to have significantly higher densities of D2-dopamine receptors in the striatum and olfactory tubercle and also more apomorphine-induced stereotypy when compared to Buffalo rats. These results confirm and extend previous studies suggesting that genetic differences in brain D2-dopamine receptors can predict behavioral differences in locomotor activity.

Amphetamine-induced hypolocomotion in mice with more brain D2 dopamine receptors

The relationship between brain D2 dopamine receptors and locomotor response to amphetamine was investigated in eight strains of mice. The D2 receptor is defined as that dopaminergic site with high affinity (nanomolar) for neuroleptics and low affinity (micromolar) for agonists. D2 receptors were measured in the striatum and olfactory tubercle using [3H]spiperone and 10 microM sulpiride to define specific binding. Four inbred strains of mice (CBA/J; C57BL/6J; DBA/2J; SEC/1ReJ) had low receptor densities of about 380 and 160 fmoles/mg protein in the striatum and olfactory tubercle, respectively; all these mice were essentially nonresponsive (i.e., locomotion) to low doses of amphetamine (0.5 and 1.0 mg/kg i.p.) or showed hyperlocomotion to high doses (5 mg/kg). Three other mouse strains (BALB/cJ; A/J; C3H/HeJ) had higher densities of about 600 and 230 fmoles/mg protein in the striatum and olfactory tubercle, respectively, and these mice all responded with hypolocomotion to the low doses and hyperlocomotion to the high dose of amphetamine. The two genetically different populations, one of which responded to amphetamine with hypolocomotion while the other did not, are analogous to hyperactive children, only 70% of whom respond to amphetamine-like drugs. Thus, the mice with high receptor density may serve as a model for studying the hyperactivity syndrome which may be associated with dopaminergic dysfunction.

BehavioraL and biochemical changes caused by muscimol in mice withdrawN from haloperidol administration

This study was designed to determine the behavioral and biochemical effects of the gamma-aminobutyric acid (GABA) agonist, muscimol, in mice withdrawn from chronic haloperidol administration. Mice received either haloperidol or vehicle In their drinking water for 35 days, after which the haloperidol was replaced with vehicle. Seven days after withdrawal from chronic treatment with haloperidol, the effect of apomorphine on the climbing behavior of haloperidol-withdrawn mice was markedly enhanced as compared to control mice that received only vehicle. Muscimol produced a dose-related reduction in the intensity of climbing behavior induced by apomorphine in both control and haloperidol-withdrawn mice. However, the inhibition of climbing behavior induced by muscimol was significantly greater in haloperidol-withdrawn animals. In addition, in haloperidol-withdrawn mice, muscimol produced a significant reduction in striatal homovanillic (HVA) levels with no change in striatal dopamine (DA) levels, suggesting a decrease in DA turnover. In support of this conclusion, muscimol decreased the disappearance of dopamine in haloperidol-withdrawn mice that were injected with alpha-methyl-p-tyrosine. Both the behavioral and biochemical effects of muscimol were blocked by the GABA antagonist, picrotoxin. These results indicate that after chronic haloperidol administration there is not only an enhanced response to dopaminergic agonists but also to GABAergic agonists.

Facilitation of active avoidance responding following chronic haloperidol treatment in rats

Rats were chronically treated with once-daily injections of either haloperidol or vehicle for 21 days. When spontaneous locomotor activity or acquisition of active avoidance in a two-way shuttle box were measured 48 h after the cessation of chronic treatment, the haloperidol-treated animals were significantly more active and performed significantly more avoidance responses. These findings suggest that the increased dopamine receptors that have been reported following chronic haloperidol treatment may have functional relevance.

Haloperidol-induced hyperactivity in neonatal rats: effect of lithium and stimulants

The effect of chronic subcutaneous administration of haloperidol directly into neonatal rats was investigated as a possible model for the hyperkinetic syndrome in human children in terms of its onset, duration and offset of hyperactivity. In addition, the ability of chronically-administered lithium in the diet of nursing mothers to attenuate the haloperidol-induced hyperactivity was investigated. Experiments with acute administration of the clinically-effective stimulants, amphetamine and methylphenidate, to the pups were also conducted to determine the adequacy of this behavioral model vis-a-vis the human condition. The results indicate that, although chronic haloperidol (2.5 mg/kg) produced hyperactivity relative to controls on the 25th day of life, this hyperactive behavior does not return to control levels at 30 days of age. Moreover, neither the stimulants nor lithium attenuates this hyperactivity and, indeed, lithium, by itself, produces increased activity. Thus, chronic haloperidol administered directly into neonatal rat pups produces hyperactivity possibly by the production of dopaminergic supersensitivity, yet this effect does not model the temporal course seen in hyperkinetic humans. In addition, the administration of drugs that are clinically-useful in treating childhood hyperactivity were unable to decrease the hyperactivity produced by haloperidol in neonatal rats. Taken together, these observations cast doubt upon the usefulness of this animal model to mimic the human condition.