Typical and Atypical Neuroleptics Induce Alteration in Blood-Brain Barrier and Brain 59FeCl3 Uptake

Abstract: Long-term neuroleptic medication of schizophrenic patients induces extrapyramidal motor side effects, of which tardive dyskinesia (TD) is the most severe. The etiology of TD is still obscure. Recently, it was suggested that abnormal iron metabolism may play a crucial role in neuroleptic-induced dopamine D₂ receptor super-sensitivity. The apparent relationship between neuroleptics and iron is further supported by the increase of iron in the basal ganglia of patients with TD. We now report on the ability of neuroleptics to alter the blood-brain barrier in the rat and to potentiate the normally limited iron transport into the brain. Thus, chronic treatment of rats with chlorpromazine and haloperidol facilitated ⁵⁹Fe³⁺ uptake into brain cells. In contrast, clozapine, an atypical antipsychotic neuroleptic with little extrapyramidal motor side effects, caused iron sedimentation in brain blood vessels with no sign of detectable iron in the cells. Moreover, chronic treatment with chlorpromazine and haloperidol caused a 43% and 24% reduction, respectively, in liver nonheme iron, whereas clozapine induced an 81% increase. The apparent different potentials of chlorpromazine, haloperidol, and clozapine to increase iron transport into the brain from its peripheral stores may be linked to the severity of extrapyramidal motor side effects they induce and to the pathophysiology of TD.     

Comparative neurochemical changes associated with chronic administration of typical and atypical neuroleptics: implications in tardive dyskinesia

An important goal of current neuroleptic research is to develop antipsychotic compounds with the low incidence of extrapyramidal side effects. The therapeutic success and less side-effect of atypical anti-psychotics such as clozapine and risperidone has focused the attention on the role of receptor systems other than dopaminergic system in the pathophysiology of neuroleptics-associated extrapyramidal side effects. The present study compares the effect of chronic administration of typical and atypical antipsychotics on neurochemical profile in rat forebrain. The study was planned to study changes in extracellular levels of norepinephrine, dopamine and serotonin in forebrain region of brain and tried to correlate them with hyperkinetic motor activities (vacuous chewing movements (VCM's), tongue protrusions and facial jerking) in rats, hall mark of chronic extrapyramidal side-effect of neuroleptic therapy tardive dyskinesia. Chronic administration of haloperidol (1 mg/kg) and chlorpromazine (5 mg/kg) resulted in significant increase in orofacial hyperkinetic movements where as clozapine and risperidone showed less significant increase in orofacial hyperkinetic movements as compared to control. There were also significant decrease in the extracellular levels of neurotransmitters dopamine, norepinephrine and serotonin in fore-brain as measured by HPLC/ED after chronic administration of haloperidol and chlorpromazine. Chronic administration of atypical neuroleptics clozapine and risperidone resulted in the decrease in extracellular concentration of dopamine and norepinephrine but the effect was less significant as compared to typical drugs. However, treatment with atypical neuroleptics resulted in 3 fold increase in serotonin levels as compared to forebrain of control rats. Typical and atypical neuroleptics showed varying effects on neurotransmitters, especially serotonin which may account for the difference in their profile of side effects (Tardive dyskinesia).     

Differential effects of chronic treatment with haloperidol and clozapine on the level of preprosomatostatin mRNA in the striatum,nucleus accumbens,and frontal cortex of the rat

1. The goal of this work was to determine the effects of typical and atypical neuroleptics on the level of preprosomatostatin messenger RNA (mRNA) in regions of the rat brain innervated by dopaminergic neurons. 2. Quantitative in situ hybridization histochemistry was used to measure the levels of mRNA encoding preprosomatostatin in neurons of the striatum, the nucleus accumbens, and the medial and lateral agranular areas of the frontal cortex in adult rats treated with either haloperidol or clozapine. 3. In untreated animals, the density of neurons containing preprosomatostatin mRNA was higher in the nucleus accumbens than in the striatum and frontal cortex. The intensity of labeling per neuron, however, was higher in the striatum than in the two other areas examined, suggesting that the expression of preprosomatostatin mRNA is differentially regulated in these brain regions. Chronic administration of haloperidol (1 mg/kg for 28 days) induced a significant decrease in the labeling for preprosomatostatin mRNA in neurons of the nucleus accumbens, frontal cortex, and medial but not lateral striatum. Treatment with clozapine (20 mg/kg for 28 days) increased the levels of preprosomatostatin mRNA in the nucleus accumbens but not in the striatum or the frontal cortex. 4. These results support a role for dopamine in the regulation of central somatostatinergic neurons. The differences in the effects of haloperidol, a neuroleptic which induces extrapyramidal side effects, and clozapine, which does not, suggest that somatostatinergic neurons may play an important role in the regulation of motor behavior.     

Adaptive changes in sigma and phencyclidine receptors during the long-term use of haloperidol and raclopride in rats

The experiments on male albino rats have shown that 15 days haloperidol (0.5 mg/kg) and raclopride (1 mg/kg) treatment, but not acute administration, causes the increase of density of sigma receptors in the brain. The number of phencyclidine receptors was also elevated, but this increase was not statistically evident. The behavioral effects of ketamine (5 mg/kg) were evidently decreased after long-term haloperidol and raclopride treatment. The motor stimulation and stereotyped behavior induced by apomorphine (0.15 mg/kg) were increased only after treatment of haloperidol, but not raclopride. It seems probable that repeated neuroleptic (haloperidol and raclopride) treatment causes the hyposensitivity of sigma and phencyclidine receptors, despite the increase of their number. It is possible that this change is related to the depolarization inactivation of dopamine neurons caused by repeated neuroleptic administration.     

Functional Consequences of Iron Overload in Catecholaminergic Interactions: the Youdim Factor

The influence of postnatal iron overload upon implications of the functional and interactive role of dopaminergic and noradrenergic pathways that contribute to the expressions of movement disorder and psychotic behaviours in mice was studied in a series of experiments. (1) Postnatal iron overload at doses of 7.5 mg/kg (administered on Days 10–12 post partum) and above, invariably induced a behavioural syndrome consisting of an initial (1st 20–40 min of a 60-min test session) hypoactivity followed by a later (final 20 min of a 60-min test session) hyperactivity, when the mice were tested at adult ages (age 60 days or more). (2) Following postnatal iron overload, subchronic treatment with the neuroleptic compounds, clozapine and haloperidol, dose-dependently reversed the initial hypoactivity and later hyperactivity induced by the metal. Furthermore, DA D₂ receptor supersensitivity (as assessed using the apomorphine-induced behaviour test) was directly and positively correlated with iron concentrations in the basal ganglia. (3) Brain noradrenaline (NA) denervation, using the selective NA neurotoxin, DSP4, prior to administration of the selective DA neurotoxin, MPTP, exacerbated both the functional (hypokinesia) and neurochemical (DA depletion) effects of the latter neurotoxin. Treatment with L-Dopa restored motor activity only in the animals that had not undergone NA denervation. These findings suggest an essential neonatal iron overload, termed “the Youdim factor”, directing a DA–NA interactive component in co-morbid disorders of nigrostriatal-limbic brain regions. Special issue dedicated to Dr. Moussa Youdim.     

Haloperidol and atypical antipsychotics share a same action of decreasing P75(NTR) mRNA levels in PC12 cells

P75(NTR) is a common neurotrophin receptor which binds all neurotrophins with similar affinities and has been shown to be capable of mediating programmed cell death. In this study, we investigated effects of the antipsychotic drugs (APDs) haloperidol, clozapine, quetiapine, and risperidone on p75(NTR) mRNA levels in PC12 cells. Haloperidol is a prototype of typical APDs, and the other three drugs are atypical APDs, which are effective in reducing negative symptoms and cognitive deficits of schizophrenia, cause less side effects, and are more tolerable compared to haloperidol. PC12 cells were cultured with various concentrations of haloperidol, clozapine, quetiapine, or risperidone, in their media. After culture for 48h, the cell viabilities and p75(NTR) mRNA levels were measured. It was shown that both haloperidol and the atypical APDs used in this study deceased p75(NTR) mRNA levels in PC12 cells in a dose dependent manner, while not affecting cell viabilities. In further experiments, doses that produced significant/greatest effects were chosen and provided in the culture media for various periods. Decreases in p75(NTR) mRNA levels were observed in cultures treated for 12h with quetiapine, 24h with clozapine or risperidone, or for 48h with haloperidol. These results suggest that both haloperidol and atypical APDs have the same action of decreasing p75(NTR) mRNA levels in PC12 cells. Although the underlying molecular mechanism of this action remains to be elucidated, this finding is particularly relevant given the neurodevelopmental deficits associated with schizophrenia and important roles of p75(NTR) in mediating cell death.     

Haloperidol-loaded polysorbate-coated polymeric nanocapsules decrease its adverse motor side effects and oxidative stress markers in rats

Haloperidol is the most widely used antipsychotic drug in the treatment of psychiatric disorders. Despite its satisfactory therapeutic effect, its chronic use is related to severe motor side effects. Here, we investigate the incidence of motor side effects of haloperidol-loaded nanocapsules when compared to free haloperidol and the relation with oxidative stress (OS) development. Both vehicle (B-NcFO) and haloperidol loaded polysorbate-coated nanocapsules suspension (H-NcFO) prepared with fish oil as core showed uniform and rounded particles, nanometric size, negative zeta potential, low polydispersity indices and high encapsulation efficiency. Wistar rats received a single dose of free haloperidol (FH), B-NcFO or H-NcFO (0.2mg/kg ip) and were submitted to acute motor side effects evaluation 1h after the injection. Lower catalepsy time and oral dyskinesia were observed in H-NcFO-treated group than in FH group; however, both formulations decreased animals' locomotor activity. In a experiment performed subchronically, rats injected daily with H-NcFO (0.2mg/kg-ip) for 28days showed decreased oral dyskinesia frequency and catalepsy time and no impairment on locomotor activity as compared to FH group (0.2mg/kg-ip). FH group showed higher OS, as observed by increased lipid peroxidation and reduced glutathione levels and catalase activity in extrapyramidal region. Our findings showed that nanocapsules may be an efficient form to prevent or minimize haloperidol motor side effects, which are related to OS development, ameliorating psychiatric patients' quality of life.     

Effects of Subchronic Clozapine and Haloperidol on Striatal Glutamatergic Synapses

Abstract: Subchronic treatment with haloperidol increases the number of asymmetric glutamate synapses associated with a perforated postsynaptic density in the striatum. To characterize these synaptic changes further, the effects of subchronic (28 days) administration of an atypical antipsychotic, clozapine (30 mg/kg, s.c.), or a typical antipsychotic, haloperidol (0.5 mg/kg, s.c.), on the binding of [³H]MK-801 to the NMDA receptor-linked ion channel complex and on the in situ hybridization of riboprobes for NMDAR2A and 2B subunits and splice variants of the NMDAR1 subunit were examined in striatal preparations from rats. The density of striatal glutamate immunogold labeling associated with nerve terminals of all asymmetric synapses and the immunoreactivity of those asymmetric synapses associated with a perforated postsynaptic density were also examined by electron microscopy. Subchronic neuroleptic administration had no effect on [³H]MK-801 binding to striatal membrane preparations. Both drugs increased glutamate immunogold labeling in nerve terminals of all asymmetric synapses, but only haloperidol increased the density of glutamate immunoreactivity within nerve terminals of asymmetric synapses containing a perforated postsynaptic density. Whereas subchronic administration of clozapine, but not haloperidol, resulted in a significant increase in the hybridization of a riboprobe that labels all splice variants of the NMDAR1 subunit, both drugs significantly decreased the abundance of NMDAR1 subunit mRNA containing a 63-base insert. Neither drug altered mRNA for the 2A subunit, but clozapine significantly increased hybridization of a probe for the 2B subunit. The data suggest that some neuroleptic effects may be mediated by glutamatergic systems and that typical and atypical antipsychotics can have varying effects on the density of glutamate in presynaptic terminals and on the expression of specific NMDA receptor splice variant mRNAs. Alternatively, NMDAR1 subunit splice variants may differentially respond to interactions with glutamate.     

Clozapine but not haloperidol suppresses the changes in the levels of neuropeptides in MK-801-treated rat brain regions

Noncompetitive NMDA receptor antagonist (+)MK-801 is known to induce neurotoxicity and schizophrenia-like symptomatology where atypical neuroleptic clozapine is effective in contrast to typical neuroleptic, haloperidol. Although neuropeptides are implicated in memory and cognition, their roles in schizophrenia are not well understood. In the present study, we therefore examined the possible roles of neuropeptides, cholecystokinin (CCK) and somatostatin (SS) in the posterior cingulate/retrosplenial cortices (PC/RSC), frontal cortex, and hippocampus of a MK-801-induced schizophrenia-like model rat brain. This study further investigated the pretreated effect of atypical versus typical neuroleptics on the peptidergic system. SS mRNA and peptide levels significantly decreased in the PC/RSC and hippocampus but not in the frontal cortex 3 days after 0.5 mg/kg MK-801 treatment whereas CCK mRNA and peptide levels significantly decreased in all of the brain regions examined. Pretreatment with clozapine but not haloperidol completely recovered the changes in both mRNA and peptide levels of SS and CCK in those brain regions. These data suggest that peptidergic system in the brain presumably plays an important role in the control of negative schizophrenia.     

Haloperidol but Not Clozapine Increases Neurotensin Receptor mRNA Levels in Rat Substantia Nigra

Abstract: We examined the effects of chronic (2 weeks) treatment with a typical neuroleptic, haloperidol (1 mg/kg, s.c.), and an atypical neuroleptic, clozapine (20 mg/kg, s.c.), on neurotensin receptor (NTR) mRNA levels by in situ hybridization histochemistry. Quantitative OD analysis showed haloperidol-induced NTR mRNA levels in the substantia nigra/ventral tegmental area (SN/ VTA) 110% over control levels (significant difference from the control, p < 0.05). In contrast, the same analysis applied to the sections from clozapine-treated animals showed no significant change in NTR mRNA levels compared with matched control sections ( p > 0.05). Thus, chronic treatment with haloperidol but not clozapine resulted in elevated levels of NTR mRNA within the SN/VTA. These results suggest that the high incidence of extrapyramidal side effects of typical neuroleptics could result from changes in NTR expression in the SN/VTA.     

Neuroleptics and Dopamine Transporters

The effects of neuroleptic treatments on dopamine transporters and on dopamine receptors was investigated in the forebrain of adult rats treated for 21 days with either haloperidol, clozapine or saline. The dopamine D₁receptors, labeled with [³H]SCH23390, increased in nucleus accumbens, latero-dorsal rostral neostriatum and substantia nigra, after clozapine but not haloperidol. The dopamine D₂receptors, studied with [³H]raclopride, increased in nucleus accumbens and in dorsolateral, ventro-medial and dorso-medial quadrants of the rostral neostriatum after either haloperidol or clozapine treatments, and also in latero-ventral rostral neostriatum but only after haloperidol. Haloperidol also up-regulated D₂receptors in rostral and caudal neostriatum, but clozapine produced a more uneven increase, especially in caudal neostriatum. In contrast, the densities of dopamine uptake sites, or transporters, labeled with [^I25I]RTI-121, remained unchanged after both neuroleptic treatments. The observation that dopamine transporters are resistant to treatments that modify D₁and D₂receptors indicates that these uptake sites can probably be ruled out as the target of neuroleptic drugs, and that dopamine receptor up-regulations can indeed occur independently of the densities of nerve endings at the terminal fields of innervation.     

Differential effects of acute and chronic treatment with typical and atypical neuroleptics on c-fos mRNA expression in rat forebrain regions using non-radioactive in situ hybridization.

The regional difference in the expression of c-fos mRNA in rat forebrain after either acute or chronic administration of typical (haloperidol and fluphenazine) and atypical neuroleptics (clozapine and (+/-)-sulpiride) was investigated. Rats were injected intraperitoneally with vehicle or neuroleptics daily for 14 days. Twenty-four hours after the last injection, the rats were challenged with vehicle or neuroleptics. C-fos mRNA expression was determined by non-radioactive in situ hybridization. Acute treatment with typical neuroleptics induced a remarkable induction of c-fos mRNA in the dorsolateral striatum, whereas this induction was greatly attenuated by chronic administration. All neuroleptics examined induced c-fos mRNA in the shell region of N. accumbens by acute administration and this expression was still elevated after chronic treatment. Since chronic neuroleptics do not induce tolerance to their antipsychotic activities, our study suggests that the shell region of N. accumbens is an important target site for antipsychotic effects of neuroleptics.     

The effects of a hypothalamic peptide factor,MIF and its cyclic analog on tolerance to haloperidol in the rat

The effects of the hypothalamic peptide, ProLeuGlyNH₂ (MIF) and its analog, cyclo (LeuGly) (CLG) on the development of tolerance to haloperidol were investigated in male Sprague-Dawley rats. Chronic oral administration of haloperidol (1.5 mg/kg/day) for 21 days resulted in the development of tolerance to its pharmacological effects. A dose of haloperidol (3 mg/kg ip) exhibited an absence of cataleptic as well as hypothermic response in chronically haloperidol treated rats. Subcutaneous administration of MIF or CLG (2 mg/kg each) daily one hour prior to haloperidol injection blocked the haloperidol-induced tolerance as evidenced by the appearance of both the cataleptic and hypothermic responses. It is concluded that the hypothalamic peptide hormone, MIF may be important in regulating chronic effects of neuroleptic drugs.     

Haloperidol induces calcium ion influx via L-type calcium channels in hippocampal HN33 cells and renders the neurons more susceptible to oxidative stress

Haloperidol is a classical neuroleptic drug that is still in clinical use and can lead to abnormal motor activity following repeated administration. However, there is little knowledge of how it triggers neuronal impairment. In this study, we report that it induced calcium ion influx via L-type calcium channels and that the elevation of calcium ions induced by haloperidol appeared to render hippocampal cells more susceptible to oxidative stress. Indeed, the level of cytotoxic reactive oxygen species (ROS) and the expression of pro-apoptotic Bax increased in response to oxidative stress in haloperidol-treated cells, and these effects were inhibited by verapamil, a specific L-type calcium channel blocker, but not by the T-type calcium channel blocker, mibefradil. These findings indicate that haloperidol induces calcium ion influx via L-type calcium channels and that this calcium influx influences neuronal fate.     

The characteristics of the radiation-initiated peroxidation of the phosphatidylcholine making up liposomes containing phospholipids which are susceptible to free-radical fragmentation

The regularities of accumulation of conjugated dienes and thiobarbituric acid (TBA)-reactive substances under gamma-irradiation of liposomes from rat liver phosphatidylcholine (PC) and its mixtures with the resistant to lipid peroxidation saturated phospholipids and bovine brain sphingomyelin (SM) were studied. It was established that the incorporation of negatively charged dipalmitoylphosphatidylglycerol (DPPG) and dipalmitoylphosphatidylethanol (DPPET) into lipid bilayer resulted in the increase of primary and secondary products of LPO, whereas neutral dipalmitoylphosphatidylcholine (DPPC) and SM involving in the phospholipid mixtures inhibited the peroxidation of PC. For anionic phospholipids, DPPG had more profound activating action on LPO, amongst the neutral phospholipids SM was more potent inhibitor of the reaction. Unlike DPPET and DPPC, DPPG and SM were subjected to free radical fragmentation on gamma-radiation. It is suggested that the intermediates and products of free radical fragmentation may modulate the progress of LPO.     

Dopaminergic supersensitivity in striatum and olfactory tubercle following chronic administration of haloperidol of clozapine

Mice were maintained on diets containing haloperidol or clozapine for 8–10 days. Two days after these drug-containing diets were withdrawn the effects of apomorphine were determined on locomotor activity and on the retardation of dopamine depletion produced by synthesis inhibition with α-methyltyrosine. After either neuroleptic the effects of apomorphine were enhanced when compared with mice maintained on a control diet, suggesting the development of supersensitive dopamine receptors.     

The role of glutamate receptors in antipsychotic drug action

Summary. It has recently been postulated that disturbances in glutamatergic neurotransmission may contribute to the pathophysiology of schizophrenia. Therefore the aim of the present study was to evaluate the role of glutamate NMDA and group II metabotropic receptors in the antipsychotic drug action. To this aim the influence of some well-known neuroleptics on cortical NMDA receptors was examined. Furthermore, their behavioral effects were compared with those of the novel agonist of group II glutamate metabotropic receptors, LY 354740, in some animal models of schizophrenic deficits. We found that long-term administration of the typical neuroleptic haloperidol and the atypical one clozapine increased the number of NMDA receptors labelled with [³H]CGP 39653 in different cortical areas. Long-, but not short-term, treatment with haloperidol and raclopride diminished the deficit of prepulse inhibition produced by phencyclidine, which is a model of sensorimotor gating deficit in schizophrenia. In contrast, neither short- nor long-term treatment with clozapine influenced the phencyclidine effect in that model. Acute treatment with LY 354740 reversed neither (1) the deficit of prepulse inhibition produced by phencyclidine or apomorphine, nor (2) the impairment in a delayed alternation task induced by MK-801, which is commonly used to model the frontal lobe deficits associated with schizophrenia. The present study suggests that an increase in the density of cortical NMDA receptors may be important to a longterm neuroleptic therapy. Conversely, the results do not support the role of group II metabotropic glutamate receptors in the antipsychotic drug action. Received August 31, 1999 Accepted September 20, 1999     

Protein thiol oxidation by haloperidol results in inhibition of mitochondrial complex I in brain regions: comparison with atypical antipsychotics

Usage of 'typical' but not 'atypical' antipsychotic drugs is associated with severe side effects involving extrapyramidal tract (EPT). Single dose of haloperidol caused selective inhibition of complex I in frontal cortex, striatum and midbrain (41 and 26%, respectively) which was abolished by pretreatment of mice with thiol antioxidants, alpha-lipoic acid and glutathione isopropyl ester, and reversed, in vitro, by disulfide reductant, dithiothreitol. Prolonged administration of haloperidol to mice resulted in complex I loss in frontal cortex, hippocampus, striatum and midbrain, while chronic dosing with clozapine affected only hippocampus and frontal cortex. Risperidone caused complex I loss in frontal cortex, hippocampus and striatum but not in midbrain from which extrapyramidal tract emanates. Inhibition of the electron transport chain component, complex I by haloperidol is mediated through oxidation of essential thiol groups to disulfides, in vivo. Further, loss of complex I in extrapyramidal brain regions by anti-psychotics correlated with their known propensity to generate side-effects involving extra-pyramidal tract.