Chronic haloperidol treatment with low doses may enhance the increase of homovanillic acid in rat brain

Does haloperidol have side effects on histological and stereological structure of the rat kidneys?

Haloperidol, a typical antipsychotic, is the most commonly prescribed medication for the treatment of mental health problems such as agitation and psychosis. We attempted to determine the effects of haloperidol treatment on the kidneys of female rats. In addition, we aimed to estimate the numerical density, total number, and height of renal glomeruli and the volume and volumetric fractions of the cortex, medulla, and whole kidneys, and tried to determine whether there was a change in these stereological parameters depending on haloperidol treatment. Both the qualitative and quantitative histological features of the kidney samples were analyzed with conventional histopathological and modern stereological methods at the light microscopic level. The total number of glomeruli and numerical density of glomerulus in the haloperidol-treated groups was not changed by increasing the dose in comparison to the control group. The mean height of the glomerulus significantly increased, especially in low-dose groups. In the haloperidol-treated groups, the volumetric fractions of the cortex to the whole kidney of the rats were significantly decreased by increasing the dose. The volumetric fractions of the medulla to the whole kidney of the rats were increased significantly in parallel by the given dose. In addition, we present quantitative findings showing that haloperidol is associated with many alterations in rat kidneys. It was shown that haloperidol may lead to undesirable changes in the kidney after chronic treatment with especially high doses.

Reduced neuronal expression of insulin-degrading enzyme in the dorsolateral prefrontal cortex of patients with haloperidol-treated, chronic schizophrenia

Insulin-degrading enzyme (IDE) is a neutral thiol metalloprotease, which cleaves insulin with high specificity. Additionally, IDE hydrolyzes Abeta, glucagon, IGF I and II, and beta-endorphin. We studied the expression of IDE protein in postmortem brains of patients with schizophrenia and controls because: (1) the gene encoding IDE is located on chromosome 10q23-q25, a gene locus linked to schizophrenia; (2) insulin resistance with brain insulin receptor deficits/receptor dysfunction was reported in schizophrenia; (3) the enzyme cleaves IGF-I and IGF-II which are implicated in the pathophysiology of the disease; and (4) brain gamma-endorphin levels, liberated from beta-endorphin exclusively by IDE, have been reported to be altered in schizophrenia. We counted the number of IDE immunoreactive neurons in the dorsolateral prefrontal cortex, the hypothalamic paraventricular and supraoptic nuclei, and the basal nucleus of Meynert of 14 patients with schizophrenia and 14 matched control cases. Patients had long-term haloperidol treatment. In addition, relative concentrations of IDE protein in the dorsolateral prefrontal cortex were estimated by Western blot analysis. There was a significantly reduced number of IDE expressing neurons and IDE protein content in the left and right dorsolateral prefrontal cortex in schizophrenia compared with controls, but not in other brain areas investigated. Results of our studies on the influence of haloperidol on IDE mRNA expression in SHSY5Y neuroblastoma cells, as well as the effect of long-term treatment with haloperidol on the number of IDE immunoreactive neurons in rat brain, indicate that haloperidol per se, is not responsible for the decreased neuronal expression of the enzyme in schizophrenics. Haloperidol however, might exert some effect on IDE, through changes of the expression levels of its substrates IGF-I and II, insulin and beta-endorphin. Reduced cortical IDE expression might be part of the disturbed insulin signaling cascades found in schizophrenia. Furthermore, it might contribute to the altered metabolism of certain neuropeptides (IGF-I and IGF-II, beta-endorphin), in schizophrenia.

Effect of chronic treatment of haloperidol on the rat liver: a stereological and histopathological study

Haloperidol is commonly used in therapy for patients with acute and chronic schizophrenia. Because it can have some adverse effects on specific target organs such as the liver, we analyzed whether haloperidol exerts a toxic effect on rat liver by means of stereological and histopathological methods. Fifteen adult male rats, divided into three groups, were used in the experiments. Once a day for 6 weeks, either saline or 0.4 or 0.8 mg kg(-1) doses of haloperidol were given interperitoneally to the control, low-dose, and high-dose groups, respectively. At the end of the experiment, rats were killed by an overdose of a general anesthetic, and the livers were dissected out, fixed for sectioning, and evaluated using stereological and histopathological methods. Hepatocyte numbers were found to be 271.672, 291.072, and 238.415 hepatocytes per cubic millimeter in the liver of the control, low-dose, and high-dose groups, respectively. The differences between high-dose and control groups and also between high-dose and low-dose groups were significant (p < 0.05). Our histopathological findings at both the structural and the ultra-structural level were confirmed by stereological estimations. Results suggest a relationship between haloperidol dose and toxic effects on the liver, and they indicate that a high dose of haloperidol may result in irreversible liver damage.

Pharmacology and behavioral pharmacology of the mesocortical dopamine system

The prefrontal cortex (PFC) has long been known to be involved in the mediation of complex behavioral responses. Considerable research efforts are directed towards refining the knowledge about the function of this brain area and the role it plays in cognitive performance and behavioral output. In the first part, this review provides, from a pharmacological perspective, an overview of anatomical, electrophysiological and neurochemical aspects of the function of the PFC, with an emphasis on the mesocortical dopamine system. Anatomy of the mesocortical system, basic physiological and pharmacological properties of neurotransmission within the PFC, and interactions between dopamine and glutamate as well as other transmitters within the mesocorticolimbic circuit are included. The coverage of these data is largely restricted to what is relevant for the second part of the review which focuses on behavioral studies that have examined the role of the PFC in a variety of phenomena, behaviors and paradigms. These include reward and addiction, locomotor activity and sensitization, learning, cognition, and schizophrenia. Although the focus of this review is on the mesocortical dopamine system, given the intricate interactions of dopamine with other transmitter systems within the PFC and the importance of the PFC as a source of glutamate in subcortical areas, these aspects are also covered in some detail where appropriate. Naturally, a topic as complex as this cannot be covered comprehensively in its entirety. Therefore this review is largely limited to data derived from studies using rats, and it is also specifically restricted to data concerning the medial PFC (mPFC). Since in several fields of research the findings concerning the function or role of the mPFC are relatively inconsistent, the question is addressed whether these inconsistencies might, at least in part, be related to the anatomical and functional heterogeneity of this brain area.

Effects of haloperidol and GM1 ganglioside treatment on striatal D2 receptor binding and dopamine turnover

Previous studies have shown that whereas exogenous GM1 ganglioside co-administration leads to an increase of haloperidol-induced behavioral supersensitivity, GM1 significantly attenuates the behavioral parameters of dopaminergic supersensitivity when administered after abrupt haloperidol withdrawal. In the present study, the effects of GM1 and haloperidol co-administration (5 mg/kg GM1 i.p. and 1 mg/kg haloperidol i.p., twice daily, for 30 days) as well as the effects of a 3 day treatment with GM1 were investigated in rats withdrawn from haloperidol administration by measuring striatal D2 dopamine receptor binding and dopamine turnover. The results showed that under these two experimental conditions GM1 modified neither the haloperidol-induced striatal D2 dopamine receptor up regulation nor the decrease in dopamine turnover produced by haloperidol withdrawal. These results suggest that the effects of GM1 on behavioral supersensitivity are not related to modifications in dopamine receptor number or affinity and in the synaptic availability of this catecholamine.

Dopamine, the prefrontal cortex and schizophrenia

Dysfunction of the prefrontal cortex (PFC) in schizophrenia has been suspected based on observations from clinical, neuropsychological and neuroimaging studies. Since the PFC receives a dense dopaminergic innervation, abnormalities of the mesocortical dopamine system have been proposed to contribute to the pathophysiology of schizophrenia. In this review, aspects of the anatomy, physiology and pharmacology of the mesencephalic-frontal cortical dopamine system as they may relate to schizophrenia are described, and evidence for altered dopaminergic neurotransmission in the frontal cortex of schizophrenic patients is presented.

Comparative study of dopamine metabolism with local cerebral glucose utilization in rat brain following the administration of haloperidol decanoate

The effects of haloperidol decanoate on dopamine (DA) metabolism in discrete regions of rat brain were investigated and compared with changes in local cerebral glucose utilization (LCGU). The concentration of DA and its metabolite, homovanillic acid, and the alpha-methyl-p-tyrosine (alpha-MT)-induced decline of DA were measured in 6 brain regions by a high-performance liquid chromatographic assay. LCGU in 26 brain regions were examined by [14C]2-deoxy-D-glucose autoradiography. At 24-hr after intramuscular injection of haloperidol decanoate (60 mg eq/kg to haloperidol), the concentration of homovanillic acid in the prefrontal cortex, caudate-putamen, accumbens nucleus, lateral amygdala, and medial thalamus showed significant increase compared with control values. On day 21, the increase in these regions was significantly attenuated with no significant difference from the controls. Furthermore, chronic haloperidol rats showed alpha-MT-induced decline of DA to a similar extent in the control rats. LCGU on day 21 showed significant decrease in the parietal cortex, and a tendency toward decrease in the prefrontal cortex, lateral amygdala and medial thalamus compared with the controls. There was no significant change in LCGU in the caudate-putamen or accumbens nucleus. Chronic haloperidol would thus appear to affect energy metabolism mainly in the cortico-thalamo-limbic circuits, and this may not correspond well to presynaptic DA metabolism.

Acute versus chronic haloperidol: relationship between tolerance to catalepsy and striatal and accumbens dopamine, GABA and acetylcholine release

Using in vivo microdialysis, changes in extracellular dorsolateral striatum and nucleus accumbens dopamine, GABA and acetylcholine following acute and chronic haloperidol (0.25 mg/kg, s.c.) were evaluated in rats concurrent with the measurement of catalepsy. When administered to drug-naive and chronically treated rats, haloperidol was associated with a consistent and prolonged (> 150 min) increase in dorsolateral striatum and nucleus accumbens DA release and a transient (60 min) increase in dorsolateral striatum GABA release. Haloperidol was also associated with a transient (30 min) increase in dorsolateral striatum acetylcholine release in the chronically treated rats. Basal dopamine and acetylcholine levels were similar in both brain regions; however, basal dorsolateral striatum GABA levels were two-fold higher in the chronically treated rats. Administration of haloperidol was associated with a prolonged (> 150 min) catalepsy in the drug-naive rats which was greatly diminished or absent in chronically treated rats. Additionally, serum haloperidol levels were shown to be similar 120 min following administration of haloperidol in both groups. These results indicate a marked behavioral difference in the effects of haloperidol in drug-naive and chronically treated rats which is not related to an altered bioavailability of the drug and which is dissociated from both basal and haloperidol induced effects on dopamine and acetylcholine release in both brain regions. However, the selective elevation of basal dorsolateral striatum GABA release following chronic administration of haloperidol may contribute to the development of tolerance to catalepsy as well as providing an in vivo neurochemical marker of the long-term effects of haloperidol.

Chronic neuroleptic treatment does not suppress the dynamic characteristics of the dopaminergic receptor D2 system

1. Rats were treated with either haloperidol (0.5 mg/kg) or haloperidol plus an anticholinergic drug (0.5 and 0.15 mg/kg/day respectively) for 3 days, 7 days and 16 months. 2. Estimates made twenty hours after the last doses showed that haloperidol reduced the concentrations of the dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum and the olfactory tubercle. 3. A challenge dose of either haloperidol or haloperidol plus an anticholinergic drug was administered to rats pretreated with haloperidol or haloperidol plus an anticholinergic drug; this challenge dose reversed the reduction in dopamine metabolites caused by neuroleptic administration. 4. After sixteen months of haloperidol administration dopamine levels were reduced, but adding an anticholinergic drug to haloperidol treatment prevented this reduction in dopamine concentration.

The enhancement of the hypomotility induced by small doses of haloperidol in the phase of dopaminergic supersensitivity in mice

Dopaminergic supersensitivity in mice was induced by pretreatment with a single injection of haloperidol (4.8 mg/kg). After the pretreatment, further treatment with haloperidol (0.6 or 0.01 mg/kg) was made at varying intervals, and catalepsy, locomotor activity and homovanillic acid (HVA) were measured. The intensity of the supersensitivity was evaluated by enhanced apomorphine (1 mg/kg)-induced climbing behavior. Supersensitivity was displayed on the 2nd and the 4th day. The cataleptogenic effect of haloperidol (0.6 mg/kg) was significantly weakened on the 1st, 2nd and 4th days. The motor inhibitory effect of haloperidol (0.01 mg/kg) increased on the 1st, 2nd and 4th days. Homovanillic acid was measured in the striatum and the prefrontal cortex on the 2nd day. Haloperidol (0.6 mg/kg) increased the concentrations of HVA in both regions of the brain. The increase in the concentrations of HVA in the striatum was blunted after the pretreatment, but such tolerance did not develop in the prefrontal cortex. Haloperidol (0.01 mg/kg) did not influence the concentration of HVA in both regions. These results suggest that the behavioral effect of a small dose of haloperidol may be enhanced, rather than reduced, in the phase of supersensitivity.

Influence of acute and chronic haloperidol treatment on dopamine metabolism in the rat caudate-putamen, prefrontal cortex and amygdala

The present study investigated the actions of single and repeated injections of the classical antipsychotic drug, haloperidol (1 mg.kg-1 IP), on dopamine (DA) metabolism in three distinct rat brain regions, namely the prefrontal cortex, amygdala and caudate-putamen (CP), using a high-performance liquid chromatographic assay. Acute administration of the drug caused significant elevations in concentrations of two major DA metabolites in all three areas studied. Less marked acute increases were seen in the CP following 10 days of repeated haloperidol treatment. However, in both the prefrontal cortex and the amygdala, the development of such "tolerance" was somewhat delayed in comparison, occurring only after a 22-day treatment schedule. The amygdala displayed the greatest degree of neurochemical tolerance, returning to control values by day 22 of chronic treatment. When allowance was made for the withdrawal effects of antipsychotic drug administration, a genuine tolerance phenomenon was observed in all three areas examined. These data suggest that if neurochemical tolerance is a prerequisite for functional DA receptor blockade and hence therapeutic efficacy, then both the prefrontal cortex and amygdala should be considered as potential therapeutic targets of haloperidol and perhaps antipsychotic drugs in general.

Neurochemical effects of chronic haloperidol and lithium assessed by brain microdialysis in rats

1. Psychotropic drugs ameliorate psychotic symptoms only after repeated administration. 2. To assess the neurochemical effects of chronic haloperidol and lithium administration, microdialysis was performed simultaneously in the prefrontal cortex, the nucleus accumbens, and the striatum after haloperidol, and separately in the lateral hypothalamus and the hippocampus after lithium. 3. Chronic administration of haloperidol decreased dopamine turnover in the prefrontal cortex and the striatum. It did not affect the nucleus accumbens detectably. 4. No tolerance to haloperidol developed in any of the three regions. 5. Lithium enhanced the response of the serotonergic system to amphetamine in the lateral hypothalamus but not in the hippocampus. 6. The antipsychotic effect of haloperidol might be related to dopamine turnover decrease in the prefrontal cortex. 7. The antidepressant effect of lithium might be related to enhancement of serotonin responsiveness in the hypothalamus.