Evaluation of the Influence of Adalimumab on the Expression Profile of Leptin-Related Genes and Proteins in Keratinocytes Treated with Lipopolysaccharide A.

Psoriasis is a disease with a proinflammatory base, in which an increased expression of leptin, tumor necrosis factor alpha (TNF-α), interleukin (IL) IL-12/23, IL-6, is observed. A drug used in the treatment of psoriasis of moderate and acute strength is the monoclonal antibody anti-TNF-adalimumab. The goal of this study was to evaluate the influence of adalimumab on changes in the expression profile of leptin-related genes in human keratinocyte cells exposed to lipopolysaccharide A and analyze if adalimumab acts via leptin pathways. The evaluation of changes of the pattern of genes connected with leptin and proteins coded by them was marked in a culture of human keratinocytes (HaCaT) exposed to 1 µg/mL lipopolysaccharide A (LPS) for 8 h in order to induce the inflammatory process, then to 8 µg/mL of adalimumab for 2.8 and 24 h in comparison with the control (cells not treated with the substances). The techniques used were mRNA microarray, Real-Time Quantitative Reverse Transcription Reaction (RTqPCR), Enzyme-Linked Immunosorbent Assay (ELISA), as well as transfections of HaCaT culture with leptin small interfering RNA (siRNA) in order to see whether adalimumab works through pathways dependent on leptin. A statistically lower expression of leptin and its receptors was observed under the influence of the drug, independent of the exposition time of keratinocytes to adalimumab. In the cells transfected with leptin siRNA, a lower concentration of JAK2 and STAT3 proteins was observed, which confirms that adalimumab works through pathways dependent on leptin. Adalimumab has a modulatory effect on the gene expression pattern and the proteins coded by them connected with leptin in keratinocytes treated with LPS in vitro.

The Influence of Adalimumab and Cyclosporine A on the Expression Profile of the Genes Related to TGFß Signaling Pathways in Keratinocyte Cells Treated with Lipopolysaccharide A.

BACKGROUND: In the treatment of moderate to severe psoriasis, cyclosporine A (CsA) conventional therapy is used and biological, anti-cytokine treatment using, for example, anti-TNF drug-adalimumab. AIM: This study aimed at investigating the effect of CsA and adalimumab on the profile of mRNAs and protein expression associated with transforming growth factor ß (TGFß) pathways in human keratinocyte (HaCaT) culture previously exposed to lipopolysaccharide (LPS). MATERIALS AND METHODS: HaCaT culture was exposed to 1 ng/ml LPS for 8 hours+8 µg/ml adalimumab for 2, 8, and 24 hours or 1 ng/ml LPS for 8 hours+100 ng/ml CsA for 2, 8, and 24 hours and compared to the control culture. Sulphorodamine B cytotoxicity assay was performed. The expression profile of mRNA related to TGFß paths was indicated by microarray and RTqPCR analyses. The ELISA test was used to analyze changes on the proteome level. Statistical analysis consisted of ANOVA analysis and the post hoc Tukey test (p < 0.05). RESULTS: The cytotoxicity test showed that LPS, adalimumab, and cyclosporine in the concentration used in this experiment did not have any cytotoxicity effect on HaCaT cells. The largest fold changes (FC) in expression in (∣FC | >4.00) was determined for TGFß1-3, TGFßRI-III, SKIL, SMURF2, SMAD3, BMP2, BMP6, JAK2, UBE2D1, SKP2, EDN1, and PRKAR2B (p < 0.05). In addition, on the protein level, the direct changes observed at mRNA were the same. CONCLUSION: Analysis of the microarray expression profile of genes associated with TGFß signaling pathways has demonstrated the potential of cyclosporin A and adalimumab to induce changes in their transcriptional activity. The anti-TNF drug seems to affect TGFß cascades to a greater extent than cyclosporin A. The obtained results suggest that the regularity of taking the drug is important for the efficacy of psoriasis therapy.

Changes in the Expression Profile of VEGF-A, VEGF-B, VEGFR-1, VEGFR-2 in Different Grades of Endometrial Cancer.

BACKGROUND: VEGF-A, VEGF-B, VEGFR-1 and VEGFR-2 are important proteins involved in the induction and development of a new blood vessel network through which the tumor is properly nourished and oxygenated. OBJECTIVES: The aim of the study was to evaluate changes in VEGF-A, VEGF-B, VEGFR-1 and VEGFR-2 expression in endometrial cancer depending on its grade and to determine the VEGFR-1 to VEGFR-2 concentration ratio. METHODS: The study group consisted of 45 patients diagnosed with endometrial cancer (G1, 17; G2, 15; G3, 13). The control group included 15 patients. VEGF-A, VEGF-B, VEGF-R1, VEGFR-2 expression was assessed using the immunohistochemical method. Statistical analysis was carried out using the Statistica 12 PL program (StatSoft, Cracow, Poland). It included the one-way ANOVA and Tukey's post-hoc test (p<0.05). RESULTS: Statistically significant differences in the level of VEGF-A, VEGF-B, VEGF-R1, VEGFR-2 were observed between the majority of analyzed groups (except for VEGF-B; G3 vs. G1, p=0.997700). The expression pattern of VEGF-A, VEGF-R1, VEGFR-2 was as follows: G3>G2>G1>C; VEGF-B: G2> G3> G1>C. A lower concentration of VEGFR-1 than VEGFR-2 was found regardless of the cancer grade. CONCLUSION: VEGF-A, VEGF-B, VEGF-R1, VEGFR-2 are key proteins involved in tumor angiogenesis. The analysis of the entire panel of proteins participating in a given process is an important element of modern diagnostics. The concentration ratio of VEGFR-1 to VEGFR-2 appears to be a determining factor in the patients' survival prognosis.

Expression of NRP-1 and NRP-2 in Endometrial Cancer.

BACKGROUND: Neuropilins (NRPs) participate in many processes related to cancer development such as angiogenesis, lymphangiogenesis and metastasis. Although endometrial cancer is one of the most common gynecological cancers, it has not been studied in terms of NRPs expression. OBJECTIVE: The aim of this study was to investigate the potential utility of NRPs as important factors in the diagnosis and treatment of endometrial cancer. METHODS: Our study consisted of 45 women diagnosed with endometrial cancer at the following degrees of histological differentiation: G1, 17; G2, 15; G3, 13 cases. The control group included 15 women without neoplastic changes. The immunohistochemical reactions were evaluated using light microscopy. RESULTS: We did not detect the expression of NRP-1 and NRP-2 in the control group. NRP-1 expression was found exclusively in cancer cells. It was higher in G2 and G3 and reached about 190% of G1. NRP-2 expression was observed in the endothelium and was similar across all three cancer grades. In cancer cells, NRP-2 expression increased with the degree of histological differentiation. CONCLUSION: NRP1 and NRP2 are candidates for complementary diagnostic molecular markers and promising new targets for molecular, personalized anticancer therapies.

Perinatal Treatments with the Dopamine D2-Receptor Agonist Quinpirole Produces Permanent D2-Receptor Supersensitization: a Model of Schizophrenia.

Repeated daily treatments of perinatal rats with the dopamine D2-receptor (D2-R) agonist quinpirole for a week or more produces the phenomenon of 'priming'-gradual but long-term sensitization of D2-R. In fact a daily dose of quinpirole as low as 50 µg/kg/day is adequate for sensitizing D2-R. Primed rats as neonates and in adolescence, when acutely treated with quinpirole display enhanced eating/gnawing/nursing on dams, also horizontal locomotor activity. Between 3 and 5 weeks of age, acute quinpirole treatment of primed rats produces profound vertical jumping with paw treading-a behavior that is not observed in control rats. At later ages acute quinpirole treatment is associated with enhanced yawning, a D2-R-associated behavior. This long-term D2-R supersensitivity is believed to be life-long, despite the relatively brief period of D2-R priming near the time of birth. D2-R supersensitivity is not associated with an increase in the number or affinity of D2-R, as assessed in the striatum of rats; nor is it induced with the D3-R agonist 7-OH-DPAT. However, quinpirole-induced D2-R supersensitivity is associated with cognitive deficits, also a deficit in pre-pulse inhibition and in neurotrophic factors, and low levels of the transcript regulator of G-protein signaling (RGS) RGS9 in brain; and acute reversal of these alterations by the antipsychotic agent olanzapine. In sum, rats ontogenetically D2-R supersensitized have face validity, construct validity and predictive ability for schizophrenia.

Perinatal 6-Hydroxydopamine to Produce a Lifelong Model of Severe Parkinson's Disease.

The classic rodent model of Parkinson's disease (PD) is produced by unilateral lesioning of pars compacta substantia nigra (SNpc) in adult rats, producing unilateral motor deficits which can be assessed by dopamine (DA) D2 receptor (D2-R) agonist induction of measurable unilateral rotations. Bilateral SNpc lesions in adult rats produce life-threatening aphagia, adipsia, and severe motor disability resembling paralysis-a PD model that is so compromised that it is seldom used. Described in this paper is a PD rodent model in which there is bilateral 99 % loss of striatal dopaminergic innervation, produced by bilateral intracerebroventricular or intracisternal 6-hydroxydopamine (6-OHDA) administration to perinatal rats. This procedure produces no lethality and does not shorten the life span, while rat pups continue to suckle through the pre-weaning period; and eat without impairment post-weaning. There is no obvious motor deficit during or after weaning, except with special testing, so that parkinsonian rats are indistinguishable from control and thus allow for behavioral assessments to be conducted in a blinded manner. L-DOPA (L-3,4-dihydroxyphenylalanine) treatment increases DA content in striatal tissue, also evokes a rise in extraneuronal (i.e., in vivo microdialysate) DA, and is able to evoke dyskinesias. D2-R agonists produce effects similar to those of L-DOPA. In addition, effects of both D1- and D2-R agonist effects on overt or latent receptor supersensitization are amenable to study. Elevated basal levels of reactive oxygen species (ROS), namely hydroxyl radical, occurring in dopaminergic denervated striatum are suppressed by L-DOPA treatment. Striatal serotoninergic hyperinnervation ensuing after perinatal dopaminergic denervation does not appear to interfere with assessments of the dopaminergic system by L-DOPA or D1- or D2-R agonist challenge. Partial lesioning of serotonin fibers with a selective neurotoxin either at birth or in adulthood is able to eliminate serotoninergic hyperinnervation and restore the normal level of serotoninergic innervation. Of all the animal models of PD, that produced by perinatal 6-OHDA lesioning provides the most pronounced destruction of nigrostriatal neurons, thus representing a model of severe PD, as the neurochemical outcome resembles the status of severe PD in humans but without obvious motor deficits.

Perinatal 6-Hydroxydopamine Modeling of ADHD.

The neonatally 6-hydroxydopamine (n6-OHDA)-lesioned rat has been the standard for 40 years, as an animal model of attention-deficit hyperactivity disorder (ADHD). Rats so lesioned during postnatal ontogeny are characterized by ~99 % destruction of dopaminergic nerves in pars compacta substantia nigra, with comparable destruction of the nigrostriatal tract and lifelong ~99 % dopaminergic denervation of striatum, with lesser destructive effect on the ventral tegmental nucleus and associated lesser dopaminergic denervation of nucleus accumbens and prefrontal cortex. As a consequence of striatal dopaminergic denervation, reactive serotoninergic hyperinnervation of striatum ensues. The striatal extraneuronal milieu of DA and serotonin is markedly altered. Also, a variety of sensitization changes occur for dopaminergic D1 and D2 receptors, and for serotoninergic receptors. Behaviorally, these rats in adulthood display spontaneous hyperlocomotor activity, attentional deficits, and cognitive impairment-all of which are acutely attenuated by the psychostimulants amphetamine (AMPH) and methylphenidate (MPH) (i.e., opposite to the acute effects of AMPH and MPH in intact control rats). The acute behavioral effects of AMPH and MPH in intact and lesioned rats are analogous to their respective acute effects in non-ADHD and in ADHD humans. The neurochemical template of brain, and behavioral series of changes in n6-OHDA-lesioned rats, is described in the review. Despite the fact that nigrostriatal damage is not an underlying pathophysiological process of human ADHD (i.e., lacking construct validity), the described animal model has face validity (behavioral profile) and predictive validity (mirror of ADHD/MPH effects, as well as putative and new ADHD treatment effects). Also described in this review is a modification of the n6-OHDA rat, produced by adulthood partial lesioning of the serotoninergic fiber overgrowth. This ADHD model has even more accentuated hyperlocomotor and attentional deficits, counteracted by AMPH-thus providing a more robust means of animal modeling of ADHD. The n6-OHDA rat as a model of ADHD continues to be important in the search for new ADHD treatments.

Lifelong Rodent Model of Tardive Dyskinesia-Persistence After Antipsychotic Drug Withdrawal.

Tardive dyskinesia (TD), first appearing in humans after introduction of the phenothiazine class of antipsychotics in the 1950s, is now recognized as an abnormality resulting predominately by long-term block of dopamine (DA) D2 receptors (R). TD is thus reproduced in primates and rodents by chronic administration of D2-R antagonists. Through a series of studies predominately since the 1980s, it has been shown in rodent modeling of TD that when haloperidol or other D2-R antagonist is added to drinking water, rats develop spontaneous oral dyskinesias, vacuous chewing movements (VCMs), after ~3 months, and this TD is associated with an increase in the number of striatal D2-R. This TD persists for the duration of haloperidol administration and another ~2 months after haloperidol withdrawal. By neonatally lesioning dopaminergic nerves in brain in neonatal rats with 6-hydroxydopamine (6-OHDA), it has been found that TD develops sooner, at ~2 months, and also is accompanied by a much higher number of VCMs in these haloperidol-treated lesioned rats, and the TD persists lifelong after haloperidol withdrawal, but is not associated with an increased D2-R number in the haloperidol-withdrawn phase. TD apparently is related in part to supersensitization of both D1-R and serotoninergic 5-HT2-R, which is also a typical outcome of neonatal 6-OHDA (n6-OHDA) lesioning. Testing during the haloperidol-withdrawn phase in n6-OHDA rats displaying TD reveals that receptor agonists and antagonists of a host of neuronal phenotypic classes have virtually no effect on spontaneous VCM number, except for 5-HT2-R antagonists which acutely abate the incidence of VCMs in part. Extrapolating to human TD, it appears that (1) 5-HT2-R supersensitization is the crucial alteration accounting for persistence of TD, (2) dopaminergic-perhaps age-related partial denervation-is a risk factor for the development of TD, and (3) 5-HT2-R antagonists have the therapeutic potential to alleviate TD, particularly if/when an antipsychotic D2-R blocker is withdrawn.

Perinatal manganese exposure and hydroxyl radical formation in rat brain.

The present study was designed to investigate the role of pre- and postnatal manganese (Mn) exposure on hydroxyl radical (HO(•)) formation in the brains of dopamine (DA) partially denervated rats (Parkinsonian rats). Wistar rats were given tap water containing 10,000 ppm manganese chloride during the duration of pregnancy and until the time of weaning. Control rat dams consumed tap water without added Mn. Three days after birth, rats of both groups were treated with 6-hydroxydopamine at one of three doses (15, 30, or 67 µg, intraventricular on each side), or saline vehicle. We found that Mn content in the brain, kidney, liver, and bone was significantly elevated in dams exposed to Mn during pregnancy. In neonates, the major organs that accumulated Mn were the femoral bone and liver. However, Mn was not elevated in tissues in adulthood. To determine the possible effect on generation of the reactive species, HO(•) in Mn-induced neurotoxicity, we analyzed the contents of 2.3- and 2.5-dihydroxybenzoic acid (spin trap products of salicylate; HO(•) being an index of in vivo HO(•) generation), as well as antioxidant enzyme activities of superoxide dismutase (SOD) isoenzymes and glutathione S-transferase (GST). 6-OHDA-depletion of DA produced enhanced HO(•) formation in the brain tissue of newborn and adulthood rats that had been exposed to Mn, and the latter effect did not depend on the extent of DA denervation. Additionally, the extraneuronal, microdialysate, content of HO(•) in neostriatum was likewise elevated in 6-OHDA-lesioned rats. Interestingly, there was no difference in extraneuronal HO(•) formation in the neostriatum of Mn-exposed versus control rats. In summary, findings in this study indicate that Mn crosses the placenta but in contrast to other heavy metals, Mn is not deposited long term in tissues. Also, damage to the dopaminergic system acts as a "trigger mechanism," initiating a cascade of adverse events leading to a protracted increase in HO(•) generation, and the effects of Mn and 6-OHDA are compounded. Moreover, HO(•) generation parallels the suppression of SOD isoenzymes and GST in the brains of rats lesioned with 6-OHDA and/or intoxicated with Mn-the most prominent impairments being in frontal cortex, striatum, and brain stem. In conclusion, ontogenetic Mn exposure, resulting in reactive oxygen species, HO(•) formation, represents a risk factor for dopaminergic neurotoxicity and development of neurodegenerative disorders.

Ontogenetic manganese exposure with perinatal 6-OHDA lesioning alters behavioral responses of rats to dopamine D1 and D2 agonist treatments.

The effect of neonatal manganese (Mn) exposure in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson's disease was investigated. Pregnant Wistar rats were given drinking water with 10,000 ppm of Manganese (MnCl2.4H2O) from the time of conception until weaning on the 21st day after delivery. Control rats consumed tap water. Three days after the birth, other groups of neonatal rat pups were pretreated with desipramine (20 mg/kg ip 1h) prior to bilateral ICV administration of 6-OHDA or its vehicle, saline-ascorbic (0.1%) (control). Two months after the birth, striatal dopamine and homovanilic acid efflux measured by an in vivo microdialysis method were reduced in rats lesioned with 6-OHDA. Co-exposure to perinatal Mn did not modify neurotransmission alterations. However, there were prominent abnormalities in behavioral testing in rats perinatally exposed to Mn and treated neonatally with 6-OHDA. These findings demonstrate that although Mn did not further damage neurotransmitter activity in the neostriatum, ontogenetic exposure to Mn enhances the behavioral toxicity to 6-OHDA.

Neonatal DSP-4 treatment modifies antinociceptive effects of the CB1 receptor agonist methanandamide in adult rats.

To study the influence of the central noradrenergic system on antinociceptive effects mediated by the CB(1)-receptor agonist methanandamide, intact rats were contrasted with rats in which noradrenergic nerves were largely destroyed shortly after birth with the neurotoxin DSP-4 [N-(-2-chloroethyl)-N-ethyl-2-bromobenzylamine (50 mg/kg sc × 2, P1 and P3); zimelidine (10 mg/kg sc, 30 min pretreatment, selective serotonin reuptake inhibitor). When rats attained 10 weeks of age, monoamine and their metabolite concentrations were determined in the frontal cortex, thalamus, and spinal cord by an HPLC/ED method. Antinociceptive effects after methanandamide (10 mg/kg ip) apply were evaluated by a battery of tests. In addition, immunohistochemistry and densitometric analysis of the cannabinoid CB(1) receptor in the rat brain was performed. DSP-4 lesioning was associated with a reduction in norepinephrine content of the frontal cortex (>90 %) and spinal cord (>80 %) with no changes in the thalamus. Neonatal DSP-4 treatment produced a significant reduction in the antinociceptive effect of methanandamide in the tail-immersion test, hot-plate test and writhing tests. In the paw pressure and formalin hind paw tests results were ambiguous. These findings indicate that the noradrenergic system exerts a prominent influence on analgesia acting via the cannabinoid system in brain, without directly altering CB(1) receptor density in the brain.

Effect of pre- and postnatal manganese exposure on brain histamine content in a rodent model of Parkinson's disease.

Rats lesioned shortly after birth with 6-hydroxydopamine (6-OHDA; 134 µg icv) represent a near-ideal model of severe Parkinson's disease because of the near-total destruction of nigrostriatal dopaminergic fibers. There are scarce data that in Parkinson's disease, activity of the central histaminergic system is increased. The element manganese, an essential cofactor for many enzymatic reactions, itself in toxic amount, replicates some clinical features similar to those of Parkinson's disease. The aim of this study was to examine the effect of neonatal manganese exposure on 6-OHDA modeling of Parkinson's disease in rats, and to determine effects on histamine content in the brain of these rats in adulthood. Manganese (MnCl2·4H2O; 10,000 ppm) was included in the drinking water of pregnant Wistar rats from the time of conception until the 21st day after delivery, the age when neonatal rats were weaned. Control rats consumed tap water. Other groups of neonatal rat pups, on the 3rd day after birth, were pretreated with desipramine (20 mg/kg ip 1 h) prior to bilateral icv administration of 6-OHDA (60 or 134 µg) or its vehicle saline-ascorbic (0.1%) (control). At 2 months after birth, in rats lesioned with 60 or 134 µg 6-OHDA, endogenous striatal dopamine (DA) content was reduced, respectively, by 92 and 98% (HPLC/ED), while co-exposure of these groups to perinatal manganese did not magnify the DA depletion. However, there was prominent enhancement of histamine content in frontal cortex, hippocampus, hypothalamus, and medulla oblongata of adult rat brain after 6-OHDA (60 and 134 µg) injection on the day 3rd postnatal day. These findings indicate that histamine and the central histaminergic system are altered in the brain of rats lesioned to model Parkinson's disease, and that manganese enhances effects of 6-OHDA on histamine in brain.

Ontogenetic serotoninergic lesioning alters histaminergic activity in rats in adulthood.

The aim of this study was to determine histamine content in the brain and the effect of histamine receptor antagonists on behavior of adult rats lesioned as neonates with the serotonin (5-HT) neurotoxin 5,7-dihydroxytryptamine (5,7-DHT). At 3 days after birth Wistar rats were pretreated with desipramine (20 mg/kg ip) before bilateral icv administration of 5,7-DHT (37.5 µg base on each side) or saline-ascorbic (0.1%) vehicle (control). At 10 week levels of 5-HT and its metabolite 5-hydroxyindole acetic acid (5-HIAA) were determined in frontal cortex, striatum, and hippocampus by an HPLC/ED technique. In the hypothalamus, frontal cortex, hippocampus and medulla oblongata, the level of histamine was analyzed by an immunoenzymatic method. Behavioral observations (locomotion, exploratory-, oral-, and stereotyped activity) were performed, and effects of DA receptor agonists (SKF 38393, apomorphine) and histamine receptor antagonists S(+)chlorpheniramine (H(1)), cimetidine (H(2)), and thioperamide (H(3)) were determined. We confirmed that 5,7-DHT profoundly reduced contents of 5-HT and 5-HIAA in the brain in adulthood. Histamine content was also reduced in all examined brain regions. Moreover, in 5,7-DHT-lesioned rats the locomotor and oral activity responses to thioperamide were altered, and apomorphine-induced stereotype was intensified. From the above, we conclude that an intact central serotoninergic system modulates histamine H(3) receptor antagonist effects on the dopaminergic neurons in rats.

Thioperamide, an H3 receptor antagonist prevents [³H]glucose uptake in brain of adult rats lesioned as neonates with 5,7-dihydroxytryptamine.

As a first attempt at exploring an association between histaminergic and serotoninergic neuronal phenotypes in glucose regulation, the influence of the histamine H3 receptor antagonist thioperamide on glucose uptake by brain was determined in rats in which the serotoninergic innervations of brain was largely destroyed perinatally. Male Wistar rats were initially treated on the 3rd day after birth with the serotoninergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) (75 µg icv) or saline vehicle (10 µl icv). At 8 weeks lesioned and control rats were terminated in order to validate the effectiveness of 5,7-DHT: reduction in 5-HT and 5-HIAA by 83-91% and 69-83% in striatum, frontal cortex, and hippocampus (HPLC/ED method). Other groups of rats were pretreated with thioperamide (5.0 mg/kg ip) or saline vehicle 60 min prior to 6-[³H]-D-glucose (500 µCi/kg ip). Fifteen-min later rats were decapitated and brains were excised and dissected to remove frontal cortex, striatum, hippocampus, thalamus/hypothalamus, pons, and cerebellum. Liquid scintillation spectroscopy was used to determine that [³H]glucose uptake, which was enhanced in 5,7-DHT lesioned rats in cortex (by 88%), hippocampus, thalamus/hypothalamus, pons and cerebellum (each by 47-56%), and in striatum (by 35%). In contrast, thioperamide prevented the enhancement in [³H]glucose uptake in all brain regions of 5,7-DHT neonatally lesioned rats; and [³H]glucose levels were significantly different in all brain regions (except thalamus/hypothalamus) in thioperamide-versus saline-treated rats. These findings indicate a functional association between histaminergic and serotoninergic systems in brain in relation to glucose regulation.

Ontogenetic exposure of rats to pre- and post-natal manganese enhances behavioral impairments produced by perinatal 6-hydroxydopamine.

Rats lesioned shortly after birth with 6-hydroxydopamine (6-OHDA; 134 µg icv) represent a near-ideal model of severe Parkinson's disease because of the near-total destruction of nigrostriatal dopaminergic fibers. The element manganese, an essential cofactor for many enzymatic reactions, itself in toxic amount, replicates some clinical features similar to those of Parkinson's disease. The aim of this study was to examine the effect of neonatal manganese exposure on 6-OHDA modeling of Parkinson's disease in rats. Manganese (MnCl(2)·4H(2)O) 10,000 ppm was included in the drinking water of pregnant Wistar rats from the time of conception until the 21st day after delivery, the age when neonatal rats were weaned. Control rats consumed tap water. Other groups of neonatal rat pups, on the 3rd day after birth, were pretreated with desipramine (20 mg/kg ip 1 h) prior to bilateral icv administration of 6-OHDA (30, 60, or 137 µg) or its vehicle saline-ascorbic (0.1%) (control). At 2 months after birth, in rats lesioned with 30, 60, or 134 µg 6-OHDA, endogenous striatal dopamine (DA) content was reduced, respectively, by 66, 92, and 98% (HPLC/ED), while co-exposure of these groups to perinatal manganese did not magnify the DA depletion. However, there was prominent enhancement of DA D(1) agonist (i.e., SKF 38393)-induced oral activity in the group of rats exposed perinatally to manganese and also treated neonatally with the 30 mg/kg dose of 6-OHDA. The 30 mg/kg 6-OHDA group, demonstrating cataleptogenic responses to SCH 23390 (0.5 mg/kg) and haloperidol (0.5 mg/kg ip), developed resistance if co-exposed to perinatal manganese. In the group exposed to manganese and lesioned with the 60 mg/kg dose of 6-OHDA, there was a reduction in D(2) agonist (i.e., quinpirole, 0.1 mg/kg)-induced yawning. The series of findings demonstrate that ontogenetic exposure to manganese results in an enhancement of behavioral toxicity to a moderate dose of 6-OHDA, despite the fact that there is no enhanced depletion of striatal DA depletion by the manganese treatment.

Stereotypic progressions in psychotic behavior.

Dopamine receptor supersensitivity (DARSS) often is invoked as a mechanism possibly underlying disordered thought processes and agitation states in psychiatric disorders. This review is focused on identified means for producing DARSS and associating the role of other monoaminergic systems in modulating DARSS. Dopamine (DA) receptors, experimentally, are prone to become supersensitive and to thus elicit abnormal behaviors when coupled with DA or a receptor agonist. In intact (control) rats repeated DA D1 agonist treatments fail to sensitize D1 receptors, while repeated D2 agonist treatments sensitize D2 receptors. D2 RSS is attenuated by a lesion with DSP-4 (N-(2-chlorethyl)-N-ethyl-2-bromobenzylamine) in early postnatal ontogeny, indicating that noradrenergic nerves have a permissive effect on D2 DARSS. However, if DSP-4 is co-administered with 5,7-dihydroxytryptamine to destroy serotonin (5-HT) nerves, then D2 RSS is restored. In rats treated early in postnatal ontogeny with the neurotoxin 6-hydroxydopamine to largely destroy DA innervation of striatum, both repeated D1 and D2 agonists sensitize D1 receptors. 5-HT nerves appear to have a permissive effect on D1 DARSS, as a 5-HT lesion reduces the otherwise enhanced effect of a D1 agonist. The series of findings demonstrate that DARSS is able to be produced by repeated agonist treatments, albeit under different circumstances. The involvement of other neuronal phenotypes as modulators of DARSS provides the potential for targeting a variety of sites in the aim to prevent or attenuate DARSS. This therapeutic potential broadens the realm of approaches toward treating psychiatric disorders.

Neonatal co-lesion by DSP-4 and 5,7-DHT produces adulthood behavioral sensitization to dopamine D(2) receptor agonists.

To assess the possible modulatory effects of noradrenergic and serotoninergic neurons on dopaminergic neuronal activity, the noradrenergic and serotoninergic neurotoxins DSP-4 N-(2-chlorethyl)-N-ethyl-2-bromobenzylamine (50.0 mg/kg, sc) and 5,7-dihydroxytryptamine (5,7-DHT) (37.5 microg icv, half in each lateral ventricle), respectively, were administered toWistar rats on the first and third days of postnatal ontogeny, and dopamine (DA) agonist-induced behaviors were assessed in adulthood. At eight weeks, using an HPLC/ED technique, DSP-4 treatment was associated with a reduction in NE content of the corpus striatum (> 60%), hippocampus (95%), and frontal cortex (> 85%), while 5,7-DHT was associated with an 80-90% serotonin reduction in the same brain regions. DA content was unaltered in the striatum and the cortex. In the group lesioned with both DSP-4 and 5,7-DHT, quinpirole-induced (DA D(2) agonist) yawning, 7-hydroxy-DPAT-induced (DA D(3) agonist) yawning, and apomorphine-induced (non-selective DA agonist) stereotypies were enhanced. However, SKF 38393-induced (DA D(1) agonist) oral activity was reduced in the DSP-4 + 5,7-DHT group. These findings demonstrate that DA D(2)- and D(3)-agonist-induced behaviors are enhanced while DA D(1)-agonist-induced behaviors are suppressed in adult rats in which brain noradrenergic and serotoninergic innervation of the brain has largely been destroyed. This study indicates that noradrenergic and serotoninergic neurons have a great impact on the development of DA receptor reactivity (sensitivity).

Histaminergic activity in a rodent model of Parkinson's disease.

Rats lesioned shortly after birth with 6-OHDA have been proposed to be a near-ideal model of severe Parkinson's disease, because of non-lethality of the procedure, near-total destruction of nigrostriatal dopaminergic fibers, and near-total dopamine (DA) denervation of striatum. There are scarce data that in Parkinson's disease, activity of the central histaminergic system is increased. Therefore, the aim of this study was to determine histamine content in the brain and the effect of histamine receptor antagonists on behavior of adult rats. At 3 days after birth, Wistar rats were pretreated with desipramine (20.0 mg/kg ip) 1 h before bilateral icv administration of the catecholaminergic neurotoxin 6-OHDA (67 microg base, on each side) or saline-ascorbic acid (0.1%) vehicle (control). At 8 weeks levels of DA and its metabolites L: -3,4-dihydroxyphenylalanine (DOPAC) and homovanillic acid (HVA) were estimated in the striatum and frontal cortex by HPCL/ED technique. In the hypothalamus, hippocampus, frontal cortex, and medulla oblongata, the level of histamine was analyzed by immunoenzymatic method. Behavioral observations (locomotion, exploratory-, oral-, and stereotyped-activity) were additionally made on control and 6-OHDA neonatally lesioned rats. Effects of DA receptor agonists (SKF 38393, apomorphine) and histamine receptor antagonists (e.g., S(+)chlorpheniramine, H(1); cimetidine, H(2); thioperamide, H(3) agonist) were determined. We confirmed that 6-OHDA significantly reduced contents of DA and its metabolites in the brain in adulthood. Histamine content was significantly increased in the hypothalamus, hipocampus, and medulla oblongata. Moreover, in 6-OHDA-lesioned rats behavioral response was altered mainly by thioperamide (H(3) antagonist). These findings indicate that histamine and the central histaminergic system are altered in the brain of rats lesioned to model Parkinson's disease, and that histaminergic neurons exert a modulating role in Parkinsonian 6-OHDA-lesioned rats.

Dopamine receptor supersensitivity: development, mechanisms, presentation, and clinical applicability.

The process of receptor supersensitivity (RSS) has a long history and is an epiphenomenon of neuronal denervation. Dopamine (DA) RSS (DARSS) similarly occurs after DA denervation, and this process is invoked in neuropsychiatric and neurodegenerative disorders. From studies largely over the past 25 years, much has been learned regarding DARSS. For example, overt D1 DARSS occurs after perinatal destruction of nigrostriatal DA fibers. However, following perinatal destruction of DA innervation, the most-prominent behavioral effects of a D1 agonist are observed after a series of D1 agonist treatments--a process known as priming of D1 DA receptors. Moreover, perinatal lesioning of DA fibers produces prominent serotonin (5-HT) RSS, and in fact 5-HT RSS appears to modulate D1 DA RSS. In rodents, receptor supersensitization by these means appears to be irreversible. In contrast to the observed D1 DARSS, D2 DARSS apparently does not occur after perinatal DA denervation. Also, while repeated D1 agonist treatment of intact rats has no observable effect, repeated D2 agonist treatments, during or after the ontogenetic phase, produces prominent life-long D2 RSS. The process may have an association with substance abuse. Therefore, production of D1 and D2 DARSS occurs by different means and under different circumstances, and in association with perhaps different neuronal phenotypes, and with greater incidence in either intact (D2) or DA-lesioned counterparts (D1). The physiological consequence of RSS are multiple.

Reactivity of 5-HT1A receptor in adult rats after neonatal noradrenergic neurons' lesion--implications for antidepressant-like action.

The aim of this study was to assess the 5-HT1A receptor reactivity after neonatal noradrenergic neurons' lesion. DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine), 50 mg/kg, was administered 30 min after a selective serotonin reuptake inhibitor (SSRI)--zimelidine (10 mg/kg) on the 1st and 3rd day of life. Zimelidine was used to prevent serotonin (5-HT) depletion. 5-HT1A autoreceptor is involved in the regulation of 5-HT release as well as the pathogenesis of depression. During a microdialysis study of anaesthetized rats, the 5-HT1A receptor agonist, R-(+)-8-OH-DPAT (0.1 mg/kg), decreased 5-HT release in the medial prefrontal cortex of control rats but this effect was significantly attenuated in DSP-4-treated animals (10-12 weeks old). To further determine which type of receptor, either pre or postsynaptically located, is involved in the attenuated response to the 5-HT1A receptor agonist in lesioned rats, behavioral tests were conducted. In the forced swimming test, DSP-4 treated rats after saline injection, displayed shorter immobility time in comparison to control rats. R-(+)-8-OH-DPAT (0.5 mg/kg) evoked an antidepressant-like effect in control and DSP-4 treated rats in a learned helplessness paradigm as well as the forced swimming test. The results of this study provided further support for the exclusive desensitization of 5-HT1A autoreceptor in adult rats with neonatal lesion of the central noradrenergic system.