The elevated gradient of aversion: a new apparatus to study the rat behavior dimensions of anxiety, fear, and impulsivity

Few behavioral tests allow measuring several characteristics and most require training, complex analyses, and/or are time-consuming. We present an apparatus based on rat exploratory behavior. Composed of three different environments, it allows the assessment of more than one behavioral characteristic in a short 3-min session. Factorial analyses have defined three behavioral dimensions, which we named Exploration, Impulsivity, and Self-protection. Behaviors composing the Exploration factor were increased by chlordiazepoxide and apomorphine and decreased by pentylenetetrazole. Behaviors composing the Impulsivity factor were increased by chlordiazepoxide, apomorphine, and both acute and chronic imipramine treatments. Behaviors composing the Self-protection factor were decreased by apomorphine. We submitted Wistar rats to the open-field test, the elevated-plus maze, and to the apparatus we are proposing. Measures related to exploratory behavior in all three tests were correlated. Measures composing the factors Impulsivity and Self-protection did not correlate with any measures from the two standard tests. Also, compared with existing impulsivity tests, the one we proposed did not require previous learning, training, or sophisticated analysis. Exploration measures from our test are as easy to obtain as the ones from other standard tests. Thus, we have proposed an apparatus that measured three different behavioral characteristics, was simple and fast, did not require subjects to be submitted to previous learning or training, was sensitive to drug treatments, and did not require sophisticated data analyses.

Ropinirole alters gene expression profiles in SH-SY5Y cells: a whole genome microarray study

Ropinirole (ROP) is a dopamine agonist that has been used as therapy for Parkinson's disease. In the present study, we aimed to detect whether gene expression was modulated by ROP in SH-SY5Y cells. SH-SY5Y cell lines were treated with 10 µM ROP for 2 h, after which total RNA was extracted for whole genome analysis. Gene expression profiling revealed that 113 genes were differentially expressed after ROP treatment compared with control cells. Further pathway analysis revealed modulation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway, with prominent upregulation of PIK3C2B. Moreover, batches of regulated genes, including PIK3C2B, were found to be located on chromosome 1. These findings were validated by quantitative RT-PCR and Western blot analysis. Our study, therefore, revealed that ROP altered gene expression in SH-SY5Y cells, and future investigation of PIK3C2B and other loci on chromosome 1 may provide long-term implications for identifying novel target genes of Parkinson's disease.

Novedosos agentes dopaminérgicos centrales derivados del 2-aminoindano-4,7 disustituido atípico. Síntesis y perfil farmacológico central / Novel central dopaminergic agents derived from atypical di-substituted 2-aminoindane-4, 7. Synthesis and central pharmacological profile

En las últimas décadas son muchos los compuestos con actividad dopaminérgica central que se han diseñado, sintetizado y evaluado farmacológicamente. A pesar de ello, no se ha logrado obtener un fármaco capaz de mejorar o curar las patologías que involucran la regulación dopaminérgica en el sistema nervioso central tales como la Enfermedad de Parkinson y la esquizofrenia, entre otras. Tomando en consideración el término de “farmacóforo atípico” y a partir del compuesto 5, se incorporó el fragmento aralquil y se sintetizaron los compuestos 10, 11, 13a-h y 14a-h. Tanto los compuestos 10 y 13a-h bajo su forma metoxilada como los compuestos 11 y 14a-h bajo su forma fenólica, fueron evaluados farmacológicamente para determinar su actividad agonística y antagonística sobre el sistema dopaminérgico central. Para ello se determinó el efecto de la inyección intracerebroventricular de dichos compuestos sobre el balance hidromineral y la conducta estereotipada en ratas. Los resultados de la evaluación farmacológica preliminar muestran una acción central a través de mecanismos dopaminérgicos, siendo que los compuestos 10, 11, 13d-h y 14a mostraron respuestas como agonistas, mientras que los compuestos 14b-h, tuvieron respuestas como antagonistas.

In recent decades, many compounds with central dopaminergic activity have been designed, synthesized and evaluated pharmacologically. However, it has not been possible to obtain a drug able to improve or cure diseases involving dopaminergic regulation in the central nervous system, such as Parkinson’s disease and schizophrenia, among others. Taking into consideration the term “atypical pharmacophore” and from the compound 5, the aralkyl fragment was incorporated, and the compounds 10, 11, 13a-h and 14a-h were synthesized. Both the compounds 10 and 13a-h under its methoxylated form and the compounds 11 and 14a-h under the phenolic form, were evaluated to determine their pharmacologically agonistic and antagonistic effects on central dopaminergic activity. For this, the effect of intracerebroventricular injection of said compounds on the hydromineral balance and stereotyped behavior in rats, was determined. The results of the preliminary pharmacological evaluation show a centrally acting action through dopamine mechanisms, in which the compounds 10, 11, 13d-h and 14a showed responses as agonists, whereas compounds 14b-h, had responses as antagonists.

Effects of apomorphine on locomotive activity and monoamine metabolism: a dose related study

We have monitored dose dependent effects of apomorphine on motor activity and monoamine metabolism. Behavioral sensitization and craving, which develop upon repeated treatment with dopamine receptor agonist apomorphine, are major limitations of the therapeutic use of apomorphine in Parkinson's patients. Effects of single [intraperitoneal] injection of apomorphine at different doses [i.e., 1.0, 2.0 and 4.0 mg/kg] on exploration in a novel environment [open field] and locomotion in a familiar environment [home cage] were investigated. Results show significantly enhanced activity in home cage [monitored 5min post injection] in a dose dependent manner. However, no significant influence of apomorphine on exploration of open field was observed in the present study [monitored 15min and 40min post injection]. Animals were decapitated 1 hr post apomorphine injection and whole brains of animals were collected and stored at -70°C. Biogenic amines [i.e., 5-Hydroxytryptamine and dopamine] and metabolites [i.e., Dihydroxyphenylacetic acid, Homovanillic acid and 5-Hydroxyindoleacetic acid] were estimated by reverse phase High Performance Liquid Chromatography with electrochemical detector [HPLC-EC]. Effect of low [l.0mg/kg] dose of apomorphine was found to be nonsignificant on 5-Hydroxytryptamine [5-HT], 5-Hydroxyindoleacetic acid [5-HIAA] and dopamine [DA] levels. Moderate [2.0 mg/kg] dose of drug increased [p<0.05] levels of Homovanillic acid [HVA]. Whereas, high [4.0 mg/kg] dose of apomorphine decreased Dihydroxyphenylacetic acid [DOPAC] levels. Results could be helpful in elucidating the effect of apomorphine at different doses and its implication for extending therapeutics in Parkinson's and related disorders

Comparison of the effect of gonadotropin-releasing hormone agonist and dopamine receptor agonist on uterine myoma growth. Histologic, sonographic, and intra-operative changes

To investigate the effect of 2 medications; Diphereline and Cabergoline, on uterine leiomyoma growth, and its histologic, sonographic, and intra-operative changes. In an effort to treat large uterine leiomyoma in symptomatic patients in the Gynecology Clinics of the Alzahra Teaching Hospital of Tabriz University of Medical Sciences, Tabriz, Iran, from September 2007 to November 2008, 60 candidates randomized to receive Diphereline 3.75 mg, 4 times every 28 days [group I], and Cabergoline 0.5 mg, once a week for 6 weeks [group II], were included in this study. Clinical symptoms, feasibility of intra-operative dissection, intraoperative complications, sonographic, and pathologic characteristics of the tumor were evaluated. Thirteen patients from group I, and 10 patients from group II underwent surgery. There was a significant difference between the groups in the rate of lymphocyte infiltration [p=0.003], but not in other pathologic features. In both groups, the mitotic index was between 0-10. While there was no significant difference between the groups in the number [p=0.30], and volume of leiomyomas [p=0.65], however, changes in the uterine artery circulation was significant [p=0.001 [group I], p=0.026 [group II]]. In addition, there was a significant difference between the groups for intra-operative hemorrhage and adhesion of leiomyomas to the uterine wall. This study found that Cabergoline is as effective as Diphereline in the shrinkage of myomas, accompanied by improvement in the sonographic, clinical, and intra-operative outcomes without any adverse pathological changes, and could be a good medical regimen as an adjunct to surgical management

Effects of dextromethorphan on dopamine dependent behaviours in rats.

Dextromethorphan, a noncompetitive blocker of N-methyl-D- aspartate (NMDA) type of glutamate receptor, at 7.5-75 mg/kg, ip did not induce oral stereotypies or catalepsy and did not antagonize apomorphine stereotypy in rats. These results indicate that dextromethorphan at 7.5-75 mg/kg does not stimulate or block postsynaptic striatal D2 and D1 dopamine (DA) receptors. Pretreatment with 15 and 30 mg/kg dextromethorphan potentiated dexamphetamine stereotypy and antagonised haloperidol catalepsy. Pretreatment with 45, 60 and 75 mg/kg dextromethorphan, which release 5-hydroxytryptamine (5-HT), however, antagonised dexamphetamine stereotypy and potentiated haloperidol catalepsy. Apomorphine stereotypy was not potentiated or antagonised by pretreatment with 7.5-75 mg/kg dextromethorphan. This respectively indicates that at 7.5-75 mg/kg dextromethorphan does not exert facilitatory or inhibitory effect at or beyond the postsynaptic striatal D2 and D1 DA receptors. The results are explained on the basis of dextromethorphan (15-75 mg/kg)-induced blockade of NMDA receptors in striatum and substantia nigra pars compacta. Dextromethorphan at 15 and 30 mg/kg, by blocking NMDA receptors, activates nigrostriatal dopaminergic neurons and thereby potentiates dexampetamine stereotypy and antagonizes haloperidol catalepsy. Dextromethorphan at 45, 60 and 75 mg/kg, by blocking NMDA receptors, releases 5-HT and through the released 5-HT exerts an inhibitory influence on the nigrostriatal dopaminergic neurons with resultant antagonism of dexampetamine stereotypy and potentiation of haloperidol catalepsy.

Genotoxic, neurotoxic and neuroprotective activities of apomorphine and its oxidized derivative 8-oxo-apomorphine

Apomorphine is a dopamine receptor agonist proposed to be a neuroprotective agent in the treatment of patients with Parkinson's disease. Both in vivo and in vitro studies have shown that apomorphine displays both antioxidant and pro-oxidant actions, and might have either neuroprotective or neurotoxic effects on the central nervous system. Some of the neurotoxic effects of apomorphine are mediated by its oxidation derivatives. In the present review, we discuss recent studies from our laboratory in which the molecular, cellular and neurobehavioral effects of apomorphine and its oxidized derivative, 8-oxo-apomorphine-semiquinone (8-OASQ), were evaluated in different experimental models, i.e., in vitro genotoxicity in Salmonella/microsome assay and WP2 Mutoxitest, sensitivity assay in Saccharomyces cerevisiae, neurobehavioral procedures (inhibition avoidance task, open field behavior, and habituation) in rats, stereotyped behavior in mice, and Comet assay and oxidative stress analyses in mouse brain. Our results show that apomorphine and 8-OASQ induce differential mutagenic, neurochemical and neurobehavioral effects. 8-OASQ displays cytotoxic effects and oxidative and frameshift mutagenic activities, while apomorphine shows antimutagenic and antioxidant effects in vitro. 8-OASQ induces a significant increase of DNA damage in mouse brain tissue. Both apomorphine and 8-OASQ impair memory for aversive training in rats, although the two drugs showed a different dose-response pattern. 8-OASQ fails to induce stereotyped behaviors in mice. The implications of these findings are discussed in the light of evidence from studies by other groups. We propose that the neuroprotective and neurotoxic effects of dopamine agonists might be mediated, in part, by their oxidized metabolites.

Increased Burst Firing in Substantia Nigra Pars Reticulata Neurons and Enhanced Response to Selective D2 Agonist in Hemiparkinsonian Rats After Repeated Administration of Apomorphine

Intermittent administrations of dopaminergic agents in hemiparkinsonian rat enhances the behavioral response to subsequent administration of the drugs. This phenomenon is known as "priming" and thought as comparable to drug-induced dyskinesia in patients with Parkinson's disease. We investigated the behavioral and electrophysiological changes in 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian rats after repeated administrations of apomorphine. Administration of apomorphine (0.32 mg/kg, intraperitoneal, i.p.) twice daily for 6 days enhanced the rotation induced by apomorphine from 341 turns/hour at the beginning to 755 turns/hr at the end. At the same time, the response to selective D2 agonist quinpirole (0.26 mg/kg, i.p.) was also enhanced from 203 to 555 turns/hr. Extracellular single unit recording revealed no significant difference in the basal firing rates of substantia nigra pars reticulata (SNr) neurons between the ipsilateral and contralateral side of the 6-OHDA lesion regardless of the repeated administrations of apomorphine. In SNr of the lesion side, the units with burst firing pattern were found more frequently after repeated administrations of apomorphine and the suppressive effect of quinpirole on the firing rate was enhanced. These findings suggest that the increased percentage of the burst units is the important electrophysiological change in the development of enhanced response to selective D2 agonist.

Involvement of dopamine D2 and 5-HT1A receptors in roxindole-induced antinociception.

Roxindole, a DA D2 receptor agonist (2-16 mg/kg) produced dose-dependent increase in percentage antinociception. The effect which was blocked by DA D2 antagonist (-)sulpiride (50 mg/kg) and 5-HT1A receptor antagonist (-) pindolol (5 mg/kg). Roxindole (4 and 8 mg/kg) reversed both naloxone (20 mg/kg)-induced hyperalgesia and reserpine (2 mg/kg)-induced hyperalgesia. This reversal was sensitive to blockade by both (-)sulpiride (50 mg/kg) and (-) pindolol (5 mg/kg). The present study suggests that roxindole-induced antinociception is mediated by postsynaptic DA D2 and 5-HT1A receptors.

Dose-response functions of apomorphine, SKF 38393, LY 171555, haloperidol and clonidine on the self-stimulation evoked from lateral hypothalamus and ventral tegmentum.

The experimental animals were implanted with two bipolar electodes, one in the lateral hypothalamus including medial forebrain bundle (LH-MFB) and other in ipsilateral ventral tegmental area-substantia nigra (VTA-SN) and were trained to press a pedal for self-stimulation. This provided the scope to compare directly the effect of a given dose of a drug on the two reward regions in the same animal in the same testing situation. The current intensity was set to produce intracranial self-stimulation (ICSS) response rates of 50% less than the maximal shaping response rates for the respective animals (M60). Following systemic (intraperitoneal) administration of apomorphine (a dopamine receptor D1/D2 mixed agonist), SKF 38393 (D1 > D3 > D2 agonist), LY 17155 or quinpirole (D3 > D2 and D1) agonist), haloperidol (a DA-D2 antagonist), and clonidine (noradrenaline receptor alpha 2 agonist), the ICSS response rates evoked from LH-MFB and VTA-SN were compared with vehicle or saline-treated animals on the basis of dose-response functions. A dose-dependent inhibitory effect at M50 was observed with apomorphine (0.01-1.00 mg/kg) and haloperidol (0.05-0.30 mg/kg) for both the sites of stimulation. These doses of haloperidol did not produce any motor deficits like catalepsy and muscular rigidity. The dose-response and time-effect functions of SKF 38393 and LY 171555 at M50 showed the facilitation and suppression of ICSS of VTA-SN and LH-MFB respectively. Clonidine (0.05-0.25 mg/kg) also produced inhibitory effect on ICSS rates, but this suppression was of different magnitude with respect to the site of stimulation. These doses of clonidine were in the range that did not prevent active pedal pressing responses. ED50 (the dose required to reduce the ICSS response rate 50% of the rate after administration of vehicle) for LY 171555 was 0.8 and 4.4 mg/kg for the ICSS of VTA-SN and LH-MFB respectively and thus statistically different ED50 for apomorphine was 0.27 and 0.36 mg/kg; and for haloperidol was 0.75 and 0.90 mg/kg for LH-MFB and VTA-SN respectively and thus not different significantly. ED50 for clonidine was 0.25 and 0.08 mg/kg for VTA-SN and LH-MFB respectively and thus statistically different. The two-way analysis of variance (ANOVAR) of interaction of dose-response function of alpha 2 agonist with respect to LH-MFB and VTA-SN showed significant independence in their suppressive effects.

Efeitos terapêuticos do hidrogênio lisurida na hiperprolactinemia: resposta clínica e hormonal / Therapeutic effects of lisuride hydrogen in hyperprolactinemia: clinical and hormonal response

O hidrogênio maleato de lisurida é de um novo derivado semi-sintético do ergot. Apresenta propriedades agonista dopaminérgico e antagonista seratoninérgico. É cerca de dez vezes mais potente potente que a bromoergocriptina e apresenta a vantagem adicional de possuir estrutura molecular mais simples, sem cadeia peptídica lateral, o que lhe assegura menor custo de síntese e de tratamento. Seis mulheres, portadoras da galactorréia e hiperprolactinemia, foram tratadas com a droga na dose máxima de 0,3mg/dia por 30 dias ou de 0,4mg/dia por 60 dias. A prolactina foi reduzida a níveis normais em 4 pacientes. A galactorréia cessou em todas, ciclos menstruais ocorreram em duas. A cefaléia foi melhorada em uma. Houve boa tolerància do medicamento.