RESUMO
Hyperprolinemia is an inherited disorder of proline metabolism and hyperprolinemic patients can present neurological manifestations, such as seizures, cognitive dysfunctions, and schizoaffective disorders. However, the mechanisms related to these symptoms are still unclear. In the present study, we evaluated the in vivo and in vitro effects of proline on acetylcholinesterase (AChE) activity and gene expression in the zebrafish brain. For the in vivo studies, animals were exposed at two proline concentrations (1.5 and 3.0mM) during 1h or 7 days (short- or long-term treatments, respectively). For the in vitro assays, different proline concentrations (ranging from 3.0 to 1000 µM) were tested. Long-term proline exposures significantly increased AChE activity for both treated groups when compared to the control (34% and 39%). Moreover, the proline-induced increase on AChE activity was completely reverted by acute administration of antipsychotic drugs (haloperidol and sulpiride), as well as the changes induced in ache expression. When assessed in vitro, proline did not promote significant changes in AChE activity. Altogether, these data indicate that the enzyme responsible for the control of acetylcholine levels might be altered after proline exposure in the adult zebrafish. These findings contribute for better understanding of the pathophysiology of hyperprolinemia and might reinforce the use of the zebrafish as a complementary vertebrate model for studying inborn errors of amino acid metabolism.
Assuntos
Acetilcolinesterase/metabolismo , Antipsicóticos/farmacologia , Química Encefálica/efeitos dos fármacos , Química Encefálica/genética , Encéfalo/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Prolina/farmacologia , Peixe-Zebra/fisiologia , Animais , Feminino , Haloperidol/farmacologia , Técnicas In Vitro , Masculino , Proteínas do Tecido Nervoso/biossíntese , Proteínas do Tecido Nervoso/genética , Sistema Nervoso Parassimpático/efeitos dos fármacos , Prolina/antagonistas & inibidores , Reação em Cadeia da Polimerase em Tempo Real , Sulpirida/farmacologiaRESUMO
Hyperprolinemia is an inherited disorder of proline metabolism and patients affected by this disease may present neurological manifestations, including seizures and cognitive dysfunctions. Moreover, an association between adulthood schizoaffective disorders and moderate hyperprolinemia has been reported. However, the mechanisms underlying these behavioral phenotypes still remain unclear. In the present study, we investigated the effect of proline treatments on behavioral parameters in zebrafish, such as locomotor activity, anxiety, and social interaction. Adult zebrafish (Danio rerio) were exposed to proline (1.5 and 3.0 mM) during 1h or 7 days (short- or long-term treatments, respectively). Short-term proline exposure did not promote significant changes on the behavioral parameters observed. Long-term exposure at 1.5 mM proline significantly increased the number of line crossing (47%), the total distance (29%), and the mean speed (33%) when compared to control group. A significant increase in the time spent in the upper portion of the test tank was also observed after this treatment (91%), which may be interpreted as an indicator of anxiolytic behavior. Proline at 1.5 mM also induced social interaction impairment (78%), when compared to the untreated group after long-term treatment. Moreover, these proline-induced behavioral changes in zebrafish were completely reversed by acute administration of an atypical antipsychotic drug (sulpiride), but not by a typical (haloperidol). These findings demonstrate that proline is able to induce schizophrenia-like symptoms in zebrafish, which reinforce the use of this species as a complementary vertebrate model for studying behavioral phenotypes associated with neurological dysfunctions characteristic of metabolic diseases.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/tratamento farmacológico , Antipsicóticos/uso terapêutico , Ansiedade/tratamento farmacológico , Locomoção/efeitos dos fármacos , Prolina/antagonistas & inibidores , Prolina/farmacologia , Comportamento Social , 1-Pirrolina-5-Carboxilato Desidrogenase/deficiência , Erros Inatos do Metabolismo dos Aminoácidos/induzido quimicamente , Erros Inatos do Metabolismo dos Aminoácidos/complicações , Animais , Antipsicóticos/farmacologia , Ansiedade/complicações , Modelos Animais de Doenças , Interações Medicamentosas , Feminino , Haloperidol/farmacologia , Haloperidol/uso terapêutico , Masculino , Prolina Oxidase/deficiência , Sulpirida/farmacologia , Sulpirida/uso terapêutico , Fatores de Tempo , Peixe-ZebraRESUMO
The biological activity of the proline-rich decapeptide Bj-PRO-10c, a processing product of the C-type natriuretic peptide precursor protein, expressed in the brain and the venom gland of the pit viper Bothrops jararaca, was originally attributed to the inhibition of the somatic angiotensin-converting enzyme activity with subsequent anti-hypertensive effect. However, recent results suggest broader biological activity may also be involved in the cardiovascular effects of this peptide. Here we show that Bj-PRO-10c enhances and sustains the generation of nitric oxide (NO) by regulating argininosuccinate synthase activity and thereby velocity of the citrullineNO cycle. Bj-PRO-10c-mediated effects not restricted to thecardiovascular system, since NO production was also induced in cells of astroglial origin. Bj-PRO-10c was internalized by C6 astroglioma cells where it induces NO production and upregulation of the citrullineNO cycle cells in a dose-dependent fashion. In view of that, astroglial cells function as L-arginine pool for NO production in neighboring neurons, we suggest a regulatory function for Bj-PRO-10c on the metabolism of this gaseous neurotransmitter in the CNS. Moreover, proliferation of astroglial cells was reduced in the presence of Bj-PRO-10c; however, cell death was not induced. Since NO donors have been studied for the treatment of solid cancers, Bj-PRO-10c may serve as structural model fordeveloping drugs to improve the effects of cancer therapy based on the peptide's ability to augment NO production.
Assuntos
Animais , Anti-Hipertensivos/antagonistas & inibidores , Anti-Hipertensivos/classificação , Bothrops , Prolina/antagonistas & inibidores , Venenos de Serpentes/antagonistas & inibidoresRESUMO
Pyroglutamyl proline-rich oligopeptides, present in the venom of the pit viper Bothrops jararaca (Bj-PROs), are the first described naturally occurring inhibitors of the angiotensin I-converting enzyme (ACE). The inhibition of ACE by the decapeptide Bj-PRO- 10c (Assuntos
Animais
, Bothrops
, Prolina/antagonistas & inibidores
, Prolina/toxicidade
, Venenos de Serpentes/antagonistas & inibidores
, Venenos de Serpentes/toxicidade
RESUMO
In the present study we investigated the in vivo and in vitro effect of proline (Pro) on acetylcholinesterase (AChE) activity in rat cerebral cortex. The action of vitamins E and C on the effects produced by Pro was also tested. Twelve-day-old rats received one s.c. injection of Pro (12.8 micromol/g body weight) or an equivalent volume of 0.9% saline solution (control) and were killed 1 h later. In another set of experiments, 5-day-old rats were pretreated for 1 week with daily i.p. administration of saline (control) or vitamins E (40 mg/kg) and C (100 mg/kg). Twelve hours after the last injection the rats received one s.c. injection of Pro (12.8 micromol/g body weight) or saline (control) and were killed 1 h later. For the in vitro studies, cerebral cortex homogenates of 12-day-old untreated rats were incubated for 1 h with various concentrations of Pro (3.0 microM-1.0 mM) or with 1.0 mM Pro, 1.0 mM trolox, or 1.0 mM Pro plus 1.0 mM trolox. Controls did not contain Pro in the incubation medium. Our results showed that the AChE activity significantly decreased (25%) in rat brain subjected to Pro administration and that the pretreatment with vitamins E and C prevented this effect. Furthermore, Pro (0.5 and 1.0 mM) also inhibits AChE activity in vitro and trolox prevented this effect. The data suggest that the inhibitory effect of Pro on AChE activity is associated with oxidative stress. Although it is difficult to extrapolate our findings to the human condition, our results may be relevant to explain, at least in part, the neurologic dysfunction associated with hyperprolinemia type II.