Search

This work describes the neuropharmacological (sedative, anxiolytic, antidepressant, and anticonvulsant) actions of Gardenin A (GA) (0.1-25 mg/kg p.o.), a flavonoid found in medicinal plants. The sedative effects of GA were assessed with the pentobarbital-induced sleep test. The anxiolytic actions of GA were evaluated with the elevated plus-maze, the light-dark box test, the exploratory cylinder assay, and the open field test. Motor coordination was evaluated with the rotarod test and the open field test. The antidepressant-like actions of GA were evaluated with the tail suspension test and forced swimming test. The mechanisms of the anxiolytic-like and antidepressant-like effects of GA were assessed using inhibitors of neurotransmission pathways. The anticonvulsant activity of GA was evaluated with the strychnine-induced seizure test. The sedative effects of GA were evident only at a dose of 25 mg/kg, which increased the duration of sleep but did not alter sleep onset. GA showed anxiolytic-like actions with activity comparable to that of clonazepam in all experimental tests. The GABAA receptor antagonist bicuculline reversed the anxiolytic-like effects of GA. Furthermore, GA showed significant antidepressant-like actions in both models with activity comparable to that of fluoxetine. Yohimbine, an α2-adrenoceptor blocker, inhibited the antidepressant-like actions of GA. In addition, GA (1-10 mg/kg) did not affect locomotor coordination in mice and delayed the onset of convulsions. These findings suggest that GA induces anxiolytic-like effects and has anticonvulsant actions by the possible involvement of the GABAergic system. The antidepressant-like actions of GA may be mediated by noradrenergic neurotransmission.

A surgical connection between portal and inferior cava veins was performed to generate an experimental model of high circulating ammonium and hepatic hypofunctioning. After 13 weeks of portacaval anastomosis (PCA), hyperammonemia and shrinkage in the liver were observed. Low glycemic levels accompanied by elevated levels of serum alanine aminotransferase were recorded. However, the activity of serum aspartate aminotransferase was reduced, without change in circulating urea. Histological and ultrastructural observations revealed ongoing vascularization and alterations in the hepatocyte nucleus (reduced diameter with indentations), fewer mitochondria, and numerous ribosomes in the endoplasmic reticulum. High activity of hepatic caspase-3 suggested apoptosis. PCA promoted a marked reduction in lipid peroxidation determined by TBARs in liver homogenate but specially in the mitochondrial and microsomal fractions. The reduced lipoperoxidative activity was also detected in assays supplemented with Fe2+. Only discreet changes were observed in conjugated dienes. Fluorescent probes showed significant attenuation in mitochondrial membrane potential, reactive oxygen species (ROS), and calcium content. Rats with PCA also showed reduced food intake and decreased energy expenditure through indirect calorimetry by measuring oxygen consumption with an open-flow respirometric system. We conclude that experimental PCA promotes an angiogenic state in the liver to confront the altered blood flow by reducing the prooxidant reactions associated with lower metabolic rate, along with significant reduction of mitochondrial content, but without a clear hepatic dysfunction.

The episodes of cerebral dysfunction, known as encephalopathy, are usually coincident with liver failure. The primary metabolic marker of liver diseases is the increase in blood ammonium, which promotes neuronal damage. In the present project, we used an experimental model of hepatic encephalopathy in male rats by portacaval anastomosis (PCA) surgery. Sham rats had a false operation. After 13 weeks of surgery, the most distinctive finding was vacuolar/spongiform neurodegeneration exclusively in the molecular layer of the cerebellum. This cerebellar damage was further characterized by metabolic, histopathological, and behavioral approaches. The results were as follows: (a) Cellular alterations, namely loss of Purkinje cells, morphological changes, such as swelling of astrocytes and Bergmann glia, and activation of microglia; (b) Cytotoxic edema, shown by an increase in aquaporin-4 and N-acetylaspartate and a reduction in taurine and choline-derivate osmolytes; (c) Metabolic adjustments, noted by the elevation of circulating ammonium, enhanced presence of glutamine synthetase, and increase in glutamine and creatine/phosphocreatine; (d) Inflammasome activation, detected by the elevation of the marker NLRP3 and microglial activation; (e) Locomotor deficits in PCA rats as assessed by the Rotarod and open field tests. These results lead us to suggest that metabolic disturbances associated with PCA can generate the cerebellar damage that is similar to morphophysiological modifications observed in amyloidogenic disorders. In conclusion, we have characterized a distinctive cerebellar multi-disruption accompanied by high levels of ammonium and associated with spongiform neurodegeneration in a model of hepatic hypofunctioning.

Introduction Spontaneous ventriculomegaly has been observed in rats that were presumed normal. Because the external phenotype of these animals is unremarkable, they can be inadvertently included in behavioral experiments, despite the considerable enlargement of the ventricular system, reduced cortical thickness, and hippocampal atrophy upon imaging. Given the role of such structures in memory consolidation, we evaluated long‐term memory retention while decision making in rats with spontaneous ventriculomegaly. Methods We studied adult male Sprague Dawley rats, identified as having spontaneous ventriculomegaly, while performing baseline magnetic resonance imaging scanning intended for a different research protocol. Control (n = 7) and experimental (n = 6) animals were submitted to a delayed‐alternation task (no delay, 30, 60, and 180 s) and an object‐in‐context recognition task. During the first task, we evaluated the number of correct choices as well as the latency to reach any of the cavities located at the end of each branch arm during each trial. The second task assessed the rodents’ ability to remember where they had previously encountered a specific object, calculating the context recognition index. Results When compared to control animals, rats with spontaneous ventriculomegaly required significantly more training sessions to reach the 80% criterion during the training phase. Moreover, they showed reduced delayed‐alternation performance in the evaluated times, reaching significance only at 180 s. Increased latencies while trying to reach the cavity were also observed. Evaluation of the long‐term memory formation during the object‐in‐context recognition task showed that subjects with ventriculomegaly spent less time investigating the familiar object, resulting in a significantly decreased recognition index value. Conclusion Our results are the first to show how spontaneous ventriculomegaly‐induced cerebral structural damage affects decision‐making behaviors, particularly when comparing between immediate and delayed trials. Moreover, this lesion disrupts the animals’ ability to recall or express contextual information., Spontaneous ventriculomegaly is a severe noninduced cerebral lesion. However, animals try to decode the challenges when exposed to memory tasks despite their grossly abnormal brain anatomy. This suggests the existence of compensation mechanisms.

The aim was to evaluate the diuretic and neuropharmacological actions of d-pinitol and describe a possible mechanism of action. The diuretic effects of d-pinitol were evaluated using mice placed in metabolic cages. The sedative, anxiolytic-like, antidepressant-like, and anticonvulsant effects of 1-100 mg/kg d-pinitol were assessed. The possible mechanisms of action of the anxiolytic-like, antidepressant-like, and anticonvulsant effects of d-pinitol were evaluated using inhibitors. d-pinitol lacked diuretic effects. However, d-pinitol showed the highest anxiolytic-like actions (ED50 = 70 mg/kg p.o. in mice) in the cylinder exploratory test and the highest antidepressant-like activity in the forced swimming test (ED50 = 26 mg/kg p.o. in mice). d-pinitol (100 mg/kg) exerted anticonvulsant actions in the pentylenetetrazole-induced seizures test. The pre-treatment with 2 mg/kg flumazenil reverted the anxiolytic-like actions and the anticonvulsant effects of d-pinitol, whereas the pre-treatment with 1 mg/kg yohimbine and 0.05 mg/kg prazosin abolished the antidepressant effects of d-pinitol. PRACTICAL APPLICATIONS: d-pinitol (3-O-methyl-d-chiro-inositol) is a polyol found in many fruits, as well as in many members of the Leguminosae and Fabaceae families. The results propose that this compound could contribute in the treatment of anxiety, depression, and convulsions. The findings suggest the possible participation of the GABAergic system in the anxiolytic-like and anticonvulsant actions of d-pinitol, whereas the noradrenergic system is probably involved in the antidepressant effects of d-pinitol. This study provides new information about other pharmacological uses for d-pinitol.

Ethnopharmacological relevance Senna septemtrionalis (Viv.) H.S. Irwin & Barneby (Fabaceae) is a shrub empirically used as diuretic, and for the treatment of neurological disorders. These pharmacological effects have not been previously evaluated. Aim of the study To evaluate the diuretic and CNS effects of a standardized ethanol extract of Senna septemtrionalis aerial parts (SSE). Materials and methods Gas chromatography mass spectrometry was used to perform a chemical analysis with SSE. In all tests, SSE was evaluated from 10 to 100 mg/kg p.o. The diuretic activity of SSE was assessed in mice individually placed in metabolic cages. After 6 h, the urine volume and the electrolyte excretion (Na and K) were measured. The role of prostaglandins and nitric oxide was assessed administrating mice with indomethacin and N(ω)-nitro-L-arginine methyl ester (L-NAME), prior the administration of 100 mg/kg SSE. The sedative effects of SSE were analyzed with the pentobarbital-induced sleeping time test. The effects of SSE on motor coordination in mice were evaluated with the rotarod test. The antidepressant-like activity of SSE was analyzed with the forced swimming test (FST) and the tail suspension test (TST). The role of 5-HT2 receptor, α1-and α2-adrenoceptors, or muscarinic receptors was assessed administrating mice with cyproheptadine, prazosin, yohimbine, and atropine, respectively, prior the administration of 100 mg/kg SSE in the FST. The anxiolytic-like activity of SSE (10–100 mg/kg p.o.) was assessed using the light-dark test (LDB), the elevated plus maze test (EPM), the cylinder exploratory test, and the open field test (OFT). The anticonvulsant effect of SSE (1–100 mg/kg) was evaluated in mice administered with different convulsant agents: strychnine, pentylenetetrazol (PTZ), isoniazid (INH) or yohimbine. Results The main compound found in SSE was D-pinitol (42.2%). SSE (100 mg/kg) increased the urinary volume (2.67-fold), as well as the excretion of Na (5.60-fold) and K (7.2-fold). The co-administration of SSE with L-NAME or indomethacin reverted the diuretic activity shown by SSE alone. SSE lacked sedative effects and did not affect motor coordination in mice. SSE (100 mg/kg) showed higher and similar antidepressant-like effect, compared to 20 mg/kg fluoxetine, in the FST and TST, respectively. The co-administration of SSE with yohimbine reverted the antidepressant-like activity shown by SSE alone. SSE (100 mg/kg) showed anxiolytic-like activity in the four models of anxiety, with similar activity with 1.5 mg/kg clonazepam. The seizure-protective effect of SSE was ED50 = 73.9 ± 8.4 mg/kg (INH) and 40.4 ± 5.2 mg/kg (yohimbine). Conclusion The diuretic effects of SSE involve the possible contribution of prostaglandins and nitric oxide. SSE showed moderate anxiolytic and anticonvulsant effects, whereas the participation of α2-adrenoceptors is probably associated in the antidepressant-like effects of SSE.

Salvia tiliifolia is used in folk medicine as a relaxant agent and for the treatment of diarrhea and neurodegenerative diseases. Tilifodiolide (TFD) is a diterpene obtained from this plant. The purpose of this work was to evaluate the antidiarrheal, vasorelaxant, and neuropharmacological actions of TFD. These effects were selected based on the folk medicinal use of S. tiliifolia. The antidiarrheal activity of 1-50 mg/kg p.o. TFD was assessed with the castor oil related tests. The vasorelaxant effect of TFD (0.9-298 μM) was performed with smooth muscle tissues from rats, and its mechanism of action was evaluated using different inhibitors. The sedative, anxiolytic, and antidepressant effects of 1-100 mg/kg TFD were assessed. The possible mechanisms of action of the anxiolytic and antidepressant effects of TFD were evaluated using inhibitors. TFD exhibited antidiarrheal (ED50 = 10.62 mg/kg) and vasorelaxant (EC50 = 48 ± 3.51 μM) effects. The coadministration of TFD with N(ω)-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), reverted the vasorelaxant action showed by TFD alone. TFD exerted anxiolytic actions (ED50 = 20 mg/kg) in the cylinder exploratory test, whereas TFD (50 mg/kg) showed antidepressant actions in the tail suspension test by 44%. The pretreatment with 2 mg/kg flumazenil partially reverted the anxiolytic actions of TFD, whereas the pretreatment with 1 mg/kg yohimbine abolished the antidepressant effects of TFD. In summary, TFD exerted antidiarrheal activity by decreasing the intestinal fluid accumulation and vasorelaxant effects mediated by nitric oxide and cyclic guanosine monophosphate. TFD showed anxiolytic and antidepressant effects by the partial involvement of gamma-Aminobutyric acid (GABA) receptors and the possible participation of α2-adrenoreceptors, respectively.

Soulattrolide is a natural coumarin synthesized by the leaves of species of Calophyllum (Calophyllaceae) rain forest trees, including the American C. brasiliense, and the Asian C. teysmanii. Soulattrolide is a potent inhibitor of the reverse transcriptase from HIV-1 (RT-HIV-1), and active against Mycobacterium tuberculosis. However, the effects of this coumarins on other systems, remains to be evaluated. C. brasiliense is used in traditional medicine for the treatment of pain and inflammation. Therefore, we decided to explore the antinociceptive, anti-inflammatory activity of soulattrolide in mice, as well as, some of its possible effects on the CNS. Soulattrolide showed antinociceptive effects in the writhing test (ED50 = 33.8 mg/kg), as well as, in the formalin test with an ED50 = 7.9, and 22.1 mg/kg for Phases 1 and 2, respectively. The highest dose of soulattrolide (50 mg/kg) induced 40% of antinociception in the hot plate test. Regarding to anti-inflammatory activity, in the 12-O-Tetradecanoylphorbol-13-acetate (TPA) test, soulattrolide showed an IC50 = 1.81 μmol/ear, whereas in the myeloperoxidase assay, it showed an inhibition of 87% (1 μmol/ear). Soulattrolide showed sedative effects on the pentobarbital-induced sleeping time test, and the rotarod test, but lacked antidepressant activity on the tail suspension test. In conclusion, we report for the first time, the antinociceptive effects of soulattrolide in mice, like those of naproxen; soulattrolide also showed mild anti-inflammatory activity, as well as mild sedative and anxiolytic properties, therefore, it has also activity on the CNS.

The globus pallidus sends a significant GABAergic projection to the thalamic reticular nucleus. Because pallidal neurons express D4-dopamine receptors, we have explored their presence on pallidoreticular terminals by studying the effect of dopamine and D4-receptor agonists on the GABAergic transmission in the thalamic reticular nucleus. We made whole-cell recordings of inhibitory postsynaptic currents (IPSCs) and miniature inhibitory postsynaptic currents (mIPSCs) in the thalamic reticular neurons. Dopamine consistently reduced the IPSCs. The effect of dopamine was associated with paired-pulse facilitation, indicating a presynaptic location of the receptors. The effect of dopamine was also measured on the mIPSCs, reducing their frequency but not affecting their amplitude, which also suggests a presynaptic site of action. The selective D4-receptor agonist PD 168,077 also reduced the IPSCs, which was also associated with paired-pulse facilitation. In addition, this agonist reduced the frequency of the mIPSCs with no effect on their amplitude. The D4-receptor antagonist L-745,870 totally blocked the effect of the D4-receptor agonist, indicating the specificity of its effect. To verify the location of the receptors on the pallidal terminals, these were eliminated by injecting kainic acid into the globus pallidus. Kainic acid produced a drastic (80%) fall in the globus pallidus neuronal population. In this condition, the effect of the activation of D4 receptors both on the IPSCs and mIPSCs was prevented, thus indicating that the location of the receptors was on the pallidal terminals. Our results demonstrate that dopamine controls the activity of the thalamic reticular neurons by regulating the inhibitory input from the globus pallidus.