Hypoglycemic effect of Coffea arabica leaf extracts and major bioactive constituents

The present study focused on investigating the antioxidant, antiglycation activity, digestive enzymes inhibition, bioaccessibility and hypoglycemic effect of C. arabica leaves extracts. The extracts deactivated the O2•-, ROO•, H2O2, HOCl reactive oxygen species. Coffee leaves showed strong inhibition of α-glucosidase (IC50 = 40.30 μg mL-1) greater than the isolated metabolites and acarbose. There was also inhibition of pancreatic lipase (IC50 = 56.43 μg mL-1) in addition to a hypoglycemic effect in zebrafish similar to acarbose and metformin. With the exception of rutin, all biocompounds were detected at all stages of in vitro digestion. Finally, these results suggest that C. arabica leaf extracts possess antidiabetic and anti-obesity properties that can be attributed to the main metabolites and the synergistic action between them.Communicated by Ramaswamy H. Sarma.

Improving recorded volume in mesial temporal lobe by optimizing stereotactic intracranial electrode implantation planning

PURPOSE

Intracranial electrodes are sometimes implanted in patients with refractory epilepsy to identify epileptic foci and propagation. Maximal recording of EEG activity from regions suspected of seizure generation is paramount. However, the location of individual contacts cannot be considered with current manual planning approaches. We propose and validate a procedure for optimizing intracranial electrode implantation planning that maximizes the recording volume, while constraining trajectories to safe paths.

METHODS

Retrospective data from 20 patients with epilepsy that had electrodes implanted in the mesial temporal lobes were studied. Clinical imaging data (CT/A and T1w MRI) were automatically segmented to obtain targets and structures to avoid. These data were used as input to the optimization procedure. Each electrode was modeled to assess risk, while individual contacts were modeled to estimate their recording capability. Ordered lists of trajectories per target were obtained. Global optimization generated the best set of electrodes. The procedure was integrated into a neuronavigation system.

RESULTS

Trajectories planned automatically covered statistically significant larger target volumes than manual plans [Formula: see text]. Median volume coverage was [Formula: see text] for automatic plans versus [Formula: see text] for manual plans. Furthermore, automatic plans remained at statistically significant safer distance to vessels [Formula: see text] and sulci [Formula: see text]. Surgeon's scores of the optimized electrode sets indicated that 95% of the automatic trajectories would be likely considered for use in a clinical setting.

CONCLUSIONS

This study suggests that automatic electrode planning for epilepsy provides safe trajectories and increases the amount of information obtained from the intracranial investigation.

Grazing behaviour of a non-herbivorous characin: revisiting plasticity

Feeding behaviour and diet of Bryconamericus microcephalus differed between canopy conditions. At the open canopy site, a behavioural modification, grazing on algae, was observed. This was also reflected in gut content analysis and suggests behavioural plasticity in response to resource availability.

Microcystins (cyanobacteria hepatotoxins) bioaccumulation in fish and crustaceans from Sepetiba Bay (Brasil, RJ)

Blooms of cyanobacteria in water bodies cause serious environmental problems and the occurrence of toxic strains are also related with the human health. Aquatic animals could bioaccumulate microcystins (cyanobacteria hepatotoxins) and so, beyond water, the ingestion of contaminated food represents a human health risk. Recently, WHO recommended a maximum concentration of microcystins (MCYSTs) in drinking water and established the tolerable daily intake (TDI) for consumption of cyanobacteria products contends MCYSTs (0.04 microg(-1) kg(-1) day(-1)). Sepetiba Bay is located in the municipal districts of Rio de Janeiro, Mangaratiba and Itaguai; being an important place of fishing activity. Due to the industrial development in the area, this bay is submitted to different environmental impacts, increasing the organic and industrial pollution. A strain of the nanoplanktonic cyanobacteria Synechocystis aquatilis f. aquatilis that produce MCYSTs was already isolated. In this study, we verified MCYSTs presence in muscle tissue of fish and crustaceans, which were harvested monthly in Sepetiba Bay during 11 months, in order to evaluate the potential risk of their ingestion. MCYSTs were analyzed by immunoassay techniques using the ELISA Microcystin Plate Kit (ENVIROLOGIX INC) and the concentration were expressed as microcystin-LR equivalent. The analyses of seston samples, water, muscle tissues showed the presence of this cyanotoxin in all samples and it was verified that 19% of the animals' samples were above the limit recommended by WHO for human consumption. The maximum value found was of 103.3 microg kg(-1) (TDI 0.52 microg kg(-1) day(-1)) and the minimum, was 0.25 microg kg(-1) in crabs muscle tissue (TDI of 0.001 microg kg(-1) day(-1)). Such data demonstrate that, although in low concentrations, there is already a contamination of fish and crustaceans from Sepetiba Bay. We highlight that the recommended limit refers to healthy adult.

Behavioral and neurochemical alterations after lithium-pilocarpine administration in young and adult rats: a comparative study

Pilocarpine and lithium-pilocarpine can induce seizures and brain damage in adult rats. However, manifestation of cerebral lesions seems to be an age-related phenomenon suggesting that maturational states of neurocircuitry may be involved. We have studied behavior changes, cerebral histopathology, and muscarinic and dopaminergic receptors density in rodents subjected to lithium-pilocarpine treatment. Wistar rats, at two different ages (21 days and 2 months), were treated with pilocarpine (15 mg/kg, SC), lithium (3 mEq/kg, IP), atropine (50 mg/kg, IP) and the combination of lithium to pilocarpine. Histopathologic studies showed that younger animals were more resistant to the development of cerebral changes and there was a preferential involvement of the striatum (Wilcoxon p = 0.02) as opposed to more generalized areas in adult animals such as hippocampus and neocortex. Lithium treatment induced an upregulation of muscarinic receptors at both ages, and this effect was reversed in younger animals after pilocarpine administration. Lithium also induced an upregulation of dopaminergic receptors in the striatum at both ages (p < 0.05), and this effect was not reversed after pilocarpine administration. Our data confirm that young animals show less brain damage after lithium-pilocarpine, and main alterations in dopaminergic receptors density occur in young and older animals after treatment with lithium and lithium combined to a low dose of pilocarpine.

Early withdrawal from repeated cocaine administration upregulates muscarinic and dopaminergic D2-like receptors in rat neostriatum

The present results show an increase in locomotor activity 24 h following repeated cocaine administration only with the higher dose (10 mg/kg, i.p., daily for 1 week) compared to controls (administered with saline). Binding assays were done and the ligands used were [3H]N-methylscopolamine ([3H]-NMS), [3H]-SCH 23390, and [3H]-spiroperidol to determine muscarinic (M1- and M2-like), D1 and D2 receptors, respectively. Scatchard analyses revealed alterations in Bmax not only for muscarinic, but also for D2-like receptors that were significantly increased. On the other hand, no alterations were detected on D1-like receptors densities and dissociation constant values. However, the Kd value was significantly increased for D2 receptors. The changes in muscarinic receptors were observed predominantly on M2-like, which presented an increase of 84% with the 10 mg/kg, i.p., dose only. On D2-like receptors, increases of 63 and 54% were demonstrated with the doses of 5 and 10 mg/kg, i.p.. The preferential effects of cocaine on muscarinic and D2-like receptors were also demonstrated in vitro where decreases in [3H]-NMS and [3H]-spiroperidol binding were observed. The results indicate that the effects of cocaine on muscarinic and dopaminergic postsynaptic receptors are functions of dose, duration of treatment, and time of drug withdrawal.

Effects of lithium, alone or associated with pilocarpine, on muscarinic and dopaminergic receptors and on phosphoinositide metabolism in rat hippocampus and striatum

The mechanism of action of lithium (Li) alone or with pilocarpine (Pilo), focusing on muscarinic and dopaminergic systems and also on phosphoinositide metabolism was studied. Li (3 mEq/kg) administered to rats once (1 d) or daily for 7 days (7 d), 24 h before Pilo (15 mg/kg), exacerbated cholinergic signs, leading to tremors. convulsions and brain lesions. Increases in muscarinic receptors (MR) of 29 and 49% were observed in the hippocampus after atropine (Atro) and Li-Atro-Pilo treatments, respectively, as compared to controls (Atro) and the Li-Pilo group (Li-Atro-Pilo). In the striatum, except for the 37% increase in the Li-Atro (50 mg/kg)-Pilo group as compared to the Li-Pilo one, no other changes were observed in MR. A decrease of 32% on average in D2-like receptors (D2R) was detected in the hippocampus in the group Li-7d. On the contrary, in the striatum an increase (25%) in the Li-7d group was observed and this effect was blocked by Li-Pilo. As far as inositol phosphates (IP) and phosphatidylinositol-4,5-biphosphate (PIP2) metabolism is concerned, Li caused a decrease (28%) and an increase (60%) in IP and PIP2 accumulations, respectively, in hippocampus slices while Pilo only altered IP accumulation (32% decrease). In this area the association of Li-Atro (10 mg/kg)-Pilo also caused a decrease (36%) in PIP2 as compared to the Li-Pilo group. In striatal slices, except for the Li, Atro (10 mg/kg) and Li-Atro (10 mg/kg)-Pilo groups which showed a decrease (33 40%) in IP accumulation, no other alteration was detected. The potentiation of the effect of Pilo by Li does not seem to depend on the PI metabolism, but instead on its involvement with muscarinic and dopaminergic systems.

Inhibitory action of a calcium channel blocker (nimodipine) on seizures and brain damage induced by pilocarpine and lithium-pilocarpine in rats

The present work studied the effect of a calcium channel blocker (nimodipine) on rat behavioural changes and brain lesions observed after seizures induced by high doses of pilocarpine (400 mg/kg, s.c.; P400), and the association of lithium (3 mEq/kg, i.p., daily during 7 days) plus pilocarpine (a single dose of 15 mg/kg, s.c.) administered 24 h after the last injection of lithium. In the P400 model, nimodipine (5 or 10 mg/kg, i.p.) inhibited convulsions, status epilepticus, and significantly decreased the percentage of death and cerebral changes (Mann-Whitney, P = 0.0057). In the lithium-pilocarpine (Li-Pi) induced seizures, nimodipine even increased convulsive action and did not interfere with brain lesions. The results suggested that a calcium channel mechanism is involved in the P400 induced seizures, and that there is a difference in the physiopathology of epileptic seizures and brain damage induced by either P400 and Li-Pi models.

Effect of pimozide on the increase of muscarinic receptors caused by mazindol and apomorphine in the rat cerebral motor cortex

The effects of pimozide, mazindol and apomorphine on muscarinic receptors in homogenates of rat cerebral motor cortex were measured by binding assays, using 3H-N-methylscopolamine (3H-NMS) alone as ligand (for the measurement of M1- and M2-like receptors) or in the presence of carbachol or pirenzepine for determination of M1- and M2-like receptors, respectively. Female Wistar rats (150 g) were treated daily for one week with pimozide, a dopaminergic antagonist (10 and 20 mg/kg, po, by gavage), or with apomorphine (1 mg/kg, ip). In another set of experiments, animals were treated with pimozide and 30 min later with mazindol (10 mg/kg, po, by gavage) or apomorphine. The drugs were administered daily for one week. Controls received the same volume of saline. 3H-NMS binding was increased from the control value of 418 +/- 17 to 548 +/- 42 fmol/mg protein by administration of mazindol (10 mg/kg) but binding was reduced to 360 +/- 11 fmol/mg protein upon administration of pimozide (20 mg/kg) plus mazindol (10 mg/kg). Similarly 10 mg/kg pimozide reduced the increase in M1-like receptors caused by mazindol from 262 +/- 31 to 220 +/- 20 fmol/mg protein. Although 20 mg/kg pimozide alone produced a decrease in M1- plus M2-like receptors (from 418 +/- 17 to 348 +/- 22 fmol/mg protein), its action was preferentially on M2-like receptors, decreasing them from 148 +/- 10 to 111 +/- 15 fmol/mg protein in the control and treated groups, respectively. At the higher dose, 20 mg/kg pimozide also inhibited the 3H-NMS binding (M1- plus M2-like receptors) in the presence of apomorphine (263 +/- 25 vs 418 +/- 17 fmol/mg protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of piracetam administration on 3H-N-methylscopolamine binding in cerebral cortex of young and old rats

Piracetam, a nootropic drug, has been used for some time in Alzheimer's disease for its facilitatory effect on learning and memory. Rats treated with piracetam (500 mg/kg, p.o.) daily, during 1 and 2 weeks, showed a significant increase in muscarinic receptor number (Bmax) and in the dissociation constant values (Kd) in the cerebral motor cortex, in binding studies using 3H-NMS as ligand. The effect was observed not only in young rats (control- Bmax = 663.4 fmol/mg protein, Kd = 0.45 nM; treated- Bmax = 961.9 fmol/mg protein, Kd = 0.82 nM) but also in aged animals (control- Bmax = 628.0 fmol/mg protein, Kd = 0.47 nM; treated-Bmax = 747.6 fmol/mg protein, Kd = 0.84 nM). Since piracetam does not interact with muscarinic receptors, the reason for its effect expressed as the enhanced number of brain muscarinic receptors is not clear but could be the result of stimulation of phospholipid synthesis and thus would represent an indirect action of the drug.

Effect of mazindol administration on (3H)-N-methylscopolamine binding to rat cerebral cortex

Mazindol has been shown to produce anorexia in several animal species including humans, and its pharmacological effects may be elicited by blockade of neuronal reuptake of dopamine and norepinephrine. Chronic treatment of rats with mazindol (10 mg/kg daily, p.o.) caused an increase in muscarinic receptor density (Bmax = 874.7 femtomoles/mg protein) as compared to controls (Bmax = 629.1 femtomoles/mg protein) in the cerebral motor cortex. An increase in dissociation constant (Kd) values was also observed which changes from 0.57 nM (control) to 1.17 nM after mazindol treatment. The mechanism underlying the observed effect of mazindol on receptors could be related to processes involving other neurotransmitters which also regulate cholinergic activity in the CNS. However, the implications of the eventual dopaminergic control on muscarinic receptors in the cortex is still an open question.