Açai pulp improves cognition and insulin sensitivity in obese mice.

SCOPE: Obesity and insulin resistance constitute risk factors for the development of tauopathies and other neurodegenerative diseases. (Poly)phenol compounds are under study for its role in protecting effects against neural injuries and degeneration. Here, we investigated the effect of Amazonian açai pulp (AP) intake in the prevention of memory and cognitive impairment resulting from a high-fat diet intake in mice. METHODS AND RESULTS: Obesity and insulin resistance was induced with a high-fat diet and supplemented with 2% AP to investigate peripheral insulin resistance, recognition memory and tau protein stability via AKT/GSK3-ß signaling pathway. The consumption of AP for 70 days improved peripheral insulin sensitivity and phosphorylation of AKT/GSK3-ß in mice hippocampi. The animals fed high-fat diets supplemented with AP showed better performance in the novel object recognition test (NOR) in comparison to the H group. Catalase activity and reduced glutathione (GSH) values were improved in the treated mice. CONCLUSIONS: These results suggest that the supplementation of AP can attenuate the effects of high-fat diet consumption in peripheral insulin resistance and improve cognitive behavior.

Biological activities of Leptodeira annulata (banded cat-eyed snake) venom on vertebrate neuromuscular preparations.

The physiological properties of colubrid snake venoms are largely unknown and less frequently investigated. In this study, we assessed the enzymatic properties and biological activities of Leptodeira annulata (banded cat-eyed snake) venom, an opistoglyphous snake from Colombia. The proteolytic, phospholipase A2 and amidolytic activities are assessed using colorimetric assays and the biological activities were analyzed in avian and mammalian neuromuscular preparations. L. annulata venom caused neuromuscular blockade in chick biventer cervicis (BC) preparations (40± 15% and 50± 3% of twitch reduction for 30 and 100 µg/ml, respectively; p < 0.05) following 120 incubation; 10 µg/ml of venom did not induce blockade. There was a mild reduction in contracture response to exogenous acetylcholine (110 µM) in BC preparations exposed to 10 and 30 µg of venom/ml (∼4% and ∼32% of reduction, respectively, p > 0.05, n = 4) compared to basal values whereas the highest concentration (100 µg/ml) abolished it after 120 min. The venom caused a significant reduction in contracture response elicited by KCl (∼58 and ∼90 of reduction for 30 and 100 µg/ml, respectively, p < 0.05, n = 4). In mouse phrenic nerve-diaphragm (PND) preparations, L. annulata venom induced a progressive muscle membrane depolarization [from -85.9 ± 1.6 mV (t0) to -72.2 ± 2.9 mV (t120), p < 0.05, n = 4); the postsynaptic receptors remained functional as shown by carbachol-induced depolarization. The morphological analyses showed a concentration-dependent number of pathological states in muscle fibers from both BC and PND preparations pre-exposed to venom. The venom showed high proteolytic activity and low phospholipase A2 activity; there was no evidence for serine protease activity. These results indicate that the neuromuscular effect induced by L. annulata venom resulted from damaged muscle fibers that lead to the blockade of twitches response. The findings suggest that the myotoxicity might be related to the presence of metalloproteases in this venom.

Neuropharmacological effects of Phoneutria nigriventer venom on astrocytes.

Bites from genus Phoneutria (Ctenidae, Araneomorpha) are the second most frequent source of spider accidents in Southeast Brazil. Severe envenoming from Phoneutria nigriventer produces vision disturbance, tremor and convulsion, suggesting that the CNS is involved; however, the mechanisms by which P. nigriventer venom (PNV) affects the CNS remain poorly understood. The present study aimed to investigate whether PNV directly impairs astrocytes. Cultured astrocytes were exposed to PNV, and intracellular Ca(2+) release and signaling were measured (Fura-2/AM), Na(+)/K(+)-ATPase and Toll-like receptor 4 (TLR4) involvement were investigated, actin filaments were stained (Alexa™ 488-conjugated phalloidin probe), the G-actin/F-actin ratio was determined, and the expression level of connexin 43 (Cx43) was assessed. Incubation in Ca(2+)-free buffer did not change the Ca(2+) responses. However, pre-incubation in thapsigargin/caffeine completely abolished these responses, suggesting that PNV-evoked Ca(2+) transients were from intracellular Ca(2+) stores. Pretreatment with a Na(+)/K(+)-ATPase antagonist (ouabain) or a TLR4 antagonist (LPS-RS) decreased or increased the Ca(2+)-evoked transients, respectively. Astrocytes showed altered actin filament structure after PNV exposure. PNV treatment increased the expression levels of Na(+)/K(+)-ATPase and Cx43 but decreased those of TLR4. The present results suggest that PNV directly affects astrocytes. Na(+)/K(+)-ATPase may thus represent a more specific drug target for controlling the neurotoxicity of PNV.

Neuromuscular activity of Bothrops alcatraz snake venom in chick biventer cervicis preparations.

Venom (10-100 µg/ml) from Bothrops alcatraz, a pitviper from the Alcatrazes Archipelago off the coast of southeastern Brazil, caused progressive, irreversible neuromuscular blockade in chick isolated biventer cervicis preparations. The venom also inhibited contractures to exogenous ACh (110 µM) and KCl (20 mM), caused myofiber damage and increased creatine kinase release. Commercial bothropic antivenom raised against mainland Bothrops species neutralized the neuromuscular activity, depending on the venom concentration.

Lonomia obliqua caterpillar venom increases permeability of the blood-brain barrier in rats.

Human envenoming by caterpillars of the saturniid moth Lonomia obliqua in southern Brazil produces a mild local response (erythema, some edema, and pain) and systemic effects that include incoagulable blood, renal failure and in severe accidents intracerebral hemorrhage. In this work, we used light and electron microscopy to investigate the morphological alterations in the brain and blood-brain barrier of rats injected intravenously with venom from L. obliqua spicules (200 microg/kg). Five semi-purified fractions of venom (200 microg/kg each) were also assayed. Quantitative morphological and ultrastructural analyses were done 6, 18, 24 and 72 h after the i.v. injection of venom and its fractions. Light microscopy showed that 6h after envenoming there was cerebellar edema, which decreased by 72 h. Intracerebral hemorrhage occurred in only one rat 24h after the injection of venom. Blood-brain barrier (BBB) breakdown, assessed by transmission electron microscopy based on the passage of an extracellular tracer (lanthanum nitrate) between brain capillary endothelial cells, was observed in the cerebellum and hippocampus 18 h after venom injection. At this time, the cerebellum was more sensitive to the venom than the hippocampus, as shown by the greater number of leaky vessels. The number of capillaries showing breakdown was lower after 72 h than after 18 h. None of the semi-purified fractions significantly increased the number of leaky vessels. These results indicate that L. obliqua caterpillar venom has a deleterious action on the rat BBB. The lack of effect of the venom fractions when administered alone suggested that a synergistic action of venom components may be responsible for the damage seen in the central nervous system, but this was not confirmed when three combinations of the fractions were tested.

Aspectos da espermatogênese de tucunaré, Cichla ocellaris Schneider, 1801 (TELEOSTEI, CICHLIDAE)

Sequential cytological events f Cichla ocellaris spermatogenesis were studied with electron microscopy from the est spermatocyte to the nature spermatozoa. Five stages of sermatid maturation were described.

São descritos os eventos citológicos sequenciais da espermatogênese de Cichla ocellaris (tucunaré) desde o espermatócito primário até o espermatozóide maduro. Verificou-se que a espermiogenese compreende cinco diferentes estágios de maturação das espermátides, caracterizadas por transformações da cromatina nuclear e das estruturas citoplasmáticas. O esperatozóide da espécie é do tipo primitivo, apresentando uma cabeça sem acrossomo e uma cauda.