Electrophysiologic alterations in the excitability of the sciatic and vagus nerves during early stages of sepsis

Background

Nonspecific and delayed diagnosis of neurologic damage contributes to the development of neuropathies in patients with severe sepsis. The present study assessed the electrophysiologic parameters related to the excitability and conductibility of sciatic and vagus nerves during early stages of sepsis.

Materials and methods

Twenty-four hours after sepsis induced by cecal ligation and puncture (CLP) model, sciatic and vagus nerves of septic (CLP group) and control (sham group) rats were removed, and selected electric stimulations were applied to measure the parameters of the first and second components of the compound action potential. The first component originated from fibers with motor and sensory functions (Types Aα and Aβ fibers) with a large conduction velocity (70-120 m/s), and the second component originated from fibers (Type Aγ) with sensorial function. To evaluate the presence of sensorial alterations, the sensitivity to non-noxious mechanical stimuli was measured by using the von Frey test. Hematoxylin and eosin staining of the nerves was performed.

Results

We observed an increase of rheobase followed by a decrease in the first component amplitude and a higher paw withdrawal threshold in response to the application of von Frey filaments in sciatic nerves from the CLP group compared to the sham group. Differently, a decrease in rheobase and an increase in the first component amplitude of vagal C fibers from CLP group were registered. No significant morphologic alteration was observed.

Conclusion

Our data showed that the electrophysiologic alterations in peripheral nerves vary with the fiber type and might be identified in the first 24 h of sepsis, before clinical signs of neuromuscular disorders.

Hepatoprotective Effect of Essential Oils from Hyptis crenata in Sepsis-Induced Liver Dysfunction

No specific therapeutics are available for the treatment of sepsis-induced liver dysfunction, a clinical complication strongly associated with the high mortality rate of septic patients. This study investigated the effect of the essential oil of Hyptis crenata (EOHc), a lamiaceae plant used to treat liver disturbances in Brazilian folk medicine, on liver function during early sepsis. Sepsis was induced by the cecal ligation and puncture (CLP) model. Rats were divided into four groups: Sham, Sham+EOHc, CLP, and CLP+EOHc. EOHc (300 mg/kg) was orally administered 12 and 24 h after surgery. The animals were sacrificed for blood collection and liver tissue samples 48 h after surgery. Hepatic function was evaluated by measuring serum bilirubin, alkaline phosphatase (ALP), aspartate aminotransferase, and alanine aminotransferase (ALT) levels. The levels of malondialdehyde and the activity of superoxide dismutase, catalase, and GSH peroxidase (GSH-Px) were measured for assessment of oxidative stress. Liver morphology was analyzed by hematoxylin and eosin staining. EOHc normalized serum ALP, ALT, and bilirubin levels and inhibited morphological changes. In addition, we observed that EOHc inhibited elevation in hepatic lipid peroxidation and reduction of the glutathione peroxidase activity induced by sepsis. Our data show that EOHc plays a protective effect against liver injury induced by sepsis.

5-Lypoxygenase products are involved in renal tubulointerstitial injury induced by albumin overload in proximal tubules in mice

The role of albumin overload in proximal tubules (PT) in the development of tubulointerstitial injury and, consequently, in the progression of renal disease has become more relevant in recent years. Despite the importance of leukotrienes (LTs) in renal disease, little is known about their role in tubulointerstitial injury. The aim of the present work was to investigate the possible role of LTs on tubulointerstitial injury induced by albumin overload. An animal model of tubulointerstitial injury challenged by bovine serum albumin was developed in SV129 mice (wild-type) and 5-lipoxygenase-deficient mice (5-LO^–/–). The changes in glomerular morphology and nestin expression observed in wild-type mice subjected to kidney insult were also observed in 5-LO^–/– mice. The levels of urinary protein observed in the 5-LO^–/– mice subjected or not to kidney insult were lower than those observed in respective wild-type mice. Furthermore, the increase in lactate dehydrogenase activity, a marker of tubule damage, observed in wild-type mice subjected to kidney insult did not occur in 5-LO^–/– mice. LTB₄ and LTD₄, 5-LO products, decreased the uptake of albumin in LLC-PK1 cells, a well-characterized porcine PT cell line. This effect correlated with activation of protein kinase C and inhibition of protein kinase B. The level of proinflammatory cytokines, tumor necrosis factor-α and interleukin (IL)-6, increased in mice subjected to kidney insult but this effect was not modified in 5-LO^–/– mice. However, 5-LO^–/– mice subjected to kidney insult presented lower macrophage infiltration and higher levels of IL-10 than wild-type mice. Our results reveal that LTs have an important role in tubulointerstitial disease induced by albumin overload.

Gastroprotective effects of the essential oil of Hyptis crenata Pohl ex Benth. on gastric ulcer models

ETHNOPHARMACOLOGICAL RELEVANCE

Hyptis crenata Pohl ex Benth (Lamiaceae), popularly known as "hortelã-brava" or "hortelã do campo", is widely distributed in the northeast of Brazil. In Brazil, the leaves of this plant have been used in traditional medicine for the treatment of gastrointestinal disturbances, including gastric ulcers. In an attempt to experimentally validate this claimed antiulcerogenic activity, the gastroprotective effects of the essential oil extracted from the leaves of the Hyptis crenata Pohl ex Benth (EOHc) were evaluated in recognized gastric ulcer models in mice.

MATERIALS AND METHODS

EOHc was obtained by hydrodistillation and analyzed using gas chromatography-mass spectrometry (GC-MS). Swiss male mice (25-30g) were used for the studies. The gastric ulcers were induced by oral administration of absolute ethanol or indomethacin 45min after oral pretreatment with EOHc, vehicle and positive control drugs. One hour after the ulcerative challenges, the stomachs were removed and the area of the lesions was measured. The volume, pH and total acidity of the gastric secretions were determined using the pylorus ligature model. The gastrointestinal motility was measured using gastric emptying and intestinal transit. The ethanol-induced gastric mucus depletion and lipid peroxidation were also analyzed.

RESULTS

Our findings are as follows: A significant inhibition of gastric lesions induced by absolute ethanol was observed in the mice pre-treated with EOHc, at a dose of 30 and 100 and 300mg/kg (5.56±1.51, 2.88±0.82 and 1.71±0.54mm(2), respectively) compared to control group (118.03±35.4mm(2)). Also, EOHc (300mg/kg) produced a gastroprotective effect against the gastric lesions induced by indomethacin (16.07±4.68mm(2)) compared to control group (38.64±6.1mm(2)). EOHc pretreatment produced a reduction in the ethanol-induced lipid peroxidation from 3.9±0.22 to 2.4±0.1μmol/mg tissue (EOHc-300mg/kg and control group, respectively). We also observed that EOHc pretreatment decreased the gastric emptying, but did not alter the intestinal transit ratio, ethanol-induced depletion of the gastric wall mucus or secretion parameters (volume, pH and [H(+)]).

CONCLUSION

Our data indicate that EOHc exerts a gastroprotective effect, indicated by its significant inhibition of gastric lesions in ethanol- and indomethacin-induced ulcer models, which may be associated with its accelerating effect on gastric emptying and reduction in oxidative damages. Our data suggest a potential therapeutic application for EOHc in the treatment of gastric ulcers.

The essential oil of Croton zehntneri and trans-anethole improves cutaneous wound healing

ETHNOPHARMACOLOGY RELEVANCE

Croton zehntneri is a Euphorbiaceae species native to northeastern Brazil, where teas and beverages made from Croton zehntneri leaves are used as healing agents. To our knowledge, there is no experimental study supporting this claim of pharmacological activity.

MATERIALS AND METHODS

Full-thickness excisional wounds were made in the left and right sides of the dorsum of anesthetised Swiss mice, and a topical pharmaceutical formulation, developed by including essential oil extracted from the leaves of Croton zehntneri (2% and 20% EOCz) in pluronic-127 (PF-127), was administered to mice twice daily for 15 days post-wounding. To evaluate the contribution of trans-anethole, the major constituent of EOCz (85.7%), in the wound healing activity of EOCz, the effect of the topical administration of trans-AT on wound tissue repair was also evaluated and compared to other groups. A macroscopic analysis of swelling and exudates was performed and scored as 0 (missing), 1 (light), 2 (moderate) and 3 (intense). The number of capillaries and leukocytes was counted in hematoxylin and eosin (HE)-stained sections of the injured tissue. For extracellular matrix remodelling analysis, fibroblasts and collagen fibres present in the photomicrography of the Masson's Trichrome (MT)-stained sections were counted. Each experimental group comprised six mice.

RESULTS

At day 3 post-wounding, it was observed that treatment with 20% EOCz greatly reduced the swelling and exudates with a similar magnitude to the dexamethasone treatment. The inflammatory cell infiltration and angiogenesis were not altered by either the EOCz- or trans-AT treatments. In contrast, an acceleration of the wound closure was observed, with an enhanced number of fibroblasts and collagen fibres in both the 20% EOCz- and trans-AT-treated mice.

CONCLUSION

Our data indicate that EOCz exerts significant wound healing activity, demonstrating its relevant therapeutic potential.

Nephroprotective Effect of Echinodorus macrophyllus Micheli on Gentamicin-Induced Nephrotoxicity in Rats

BACKGROUND/AIMS

Leaves of Echinodorus macrophyllus (EM), from the Alismataceae family, have been used in Brazilian folk medicine for their anti-inflammatory and diuretic properties. In this work, the diuretic and nephroprotective activities of crude extracts of EM were evaluated.

METHODS

Normal Wistar rats were given 0.9% NaCl containing either EM (10-300 mg/kg), furosemide (13 mg/kg) or arginine vasopressin (0.2 mg/kg). Thereafter, the rats were individually housed in metabolic cages, and urine volume was measured every 30 min for a total of 3 h. Acute kidney injury was induced by gentamicin (GM, 80 mg·kg(-1)·day(-1), b.i.d., 5 days). Along with GM, 0.9% NaCl (control) or EM (30 mg/kg) was given to the rats by gavage.

RESULTS

EM produced a dose-dependent reduction in urine elimination. EM was effective in reversing all GM-induced alterations such as polyuria and glomerular filtration rate reduction. The GM-induced morphological alterations were not observed when EM was given concomitantly with GM.

CONCLUSION

This study provides evidence that EM possesses nephroprotective effect which indicates that EM may have therapeutic applications in GM-induced acute kidney injury.

The effect of saponins from Ampelozizyphus amazonicus Ducke on the renal Na+ pumps' activities and urinary excretion of natriuretic peptides

Background

In a previous study, we showed that a saponin mixture isolated from the roots of Ampelozizyphus amazonicus Ducke (SAPAaD) reduces urine excretion in rats that were given an oral loading of 0.9 % NaCl (4 ml/100 g body weight). In the present study, we investigated whether atrial natriuretic peptides (ANP) and renal ATPases play a role in the SAPAaD- induced antidiuresis in rats.

Methods

To evaluate the effect of SAPAaD on furosemide-induced diuresis, Wistar rats (250-300 g) were given an oral loading of physiological solution (0.9 % NaCl, 4 ml/100 g body weight) to impose a uniform water and salt state. The solution containing furosemide (Furo, 13 mg/kg) was given 30 min after rats were orally treated with 50 mg/kg SAPAaD (SAPAaD + Furo) or 0.5 ml of 0.9 % NaCl (NaCl + Furo). In the SAPAaD + NaCl group, rats were pretreated with SAPAaD and 30 min later they received the oral loading of physiological solution. Animals were individually housed in metabolic cages, and urine volume was measured every 30 min throughout the experiment (3 h). To investigate the role of ANP and renal Na⁺ pumps on antidiuretic effects promoted by SAPAaD, rats were given the physiological solution (as above) containing SAPAaD (50 mg/kg). After 90 min, samples of urine and blood from the last 30 min were collected. Kidneys and atria were also removed after previous anesthesia. ANP was measured by radioimmunoassay (RIA) and renal cortical activities of Na⁺- and (Na⁺,K⁺)-ATPases were calculated from the difference between the [³²P] Pi released in the absence and presence of 1 mM furosemide/2 mM ouabain and in the absence and presence of 1 mM ouabain, respectively.

Results

It was observed that SAPAaD inhibited furosemide-induced diuresis (at 90 min: from 10.0 ± 1.0 mL, NaCl + Furo group, n = 5, to 5.9 ± 1.0 mL, SAPAaD + Furo group n = 5, p < 0.05), increased both Na⁺-ATPase (from 25.0 ± 5.9 nmol Pi.mg^-1.min^-1, control, to 52.7 ± 8.9 nmol Pi.mg^-1.min^-1, p < 0.05) and (Na⁺,K⁺)-ATPase (from 47.8 ± 13.3 nmol Pi.mg^-1.min^-1, control, to 79.8 ± 6.9 nmol Pi .mg^-1.min^-1, p < 0.05) activities in the renal cortex. SAPAaD also lowered urine ANP (from 792 ± 132 pg/mL, control, to 299 ± 88 pg/mL, p < 0.01) and had no effect on plasma or atrial ANP.

Conclusion

We concluded that the SAPAaD antidiuretic effect may be due to an increase in the renal activities of Na⁺- and (Na⁺,K⁺)-ATPases and/or a decrease in the renal ANP.

Effect of triterpene saponins from roots of Ampelozizyphus amazonicus Ducke on diuresis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ampelozizyphus amazonicus Ducke is a plant used in Brazilian folk medicine to both prevent malaria and act as a depurative.

AIM OF THE STUDY

We have investigated the effects of an ethanol crude extract of roots of Ampelozizyphus amazonicus (CEAaD), a chemically characterized saponin mixture (SAPAaD), as well as a saponin-free fraction (SAPAaD-free) obtained from CEAaD on diuresis in rats.

MATERIALS AND METHODS

Wistar rats under ad libitum water conditions or water deprivation for 12h prior to the start of the experiment were volume-expanded with 0.9% NaCl (4% body weight, by gavage) containing either CEAaD, SAPAaD, or SAPAaD-free at the doses indicated in the text. Rats were individually housed in metabolic cages, and urine volume was measured every 30 min throughout the experiment (3 h).

RESULTS

CEAaD increased urine volume in rats under conditions of both free access to water and under water deprivation. In the latter condition, CEAaD (150 mg/kg) increased the urine volume from zero to 0.9+/-0.1 ml/120 min, n=6). Similarly, the SAPAaD-free (50-200 mg/kg) mixture also increased the urine volume. In contrast, SAPAaD (12.5-1000 mg/kg) produced a significant reduction (p<0.01) in diuresis under conditions of both water deprivation and with free access to water prior to the start of the experiment.

CONCLUSION

Our data indicate that CEAaD contains compounds that cause both diuresis and antidiuresis and that the antidiuretic effect is due mainly to the presence of saponins.