Metformin improves neurobehavioral impairments of streptozotocin-treated and western diet-fed mice: Beyond glucose-lowering effects.

Brain insulin resistance has been pointed to as a possible link between diabetes and neuropsychiatric disorders; therefore, therapeutic approaches using anti-diabetic drugs to improve insulin levels or signaling could prevent type 1 (T1D) and type 2 diabetes mellitus (T2D)-induced brain dysfunction. The present study aimed to determine whether metformin exerts beneficial effects on metabolic and neurobehavioral outcomes in the streptozotocin (STZ)-induced T1D model and western diet (WD)-induced obesity model in male Swiss mice. T1D was induced by intraperitoneal injection of STZ (50 mg/kg, for five consecutive days). The animals were then treated daily with saline or metformin (200 mg/kg/day, oral gavage), and a battery of tests recapitulating different neurobehavioral anomalies related to anxiogenic/depressive-like phenotype was conducted after 18 days. WD-induced obesity was modeled in mice by high-fat and high-fructose diet (HFFD) feeding for 15 days. In the sequence, control and diet-induced obesity mice were treated daily with saline or metformin (200 mg/kg/day), and a battery of behavioral tests was performed after 17 days. STZ injection and WD feeding induced metabolic and neurobehavioral impairments in mice. Remarkably, metformin improved the metabolic and neurobehavioral parameters in WD-induced obesity mice. Moreover, metformin ameliorated STZ-induced neurobehavioral deficits while it failed to improve the associated metabolic impairments. The beneficial effects of metformin in STZ-induced neurobehavioral impairments were not mediated by improving peripheral insulin signaling. Our results suggest that conventional diabetes treatment could be repurposed to simultaneously improve neurobehavioral symptoms and diabetes.

Impact of different fructose concentrations on metabolic and behavioral parameters of male and female mice.

Clinical evidence has shown that a high consumption of sugar-sweetened beverages is a risk factor for developing obesity and metabolic syndrome. There has also been increasing interest in the potential effects of high-fructose intake on behavior. The present study evaluated sex differences in behavioral and metabolic characteristics in response to chronic fructose intake in mice. Swiss mice (3-months-old) had access to tap water or fructose-water solution (at 15% or 30% w/v) ad libitum for nine weeks. After the 8 weeks, the mice were submitted to a battery of behavioral tests. A glucose tolerance test was performed one day after these behavioral tests, and the next day blood was collected for biochemical analysis. At a 15% concentration, fructose-intaking resulted in higher plasma cholesterol levels and glucose intolerance in mice that paralleled with a passive stress-coping behavior in the female mice and lower self-care behavior in the male and the female mice. At a 30% concentration, fructose-intaking resulted in higher body mass gain and higher plasma cholesterol and triglycerides levels in the male and the female mice, whereas glucose intolerance was more pronounced in the male mice. Spatial memory impairments and lower self-care behavior were observed in the male and the female mice, while passive stress-coping behavior was observed only in the female mice. Collectively, high-fructose intake induces metabolic and behavioral alterations in mice, with the males being more susceptible to glucose metabolism dysfunctions and the females to depressive-like endophenotypes.

Antinociceptive and anti-inflammatory activities of standardized extract of polymethoxyflavones from Ageratum conyzoides.

ETHNOPHARMACOLOGICAL RELEVANCE: Ageratum conyzoides L. is a plant widely used in traditional medicine in tropical and subtropical regions of the world due to its anti-inflammatory, antinociceptive and antibacterial properties. AIM OF THE STUDY: To characterize the standardized extract of polymethoxyflavones (SEPAc) from the plant and evaluate its antinociceptive and anti-inflammatory effects. MATERIALS AND METHODS: The SEPAc purified from the ethanol extract of the plant leaves was characterized by high resolution mass spectrometry and the methoxyflavones were quantified by a validated UPLC-PDA method. The antinociceptive and anti-inflammatory activities of the SEPAc were evaluated after oral administration on the acute nocifensive behavior of mice induced by formalin, prostaglandin E2 (PGE2) and proinflammatory cytokines (interleukin-1beta (IL-1ß)) and tumor necrosis factor-alpha (TNF-α) in mice. RESULTS: Qualitative analyses revealed the presence of seven methoxyflavones in the SEPAc, also a simple UPLC-PDA method was developed and validated for the quantification of 5,6,7,3',4',5'-hexametoxyflavone; nobiletin; 5'-methoxynobiletin and eupalestin, major compounds in the extract. The SEPAc exhibited antinociceptive and anti-inflammatory activities in both formalin phases, with significant inhibition of the paw edema formation and significant reduction of the nocifensive response induced by an intraplantar injection of PGE2 and intrathecal injection of interleukin-1ß. CONCLUSIONS: The SEPAc exhibited significant antinociceptive and anti-inflammatory effects. These results provided scientific suggestion of its potential as a source of new medicines to treat inflammatory diseases, such rheumatoid arthritis.

Substituted galacturonan from starfruit: Chemical structure and antinociceptive and anti-inflammatory effects.

Starfruit (Averrhoa carambola L.) is an edible tropical fruit, which is usually consumed as a fresh table fruit or as fruit juice. It also exhibits various pharmacological activities. In this study, polysaccharides were extracted with boiling water and purified by freeze-thawing and Fehling treatments. After purification steps, a homogenous fraction was obtained. It was analyzed by sugar composition, gel permeation chromatography, methylation, and two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy analyses. It comprised arabinose (Ara), galactose (Gal), and galacturonic acid (GalA) in a molar ratio of 12.3:1.7:86.0. Methylation and NMR spectroscopy analyses showed that it contained a substituted galacturonan composed of (1→4)-linked α-D-Galp A units branched at O-2 by (1→5)-linked α-L-Araf and terminal α-L-Araf and α-D-Galp A units. The effect of PFSCW (10-300mg/kg, i.p.) on nocifensive behavior induced by intraplantar injection of formalin in mice was evaluated. The fraction demonstrated antinociceptive and anti-inflammatory properties, suggesting that it may be useful in therapeutic intervention for the management of inflammatory pain.

Chronic exposure to low mercury chloride concentration induces object recognition and aversive memories deficits in rats.

This work examines the effects of chronic exposure to low inorganic mercury (mercury chloride, HgCl(2)) concentration on the recognition and aversive memories. Forty male Wistar rats were divided into 4 groups treated during 30 or 60 days with saline (control) or HgCl(2) doses. After treated the animals were tested considering object recognition and inhibitory avoidance behavioral memory paradigms. Elevated plus maze, open field and tail flick tests were used to assess anxiety, locomotor and exploratory activity and pain thresholds. Only exposure for 60 days to HgCl(2) induced in memory deficits quantified in the object recognition task. In the inhibitory avoidance all the animals exposed to mercury (for 30 or 60 days) presented worst performance than control animals. Our results suggest that chronic exposure to low mercury chloride concentrations impairs memory formation.