Metabolic effects of manganese in the nematode Caenorhabditis elegans through DAergic pathway and transcription factors activation.

Manganese (Mn) is an essential trace element for physiological functions since it acts as an enzymatic co-factor. Nevertheless, overexposure to Mn has been associated with a pathologic condition called manganism. Furthermore, Mn has been reported to affect lipid metabolism by mechanisms which have yet to be established. Herein, we used the nematode Caenorhabditis elegans to examine Mn's effects on the dopaminergic (DAergic) system and determine which transcription factors that regulate with lipid metabolism are affected by it. Worms were exposed to Mn for four hours in the presence of bacteria and in a liquid medium (85 mM NaCl). Mn increased fat storage as evidenced both by Oil Red O accumulation and triglyceride levels. In addition, metabolic activity was reduced as a reflection of decreased oxygen consumption caused by Mn. Mn also affected feeding behavior as evidenced by decreased pharyngeal pumping rate. DAergic neurons viability were not altered by Mn, however the dopamine levels were significantly reduced following Mn exposure. Furthermore, the expression of sbp-1 transcription factor and let-363 protein kinase responsible for lipid accumulation control was increased and decreased, respectively, by Mn. Altogether, our data suggest that Mn increases the fat storage in C. elegans, secondary to DAergic system alterations, under the control of SBP-1 and LET-363 proteins.

Reversible reprotoxic effects of manganese through DAF-16 transcription factor activation and vitellogenin downregulation in Caenorhabditis elegans.

AIMS: Vitellogenesis is the yolk production process which provides the essential nutrients for the developing embryos. Yolk is a lipoprotein particle that presents lipids and lipid-binding proteins, referred to as vitellogenins (VIT). The Caenorhabditis elegans nematode has six genes encoding VIT lipoproteins. Several pathways are known to regulate vitellogenesis, including the DAF-16 transcription factor. Some reports have shown that heavy metals, such as manganese (Mn), impair brood size in C. elegans; however the mechanisms associated with this effect have yet to be identified. Our aim was to evaluate Mn's effects on C. elegans reproduction and better understand the pathways related to these effects. MAIN METHODS: Young adult larval stage worms were treated for 4h with Mn in 85mM NaCl and Escherichia coli OP50 medium. KEY FINDINGS: Mn reduced egg-production and egg-laying during the first 24h after the treatment, although the total number of progenies were indistinguishable from the control group levels. This delay may have occurred due to DAF-16 activation, which was noted only after the treatment and was not apparent 24h later. Moreover, the expression, protein levels and green fluorescent protein (GFP) fluorescence associated with VIT were decreased soon after Mn treatment and recovered after 24h. SIGNIFICANCE: Combined, these data suggest that the delay in egg-production is likely regulated by DAF-16 and followed by the inhibition of VIT transport activity. Further studies are needed to clarify the mechanisms associated with Mn-induced DAF-16 activation.

In vitro and in vivo evaluation of a desonide gel-cream photostabilized with benzophenone-3.

CONTEXT: Our group previously reported the photoinstability of some desonide topical commercial formulations under direct exposure to UVA radiation. OBJECTIVE: This study aimed to prepare and characterize a gel-cream containing desonide, with greater photostability than the commercial gel-cream (C-GC). Benzophenone-3 (BP-3) was used as a photostabilizing agent. METHODS: The gel-cream developed (D-GC) containing BP-3 at 0.1% was prepared and characterized regarding its pH, drug content, spreadability, viscosity, in vitro drug release and in vitro permeation. The in vivo anti-inflammatory effect was assessed by ear edema measurement, croton oil-induced acute skin inflammation and myeloperoxidase assay. RESULTS AND DISCUSSION: D-GC presented characteristics compatible with topical application, appropriate drug content and good spreadability, and non-Newtonian behavior with pseudoplastic flow. D-GC showed a good photostability profile, presenting a desonide content of 95.70% after 48 h of exposure to UVA radiation, and stability under room conditions during 60 days. The amount of desonide released from D-GC and C-GC was 57.8 and 51.7 µg/cm2, respectively, measured using the vertical Franz cell. The in vitro skin permeation showed that desonide reached the site of action of the topical corticosteroids, from both formulations; however, the desonide amount retained in the dermis was lower with D-GC. The in vivo evaluation of topical anti-inflammatory activity indicated that D-GC presented the same biological effect as C-GC. CONCLUSION: D-GC represents a promising approach to treat dermatological disorders, since it presented satisfactory physicochemical characteristics, the same biological activity as C-GC and superior photostability, conferred by the addition of BP-3 at 0.1%.

Antidepressant-like effect of Ilex paraguariensis in rats.

In this study, we investigated the possible antidepressant-like effect of I. paraguariensis in rats. Rats were treated for four weeks with an aqueous extract of I. paraguariensis in drinking water, following the traditional preparation of this beverage. After the period of treatment, behavioral (elevated plus-maze, open field test, and forced swimming test) and biochemical parameters (lipid peroxidation assay, thiol content, vitamin C levels, and monoamine oxidase activity) were evaluated. Animals were also analyzed on forced swimming test after 24 hours of I. paraguariensis intake. An additional group was injected with selegiline 24 hours and 30 minutes before forced swimming test as positive control. HPLC analysis revealed the profile of I. paraguariensis extract. I. paraguariensis reduced the immobility time on forced swimming test without significant changes in locomotor activity in the open field test. Any anxiolytic/anxiogenic effect of I. paraguariensis was observed in rats through the elevated plus-maze test. The antidepressant-like effect of I. paraguariensis was not accompanied by inhibitory effect on monoamine oxidase activity. There were no significant alterations on lipid peroxidation, thiol content, and vitamin C levels among the groups. In conclusion, aqueous extract of I. paraguariensis decreases the time of immobility in rats suggesting an antidepressant-like effect.