A Standardized Extract Prepared from Red Orange and Lemon Wastes Blocks High-Fat Diet-Induced Hyperglycemia and Hyperlipidemia in Mice.

Citrus fruits are a rich source of high-value bioactive compounds and their consumption has been associated with beneficial effects on human health. Red (blood) oranges (Citrus sinensis L. Osbeck) are particularly rich in anthocyanins (95% of which are represented by cyanidin-3-glucoside and cyanidin-3-6″-malonyl-glucoside), flavanones (hesperidin, narirutin, and didymin), and hydroxycinnamic acids (caffeic acid, coumaric acid, sinapic, and ferulic acid). Lemon fruit (Citrus limon) is also rich in flavanones (eriocitrin, hesperidin, and diosmin) and other polyphenols. All of these compounds are believed to play a very important role as dietary antioxidants due to their ability to scavenge free radicals. A standardized powder extract, red orange and lemon extract (RLE), was obtained by properly mixing anthocyanins and other polyphenols recovered from red orange processing waste with eriocitrin and other flavanones recovered from lemon peel by a patented extraction process. RLE was used for in vivo assays aimed at testing a potential beneficial effect on glucose and lipid metabolism. In vivo experiments performed on male CD1 mice fed with a high-fat diet showed that an 8-week treatment with RLE was able to induce a significant reduction in glucose, cholesterol and triglycerides levels in the blood, with positive effects on regulation of hyperglycemia and lipid metabolism, thus suggesting a potential use of this new phytoextract for nutraceutical purposes.

HDAC and HAT inhibitors differently affect analgesia mediated by group II metabotropic glutamate receptors.

BACKGROUND: Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are key players in epigenetic regulation of gene expression. Analgesic activity by HDAC inhibitors has been reported in different pain models including inflammatory and neuropathic pain. These drugs interfere with gene expression through different mechanisms including chromatin remodeling and/or activation of transcription factors. Among other targets, HDAC inhibitors regulate metabotropic glutamate receptors type 2 (mGlu2) expression in central and peripheral central nervous system. However whether inhibition of HAT activity also regulates mGlu2 expression has not been reported. FINDINGS: Here we report that curcumin (CUR), a naturally occurring compound endowed with p300/CREB-binding protein HAT inhibitory activity, is able to induce a drastic down-regulation of the mGlu2 receptor in the mouse spinal cord after systemic administration together with a marked hypoacetylation of histones H3 and H4 in dorsal root ganglia (DRG). Furthermore, the analgesic activity of the mGlu2/3 agonist, LY379268 is lost after a 3-day treatment with CUR. Conversely the analgesic activity of LY379268 is potentiated in mice pretreated for 5 consecutive days with the HDAC inhibitor, Suberoylanilide Hydroxamic Acid (SAHA), known to induce mGlu2-upregulation. CONCLUSIONS: Our results demonstrate that systemically injected CUR is able to inhibit H3 and H4 acetylation in the DRG and to down-regulate mGlu2 receptors in the spinal cord. We also demonstrate that long term modification of the mGlu2 expression affects the analgesic properties of the orthosteric mGlu2/3 agonist, LY379268. These data open up the possibility that epigenetic modulators might be given in combination with "traditional" drugs in a context of a multi target approach for a better analgesic efficacy.

mGlu2 metabotropic glutamate receptors restrain inflammatory pain and mediate the analgesic activity of dual mGlu2/mGlu3 receptor agonists.

Group II metabotropic glutamate receptors (mGluRs) couple to the inhibitory G-protein Gi. The group II mGluRs include two subtypes, mGlu2 and mGlu3, and their pharmacological activation produces analgesic effects in inflammatory and neuropathic pain states. However, the specific contribution of each one of the two subtypes has not been clarified due to the lack of selective orthosteric ligands that can discriminate between mGlu2 and mGlu3 subtypes.In this study we used mGlu2 or mGlu3 knock-out mice to dissect the specific role for these two receptors in the endogenous control of inflammatory pain and their specific contribution to the analgesic activity of mixed mGlu2/3 receptor agonists.Our results showed that mGlu2⁻(/)⁻ mice display a significantly greater pain response compared to their wild type littermates. Interestingly the increased pain sensitivity in mGlu2⁻(/)⁻ mice occurred only in the second phase of the formalin test. No differences were observed in the first phase. In contrast, mGlu3⁻(/)⁻ mice did not significantly differ from their wild type littermates in either phase of the formalin test.When systemically injected, a single administration of the mGlu2/3 agonist, LY379268 (3 mg/kg, ip), showed a significant reduction of both phases in wild-type mice and in mGlu3⁻(/)⁻ but not in mGlu2⁻(/)⁻ mice. However tolerance to the analgesic effect of LY379268 (3 mg/kg, ip) in mGlu3⁻(/)⁻ mice developed following 5 consecutive days of injection.Taken together, these results demonstrate that: (i) mGlu2 receptors play a predominant role over mGlu3 receptors in the control of inflammatory pain in mice; (ii) the analgesic activity of mixed mGlu2/3 agonists is entirely mediated by the activation of the mGlu2 subtype and (iii) the development of tolerance to the analgesic effect of mGlu2/3 agonists develops despite the lack of mGlu3 receptors.

Chronic Treatment with Fluoxetine Induces Sex-Dependent Analgesic Effects and Modulates HDAC2 and mGlu2 Expression in Female Mice.

Gender and sex differences in pain recognition and drug responses have been reported in clinical trials and experimental models of pain. Among antidepressants, contradictory results have been observed in patients treated with selective serotonin reuptake inhibitors (SSRIs). This study evaluated sex differences in response to the SSRI fluoxetine after chronic administration in the mouse formalin test. Adult male and female CD1 mice were intraperitoneally injected with fluoxetine (10 mg/kg) for 21 days and subjected to pain assessment. Fluoxetine treatment reduced the second phase of the formalin test only in female mice without producing behavioral changes in males. We also observed that fluoxetine was able to specifically increase the expression of metabotropic glutamate receptor type-2 (mGlu2) in females. Also a reduced expression of the epigenetic modifying enzyme, histone deacetylase 2 (HDAC2), in dorsal root ganglia (DRG) and dorsal horn (DH) together with an increase histone 3 acetylation (H3) level was observed in females but not in males. With this study we provide evidence that fluoxetine induces sex specific changes in HDAC2 and mGlu2 expression in the DH of the spinal cord and in DRGs and suggests a molecular explanation for the analgesic effects in female mice.

Development, characterization, and in vitro and in vivo evaluation of benzocaine- and lidocaine-loaded nanostructrured lipid carriers.

The present study concerns the in vitro and in vivo evaluation of benzocaine (BENZO) and lidocaine (LIDO) topical delivery from nanostructured lipid carriers (NLCs). Morphology and dimensional distribution of NLCs have been, respectively, characterized by differential scanning calorimetry (DSC) and photon correlation spectroscopy. The release pattern of BENZO and LIDO from NLCs was evaluated in vitro determining drug percutaneous absorption through excised human skin. Radiant heat tail-flick test was carried out in mice to determine the antinociceptive effect of BENZO and LIDO from NLC. DSC studies revealed that the inner oil phase of NLC plays a significant role in stabilizing the particle architecture and increasing the drug solubility. In vitro evidences show that BENZO and LIDO, when incorporated in viscosized NLC dispersions, exhibited a lower flux with respect to formulations containing the free drugs in the aqueous phase. In vivo study enabled to demonstrate that BENZO and LIDO can be released in a prolonged fashion when incorporated into lipid carriers. The results obtained pointed out NLC capability to act as an effective drug reservoir, thus prolonging the anesthetic effect of BENZO and LIDO.

Transcriptional regulation of type-2 metabotropic glutamate receptors: an epigenetic path to novel treatments for chronic pain.

Activation of metabotropic glutamate 2 (mGlu2) receptors inhibits pain transmission at the synapses between primary afferent fibers and neurons in the dorsal horn of the spinal cord. In addition, mGlu2 receptors are found in peripheral nociceptors, and in pain-regulatory centers of the brain stem and forebrain. mGlu2 receptor agonists produce analgesia in models of inflammatory and neuropathic pain, but their use is limited by the development of tolerance. A new therapeutic strategy could be based on the transcriptional regulation of mGlu2 receptors via the acetylation-promoted activation of the p65/RelA transcription factor. "Epigenetic" drugs that increase mGlu2 receptor expression, including l-acetylcarnitine and inhibitors of histone deacetylases, have a different analgesic profile with no tolerance to the therapeutic effect after repeated dosing.