Rubus occidentalis alleviates hyperalgesia induced by repeated intramuscular injection of acidic saline in rats

Cytotoxicity, anti-diabeticity, and phytocomposition investigation of Vietnamese Euphorbia tithymaloides Linn. (Euphorbiaceae)

In this study, the aerial parts of mature Vietnamese Euphorbia tithymaloides plants were put through cytotoxic, anti-diabetic, and phytocompositional evaluations. Specifically, four extracts (petroleum ether (PE), ethyl acetate (EA), methanol (Me), and aqueous (W)) were prepared by maceration at room temperature. All extracts, together with some isolated compounds, were investigated for cytotoxicity against some human normal and cancer cell lines (fibroblasts, HeLa, NCI-H460, HepG2, MCF-7, and Jurkat) using the standardized modified sulforhodamine B (SRB) assay. Additionally, the anti-diabetic activity of extracts and compounds was evaluated via their α-glucosidase inhibitory capacity. The obtained results indicated that Vietnamese E. tithymaloides extracts exhibited moderate cytotoxic activity, among which the PE extract possessed the highest values, on the NCI-H460 cell line. Second, the aqueous extract was revealed to possess very high α-glucosidase inhibitory activity (IC50 = 113.75 ± 14.02 μg ml-1). From the PE extract, three new jatrophane diterpenoids (named tithymal A, tithymal B, and tithymal C) and two known ones were isolated and structurally elucidated using NMR and MS spectroscopies. Noticeably, tithymal A exhibited significantly high inhibitory activity against α-glucosidase (IC50 = 10.71 ± 0.52 μg ml-1). These observations have significantly highlighted the medicinal potential of Vietnamese E. tithymaloides and expanded its scientific fascination.

Effectiveness of maturity of Rubus occidentalis on hyperalgesia induced by acidic saline injection in rats

Background

Rubus occidentalis, also known as black raspberry, contains several bioactive components that vary depending on the maturity of the fruit. The goal of this study was to evaluate the efficacy of immature Rubus occidentalis extract(iROE) on acid-induced hyperalgesia, investigate the mechanism involved, and compare the antihyperalgesic effect of immature and mature ROEs.

Methods

In adult male Sprague-Dawley rats, chronic muscle pain was induced via two injections of acidic saline into one gastrocnemius muscle. To evaluate the dose response, the rats were injected intraperitoneally with 0.9% saline or iROE (10, 30, 100, or 300 mg/kg) following hyperalgesia development. To evaluate the mechanism underlying iROE-induced analgesia, the rats were injected intraperitoneally with saline, yohimbine 2 mg/kg, dexmedetomidine 50 μg/kg, prazosin 1 mg/kg, atropine 5 mg/kg, mecamylamine 1 mg/kg, or naloxone 5 mg/kg 24 h after hyperalgesia development, followed by iROE 300 mg/kg administration. To compare immature versus mature ROE, the rats were injected with mature ROE 300 mg/kg and immature ROE 300 mg/kg after hyperalgesia development. For all experiments, the mechanical withdrawal threshold(MWT) was evaluated using von Frey filaments before the first acidic saline injection, 24 h after the second injection, and at various time points after drug administration. Data were analysed using multivariate analysis of variance(MANOVA) and the linear mixed-effects model(LMEM). We compared the MWT at each time point using analysis of variance with the Bonferroni correction.

Results

The iROE 300 mg/kg injection resulted in a significant increase in MWT compared with the control, iROE 30 mg/kg, and iROE 100 mg/kg injections at ipsilateral and contralateral sites. The iROE injection together with yohimbine, mecamylamine, or naloxone significantly decreased the MWT compared with iROE alone, whereas ROE together with dexmedetomidine significantly increased the MWT. According to MANOVA, the effects of immature and mature ROEs were not significantly different; however, the LMEM presented a significant difference between the two groups.

Conclusions

Immature R. occidentalis showed antihyperalgesic activity against acid-induced chronic muscle pain, which may be mediated by the α2-adrenergic, nicotinic cholinergic, and opioid receptors. The iROE displayed superior tendency regarding analgesic effect compared to mature ROE.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).