Antinociception induced by acute oral administration of sweet substance in young and adult rodents: The role of endogenous opioid peptides chemical mediators and μ1-opioid receptors
ABSTRACT The present work aimed to investigate the effects of acute sucrose treatment on the perception of painful stimuli. Specifically, we sought to determine the involvement of the endogenous opioid peptide-mediated system as well as the role of the μ(1)-opioid receptor in antinociception organisation induced by acute sucrose intake. Nociception was assessed with the tail-flick test in rats (75, 150 and 250 g) of different ages acutely pre-treated with 500 μL of a sucrose solution (25, 50, 150 and 250 g/L) or tap water. Young and Adult rats (250 g) showed antinociception after treatment with 50 g/L (during 5 min) and 150 g/L and 250 g/L (during 20 min) sucrose solutions. Surprisingly, this antinociception was more consistent in mature adult rodents than in pups. To evaluate the role of opioid systems, mature adult rodents were pre-treated with different doses (0.25, 1 or 4 mg/kg) of the non-selective opioid receptor antagonist naloxone, the selective μ(1)-opioid receptor antagonist naloxonazine or vehicle followed by 250 g/L sucrose solution treatment. Sucrose-induced antinociception was reduced by pre-treatment with both naloxone and naloxonazine. The present findings suggest that sweet substance-induced hypo-analgesia is augmented by increasing sucrose concentrations in young and adult rodents. Acute oral sucrose treatment inhibits pain in laboratory animal by mediating endogenous opioid peptide and μ(1)-opioid receptor actions.
- SourceAvailable from: Norberto Cysne Coimbra[Show abstract] [Hide abstract]
ABSTRACT: Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacological therapy for the treatment of pain. The present work investigated the effect of cannabidiol, naloxone and diazepam in combination with 10Hz and 150Hz TENS. Male Wistar rats were submitted to the tail-flick test (baseline), and each rodent received an acute administration (intraperitoneal) of naloxone (3.0mg/kg), diazepam (1.5mg/kg) or cannabidiol (0.75mg/kg, 1.5mg/kg, 3.0mg/kg, 4.5mg/kg, 6.0mg/kg and 12.0mg/kg); 10min after the acute administration, 10Hz or 150Hz TENS or a sham procedure was performed for 30min. Subsequently, tail-flick measures were recorded over a 90-min period, at 5-min intervals. 10Hz TENS increased the nociceptive threshold during the 90-min period. This antinociceptive effect was reversed by naloxone pre-treatment, was not altered by diazepam pre-treatment and was abolished by cannabidiol pre-treatment (1.5mg/kg). Moreover, 150Hz TENS increased tail-flick latencies by 35min post-treatment, which was partially inhibited by naloxone pre-treatment and totally inhibited by cannabidiol (1.5mg/kg). These data suggest the involvement of the endogenous opioid system and the cannabinoid-mediated neuromodulation of the antinociception induced by transcutaneous electrostimulation at 10Hz and 150Hz TENS.Journal of the Neurological Sciences 09/2014; 347(1-2). DOI:10.1016/j.jns.2014.09.024 · 2.26 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Dental pain, including toothache, is one of the most prevalent types of orofacial pain, causing severe, persistent pain that has a significant negative effect on quality of life, including eating disturbances, mood changes, and sleep disruption. As the primary cause of toothache pain is injury to the uniquely innervated dental pulp, rodent models of this injury provide the opportunity to study neurobiological mechanisms of tissue injury-induced persistent pain. Here we evaluated behavioral changes in mice with a dental pulp injury (DPI) produced by mechanically exposing the pulp to the oral environment. We monitored the daily life behaviors of mice with DPI, including measures of eating, drinking, and movement. During the first 48hours, the only parameter affected by DPI was locomotion, which was reduced. There was also a significant short-term decrease in the amount of weight gained by DPI animals that was not related to food consumption. As cold allodynia is frequently observed in individuals experiencing toothache pain, we tested whether mice with DPI demonstrate an aversion to drinking cold liquids using a cold-sucrose consumption test. Surprisingly, mice with DPI increased their consumption of sucrose solution, to over 150% of baseline, regardless of temperature. Both the weight loss and increased sucrose intake in the first 2days of injury were reversed by administration of indomethacin. These findings indicate that enhanced sucrose consumption may be a reliable measure of orofacial pain in rodents, and suggest that alterations in energy expenditure and motivational behaviors are under-recognized outcomes of tooth injury.Pain 04/2013; 154(8). DOI:10.1016/j.pain.2013.04.018 · 5.84 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: This paper is the thirty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2012 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).Peptides 10/2013; 50. DOI:10.1016/j.peptides.2013.10.001 · 2.61 Impact Factor