• GPER/GPR30 Estrogen Receptor: A Target for Pain Modulation

      Dun, Nae J.; Abood, Mary Ellen, 1958-; Ashby, Barrie; Brailoiu, Eugen; Unterwald, Ellen M.; Sapru, Hreday N. (Temple University. Libraries, 2012)
      The G protein-coupled estrogen receptor GPER/GPER1, also known as GPR30, was originally cloned as an orphan receptor and later shown to be specifically activated by 17-ß-estradiol. This has led to its classification as an estrogen receptor and expanded the perspective on the mechanisms underlying the rapid estrogenic effects reported over the years. GPER is strongly expressed in the central nervous system and peripheral tissues and appears to be involved in a wide variety of physiological and pathological processes. Estrogens are known to alter the processing of nociceptive sensory information and analgesic responses in the central nervous system. Both analgesic and pro-nociceptive effects of estrogens have been reported. Some pro-algesic estrogenic responses have a short latency, suggesting a non-genomic mechanism of action. Immunohistochemical studies in rodents prove the existence of GPER in pain-relevant areas of the nervous system such as dorsal root ganglia, superficial dorsal horn of the spinal cord, periaqueductal gray (PAG), amygdala, trigeminal sensory nucleus and thalamus. In the periphery, activation of GPER results in pro-nociceptive effects. However, GPER involvement in pain processing at central levels is largely unexplored. Thus, the work presented in this thesis was aimed at investigating whether GPER modulates nociception at spinal and supraspinal sites. The behavioral response to GPER activation in the spinal cord and PAG was evaluated in an acute grooming test (scratching, biting and licking behavior) and in the hot plate test, respectively. Intrathecal challenge of mice with the GPER agonist G-1 (0.1-1 nmol) induced a dose-dependent increase in pain-related behaviors, that was abolished by pre-treatment with the GPER antagonist G15 (1-10 nmol), confirming GPER specificity of the response. Likewise, intra-PAG microinjection of G-1 (10-100 pmol) to rats reduced the nociceptive threshold in the hot plate test, an effect that was G15 sensitive. To obtain further insight on the mechanisms involved in the behavioral effects observed in whole animals, we tested the effect of GPER ligands on neuronal membrane potential, intracellular calcium concentration ([Ca2+]i) and reactive oxygen species (ROS) accumulation. The membrane depolarization and the increases in [Ca2+]i and ROS levels are markers of neuronal activation, underlying pain sensitization in the spinal cord and pain facilitation in the PAG. Electrophysiological recordings from superficial dorsal horn and lateral PAG neurons indicate neuronal depolarization upon G-1 application, an effect that was fully prevented by G15 pre-treatment. Both cultured spinal neurons and cultured PAG neurons responded to G-1 administration by elevating [Ca2+]i and mitochondrial and cytosolic ROS levels. In the presence of G15, G-1 did not elicit the calcium and ROS responses. Collectively, these results demonstrate that GPER modulates both the ascending and descending pain pathways to increase nociception via cytosolic calcium elevation and ROS accumulation in spinal and PAG neurons, respectively. These findings broaden the current knowledge on GPER involvement in physiology and pathophysiology, providing the first evidence of its pro-nociceptive effects at central levels and characterizing some of the mechanisms involved. Moreover, we show for the first time ROS accumulation downstream of GPER activation, extending the current understanding of GPER signaling.
    • Interactive Role of Anxiety Sensitivity and Pain Expectancy in Dental Anxiety

      Heimberg, Richard G.; McCloskey, Michael S.; Tellez Merchán, Marisol; Drabick, Deborah A.; Giovannetti, Tania; Myers, Shannon V. (Temple University. Libraries, 2017)
      Dental anxiety is a major public health problem that leads to underutilization of dental care and poor oral health. Much research has demonstrated an association between the expectation of pain during dental treatment and dental anxiety; however, not all patients with high pain expectancy develop dental anxiety, suggesting that other factors may impact the degree to which pain expectancy increases dental anxiety. The present study examined whether anxiety sensitivity (AS; the fear of negative consequences of anxiety-related symptoms and sensations) increases the strength of the relationship between pain expectancy and dental anxiety. Participants were 104 adult patients of Temple University Kornberg School of Dentistry clinics. Baseline levels of AS and pain expectancy were assessed using self-report questionnaires. Baseline dental anxiety was assessed using self-report questionnaires and measures of psychological/physiological stress reactivity to films of dental procedures. Participants also underwent a pain expectancy induction, and all indices of dental anxiety were re-assessed following the pain expectancy induction. Linear regression analyses revealed that, in contrast to expectations, AS did not strengthen the relationship between self-reported or laboratory-induced pain expectancy and any indicators of dental anxiety. On the contrary, there was limited evidence that AS may weaken the pain expectancy-dental anxiety relationship. Consistent with previous studies, there was a strong pattern of findings supporting a direct association between pain expectancy and dental anxiety, but limited evidence of a direct association between AS and dental anxiety. AS may not be a strong risk candidate for dental anxiety, and future studies examining other theoretically-relevant vulnerability factors are needed to elucidate pathways through which pain expectancy leads to greater dental anxiety.
    • Pharmacological and Neuroanatomical Analysis of GNTI-Induced Repetitive Behavior in Mice

      Cowan, Alan, 1942-; Dun, Nae J.; Eisenstein, Toby K.; Liu-Chen, Lee-Yuan; Unterwald, Ellen M.; Ashby, Barrie; Ryan, Richard R. (Temple University. Libraries, 2010)
      This thesis is comprised of two parts. In the first part, we investigated a) the pharmacology of GNTI, a selective kappa opioid receptor antagonist, as a scratch-inducing compound in mice and b) possible mediators and receptors that may be involved in GNTI-induced scratching (itch). We studied if GNTI induces scratching through opioid, histamine, gastrin-releasing peptide (GRP) and/or muscarinic M1 receptors. In the second part, we established similarities and differences between pain and itch using GNTI-induced scratching and formalin-induced nociception models in mice. We found that GNTI (0.03-3 mg/kg, s.c., behind the neck) induces compulsive and vigorous scratching behavior in a dose-dependent manner. A standard submaximal dose (0.3 mg/kg) of GNTI caused animals to scratch 500-600 times in a 30 min observation period. Intrathecal (i.t.) or intraperitoneal (i.p.) administration of GNTI did not elicit scratching behavior. Duration of action of GNTI was 60-70 min and tolerance to the repetitive behavior did not develop. C-fos expressing neurons, in response to GNTI injection, were localized on the lateral side of the superficial layers of the dorsal horn of the cervical spinal cord. Compound 48/80, a chemically different pruritogen, evoked c-fos expression in neurons which are located on the lateral side of the superficial layer of the dorsal horn. These data suggest that both GNTI and compound 48/80 activate a group of sensory neurons located on the lateral side of lamina I and II. Pretreating (at -20 min) and posttreating (at +5 min) mice with the kappa opioid receptor agonist, nalfurafine (0.001-0.03 mg/kg, s.c.), significantly attenuated scratching induced by GNTI (0.3 mg/kg). These effects were not a consequence of behavioral depression. Tolerance did not develop to the anti-scratch activity of nalfurafine. Pretreating mice with nalfurafine (0.02 mg/kg) prevented both GNTI- and compound 48/80-provoked c-fos expression. Our c-fos results suggest that the preclinical antipruritic activity of nalfurafine occurs at the spinal level. Moreover, our results reinforce the need to evaluate nalfurafine as a potentially useful antipruritic in human conditions involving itch. GNTI still elicited excessive scratching in mice lacking mu, delta or kappa opioid receptors, respectively, as well as in mice pretreated with either naloxone or norbinaltorphimine. The H1 receptor antagonist, fexofenadine, or the H4 receptor antagonist, JNJ 10191584, did not attenuate GNTI-induced scratching. Also, pretreating mice with the peptide GRPR antagonist, [D-Phe6]bombesin(6-13) methyl ester, or the non-peptide GRPR antagonist, RC-3095, did not antagonize scratching induced by GNTI. Furthermore, GRPR mRNA levels did not change in response to GNTI injection. Telenzepine, a standard M1 receptor antagonist, had no marked effect against GNTI-elicited scratching, however (unexpectedly) McN-A-343, an M1 receptor agonist, attenuated this behavior in a dose-dependent manner. In the second part of our studies, we found that pretreating mice with lidocaine (i.d., behind the neck) inhibits GNTI-induced scratching and prevents GNTI-provoked c-fos expression in the dorsal horn of the spinal cord. Similarly, lidocaine (i.d., hind leg) inhibits formalin-induced nociception as well as formalin-provoked c-fos expression. While injection (s.c.) of formalin to the face of mice induced only wiping (indicating pain) by forepaws of the injection side, injection (s.c.) of GNTI to the face elicited grooming and scratching (indicating itch). In contrast to formalin, GNTI did not induce c-fos expression in the trigeminal nucleus suggesting that pain and itch sensations are projected differently along the sensory trigeminal pathway. In short, our main results indicate that a) the scratch-inducing activity of GNTI is not mediated by opioid, histamine or GRP receptors; b) kappa opioid receptors are involved, at least in part, in the inhibition of itch sensation and thus, on the basis of our results, nalfurafine holds promise as a potentially useful antipruritic in human conditions involving itch; and c) agonism at M1 receptors inhibits GNTI-induced scratching therefore the M1 receptor may be a key target for antipruritic drug development.
    • Single and Combined Effects of Cannabinoids on Neuropathic Pain and Cognition

      Ward, Sara Jane; Tuma, Ronald F. (Ronald Franklin); Langford, Dianne; Kirby, Lynn (Temple University. Libraries, 2016)
      Rationale. For centuries, medications derived from the marijuana plant have been used for therapeutic purposes across numerous cultures. In 1964, the primary psychoactive ingredient in cannabis, delta-9-tetrahydrocannabinol (-9-THC) was defined. This, followed by the discovery of the endocannabinoid system, marked the beginning of comprehensive research into the beneficial exploitation of this system. The cannabis plant contains various other cannabinoids besides -9-THC. Most of the effects of cannabinoid-based therapies are based on the agonistic action of -9-THC through cannabinoid receptors. Alternatively, some of these effects are caused by the actions of other cannabinoids, like cannabidiol, which does not have high affinity for cannabinoid receptors. Like -9-THC, cannabidiol (CBD), the non-psychoactive phytocannabinoid in Cannabis sativa, has been hypothesized to ameliorate adverse effects of -9-THC. Cannabidiol possesses neuroprotective, antiemetic, and anti-inflammatory properties. Sativex, a 1:1 ratio of CBD and -9-THC, is currently an approved medication in Europe for the treatment of conditions such as neuropathic pain, and has been fast tracked by the USFDA for late stage clinical trials for a host of disorders, ranging from epilepsy to irritable bowel disease. Additionally, increasing preclinical evidence demonstrates that treatment with Cannabidiol alone produces efficacy on a variety of nervous system injuries, including neuropathic pain, schizophrenia and anxiety disorders. Furthermore, there is mounting evidence of an “entourage effect” in cannabinoid-based pharmacotherapies. This effect occurs when treatment with a combination of cannabinoids derived from the plant produce more efficacy than treatment with a single cannabinoid (1). As cannabinoid-based treatments continue to develop and clinical data increases, further investigation of the entourage effect is necessary to facilitate the appropriate future treatment regimens for nervous system disorders. Hypotheses. We hypothesized that treatment with the non-psychoactive cannabis compound cannabidiol would be as effective as the psychoactive cannabis compound -9-THC, or a combination of the two, in mitigating neuropathic pain in a mouse model of chemotherapy-induced peripheral neuropathy. We additionally hypothesized that cannabidiol would not affect classic cannabinoid-agonist induced cognitive impairment in rodent models of learning and memory. Methodology. Neuropathic pain was induced by repeated injections of the chemotherapeutic agent Paclitaxel. Mechanical hypersensitivity to Paclitaxel was assessed using the Von Frey assay. Cognition was assessed using three rodent models of learning and memory: 1) Conditional Discrimination, 2) Conditional Discrimination with a reversal component, and 3) Barnes Maze. Results. Cannabidiol was found to be more potent and more effective than -9-THC in attenuating neuropathic pain in a dose dependent manner. Combinations of CBD+-9-THC revealed that lower, ineffective doses of CBD and -9-THC display supra-additive effects when given in combination while higher, individually effective doses exhibit sub-additive effects in combination. Cognitively, no deficits were observed over a range of doses of any cannabinoid tested in the conditional discrimination tasks, although a slight trend was observed in animals administered the synthetic mixed CB1/CB2 agonist WIN55,212-2. In the Barnes Maze task, treatment with -9-THC alone dose-dependently decreased number of entries and total time spent in the target zone. Cannabidiol did not produce any effects in the Barnes Maze alone, nor did it attenuate the effects seen in animals treated with -9-THC alone. Lastly, -9-THC did not affect total distance traveled or average speed, whereas combination treatment increased both locomotor measurements at all but the highest combination dose. Conclusions. The results of these studies indicate that cannabidiol is more potent than -9-THC in attenuating neuropathic pain. Results of cognitive testing indicate subtle impairment in animals treated with -9-THC and WIN55,212-2 that were not reversed by CBD.
    • The Effects of Music on Pain: A Review of Systematic Reviews and Meta-Analysis

      Dileo, Cheryl; Magee, Wendy; DuCette, Joseph P.; Confredo, Deborah A. (Temple University. Libraries, 2015)
      The purpose of this study was twofold: to critically review existing systematic reviews and meta-analyses on the topic of music and pain; and to systematically review and conduct a meta-analysis of clinical trials investigating the effect of music on pain encompassing a wide range of medical diagnoses, settings, age groups, and types of pain. For the review of systematic reviews, the author conducted a comprehensive search and identified 14 systematic reviews and meta-analyses. These studies were critically analyzed to present a comprehensive overview of findings, to evaluate methodological quality of the reviews, to determine issues or gaps in the literature, and to generate research questions for the following meta-analysis. For the meta-analysis, the author conducted electronic searches of 12 databases and a handsearch of related journals and reference lists of relevant systematic reviews, with partial restrictions on design (i.e., randomized controlled trials); language (i.e., English, German, Korean, and Japanese); year of publication (i.e., 1995 to 2014) and intervention (i.e., music therapy and music medicine). Analyzed studies included 87 music medicine (MM) and 10 music therapy (MT) trials; eighty-nine of the included studies involved adults and eight trials focused on children. In terms of the types of pain, there were 51 trials on acute, 34 on procedural, and 12 on cancer or chronic pain; the trials were conducted in over 20 different medical specialty areas. For the assessment of study quality, I used the risk of bias tool developed by the Cochrane collaboration, and pooled data from the included studies were analyzed using the Revman 5.3 software according to the effects of music on levels of pain intensity, amount of analgesic use, and changes in vital signs. The results indicated that music interventions resulted in a significant reduction of 1.13 units on 0-10 scales and a small to moderate pain reducing effect on other scales (SMD = -0.39). Participants in the music group experienced a significantly lower level of emotional distress from pain (MD = -10.8), and required significantly fewer anesthetics (SMD = -0.56), opioids (SMD = -0.24), and non-opioid medications (SMD = -0.54). Moreover, the music group showed statistically significant decreases in heart rate of 4.25 bpm, systolic blood pressure of 3.34 mmHg, diastolic blood pressure of 1.18 mmHg, and respiration rate of 1.46 breaths per minute. Findings from several analyses of moderator variables suggest: MT has a stronger effect in reducing self-rated pain intensity than MM; MT is more effective in reducing chronic/cancer pain than other types of pain, but MM seems to be more effective in managing procedural pain; children benefit more from music interventions than do adults, and more from MT than MM; providing different levels of choices in the selection of music yields different outcomes for MM; having a rationale for selection of music greatly improves the treatment outcome for MM; and an active MT approach is more effective in relieving perceived levels of pain than a passive MT approach. The results from the current meta-analysis demonstrate that music interventions may have beneficial effects on pain, emotional distress from pain, use of anesthetics and pain killers, and vital signs including heart rate, systolic blood pressure, diastolic blood pressure and respiration rate. However, these results need to be interpreted with caution due to highly heterogeneous outcomes among the included studies. Considering all the possible benefits, music interventions may provide an effective complimentary approach for the relief of acute, procedural and cancer/chronic pain in the medical setting.
    • Vitamin D and Chronic Pain: A Comprehensive Review

      Jefferies, Steven R.; Godel, Jeffrey H.; Sciote, James J.; Spannhake, Elizabeth (Temple University. Libraries, 2013)
      In recent years vitamin D has gained popularity in the media, on the internet, and throughout alternative treatment practitioners as a cheap and effective option to treat many diseases. Research showing that vitamin D receptors are present in virtually all cells of the body, and the increasing data demonstrating a relationship of vitamin D metabolites to chronic diseases, have led to widespread treatment of medical conditions with vitamin D supplementation. Chronic pain and inflammatory conditions are increasingly linked to vitamin D deficiency. The question posed in this review is whether there is significant, quality research to recommend vitamin D supplementation for patients with chronic pain conditions. Utilizing publications from PubMed for the review, various search terms were entered for vitamin D (vitamin D; vitamin D2; vitamin D3; 1,25-dihydroxyvitamin D3; 1,25-dihydroxycholecalciferol; 25 hydroxycholecalciferol; 25-hydroxyvitamin D; alfacalcidol; calcidiol; calcitriol; calcifediol; calciferol; ergocalciferal; cholecalciferol); and "pain." The search was continued from the last day of the Straub et. al. review, September 8th, 2008. The last search was conducted on December 5, 2012. The search protocol from Straub et. al was followed as well. Also, added to this search protocol were the terms: vitamin D receptor; VDR and "pain." These terms enabled a search for genetic links between vitamin D and pain. The search criteria resulted in nine relevant articles (from the original 1,069 studies) with varying treatment protocols in each article making any statistical representation impossible. Results on the effectiveness of vitamin D correlation with chronic pain were extremely variable, with most papers drawing the conclusion that more quality research needs to be implemented on the subject. Due to the variability and lack of quality randomized controlled trials, the current literature can only suggest a possible link between vitamin D levels and pain. Also, recent research into Vitamin D Receptors (VDR) has opened up a possible connection between VDR polymorphisms and pain. So, after a comprehensive review of vitamin D, Vitamin D Receptors, and pain, there is still not enough evidence to recommend supplementation to treat chronic pain conditions. However, enough evidence is available to recommend future high quality, randomized controlled trials to help determine the influence vitamin D and VDRs have on pain issues.