Publications by authors named "Bradford D Fischer"

Alcohol use disorder (AUD) affects >15 million people in the United States. Current pharmacotherapeutic treatments for AUD are only modestly effective, necessitating the identification of new targets for medications development. The cannabinoid receptor type 1 (CB1) has been a target of interest for the development of medications for substance use disorders and other compulsive disorders.

View Article and Find Full Text PDF

Up to 70 million people around the world suffer from rheumatoid arthritis. Current treatment options have varied efficacy and can cause unwanted side effects. New approaches are needed to treat this condition.

View Article and Find Full Text PDF

Background: The opioid epidemic is a rapidly growing public health concern in the USA, as the number of overdose deaths continues to increase each year. One strategy for combating the rising number of overdoses is through opioid overdose prevention programs (OOPPs).

Objective: To evaluate the effectiveness of an innovative OOPP, with changes in knowledge and attitudes serving as the primary outcome measures.

View Article and Find Full Text PDF

We have previously reported that multiple Team-Based Learning (TBL™) exercises in a 4-week pre-clinical medical school course improved final exam performance and significantly reduced the number of course failures. Here, we conducted a long-term study, with eight cohorts of first-year medical students, to determine whether the implementation of a single TBL individual readiness assessment test (iRAT) exercise in a 4-week medical school pharmacology course produces similar effects in overall course performance. We implemented a single TBL iRAT exercise that covered the subjects addressed during one week of the medical pharmacology course, with the four most recent cohorts of students matriculating at Cooper Medical School of Rowan University (n = 403).

View Article and Find Full Text PDF

Rationale: Opioid and GABA receptors are both located in central nociceptive pathways, and compounds that activate these receptors have pain-relieving properties. To date, the interactive effects of concurrent administration of these compounds in preclinical models of pain-like behaviors have not been assessed.

Objective: The purpose of this study was to examine the interactive effects of the μ-opioid agonist morphine and the α2GABA and α3GABA receptor positive allosteric modulator methyl 8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxylate (MP-III-024) in preclinical models of mechanical hyperalgesia and thermal nociception.

View Article and Find Full Text PDF
Article Synopsis
  • - IBNtxA is a new μ-opioid receptor agonist derived from naltrexone, showing promise for pain relief (anti-nociception) without significant side effects or addiction potential.
  • - In studies, a 3 mg/kg dose of IBNtxA was found to be as effective as 10 mg/kg of morphine in pain relief tests, while also reducing morphine's side effects such as hyperactivity and withdrawal symptoms.
  • - IBNtxA exhibited complex interactions with various opioid receptors, suggesting it has a unique mechanism of action that could make it a valuable candidate for future pain management medications.
View Article and Find Full Text PDF
Article Synopsis
  • Comorbidities in epilepsy can severely affect patients' quality of life, and current antiepileptic medications often don't improve cognitive and behavioral issues.
  • The study aimed to investigate the short-term effects of acute seizures on cognition and behavior by using a mouse model, mainly focusing on observing changes in memory and anxiety-like behavior following electroconvulsive seizures (ECS).
  • Findings showed that while recognition memory was unaffected by ECS, ECS-treated mice displayed increased anxiety and reduced interest in novel objects, along with decreased locomotor activity 45 minutes post-treatment, suggesting that brief seizures can have significant behavioral impacts during the early stages of epilepsy.
View Article and Find Full Text PDF

Behavioral and social science integration in clinical practice improves health outcomes across the life stages. The medical school curriculum requires an integration of the behavioral and social science principles in early medical education. We developed and delivered a four-week course entitled "LifeStages" to the first year medical students.

View Article and Find Full Text PDF

Severe chronic pain is one of the hallmarks and most debilitating manifestations of inflammatory arthritis. It represents a significant problem in the clinical management of patients with common chronic inflammatory joint conditions such as rheumatoid arthritis, psoriatic arthritis and spondyloarthropathies. The functional links between peripheral inflammatory signals and the establishment of the neuroadaptive mechanisms acting in nociceptors and in the central nervous system in the establishment of chronic and neuropathic pain are still poorly understood, representing an area of intense study and translational priority.

View Article and Find Full Text PDF

The goal of these studies was to investigate the links between chronic exposure to the pro-inflammatory cytokine tumor necrosis factor (TNF), hyperalgesia and the excitability of dorsal root ganglion (DRG) sensory neurons. We employed transgenic mice that constitutively express TNF (TNFtg mice), a well-established model of chronic systemic inflammation. At 6 months of age, TNFtg mice demonstrated increased sensitivity to both mechanical and thermal heat stimulation relative to aged-matched wild-type controls.

View Article and Find Full Text PDF

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is characterized by symptoms of chronic abdominal pain and altered bowel habits in the absence of an overtly identifiable cause. It is the most commonly diagnosed functional gastrointestinal disorder, accounting for about one third of gastroenterology visits. It generally presents as a complex of symptoms, including psychological dysfunction.

View Article and Find Full Text PDF

Studies in animal models suggest that sugar deprivation following excessive intake elicits some opioid-like withdrawal signs. In the present study, opioid-like effects of excessive sucrose intake were further characterized in C57BL/6 mice by comparing the effects of the opioid antagonist naloxone on food-reinforced responding before and during sucrose availability and, in parallel experiments, following chronic morphine administration. Results show that naloxone produced time-dependent and dose-dependent decreases in operant response rates after 4 weeks of excessive sucrose consumption, and that these effects were comparable with those produced by chronic morphine injections.

View Article and Find Full Text PDF

γ-Aminobutyric acid type A (GABA) receptors are located in spinal nociceptive circuits where they modulate the transmission of pain sensory signals from the periphery to higher centers. Benzodiazepine-type drugs bind to GABA receptors containing α1, α2, α3, and α5 subunits (α1GABA, α2GABA, α3GABA and α5GABA receptors, respectively) through which they inhibit the transmission of these signals. In the present study we describe the novel benzodiazepine site positive allosteric modulator modulator methyl 8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepine-3-carboxylate (MP-III-024).

View Article and Find Full Text PDF

Background: Chronic pain is treated most commonly with opioid analgesics, anti-inflammatory steroids and nonsteroidal anti-inflammatory drugs.

Method: However, these compounds are not uniformly effective and their clinical use is constrained by unwanted side effects. GABAergic neurons are located in spinal nociceptive circuits suggesting that drugs with affinity at these receptors, including benzodiazepine-like drugs, may provide an alternative to opioids for the treatment of pain.

View Article and Find Full Text PDF

Background: Conventional benzodiazepines bind non-selectively to GABAA receptors containing α1, α2, α3, and α5 subunits (α1GABAA, α2GABAA, α3GABAA, and α5GABAA receptors, respectively), and the role of these different GABAA receptor subtypes in the reinforcing effects of benzodiazepines has not been characterized fully. We used a pharmacological antagonist approach with available subtype-selective ligands to evaluate the role of GABAA receptor subtypes in the reinforcing effects of the non-selective conventional benzodiazepine, triazolam.

Methods: Rhesus monkeys (n=4) were trained under a progressive-ratio schedule of intravenous midazolam delivery and dose-response functions were determined for triazolam, in the absence and presence of flumazenil (non-selective antagonist), βCCT and 3-PBC (α1GABAA-preferring antagonists), and XLi-093 (α5GABAA-selective antagonist).

View Article and Find Full Text PDF

Rationale: Assays of schedule-controlled responding can be used to characterize the pharmacology of benzodiazepines and other GABAA receptor modulators, and are sensitive to changes in drug effects that are related to physical dependence.

Objective: The present study used this approach to investigate the role of GABAA receptor subtypes in mediating dependence-like effects following benzodiazepine administration.

Methods: Squirrel monkeys (n = 6) were trained on a fixed-ratio schedule of food reinforcement.

View Article and Find Full Text PDF

Benzodiazepines are prescribed widely but their utility is limited by unwanted side effects, including abuse potential. The mechanisms underlying the abuse-related effects of benzodiazepines are not well understood, although α1 subunit-containing GABAA receptors have been proposed to have a critical role. Here, we examine the reinforcing effects of several compounds that vary with respect to intrinsic efficacy at α2, α3, and α5 subunit-containing GABAA receptors but lack efficacy at α1 subunit-containing GABAA receptors ('α1-sparing compounds'): MRK-623 (functional selectivity for α2/α3 subunit-containing receptors), TPA023B (functional selectivity for α2/α3/α5 subunit-containing receptors), and TP003 (functional selectivity for α3 subunit-containing receptors).

View Article and Find Full Text PDF

This study explored the involvement of N-methyl-D-aspartate (NMDA) in the effects of μ-opioid agonists. A hot-plate procedure was used to assess antinociception and tolerance in mice in which the NR1 subunit of the NMDA receptor was reduced [knockdown (KD)] to approximately 10%, and in mice treated with the NMDA antagonist, (-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid (LY235959). The μ opioid agonists, morphine, l-methadone and fentanyl, were approximately three-fold less potent in the NR1 KD mice than in wild-type (WT) controls; however, the development of morphine tolerance and dependence did not differ markedly in the NR1 KD and the WT mice.

View Article and Find Full Text PDF

Opioid analgesics are the most frequently prescribed medications for the treatment of moderate or severe pain; however, their use is constrained by unwanted side effects. One therapeutic approach used to improve the side effect profile of opioids is the administration of a second drug in an opioid-containing mixture. Preclinical studies designed to predict the therapeutic potential of novel opioid-containing drug combinations are currently underway, and must rely on quantitative methods to assess their interactive effects.

View Article and Find Full Text PDF

Combinations of positive modulators of benzodiazepine and neuroactive steroid sites on GABA(A) receptors have been shown to act in an additive or supra-additive manner depending on the endpoint under study, but they have not been assessed on experimentally induced conflict or drug self-administration. The present study examined the interactive effects of the benzodiazepine triazolam and the neuroactive steroid pregnanolone in a rhesus monkey conflict procedure (a model of anxiolysis) and on a progressive-ratio schedule of drug self-administration (a model of abuse potential). Both triazolam and pregnanolone decreased rates of nonsuppressed responding, whereas only triazolam consistently increased rates of suppressed responding (i.

View Article and Find Full Text PDF

Rationale: Experimental evidence suggests that the differential behavioral effects of benzodiazepines depend on their relative actions at γ-aminobutyric acid type A (GABA(A)) receptors that contain either an α1, α2, α3, or α5 subunit.

Objectives: The present study was aimed at understanding the role of α3 subunit-containing GABA(A) (α3GABA(A)) receptors by examining the behavioral pharmacology of TP003 (4,2'-difluoro-5'-[8-fluoro-7-(1-hydroxy-1-methylethyl)imidazo[1,2-a]pyridine-3-yl]biphenyl-2-carbonitrile), which shows functional selectivity for α3GABA(A) receptors.

Methods: First, a conflict procedure was used to assess the anxiolytic-like effects of TP003 and a representative clinically available benzodiazepine.

View Article and Find Full Text PDF

Conflict procedures can be used to study the receptor mechanisms underlying the anxiolytic effects of benzodiazepines and other GABA(A) receptor modulators. In the present study, we first determined the efficacy and binding affinity of the benzodiazepine diazepam and recently synthesized GABA(A) receptor modulators JY-XHe-053, XHe-II-053, HZ-166, SH-053-2'F-S-CH₃ and SH-053-2'F-R-CH₃ at GABA(A) receptors containing α1, α2, α3 and α5 subunits. Results from these studies suggest that each compound displayed lower efficacy at GABA(A) receptors containing α1 subunits and varying degrees of efficacy and affinity at GABA(A) receptors containing α2, α3 and α5 subunits.

View Article and Find Full Text PDF

CB(1) cannabinoid (CB(1)) receptor agonists and N-Methyl-d-Aspartate (NMDA) receptor antagonists attenuate the development of morphine antinociceptive tolerance. The present study used dose-addition analysis to evaluate CB(1)/NMDA receptor interactions on this endpoint. Chronic morphine administration (5 days, 100 mg/kg, twice daily) resulted in a 2.

View Article and Find Full Text PDF

Rationale: Recent experimental data suggest that metabotropic glutamate receptor (mGluR) antagonists with selectivity for mGluR1 and mGluR2/3 enhance morphine-induced antinociception.

Objectives: The present study addressed the hypothesis that mGluR antagonists enhance opioid antinociception by increasing opioid efficacy.

Materials And Methods: The antinociceptive effects of the partial mu-opioid receptor agonists buprenorphine and dezocine were first assessed in a hot-plate procedure under conditions of low (53 degrees C) and high (56 degrees C) stimulus intensity.

View Article and Find Full Text PDF

The present study examined the interactive effects of morphine in combination with metabotropic glutamate (mGlu) receptor antagonists on schedule-controlled responding and thermal nociception. Drug interaction data were examined with isobolographic and dose-addition analysis. Morphine, the mGlu1 receptor antagonist JNJ16259685 [(3,4-dihydro-2H-pyrano-[2,3-b]quinolin-7-yl)-(cis-4-methoxycyclohexyl)-methanone], the mGlu5 receptor antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine hydrochloride], and the mGlu2/3 receptor antagonist LY341495 [(2S)-2-amino-2-[(1S,2S-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid] all decreased rates of schedule-controlled responding.

View Article and Find Full Text PDF