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Brain-derived neurotrophic factor (BDNF) signaling is implicated in the aetiology of many psychiatric disorders associated with altered emotional processing. Altered peripheral (plasma) BDNF levels have been proposed as a biomarker for neuropsychiatric disease risk in humans. However the relationship between peripheral and central BDNF levels and emotional brain activation is unknown. We used heterozygous BDNF knockdown rats (BDNF+/- ) to examine the effects of genetic variation in the BDNF gene on peripheral and central BDNF levels and emotional brain activation as assessed by awake fMRI. BDNF+/- and control rats were trained to associate a flashing light (conditioned stimulus; CS) with foot-shock, and brain activation in response to the CS was measured 24h later in awake rats using fMRI. Central and peripheral BDNF levels were decreased in BDNF+/- rats compared to control rats. Activation of fear circuitry (amygdala, periaqueductal gray, granular insular) was seen in control animals, however activation of this circuitry was absent in BDNF+/- animals. Behavioral experiments confirmed impaired conditioned fear responses in BDNF+/- rats, despite intact innate fear responses. These data confirm a positive correlation (r = 0.86, 95% CI [0.55, 0.96]; P = 0.0004) between peripheral and central BDNF levels and indicate a functional relationship between BDNF levels and emotional brain activation as assessed by fMRI. The results demonstrate the use of rodent fMRI as a sensitive tool for measuring brain function in preclinical translational studies using genetically modified rats and support the use of peripheral BDNF as a biomarker of central affective processing.

Subsequent to peripheral nerve compression and irritation, pathophysiological processes take place within nervous and immune systems. Here, we utilized a multimodal approach to comprehend peripheral and central soft tissue changes as well as alterations occurring in systemic analytes following unilateral chronic constriction injury (CCI) of the sciatic nerve in rodents. Using magnetic resonance imaging and [18F]-2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography, we demonstrated robust structural abnormalities and enhanced FDG uptake within the injured nerve and surrounding muscle, respectively. To assess whether central morphological changes were induced by nerve injury, diffusion tenor imaging was performed. A decrease in fractional anisotropy in primary motor cortex contralateral to the injury site was observed. Evaluation of a panel of circulating cytokines, chemokines, and growth factors showed decreased levels of interleukin-1β and Fractalkine in CCI animals. Area under the receiver operating curve (ROC) calculations of analyte levels, imaging, and behavioral end points ranged from 0.786 to 1, where behavioral and peripheral imaging end points (eg, FDG uptake in muscle) were observed to have the highest discriminatory capabilities (maximum area under ROC = 1) between nerve injury and sham conditions. Lastly, performance of correlation analysis involving all analyte, behavioral, and imaging data provided an understanding of the overall association amongst these end points, and importantly, a distinction in correlation patterns was observed between CCI and sham conditions. These findings demonstrate the multidimensional pathophysiology of sciatic nerve injury and how a combined analyte, behavioral, and imaging assessment can be implemented to probe this complexity.

Background The function of brain networks can be changed in a maladaptive manner in response to chronic neuropathic pain. Analgesics can reduce pain by acting on such networks via direct or indirect (peripheral or spinal) mechanisms. This investigation aimed to map gabapentin's pharmacodynamics (PD) in the rodent brain following induction of neuropathic pain in order to further understand its PD profile. Methods Pharmacological magnetic resonance imaging (phMRI) and a novel functional connectivity analysis procedure were performed following vehicle or gabapentin treatment in the rat spinal nerve ligation (SNL) model of neuropathic pain as well as sham animals. Results phMRI performed in SNL animals revealed robust gabapentin-induced responses throughout the hippocampal formation, yet significant (p

A novel 4-aminocyclopentapyrrolidine series of N-type Ca(2+) channel blockers have been discovered. Enantioselective synthesis of the 4-aminocyclopentapyrrolidines was enabled using N-tert-butyl sulfinamide chemistry. SAR studies demonstrate selectivity over L-type Ca(2+) channels. N-type Ca(2+) channel blockade was confirmed using electrophysiological recording techniques. Compound 25 is an N-type Ca(2+) channel blocker that produces antinociception in inflammatory and nociceptive pain models without exhibiting cardiovascular or motor liabilities.

In vivo translational imaging techniques, such as positron emission tomography and single-photon emission-computed tomography, are the only ways to adequately determine that a drug engages its target. Unfortunately, there are far more experimental mechanisms being tested in the clinic than there are radioligands, impeding the use of this risk-mitigating approach in modern drug discovery and development. Pharmacological magnetic resonance imaging (phMRI) offers an approach for developing new biomarkers with the potential to determine central activity and dose selection in animals and humans. Using phMRI, we characterized the effects of xanomeline on ketamine-induced activation on blood oxygen level-dependent (BOLD) signal. In the present studies, xanomeline alone dose-dependently increased the BOLD signal across several regions of interest, including association and motor and sensory cortical regions. It is noteworthy that xanomeline dose-dependently attenuated ketamine-induced brain activation patterns, effects that were antagonized by atropine. In conclusion, the muscarinic 1/4-preferring receptor agonist xanomeline suppressed the effects of the N-methyl-D-aspartate channel blocker ketamine in a number of brain regions, including the association cortex, motor cortex, and primary sensory cortices. The region-specific brain activation observed in this ketamine challenge phMRI study may provide a method of confirming central activity and dose selection for novel antipsychotic drugs in early clinical trials for schizophrenia, if the data obtained in animals can be recapitulated in humans.

Positive modulation of the neuronal nicotinic acetylcholine receptor (nAChR) α4β2 subtype by selective positive allosteric modulator NS-9283 has shown to potentiate the nAChR agonist ABT-594-induced anti-allodynic activity in preclinical neuropathic pain. To determine whether this benefit can be extended beyond neuropathic pain, the present study examined the analgesic activity and adverse effect profile of co-administered NS-9283 and ABT-594 in a variety of preclinical models in rats. The effect of the combined therapy on drug-induced brain activities was also determined using pharmacological magnetic resonance imaging. In carrageenan-induced thermal hyperalgesia, co-administration of NS-9283 (3.5 μmol/kg, i.p.) induced a 6-fold leftward shift of the dose–response of ABT-594 (ED 50 = 26 vs. 160 nmol/kg, i.p.). In the paw skin incision model of post-operative pain, co-administration of NS-9283 similarly induced a 6-fold leftward shift of ABT-594 (ED 50 = 26 vs. 153 nmol/kg). In monoiodo-acetate induced knee joint pain, co-administration of NS-9283 enhanced the potency of ABT-594 by 5-fold (ED 50 = 1.0 vs. 4.6 nmol/kg). In pharmacological MRI, co-administration of NS-9283 was shown to lead to a leftward shift of ABT-594 dose–response for cortical activation. ABT-594 induced CNS-related adverse effects were not exacerbated in presence of an efficacious dose of NS-9283 (3.5 μmol/kg). Acute challenge of NS-9283 produced no cross sensitization in nicotine-conditioned animals. These results demonstrate that selective positive allosteric modulation at the α4β2 nAChR potentiates nAChR agonist-induced analgesic activity across neuropathic and nociceptive preclinical pain models without potentiating ABT-594-mediated adverse effects, suggesting that selective positive modulation of α4β2 nAChR by PAM may represent a novel analgesic approach.

The histamine H(4) receptor (H(4)R) is expressed primarily on cells involved in inflammation and immune responses. To determine the potential role of H(4)R in pain transmission, the effects of JNJ7777120, a potent and selective H(4) antagonist, were characterized in preclinical pain models. Administration of JNJ7777120 fully blocked neutrophil influx observed in a mouse zymosan-induced peritonitis model (ED(50)=17 mg/kg s.c., 95% CI=8.5-26) in a mast cell-dependent manner. JNJ7777120 potently reversed thermal hyperalgesia observed following intraplantar carrageenan injection of acute inflammatory pain (ED(50)=22 mg/kg i.p., 95% CI=10-35) in rats and significantly decreased the myeloperoxide activity in the carrageenan-injected paw. In contrast, no effects were produced by either H(1)R antagonist diphenhydramine, H(2)R antagonists ranitidine, or H(3)R antagonist ABT-239. JNJ7777120 also exhibited robust anti-nociceptive activity in persistent inflammatory (CFA) pain with an ED(50) of 29 mg/kg i.p. (95% CI=19-40) and effectively reversed monoiodoacetate (MIA)-induced osteoarthritic joint pain. This compound also produced dose-dependent anti-allodynic effects in the spinal nerve ligation (ED(50)=60 mg/kg) and sciatic nerve constriction injury (ED(50)=88 mg/kg) models of chronic neuropathic pain, as well as in a skin-incision model of acute post-operative pain (ED(50)=68 mg/kg). In addition, the analgesic effects of JNJ7777120 were maintained following repeated administration and were evident at the doses that did not cause neurologic deficits in rotarod test. Our results demonstrate that selective blockade of H(4) receptors in vivo produces significant anti-nociception in animal models of inflammatory and neuropathic pain.

Activation of metabotropic glutamate (mGlu) receptors has previously been shown to play a role in inflammatory or neuropathic pain states. However, the role of mGlu type 1 receptors in post-operative pain remains to be investigated. In the present study, effects of potent and selective mGlu 1 receptor antagonists A-841720, A-794282, A-794278, and A-850002 were evaluated in a skin incision-induced post-operative pain model in rats. Post-operative pain was examined 2 h following surgery using weight-bearing difference between injured and uninjured paws as a measure of spontaneous pain. In this model, A-841720, A-794282, A-794278, and A-850002 induced significant attenuation of spontaneous post-operative pain behavior, with ED 50s of 10, 50, 50, and 65 μmol/kg i.p., respectively. Depending on the compound, significant motor side effects were also observed at 3 to 10 fold higher doses. These results support the notion that mGlu 1 receptor activation plays a significant role in nociceptive transmission in post-operative pain, though motor impairment may be a limiting factor in developing mGlu 1 receptor antagonists as novel analgesics.

We have discovered a novel, potent, and selective triazafluorenone series of metabotropic glutamate receptor 1 (mGluR1) antagonists with efficacy in various rat pain models. Pharmacokinetic and pharmacodynamic profiles of these triazafluorenone analogs revealed that brain/plasma ratios of these mGluR1 antagonists were important to achieve efficacy in neuropathic pain models. This correlation could be used to guide our in vivo SAR (structure–activity relationship) modification. For example, compound 4a has a brain/plasma ratio of 0.34, demonstrating only moderate efficacy in neuropathic pain models. On the other hand, antagonist 4b with a brain/plasma ratio of 2.70 was fully efficacious in neuropathic pain models.

Antisense (AS) oligodeoxynucleotides (ODNs) targeting the Nav 1.8 sodium channel have been reported to decrease inflammatory hyperalgesia and L5/L6 spinal nerve ligation-induced mechanical allodynia in rats. The present studies were conducted to further characterize Nav 1.8 AS antinociceptive profile in rats to better understand the role of Nav 1.8 in different pain states. Consistent with earlier reports, chronic intrathecal Nav 1.8 AS, but not mismatch (MM), ODN decreased TTX-resistant sodium current density (by 60.5+/-10.2% relative to MM; p

A series of α-amino acids were identified as ligands which compete with gabapentin for binding to the α 2 δ subunit of voltage-dependent Ca 2+ channels. Potent analogs were identified. Their activity in an in vivo pain assay is described.

Acid Sensing Ion Channels (ASICs) are a group of sodium-selective ion channels that are activated by low extracellular pH. The role of ASIC in disease states remains unclear partly due to the lack of selective pharmacological agents. In this report, we describe the effects of A-317567, a novel non-amiloride blocker, on three distinct types of native ASIC currents evoked in acutely dissociated adult rat dorsal root ganglion (DRG) neurons. A-317567 produced concentration-dependent inhibition of all pH 4.5-evoked ASIC currents with an IC50 ranging between 2 and 30muM, depending upon the type of ASIC current activated. Unlike amiloride, A-317567 equipotently blocked the sustained phase of ASIC3-like current, a biphasic current akin to cloned ASIC3, which is predominant in DRG. When evaluated in the rat Complete Freud's Adjuvant (CFA)-induced inflammatory thermal hyperalgesia model, A-317567 was fully efficacious at a dose 10-fold lower than amiloride. A-317567 was also potent and fully efficacious when tested in the skin incision model of post-operative pain. A-317567 was entirely devoid of any diuresis or natriuresis activity and showed minimal brain penetration. In summary, A-317567 is the first reported small molecule non-amiloride blocker of ASIC that is peripherally active and is more potent than amiloride in vitro and in vivo pain models. The discovery of A-317567 will greatly help to enhance our understanding of the physiological and pathophysiological role of ASICs.

The synthesis and characterization of a series of selective, orally bioavailable 1-(chroman-4-yl)urea TRPV1 antagonists is described. Whereas first-generation antagonists that inhibit all modes of TRPV1 activation can elicit hyperthermia, the compounds disclosed herein do not elevate core body temperature in preclinical models and only partially block acid activation of TRPV1. Advancing the SAR of this series led to the eventual identification of (R)-1-(7-chloro-2,2-bis(fluoromethyl)chroman-4-yl)-3-(3-methylisoquinolin-5-yl)urea (A-1165442, 52), an analogue that possesses excellent pharmacological selectivity, has a favorable pharmacokinetic profile, and demonstrates good efficacy against osteoarthritis pain in rodents.

The earliest stages of osteoarthritis are characterized by peripheral pathology; however, during disease progression chronic pain emerges-a major symptom of osteoarthritis linked to neuroplasticity. Recent clinical imaging studies involving chronic pain patients, including osteoarthritis patients, have demonstrated that functional properties of the brain are altered, and these functional changes are correlated with subjective behavioral pain measures. Currently, preclinical osteoarthritis studies have not assessed if functional properties of supraspinal pain circuitry are altered, and if these functional properties can be modulated by pharmacological therapy either by direct or indirect action on brain systems. In the current study, functional connectivity was first assessed in order to characterize the functional neuroplasticity occurring in the rodent medial meniscus tear (MMT) model of osteoarthritis-a surgical model of osteoarthritis possessing peripheral joint trauma and a hypersensitive pain state. In addition to knee joint trauma at week 3 post-MMT surgery, we observed that supraspinal networks have increased functional connectivity relative to sham animals. Importantly, we observed that early and sustained treatment with a novel, peripherally acting broad-spectrum matrix metalloproteinase (MMP) inhibitor (MMPi) significantly attenuates knee joint trauma (cartilage degradation) as well as supraspinal functional connectivity increases in MMT animals. At week 5 post-MMT surgery, the acute pharmacodynamic effects of celecoxib (selective cyclooxygenase-2 inhibitor) on brain function were evaluated using pharmacological magnetic resonance imaging (phMRI) and functional connectivity analysis. Celecoxib was chosen as a comparator, given its clinical efficacy for alleviating pain in osteoarthritis patients and its peripheral and central pharmacological action. Relative to the vehicle condition, acute celecoxib treatment in MMT animals yielded decreased phMRI infusion responses and decreased functional connectivity, the latter observation being similar to what was detected following chronic MMPi treatment. These findings demonstrate that an assessment of brain function may provide an objective means by which to further evaluate the pathology of an osteoarthritis state as well as measure the pharmacodynamic effects of therapies with peripheral or peripheral and central pharmacological action.

During the last two decades, functional neuroimaging technology, especially functional magnetic resonance imaging (fMRI), has improved tremendously, with new attention towards resting-state functional connectivity of the brain. This development has allowed scientists to study changes in brain structure and function, and probe these two properties under conditions of evoked stimulation, disease and drug administration. In the domain of functional imaging, the identification and characterization of central nervous system (CNS) functional networks have emerged as potential biomarkers for CNS disorders in humans. Recent attempts to translate clinical neuroimaging methodology to preclinical studies have also been carried out, which offer new opportunities in translational neuroscience research. In this paper, we review recent developments in structural and functional MRI and their use to probe functional connectivity in various CNS disorders such as schizophrenia, mood disorders, Alzheimer's disease (AD) and pain.

Despite the increasing interest in TRPA1 channel as a pain target, its role in cold sensation and body temperature regulation is not clear; the efficacy and particularly side effects resulting from channel blockade remain poorly understood. Here we use a potent, selective, and bioavailable antagonist to address these issues. A-967079 potently blocks human (IC(50): 51 nmol/L, electrophysiology, 67 nmol/L, Ca(2+) assay) and rat TRPA1 (IC(50): 101 nmol/L, electrophysiology, 289 nmol/L, Ca(2+) assay). It is >1000-fold selective over other TRP channels, and is >150-fold selective over 75 other ion channels, enzymes, and G-protein-coupled receptors. Oral dosing of A-967079 produces robust drug exposure in rodents, and exhibits analgesic efficacy in allyl isothiocyanate-induced nocifensive response and osteoarthritic pain in rats (ED(50): 23.2 mg/kg, p.o.). A-967079 attenuates cold allodynia produced by nerve injury but does not alter noxious cold sensation in naive animals, suggesting distinct roles of TRPA1 in physiological and pathological states. Unlike TRPV1 antagonists, A-967079 does not alter body temperature. It also does not produce locomotor or cardiovascular side effects. Collectively, these data provide novel insights into TRPA1 function and suggest that the selective TRPA1 blockade may present a viable strategy for alleviating pain without untoward side effects.

The TRPV1 antagonist A-995662 demonstrates analgesic efficacy in monoiodoacetate-induced osteoarthritic (OA) pain in rat, and repeated dosing results in increased in vivo potency and a prolonged duration of action. To identify possible mechanism(s) underlying these observations, release of neuropeptides and the neurotransmitter glutamate from isolated spinal cord was measured. In OA rats, basal release of glutamate, bradykinin and calcitonin gene-related peptide (CGRP) was significantly elevated compared to naive levels, whereas substance P (SP) levels were not changed. In vitro studies showed that capsaicin-evoked TRPV1-dependent CGRP release was 54.7+/-7.7% higher in OA, relative to levels measured for naive rats, suggesting that TRPV1 activity was higher under OA conditions. The efficacy of A-995662 in OA corresponded with its ability to inhibit glutamate and CGRP release from the spinal cord. A single, fully efficacious dose of A-995662, 100 micromol/kg, reduced spinal glutamate and CGRP release, while a single sub-efficacious dose of A-995662 (25 micromol/kg) was ineffective. Multiple dosing with A-995662 increased the potency and duration of efficacy in OA rats. Changes in efficacy did not correlate with plasma concentrations of A-995662, but were accompanied with reductions in spinal glutamate release. These findings suggest that repeated dosing of TRPV1 antagonists enhances therapeutic potency and duration of action against OA pain, at least in part, by the sustained reduction in release of glutamate and CGRP from the spinal cord.

Most animal models of pain cannot separate the sensory and affective components of pain. One model that has been used to assess affective pain is the place escape avoidance paradigm (PEAP). The aim of the current study is two-fold. First, validate PEAP with Complete Freund's Adjuvant (CFA)-induced inflammation for the assessment of the affective component of pain using the reference analgesics celecoxib, diclofenac and duloxetine; fluoxetine and scopolamine were tested as negative controls. Secondly, determine if there is a difference in efficacy in PEAP in comparison to the effects of the same compounds on von Frey-evoked mechanical allodynia in CFA animals. All compounds were tested in mechanical allodynia, place escape/avoidance, and for potentially confounding side effects in locomotor activity. Results show that celecoxib, diclofenac, and duloxetine significantly increased the time spent on the side associated with stimulation of the injured paw, whereas fluoxetine and scopolamine had no effect. Higher doses of celecoxib, diclofenac, duloxetine, and fluoxetine were required to attenuate von Frey-evoked mechanical allodynia. In the side effect assays, only fluoxetine decreased locomotor activity at doses used in PEAP. These results show that in inflammatory pain induced by CFA injection, PEAP is more sensitive to the effects of pain relieving compounds than mechanical allodynia. Fluoxetine showed efficacy in the mechanical allodynia test, but not PEAP, whereas duloxetine showed efficacy in mechanical allodynia and PEAP. These studies show that methods other than reflex based measures of pain such as affective pain models could be more predictive of efficacy/potency in the clinic.

The pituitary adenylate cyclase-activating polypeptide type 1 receptor (PAC(1)-R) is a member of the 7-transmembrane domain, group 2 G-protein coupled receptor family. PAC(1)-Rs modulate neurotransmission and neurotrophic actions and have been implicated in both pronociception and antinociception. To better understand the role of PAC(1)-Rs in pain, PACAP 6-38, a PAC(1)-R antagonist, was evaluated in several inflammatory and neuropathic pain models after intrathecal (i.t.) administration. PACAP 6-38 potently reduced mechanical allodynia in a neuropathic spinal nerve ligation model (77% +/- 15% maximal effect at 12 nmol, P.01) and was also effective in reducing thermal hyperalgesia in the carrageenan model of inflammatory pain (89% +/- 17% maximal effect at 12 nmol, P.01). Although nociceptive responses were also attenuated with PACAP 6-38 in a dose-dependent manner in models of chronic inflammatory and persistent pain, no effects on motor performance were observed at analgesic doses. Taken together, these data demonstrate that blockade of the PAC(1)-R/PACAP complex by PACAP 6-38 can effectively attenuate thermal hyperalgesia and mechanical allodynia associated with inflammatory and neuropathic pain states. These results further emphasize that at the level of the spinal cord, PAC(1)-R activation is pronociceptive.This article presents the analgesic profile generated by the blockade, at the spinal cord level, of the PAC-1 receptor by a potent peptide antagonist. This comprehensive data set demonstrates that if small molecule PAC-1 receptor antagonists could be identified, they would potentially produce broad-spectrum analgesia in both inflammatory and neuropathic pain states.

Three adult females of various ages and one juvenile are represented in the osteological material recovered from site 25HN118. No absolute dates were calculated for this site. Mortuary practices inferred for site 25HN118 are compared to those of the Valley and Keith focus of the Plains Woodland tradition. Differences in the amount of grave offerings and the frequencies of certain bone elements are an important indicator of cultural affiliation. The remains of an individual male were recovered from site 25HN174. This site has been radiocarbon dated at 1600 - or + 110 years before present. (SDW)

Human skeletal remains recovered during the construction of the Blue Springs Lake Project were analyzed for sex, race, injury, and age determinations. Two females and a male, were studied. Radiocarbon dating of the materials placed the burials at approximately 3500 B.C. in the Middle to Late Archaic period. (fr)