Matched Filter Cyclone Maximum Wind Retrievals Using CYGNSS: Progress Update and Error Analysis.

This article describes progress relating to a previously reported matched filter retrieval approach for the estimation of hurricane maximum winds using delay Doppler map (DDM) measurements of the Cyclone Global Navigation Satellite System (CYGNSS) mission. The retrievals presented are based on comparisons of these measured DDMs, and their simulated counterparts as a set of storm parameters are varied. The analysis presented examines the dependencies of retrieval performance on the synthetic storm model used as part of the forward modeling process using a set of CYGNSS storm-observing full DDM downlinks containing 68 tracks and spanning 18 storms over the period 2017-2020. Based on the combined use of multiple parametric storm models, retrieved hurricane maximum wind speed estimates showed correlations of 92%, root-mean-square error (RMSE) of 6.05 m/s, unbiased RMSE of 6.05 m/s, mean difference of 4.83 m/s, and a bias of 0.09 m/s relative to reference data. Mean retrieval error relative to storm maximum wind is 11.11%. The dependence of retrieval error on measurement maximum delay extent is also analyzed using CYGNSS Raw I/F downlinks, from which a significant near-monotonic decrease in retrieval errors is observed as the delay extent of the measurement is increased. The analysis presented in this work highlights the potential for using matched filter retrieval methodologies for cyclone wind speed estimation in spaceborne Global Navigation Satellite Systems Reflectometry systems.

A medium throughput rodent model of relapse from addiction with behavioral and pharmacological specificity.

One of most formidable problems in the treatment of addiction is the high rate of relapse. The discovery of medicines to help mitigate relapse are aided by animal models that currently involve weeks of training and require surgical preparations and drug delivery devices. The present set of experiments was initiated to investigate a rapid 8-day screening method that utilizes food instead of intravenous drug administration. Male Sprague-Dawley rats were trained in a reinstatement paradigm in which every lever press produced a 45 mg food pellet concurrently paired with a light and tone. Behavior was subsequently extinguished with lever responses producing neither food nor food-associated stimuli. Reinstatement of responding was evaluated under conditions in which the first three responses of every 5 min time bin produced a food pellet along with food-associated stimuli. The mGlu5 receptor antagonists MPEP and MTEP produced a significant reduction in reinstatement while failing to alter responding where every response produced food. The cannabinoid CB1 receptor antagonist rimonabant and the mGlu2/3 receptor agonist LY379268 also selectively reduced reinstatement. Other compounds including clozapine, d-amphetamine, chlordiazepoxide, ABT-431, naltrexone and citalopram were without effect. The results suggest that relapse-like behavioral effects can be extended to non-pharmacological reinforcers. Drug effects demonstrated both behavioral and pharmacological specificity. The present experimental design thus allows for efficient and rapid assessment of the effects of drugs that might be useful in the treatment of addiction-associated relapse.

Microporous polysaccharide hemosphere efficacy and safety in primary total knee arthroplasty.

Absorbable hemostats such as microporous polysaccharide hemospheres (MPH) are used to manage hemostasis and prevent complications in total knee arthroplasty (TKA). We aimed to determine safety and effectiveness of MPH use in TKA. Records were reviewed for blood loss, hematomas, and infections. No differences existed regarding demographics, superficial infections (P = 0.933) or hematomas (P = 0.393). Positive correlation existed between hematoma and superficial infection (P = 0.009). Blood loss was greater in the treatment group (P = 0.014). MPH demonstrated inferior bleeding control and had no effect on complications. Our results suggest application of this agent may be unnecessary.

Effects of 5-HT7 receptor antagonists on behaviors of mice that detect drugs used in the treatment of anxiety, depression, or schizophrenia.

5-HT7 receptors have been suggested to play a role in the regulation of psychiatric disorders. The experimental literature however is not fully consistent on this possibility. Two selective 5-HT7 receptor antagonists, DR-4004 and SB-269970, were evaluated in mouse models used to detect drugs used to treat anxiety, depression, or schizophrenia. A 5-HT-induced hypothermia assay was used to define the doses of DR-4004 and SB-269970 predicted to impact 5-HT7 receptors in the brain in vivo. 5-HT produced hypothermia in wildtype mice by either i.p. or i.c.v. routes but did not in 5-HT7 receptor knockout mice. 5-HT-induced hypothermia was not attenuated by drugs selectively blocking alpha1 or 5-HT1A receptors. Doses of DR-4004 and SB-269970 that blocked 5-HT-induced hypothermia, did not display significant anxiolytic-like (elevated plus maze; vogel conflict) or antidepressant-like efficacy (tail-suspension test) in mouse models. These compounds did demonstrate some antipsychotic-like properties in the PCP-induced hyperactivity assay and anxiolytic/anti-stress effects in the stress-induced cGMP assay. Negative findings were substantiated by positive control drugs that were active in each assay system. We conclude that 5-HT-induced hypothermia can be used to estimate blockade of central 5-HT7 receptors. Effects of DR-4004 and SB-269970 in animal models are generally consistent with the experimental literature that the evidence is mixed or not robust regarding the potential efficacy of 5-HT7 receptor antagonism in the treatment of anxiety, depression, or schizophrenia.

Evaluation of 5-HT7 receptor antagonism for the treatment of anxiety, depression, and schizophrenia through the use of receptor-deficient mice.

The 5-HT7 receptor is the most recently identified receptor subtype within a family of 5-HT receptors activated by the neurotransmitter serotonin. There has been significant interest in investigating the potential role of this receptor in psychiatric disorders including depression, anxiety, and schizophrenia. Behaviors of 5-HT7 +/+ (wild-type or WT) and 5-HT7 -/- (receptor knockout or KO) mice were compared across 10 different assays (7 for anxiety, 1 for depression, 2 for psychosis) to identify differences that could indicate clinical potential for 5-HT7 receptor antagonism. Evaluation of KO vs. WT mice demonstrated significant differences between the genotypes in the fear conditioning, shock-probe burying, novelty-suppressed feeding, punishment memory, forced swim test, and d-amphetamine hyperactivity assays. There was not consistency in either the direction of behavioral effects across genotypes or across assays. Thus, data from these behavioral assays did not uniformly support the idea that 5-HT7 receptors constitute an important drug target for these psychiatric disorders. The present findings are generally congruent with the mixed results in the literature on the behaviors of 5-HT7 -/-mice and with the data on effects of 5-HT7 receptor antagonists in rodent models that detect activity of anxiolytic, antidepressant, and antipsychotic effects.

Pharmacological characterization of the neurotrophic sesquiterpene jiadifenolide reveals a non-convulsant signature and potential for progression in neurodegenerative disease studies.

The 'neurotrophic sesquiterpenes' refer to a group of molecules derived from the Illicium genus of flowering plant. They display neurotrophic effects in cultured neuron preparations and have been suggested to be cognitive enhancers and potential therapeutics for neurodegenerative disorders and dementias. Recent synthetic advances generated sufficient quantities of jiadifenolide for in vivo investigation into its biological effects. Jiadifenolide did not induce convulsions in mice nor did it enhance or diminish convulsions induced by pentylenetetrazole. Other negative allosteric modulators of GABAA receptors, picrotoxin, tetramethylenedisulfotetramine (TETS), and bilobalide all induced convulsions. Either i.p. or i.c.v. dosing generated micromolar plasma and brain levels of jiadifenolide but only small effects on locomotion of mice. However, jiadifenolide decreased d-amphetamine-induced hyperlocomotion in mice, an antipsychotic-like drug effect. Jiadifenolide did not significantly alter body temperature or behavior in the forced-swim test in mice. Molecular simulation data suggested a potential site in the pore/M2 helix region that is at an overlapping, yet lower position than those observed for other 'cage convulsant' compounds such as TETS and picrotoxin. We hypothesize that a position nearer to the entrance of the pore channel may allow for easier displacement of jiadifenolide from its blocking location leading to lower potency and lower side-effect liability. Like jiadifenolide, memantine (Namenda), one of the few drugs used in the symptomatic treatment of dementias, occupies a unique site on the NMDA receptor complex that creates low binding affinity that is associated with its reduced side-effect profile. Given the potential therapeutic applications of jiadifenolide and its relatively inert effects on overt behavior, the possibility of clinical utility for jiadifenolide and related compounds becomes intriguing.

Vessel scaling in evergreen angiosperm leaves conforms with Murray's law and area-filling assumptions: implications for plant size, leaf size and cold tolerance.

Water transport in leaf vasculature is a fundamental process affecting plant growth, ecological interactions and ecosystem productivity, yet the architecture of leaf vascular networks is poorly understood. Although Murray's law and the West-Brown-Enquist (WBE) theories predict convergent scaling of conduit width and number, it is not known how conduit scaling is affected by habitat aridity or temperature. We measured the scaling of leaf size, conduit width and conduit number within the leaves of 36 evergreen Angiosperms spanning a large range in aridity and temperature in eastern Australia. Scaling of conduit width and number in midribs and 2° veins did not differ across species and habitats (P > 0.786), and did not differ from that predicted by Murray's law (P = 0.151). Leaf size was strongly correlated with the hydraulic radius of petiole conduits (r2  = 0.83, P < 0.001) and did not differ among habitats (P > 0.064), nor did the scaling exponent differ significantly from that predicted by hydraulic theory (P = 0.086). The maximum radius of conduits in petioles was positively correlated with the temperature of the coldest quarter (r2  = 0.67; P < 0.001), suggesting that habitat temperature restricts the occurrence of wide-conduit species in cold habitats.

Chronic pain impairs cognitive flexibility and engages novel learning strategies in rats.

Cognitive flexibility, the ability to adapt behavior to changing outcomes, is critical to survival. The prefrontal cortex is a key site of cognitive control, and chronic pain is known to lead to significant morphological changes to this brain region. Nevertheless, the effects of chronic pain on cognitive flexibility and learning remain uncertain. We used an instrumental paradigm to assess adaptive learning in an experimental model of chronic pain induced by tight ligation of the spinal nerves L5/6 (spinal nerve ligation model). Naive, sham-operated, and spinal nerve ligation (SNL) rats were trained to perform fixed-ratio, variable-ratio, and contingency-shift behaviors for food reward. Although all groups learned an initial lever-reward contingency, learning was slower in SNL animals in a subsequent choice task that reversed reinforcement contingencies. Temporal analysis of lever-press responses across sessions indicated no apparent deficits in memory consolidation or retrieval. However, analysis of learning within sessions revealed that the lever presses of SNL animals occurred in bursts, followed by delays. Unexpectedly, the degree of bursting correlated positively with learning. Under a variable-ratio probabilistic task, SNL rats chose a less profitable behavioral strategy compared with naive and sham-operated animals. After extinction of behavior for learned preferences, SNL animals reverted to their initially preferred (ie, less profitable) behavioral choice. Our data suggest that in the face of uncertainty, chronic pain drives a preference for familiar associations, consistent with reduced cognitive flexibility. The observed burst-like responding may represent a novel learning strategy in animals with chronic pain.

Negative allosteric modulation of alpha 5-containing GABAA receptors engenders antidepressant-like effects and selectively prevents age-associated hyperactivity in tau-depositing mice.

RATIONALE: Associated with frank neuropathology, patients with Alzheimer's disease suffer from a host of neuropsychiatric symptoms that include depression, apathy, agitation, and aggression. Negative allosteric modulators (NAMs) of α5-containing GABAA receptors have been suggested to be a novel target for antidepressant action. We hypothesized that pharmacological modulation of this target would engender increased motivation in stressful environments. METHODS: We utilized electrophysiological recordings from Xenopus oocytes and behavioral measures in mice to address this hypothesis. RESULTS: In the forced-swim assay in mice that detects antidepressant drugs, the α5ß3γ2 GABAΑ receptor NAM, RY-080 produced a marked antidepressant phenotype. Another compound, PWZ-029, was characterized as an α5ß3γ2 receptor NAM of lower intrinsic efficacy in electrophysiological studies in Xenopus oocytes. In contrast to RY-080, PWZ-029 was only moderately active in the forced-swim assay and the α5ß3γ2 receptor antagonist, Xli-093, was not active at all. The effects of RY-080 were prevented by the non-selective benzodiazepine receptor antagonist flumazenil as well as by the selective ligands, PWZ-029 and Xli-093. These findings demonstrate that this effect of RY-080 is driven by negative allosteric modulation of α5ßγ2 GABAA receptors. RY-080 was not active in the tail-suspension test. We also demonstrated a reduction in the age-dependent hyperactivity exhibited by transgenic mice that accumulate pathological tau (rTg4510 mice) by RY-080. The decrease in hyperactivity by RY-080 was selective for the hyperactivity of the rTg4510 mice since the locomotion of control strains of mice were not significantly affected by RY-080. CONCLUSIONS: α5ßγ2 GABAA receptor NAMs might function as a pharmacological treatment for mood, amotivational syndromes, and psychomotor agitation in patients with Alzheimer's and other neurodegenerative disorders.

Efficacy of Intravenous Acetaminophen for Postoperative Analgesia in Primary Total Knee Arthroplasty.

BACKGROUND: The use of intravenous acetaminophen has seen recent enthusiasm as one component of a multimodal approach to pain management. However, there is a lack of literature examining the efficacy of intravenous acetaminophen for pain control in total joint arthroplasty. The purpose of this study was to evaluate the efficacy of intravenous acetaminophen following primary total knee arthroplasty. METHODS: This is a retrospective review of 38 patients undergoing primary total knee arthroplasty by a single surgeon at one institution. Twenty-five patients received 1 gram of intravenous acetaminophen every 6 hours for 24 hours postoperatively. Thirteen patients received no additional intervention. Exclusion criteria were bilateral or concomitant procedures, allergy to medications included in the standard postoperative protocol, neuropathy or sensory disturbances, history of opioid dependence or abuse, deviations from protocol, revision procedures, and incomplete data. Primary outcomes were change in patient-reported visual analog scale (VAS) pain score, overall opioid consumption measured in morphine milligram equivalents, and hospital length of stay. RESULTS: We found no difference in length of stay, at 3.3 days in the control group and 2.9 days in the intervention group. There was a significant difference in VAS score between 16 and 24 hours. There was a statistically significant decrease in overall opioid consumption in the intravenous acetaminophen group 37.6 vs 18.6 morphine milligram equivalents. CONCLUSION: Intravenous acetaminophen is effective in significantly reducing opioid requirements in the first 24 hours following primary total knee arthroplasty. Additionally, there is a clinically significant decrease in VAS pain scores in patients receiving this intervention.

Targeted Blockade of TARP-γ8-Associated AMPA Receptors: Anticonvulsant Activity with the Selective Antagonist LY3130481 (CERC-611).

BACKGROUND & OBJECTIVE: 6-[(1S)-1-[1-[5-(2-hydroxyethoxy)-2-pyridyl]pyrazol-3-yl]ethyl]- 3H-1,3-benzothiazol-2-one (LY3130481 or CERC-611) is a selective antagonist of AMPA receptors containing transmembrane AMPA receptor regulatory protein (TARP) γ-8 that is under development for epilepsy. The present study provided a broad inquiry into its anticonvulsant properties. LY3130481 was anticonvulsant in multiple acute seizure provocation models in mice and rats. In addition, LY3130481 was effective against absence seizures in the GAERS genetic model and in the Frings mouse model. Likewise, LY3130481 attenuated convulsions in mice and rats with long-term induction of seizures (e.g., corneal, pentylenetetrazole, hippocampal, and amygdala kindled seizures). In slices of epileptic human cortex, LY3130481 significantly decreased neuronal firing frequencies. LY3130481 displaced from rat brain a radioligand specific for AMPA receptors associated with TARP γ-8 whereas non-TARP-selective molecules did not. Binding was also observed in hippocampus freshly transected from a patient. RESULTS & CONCLUSION: Taken as a whole, the findings reported here establish the broad anticonvulsant efficacy of LY3130481 indicating that blockade of AMPA receptors associated with TARP γ-8 is sufficient for these protective effects.

Electroencephalographic, cognitive, and neurochemical effects of LY3130481 (CERC-611), a selective antagonist of TARP-γ8-associated AMPA receptors.

6-[(1S)-1-[1-[5-(2-hydroxyethoxy)-2-pyridyl]pyrazol-3-yl]ethyl]-3H-1,3-benzothiazol-2-one (LY3130481 or CERC-611) is a selective antagonist of AMPA receptors containing transmembrane AMPA receptor regulatory protein (TARP) γ-8. This molecule has been characterized as a potent and efficacious anticonvulsant in an array of acute and chronic epilepsy models in rodents. The present set of experiments was designed to assess the effects of LY3130481 on the electroencephelogram (EEG), cognitive function, and neurochemical outflow. LY3130481 disrupted food-maintained responding in rats and spontaneous alternation in a Y-maze in mice. In rat fear conditioning, LY3130481 caused a deficit in trace (hippocampal-dependent), but not in delay fear conditioning. Although these effects on cognitive performances were observed, the known cognitive-impairing anticonvulsant, topiramate, did not always produce deficits under these assay conditions. LY3130481 produced modest increases in wake times in rats. In addition, LY3130481 was able to attenuate some impairing effects of standard antiepileptic drugs. The motor-impairing effects of the lacosamide were attenuated by LY3130481 as was the decrease in non-rapid-eye movement sleep induced by carbamazepine. Evaluation of the effect of LY3130481 on neurotransmitter and metabolite efflux in the rat medial prefrontal cortex, using in vivo microdialysis, revealed significant increases in the pro-cognitive and wake-promoting neurotransmitters, histamine and acetylcholine, as well as in serotonin, telemethylhistamine, 5-HIAA, HVA and MHPG. LY3130481 thus presents a novel behavioral profile that will have to be evaluated in patients to fully appreciate its implications for therapeutics. LY3130481 is currently under clinical development as CERC-611 as an antiepileptic.

Forebrain-selective AMPA-receptor antagonism guided by TARP γ-8 as an antiepileptic mechanism.

Pharmacological manipulation of specific neural circuits to optimize therapeutic index is an unrealized goal in neurology and psychiatry. AMPA receptors are important for excitatory synaptic transmission, and their antagonists are antiepileptic. Although efficacious, AMPA-receptor antagonists, including perampanel (Fycompa), the only approved antagonist for epilepsy, induce dizziness and motor impairment. We hypothesized that blockade of forebrain AMPA receptors without blocking cerebellar AMPA receptors would be antiepileptic and devoid of motor impairment. Taking advantage of an AMPA receptor auxiliary protein, TARP γ-8, which is selectively expressed in the forebrain and modulates the pharmacological properties of AMPA receptors, we discovered that LY3130481 selectively antagonized recombinant and native AMPA receptors containing γ-8, but not γ-2 (cerebellum) or other TARP members. Two amino acid residues unique to γ-8 determined this selectivity. We also observed antagonism of AMPA receptors expressed in hippocampal, but not cerebellar, tissue from an patient with epilepsy. Corresponding to this selective activity, LY3130481 prevented multiple seizure types in rats and mice and without motor side effects. These findings demonstrate the first rationally discovered molecule targeting specific neural circuitries for therapeutic advantage.

Hedonic and motivational responses to food reward are unchanged in rats with neuropathic pain.

Rewards influence responses to acute painful stimuli, but the relationship of chronic pain to hedonic or motivational aspects of reward is not well understood. We independently evaluated hedonic qualities of sweet or bitter tastants and motivation to seek food reward in rats with experimental neuropathic pain induced by L5/6 spinal nerve ligation. Hedonic response was measured by implantation of intraoral catheters to allow passive delivery of liquid solutions, and "liking/disliking" responses were scored according to a facial reactivity scale. Spinal nerve ligation rats did not differ from controls in either "liking" or "disliking" reactions to intraoral sucrose or quinine, respectively, at postsurgery day 21, suggesting no differences in perceived hedonic value of sweet or bitter tastants. To assess possible motivational deficits during acute and chronic pain, we used fixed- and progressive-ratio response paradigms of sucrose pellet presentation in rats with transient inflammatory or chronic neuropathic pain. Assessment of response acquisition and break points under the progressive ratio schedule revealed no differences between sham and spinal nerve ligation rats for up to 120 days after injury. However, rats with inflammation showed decrements in lever pressing and break points on days 1 and 2 after complete Freund adjuvant injection that normalized by day 4, consistent with transient ongoing pain. Thus, although acute ongoing inflammatory pain may transiently reduce reward motivation, we did not detect influences of chronic neuropathic pain on hedonic or motivational responses to food rewards. Adaptations that allow normal reward responding to food regardless of chronic pain may be of evolutionary benefit to promote survival.

Discovery of the First α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptor Antagonist Dependent upon Transmembrane AMPA Receptor Regulatory Protein (TARP) γ-8.

Transmembrane AMPA receptor regulatory proteins (TARPs) are a family of scaffolding proteins that regulate AMPA receptor trafficking and function. TARP γ-8 is one member of this family and is highly expressed within the hippocampus relative to the cerebellum. A selective TARP γ-8-dependent AMPA receptor antagonist (TDAA) is an innovative approach to modulate AMPA receptors in specific brain regions to potentially increase the therapeutic index relative to known non-TARP-dependent AMPA antagonists. We describe here, for the first time, the discovery of a noncompetitive AMPA receptor antagonist that is dependent on the presence of TARP γ-8. Three major iteration cycles were employed to improve upon potency, CYP1A2-dependent challenges, and in vivo clearance. An optimized molecule, compound (-)-25 (LY3130481), was fully protective against pentylenetetrazole-induced convulsions in rats without the motor impairment associated with non-TARP-dependent AMPA receptor antagonists. Compound (-)-25 could be utilized to provide proof of concept for antiepileptic efficacy with reduced motor side effects in patients.

Preclinical findings predicting efficacy and side-effect profile of LY2940094, an antagonist of nociceptin receptors.

Nociceptin/Orphanin FQ (N/OFQ) is a 17 amino acid peptide whose receptor is designated ORL1 or nociceptin receptor (NOP). We utilized a potent, selective, and orally bioavailable antagonist with documented engagement with NOP receptors in vivo to assess antidepressant- and anxiolytic-related pharmacological effects of NOP receptor blockade along with measures of cognitive and motor impingement. LY2940094 ([2-[4-[(2-chloro-4,4-difluoro-spiro[5H-thieno[2,3-c]pyran-7,4'-piperidine]-1'-yl)methyl]-3-methyl-pyrazol-1-yl]-3-pyridyl]methanol) displayed antidepressant-like behavioral effects in the forced-swim test in mice, an effect absent in NOP -/- mice. LY2940094 also augmented the behavioral effect of fluoxetine without changing target occupancies (NOP and serotonin reuptake transporter [SERT]). LY2940094 did not have effects under a differential-reinforcement of low rate schedule. Although anxiolytic-like effects were not observed in some animal models (conditioned suppression, 4-plate test, novelty-suppressed feeding), LY2940094 had effects like that of anxiolytic drugs in three assays: fear-conditioned freezing in mice, stress-induced increases in cerebellar cGMP in mice, and stress-induced hyperthermia in rats. These are the first reports of anxiolytic-like activity with a systemically viable NOP receptor antagonist. LY2940094 did not disrupt performance in either a 5-choice serial reaction time or delayed matching-to-position assay. LY2940094 was also not an activator or suppressor of locomotion in rodents nor did it induce failures of rotarod performance. These data suggest that LY2940094 has unique antidepressant- and anxiolytic-related pharmacological effects in rodents. Clinical proof of concept data on this molecule in depressed patients have been reported elsewhere.

Inquiries into the Biological Significance of Transmembrane AMPA Receptor Regulatory Protein (TARP) γ-8 Through Investigations of TARP γ-8 Null Mice§.

Transmembrane AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor regulatory protein (TARP) γ-8 is an auxiliary protein associated with some AMPA receptors. Most strikingly, AMPA receptors associated with this TARP have a relatively high localization in the hippocampus. TARP γ-8 also modifies the pharmacology and trafficking of AMPA receptors. However, to date there is little understanding of the biological significance of this auxiliary protein. In the present set of studies we provide a characterization of the differential pharmacology and behavioral consequences of deletion of TARP γ-8 by comparing the wild type (WT) and γ-8 -/- (knock-out, KO) mouse. KO mice were mildly hyperactive in a locomotor arena but not in other environments compared to WT mice. Additionally, the KO mice demonstrated enhanced locomotor stimulatory effects of both d-amphetamine and phencyclidine. Marble-burying and digging behaviors were dramatically reduced in KO mice. In another assay that can detect anxiety-like phenotypes, the elevated plus maze, no differences were observed in overall movement or open arm entries. In the forced-swim assay, KO mice displayed decreases in immobility time like the antidepressant imipramine and the AMPA receptor potentiator, LY392098. In KO mice, the antidepressant-like effects of LY392098 were prevented whereas the effects of imipramine were unaffected. Convulsions were induced by pentylenetetrazole, N-methyl-D-aspartate, and by kainic acid. However, in KO mice, kainic acid produced less tonic convulsions and lethality. KO mice had reduced levels of norepinephrine in hippocampus and cerebellum but not in hypothalamus or prefrontal cortex, decreased levels of cAMP in hippocampus, and increased levels of acetylcholine in the hypothalamus and prefrontal cortex. KO mice displayed decreased turnover of dopamine and increased histamine turnover in multiple brain areas In contrast, serotonin and its metabolites were not significantly affected by deletion of the γ-8 protein. Of a large panel of plasma lipids, only two monoacylglycerols (1OG and 2OG) were marginally but nonsignificantly altered in WT vs KO mice. Overall, the data suggest genetic inactivation of this specific population of AMPA receptors results in modest changes in behavior characterized by a mild hyperactivity which is condition dependent and a marked reduction in digging and burying behaviors. Despite deletion of TARP γ-8, chemoconvulsants were still active. Consistent with their predicted pharmacological actions, the convulsant effects of kainate and the antidepressant-like effects of an AMPA receptor potentiator (both acting upon AMPA receptors) were reduced or absent in KO mice.

Further evaluation of the neuropharmacological determinants of the antidepressant-like effects of curcumin.

Curcumin, the major constituent of the spice tumeric produces a plethora of biological actions that have translated in vivo into behavioral and neurochemical effects in rodents that are also produced by clinically-used antidepressants. The present study was designed to provide a systematic replication of prior behavioral, pharmacological, and neurochemical experiments. In particular, the ability of curcumin to engender anti-immobility effects in the mouse forced-swim assay was established. Although prior work had shown curcumin to function as an inhibitor of the monoamine metabolizing enzyme, monoamine oxidase (MAO), neither MAOA nor MAOB was inhibitied by curcumin in the present study. Curcumin had also been reported previously to function as a cannabinoid CB1 receptor inverse agonist/antagonist. However, in our hands, curcumin did not potently alter GTP-γ.-35S binding indicative of functional CB1 antagonism (Kb = 2080 nM). Moreover, curcumin was not able to prevent the hypothermic effects of the cannabinoid receptor agonist (-)-cis-3-[2-Hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol (CP 55,940). Nonetheless, the anti-immobility effects of curcumin did not occur in CB1 -/- mice. Finally, a broad array of protein receptors and enzymes were evaluated in vitro for their potential interaction with and/or functional engagement with curcumin. Of the more than 100 targets screened, curcumin had very low potency in most. Of those targets with appreciable activity, curcumin had affinities for the human cloned muscarinic receptor subtypes (Ki = 1.3-3.1 uM). Moreover, the plasma and brain levels of curcumin at behaviorally-active doses were below quantitative limits. Given these findings, it is concluded that the prominent antidepressant-like behavioral effects of curcumin, replicated here and in multiple acute and chronic rodent models detailed in the literature, are the result of as yet undisclosed mechanisms of action. The scientific and patient communities await the full scale clinical evaluation of a sufficiently bioavailable curcumin analog in major depressive disorder.

Multiple dopamine receptors mediate the discriminative stimulus effects of dihydrexidine in rats.

The dopamine D(1) receptor agonist dihydrexidine (DHX) [(±)-trans-10,11-dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a] phenanthridine hydrochloride] has shown efficacy in animal models of Parkinson's disease and improved cerebral blood flow and working memory of schizophrenic patients. Although the discriminative stimulus effects of DHX, an in-vivo predictor of human subjective effect profile, have only been characterized with respect to activity at D(1) receptors, DHX also has significant affinity for D(2) receptors. This study was designed to characterize the role of D(1) and D(2)/D(3) receptors in mediating the discriminative stimulus effects of DHX. Rats were trained to discriminate DHX [3 mg/kg, intraperitoneally (i.p.)] from the vehicle. The selective dopamine D(1) receptor partial agonist SKF 38393 was fully substituted for DHX. The D(1) receptor antagonist SCH 23390 (0.1 mg/kg, s.c.) and the D(3)-selective antagonist U99194 (10 mg/kg, i.p.) significantly attenuated the discriminative stimulus effects of the training dose of DHX by 80 and 60%, respectively, suggesting that both D(1) and D(3) receptors mediate the discriminative stimulus effects of DHX. In contrast, raclopride (1 mg/kg, i.p.) did not significantly alter the discriminative stimulus effects of DHX, indicating a lack of D(2)-mediated effects. The D(2)/D(3) receptor preferring agonists, quinpirole and (+)-PD 128907 were fully substituted, whereas (+)-7-OH-DPAT was partially substituted for DHX. The DHX bound to D(2) receptors with a Ki of 4.3+0.7 nmol/l was compared with 33.7+4.6 nmol/l at D(3) receptors. Determinations of activity at second messenger systems revealed that DHX functioned as a full agonist at D(3) receptors and a partial agonist at D(2) receptors in vitro. These activities at D(2)/D(3) receptors have shown effects in some preclinical models and clinical disease states. Therefore, the prominent in-vivo agonist activity of DHX at both D(1) receptors and D(2)/D(3) receptors should be considered while making predictions of effects in humans.

A parametric analysis of punishment frequency as a determinant of the response to chlordiazepoxide in the Vogel conflict test in rats.

The Vogel conflict test has been widely used as a methodology for detecting anxiolytic-like effects of drugs with a broad spectrum of pharmacological activities. Despite widespread acceptance of the Vogel assay as a preclinical predictor of efficacy for anxiolytic-like compounds, detailed parametrics have not been reported on the optimization of this assay to determine how the schedule of reinforcement, the rate of responding and the frequency and temporal distribution of punishing events determine drug effect. The current report documents results of a systematic study of the relationship between number of shocks delivered and efficacy of the prototypical 1,4-benzodiazepine anxiolytic chlordiazepoxide (CDAP) in rats. Under this procedure, water-deprived rats were given access to water and during the later part of this access period, contacts with the drinking tube produced a brief electric shock. CDAP (5-20 mg/kg, i.p.) was first tested under a fixed-ratio 20 response schedule (every 20 th lick produced shock delivered via the sipper tube). CDAP produced dose-dependent increases in punished licking to approximately 275% of control at 20 mg/kg. Increasing the number of shocks during the first ten responses of the punishment component decreased the number of licks made under vehicle control conditions. The frequency of shock delivery produced both quantitative and qualitative changes in the effects of chlordiazepoxide ranging from no effect to 7000% increases in responding. The effects of chlordiazepoxide were dependent both on the control rate of responding and, independently, on the frequency of shock deliveries. Parametric variation under the Vogel conflict test may be useful in comparing the efficacy of novel approaches to the treatment of anxiety disorders.