A method to measure cutaneous hyperalgesia to thermal stimulation in unrestrained animals is described. The testing paradigm uses an automated detection of the behavioral end-point; repeated testing does not contribute to the development of the observed hyperalgesia. Carrageenan-induced inflammation resulted in significantly shorter paw withdrawal latencies as compared to saline-treated paws and these latency changes corresponded to a decreased thermal nociceptive threshold. Both the thermal method and the Randall-Selitto mechanical method detected dose-related hyperalgesia and its blockade by either morphine or indomethacin. However, the thermal method showed greater bioassay sensitivity and allowed for the measurement of other behavioral parameters in addition to the nociceptive threshold.

A new and sensitive method for measuring thermal nociception in cutaneous hyperalgesia.

A series of sulfonamide-containing 1,5-diarylpyrazole derivatives were prepared and evaluated for their ability to block cyclooxygenase-2 (COX-2) in vitro and in vivo. Extensive structure-activity relationship (SAR) work was carried out within this series, and a number of potent and selective inhibitors of COX-2 were identified. Since an early structural lead (1f, SC-236) exhibited an unacceptably long plasma half-life, a number of pyrazole analogs containing potential metabolic sites were evaluated further in vivo in an effort to identify compounds with acceptable pharmacokinetic profiles. This work led to the identification of 1i (4-[5-(4-methylphenyl)-3-(trifluoromethyl)- H-pyrazol-1-yl]benzenesulfonamide, SC-58635, celecoxib), which is currently in phase III clinical trials for the treatment of rheumatoid arthritis and osteoarthritis.

Synthesis and biological evaluation of the 1,5-diarylpyrazole class of cyclooxygenase-2 inhibitors: identification of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benze nesulfonamide (SC-58635, celecoxib).

Studies on the mediators of the acute inflammatory response induced in rats in different sites by carrageenan and turpentine.

3-(Acylamino)-5-phenyl-2H-1,4-benzodiazepines, antagonists of the peptide hormone cholecystokinin (CCK), are described. Developed by reasoned modification of the known anxiolytic benzodiazepines, these compounds provide highly potent, orally effective ligands selective for peripheral (CCK-A) receptors, with binding affinities approaching or equaling that of the natural ligand CCK-8. The distinction between CCK-A receptors on the one hand and CNS (CCK-B), gastrin, and central benzodiazepine receptors on the other is demonstrated by using the structure-activity profiles of the new compounds. Details of the binding of these agents to CCK-A receptors are examined, and the method of development of these compounds is discussed in terms of its relevance to the general problem of drug discovery.

Methods for drug discovery: development of potent, selective, orally effective cholecystokinin antagonists

SummaryA method is presented for measuring the edema induced by injection of 0.05 ml of 1% solution of carrageenin, an extract of Chondrus, into the plantar tissues of the hind paw of the rat. Peak...

Carrageenin-Induced Edema in Hind Paw of the Rat as an Assay for Antiinflammatory Drugs

Indomethacin, 1-( p -chlorobenzoyl) - 5 methoxy-2-methylindole-3-acetic acid, is a potent anti-inflammatory and antipyretic compound. It is orally active as an inhibitor of cotton pellet granuloma formation in the rat, with a potency about 85 times that of phenylbutazone and about 4 times that of hydrocortisone. It is equally active in intact or adrenalectomized rats and is effective when applied directly to the cotton pellet. When used in conjunction with a steroid, the action of the latter is enhanced. Indomethacin is also a potent inhibitor of edema induced in the rat9s foot by subplantar injection of carrageenin. The compound is an active antipyretic drug, with potency 10 to 20 times that of phenylbutazone.

Anti-inflammatory and antipyretic activities of indomethacin, 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid.

After pretreatment of rat brain synaptic membranes with adenosine deaminase to remove endogenous adenosine, 2-chloro[3H]adenosine, a stable analog of adenosine, binds to two sites with Kd values of 1.3 and 16 nM and corresponding Bmax values of 207 and 380 fmol/mg of protein. Binding is reversible, and the highest density of sites occurs in enriched synaptosomal fractions. In peripheral tissue, negligible binding is observed in heart, kidney, and liver, while testicle has 11 fmol of binding sites/mg of protein. In brain, caudate and hippocampus have the highest density of sites, and spinal cord and hypothalamus have the lowest. This high-affinity binding is stereospecific; the L diasteromer of N6-phenylisopropyladenosine is approximately 30-times more potent as a displacer of 2-chloro[3H]adenosine than the D isomer and is also sensitive to theophylline (IC50 = 8.8 microM) and other purine-related compounds. Several putative neurotransmitters, neurotransmitter antagonists, and other centrally active compounds have no effect on binding. The data are consistent with the hypothesis that 2-chloro[3H]adenosine is binding to central purinergic receptors.

https://www.jstor.org/stable/pdfplus/9668.pdf

Biochemical characterization of putative central purinergic receptors by using 2-chloro[3H]adenosine, a stable analog of adenosine.

— The binding of [3H]muscimol, a potent GABA agonist, to crude synaptic membranes prepared from rat brain was studied using a filtration method to isolate membrane-bound ligand. Specific binding was found to be saturable and occurred to two binding sites of Kd5 5 and 30 nm. Binding was Na+-independent and enhanced by both freezing and Triton treatment. Regional and subcellular distribution studies and pharmacological characterization of specific [3H]muscimol binding are consistent with binding to the synaptic GABA receptor.

Characterization of the binding of [3H]muscimol, a potent gamma-aminobutyric acid agonist, to rat brain synaptosomal membranes using a filtration assay.

MK-801 was evaluated in rats for “antipunishment” and “anticonflict” activity in two procedures: (1) A conditioned emotional response (CER) test involving the suppression of lever-pressing by unaviodable shock and (2) a simple conflict test in water-deprived animals that were shocked for licking water. The effect of MK-801 in both procedures was qualitatively similar to the benzodiazepines. Lever-pressing in the CER test was increased by MK-801 at doses ranging from 50–400 μg/kg administered orally (p.o.) at either 0.5 or 2 hours prior to testing. The number of shocks received in the “thirsty rat” conflict procedure was increased by MK-801 at doses from 110–1,000 μg/kg p.o., providing the compound was given 2 or more hours before test. MK-801 was without anticonflict activity when administered 1 hour prior to study.



In squirrel monkeys trained in a response-contingent conflict paradigm, a specific anticonflict effect for MK-801 (50–400 μ/kg p.o.) was not demonstrable. As assessed by observing the overt behavior of squirrel monkeys, MK-801 at doses greater than 100 μg/kg p.o. caused apparent “taming” or “tranquilization.” Chlordizepoxide and diazepam given, respectively, at doses above 1 and 2 mg/kg p.o. had a similar “taming” action. The benzodiazepines possessed a greater separation between doses producing “taming” and those causing ataxia than did MK-801.



The mode of action for the antipunishment effect of MK-801 in rats is not known, but it was found that naloxone (2 or 5 mg/kg SC) antagonized the anticonflict actions of both MK-801 and chlordiazepoxide. In vitro, MK-801 was inactive (IC50 > 2 μM) with respect to competing for binding to rat brain tissue by various radioligands (diazepam, muscimol, apomorphine, spiroperidol, serotonin, LSD, WB-4101, dihydroalprenolol, QNB, and 2-chloroadenosine). An increase in 3H-diazepam binding in vitro in rat brain tissue was detected following acute, but not chronic, treatment in vivo with MK-801.

Restoration of shock‐suppressed behavior by treatment with (+)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzo[a, d]cyclohepten‐5, 10‐imine (MK‐801), a substance with potent anticonvulsant, central sympathomimetic, and apparent anxiolytic properties

Edwin A. Risley

Papers

Carrageenin-Induced Edema in Hind Paw of the Rat as an Assay for Antiinflammatory Drugs

Anti-inflammatory and antipyretic activities of indomethacin, 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid.

Biochemical characterization of putative central purinergic receptors by using 2-chloro[3H]adenosine, a stable analog of adenosine.

Characterization of the binding of [3H]muscimol, a potent gamma-aminobutyric acid agonist, to rat brain synaptosomal membranes using a filtration assay.

Restoration of shock‐suppressed behavior by treatment with (+)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzo[a, d]cyclohepten‐5, 10‐imine (MK‐801), a substance with potent anticonvulsant, central sympathomimetic, and apparent anxiolytic properties