piperidines and 3-(piperidine-1-yl)propyl-4-amino-5-chloro-2-methoxybenzoate-hydrochloride

Behavioral studies have suggested a key role for the cannabinoid system in the modulation of conditioned fear memory. Likewise, much of the literature has revealed that the serotonergic system affects Pavlovian fear conditioning and extinction. A high level of functional overlap between the serotonin and cannabinoid systems has also been reported. To clarify the interaction between the hippocampal serotonin (5-HT4) receptor and the cannabinoid CB1 receptor in the acquisition of fear memory, the effects of 5-HT4 agents, arachidonylcyclopropylamide (ACPA; CB1 receptor agonist), and the combined use of these drugs on fear learning were studied in a fear conditioning task in adult male NMRI mice. Pre-training intraperitoneal administration of ACPA (0.1 mg/kg) decreased the percentage of freezing time in both context- and tone-dependent fear conditions, suggesting impairment of the acquisition of fear memory. Pre-training, intra-hippocampal (CA1) microinjection of RS67333, a 5-HT4 receptor agonist, at doses of 0.1 and 0.2 or 0.2 µg/mouse impaired contextual and tone fear memory, respectively. A subthreshold dose of RS67333 (0.005 µg/mouse) did not alter the ACPA response in either condition. Moreover, intra-CA1 microinjection of RS23597 as a 5-HT4 receptor antagonist did not alter context-dependent fear memory acquisition, but it did impair tone-dependent fear memory acquisition. However, a subthreshold dose of the RS23597 (0.01 µg/mouse) potentiated ACPA-induced fear memory impairment in both conditions. Therefore, we suggest that the blockade of hippocampal 5-HT4 serotonergic system modulates cannabinoid signaling induced by the activation of CB1 receptors in conditioned fear.

Topics: Aniline Compounds; Animals; Arachidonic Acids; Cannabinoid Receptor Agonists; Cannabinoids; Conditioning, Classical; Dose-Response Relationship, Drug; Fear; Freezing Reaction, Cataleptic; Hippocampus; Male; Memory; Mice; para-Aminobenzoates; Piperidines; Receptor, Cannabinoid, CB1; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin 5-HT4 Receptor Antagonists

In this study, the effects of 5-HT4 receptors of the CA1 on MK801-induced amnesia and hyperlocomotion were examined. One-trial step-down method was used to assess memory retention and then, the hole-board method to assess exploratory behaviors. The results showed that post-training intra-CA1 administration of RS67333 (62.5 and 625 ng/mouse) and RS23597 (1 and 10 ng/mouse) decreased memory consolidation, but it did not alter head-dip counts, head-dip latency and locomotor activity. Similarly, MK801 (0.5 and 1 μg/mouse) decreased memory consolidation, but had no effect on head-dip counts and head-dip latency. Interestingly, it increased locomotor activity. The results also showed that post-training intra-CA1 injection of a sub-threshold dose of RS67333 (6.25 ng/mouse) or RS23597 (0.1 ng/mouse) could heighten MK801 induced amnesia and decrease locomotor activity, but it did not alter head-dip counts and head-dip latency. In conclusion, our findings suggest that the CA1 5-HT4 receptors are involved in MK801-induced amnesia and hyperlocomotion.

Topics: Amnesia; Aniline Compounds; Animals; CA1 Region, Hippocampal; Dizocilpine Maleate; Drug Partial Agonism; Exploratory Behavior; Male; Memory; Mice; Motor Activity; para-Aminobenzoates; Piperidines; Receptors, N-Methyl-D-Aspartate; Receptors, Serotonin, 5-HT4; Serotonin 5-HT4 Receptor Agonists; Serotonin 5-HT4 Receptor Antagonists

Interactions between the cannabinoid and serotonin systems have been reported in many studies. In the present study, we investigated the influence of the serotonergic receptor agents on amnesia induced by the cannabinoid CB1 receptor agonist, arachydonilcyclopropylamide (ACPA). Bilateral guide-cannulae were implanted to allow intra-CA3 microinjection of the drugs. The results showed that the intra-peritoneal (i.p.) injection of ACPA induce amnesia but did not alter head dip latency, head dip counts, and locomotion. Moreover, intra-CA3 injection of M-Chlorophenylbiguanide (M-CHL, a 5-HT3 serotonin receptor agonist), Y-25130 (a 5-HT3 serotonin receptor antagonist), RS67333 (a 5-HT4 serotonin receptor agonist), and RS23597-190 (a 5-HT4 serotonin receptor antagonist) impaired memory but have no effect on head dip latency and locomotor activity. In addition, intra-CA3 injection of Y-25130, RS67333, and RS23597-190 heighten the ACPA-induced amnesia and head dip counts while did not alter head dip latency and locomotor activity. On the other hand, intra-CA3 microinjection of M-CHL could not modify the ACPA-induced amnesia, head dip latency and locomotor activity whereas increased head dip counts. It can be concluded that the amnesia induced by i.p. administration of ACPA is at least partly mediated through the serotonergic receptor mechanism in the CA3 area.

Topics: Amnesia; Aniline Compounds; Animals; Arachidonic Acids; Biguanides; Bridged Bicyclo Compounds, Heterocyclic; CA3 Region, Hippocampal; Cannabinoid Receptor Agonists; Catheters, Indwelling; Male; Mice; Oxazines; para-Aminobenzoates; Piperidines; Receptor, Cannabinoid, CB1; Receptors, Serotonin, 5-HT3; Receptors, Serotonin, 5-HT4; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists

Serotonin (5HT) has been shown to be a mitogenic factor in several carcinomas. Its mitogenic effect is elicited through a wide range of 5HT receptor subtypes. In this study, the effects of 5HT, 5HT3 (1-phenylbiguanide hydrochloride) and 5HT4 (cisapride) agonists in promoting the growth of the HT29 cell line and the growth-inhibition effect of the 5HT3 receptor antagonist (Y-25130 hydrochloride) and 5HT4 receptor antagonist (RS 23597-190) were investigated. The expressions of 5HT3 and 5HT4 receptors in human colon cancer tissues and the HT29 cell line were studied.. The growth-promoting and growth-inhibition effects of 5-HT, 5HT3 and 5HT4 agonists and antagonists on the HT29 cell line were studied using MTT assay. Receptor expression has been demonstrated by western blotting.. The results showed that 5HT, 5HT3, and 5HT4 agonists caused significant proliferation of HT29 cells. 5HT3 and 5HT4 receptor antagonists had an inhibitory effect on the growth of these cells. Western blot analysis gave bands from colon tissue extracts and the HT29 cell line.. The results indicate which 5HT3 and 5HT4 receptors are significantly expressed in both colon cancer tissue and the HT29 cell line. Expression for the 5HT3 receptor is more potent. Furthermore, 5HT plays a mitogenic role in colon cancer cells and antagonists of 5HT3, and 5HT4 receptors can inhibit cancer cell growth.

Topics: Adenocarcinoma; Aminobenzoates; Biguanides; Blotting, Western; Bridged Bicyclo Compounds, Heterocyclic; Cell Proliferation; Cisapride; Colonic Neoplasms; HT29 Cells; Humans; Oxazines; para-Aminobenzoates; Piperidines; Receptors, Serotonin, 5-HT3; Receptors, Serotonin, 5-HT4; Serotonin 5-HT3 Receptor Agonists; Serotonin 5-HT3 Receptor Antagonists; Serotonin 5-HT4 Receptor Agonists; Serotonin 5-HT4 Receptor Antagonists

Serotonin (5-hydroxytryptamine [5-HT]) receptors are located in peripheral tissues as well as in the central nervous system. Serotonin receptors mediate positive inotropic and chronotropic effects in atria. The aim of this study was to investigate physiological role of endogenous serotonin on the regulation of atrial natriuretic peptide (ANP) secretion from the atria.. An isolated perfused nonbeating rat atrial model was used. Changes in atrial volume induced by increasing intra-atrial pressure were measured. The concentration of ANP was measured by radioimmunoassay and the translocation of ECF was measured by [3H]-inulin clearance.. Serotonin, an endogenous 5-HT receptor agonist, caused concentration-dependent suppressions of stretch-induced ANP secretion, which were less pronounced than those caused by alpha-methyl-5-HT maleate, a 5-HT(2) receptor selective agonist. The suppression of stretch-induced ANP secretion due to serotonin and alpha-methyl-5-HT maleate was attenuated by ketanserin, a 5-HT(2) receptor antagonist, and accentuated by RS23597-190, a 5-HT(4) receptor antagonist. The suppressive effect of serotonin on ANP secretion was attenuated by neomycin, staurosporine, and chelerythrine. In contrast, 2-[1-(4-piperonyl)piperazinyl]benzothiazole, a 5-HT(4) receptor selective agonist, caused an accentuation of stretch-induced ANP secretion, which was completely blocked by RS23597-190 and SB203186 HCl but not by ketanserin. This effect was not affected by MDL12330, KT-5720, or H-89. The intracellular Ca(2+) concentration in single atrial myocytes was not changed by serotonin and agonist for either 5-HT(2) or 5-HT(4) receptor.. These results suggest that atrial 5-HT(2) and 5-HT(4) receptor agonists have opposite actions on the regulation of ANP secretion and the suppressive effect of serotonin on the ANP secretion may act through 5-HT(2) receptor and phospholipase C pathway.

Topics: Adenylyl Cyclase Inhibitors; Alkaloids; Aminobenzoates; Animals; Atrial Natriuretic Factor; Benzophenanthridines; Benzothiazoles; Calcium; Carbazoles; Cyclic AMP-Dependent Protein Kinases; Depression, Chemical; Dose-Response Relationship, Drug; Heart; Heart Atria; Imines; Indoles; Isoquinolines; Ketanserin; Male; Myocytes, Cardiac; Neomycin; para-Aminobenzoates; Perfusion; Phenanthridines; Piperazines; Piperidines; Protein Kinase C; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, Serotonin; Receptors, Serotonin, 5-HT4; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists; Staurosporine; Sulfonamides; Thiazoles; Type C Phospholipases

We studied the pharmacological properties of twenty-four 5-hydroxytryptamine (5-HT)(4) receptor ligands known to act as antagonists on 5-HT(4) receptors positively coupled to adenylyl cyclase endogenously expressed in mouse colliculi neurons. In COS-7 cells expressing human or mouse 5-HT(4(a)) receptors (100-8000 fmol/mg of protein), we found neutral antagonists, partial agonists, and inverse agonists. The majority of neutral antagonists belong to the benzodioxanyl ketone class, whereas partial agonists belong to different chemical classes. We found only two inverse agonists, GR 125487 and SB 207266, which are both indoles. Analysis of pharmacological characteristics of the constitutively active wild-type and constitutively active mutated receptors revealed that 1) the ratio between the efficiencies of the full agonist 5-HT and the partial agonist RS 23597 was invariable when the receptor density increased, but was dependent on receptor structure; 2) similarly, the efficacy of the inverse agonist SB 207266 was not dependent on receptor density but was dependent on receptor structure; 3) when the receptor concentration increased, the EC(50) values of the full agonist 5-HT were not modified and the increase in basal constitutive activity, as well as its stimulation by 5-HT, followed a parallel evolution; and 4) the stimulation of basal constitutive activity by 5-HT was not modified by the overexpression of Galphas. All these results indicate that in COS-7 cells, the coupling of the 5-HT(4) receptor to adenylyl cyclase was linear with no indication of spare receptors even at high receptor density (8 pmol/mg). These results are also in accordance with a precoupling between the activated receptor (f(R*)) and adenylyl cyclase. Such observations allowed us to use the two-state model to calculate the constant J, i.e., the equilibrium allosteric constant denoting the ratio of the receptor in the inactive versus active state (J = [R]/[R*]). We found that J was a receptor structural characteristic, independent of receptor density.

Topics: Adenylyl Cyclases; Allosteric Regulation; Aminobenzoates; Animals; COS Cells; Cyclic AMP; Dose-Response Relationship, Drug; GTP-Binding Protein alpha Subunits, Gs; Humans; Indoles; Mice; Models, Biological; Mutation; para-Aminobenzoates; Piperidines; Receptors, Serotonin; Receptors, Serotonin, 5-HT4; Serotonin Antagonists; Sulfonamides; Transfection

Although many 5-HT (serotonin, 5-hydroxytryptamine)(4) receptor antagonists have been described, none possess the requisite oral activity and duration of action for a clinically effective therapeutic agent. The present report identifies LY353433 (1-(1-methylethyl)-N-[2-[4-[tricyclo[3.3.1.1(3,7)]dec-1-ylcarbo nyl) amino]-1-piperidinyl]ethyl]-1H-indazole-3-carboxamide), an indazole amide, as a high affinity antagonist at the 5-HT(4) receptor in the rat esophagus. LY353433 (10(-8), 3 x 10(-8), 10(-7) M) inhibited 5-HT-induced relaxation of carbamylcholine-contracted esophagus with greater potency than cisapride or RS23597-190, a known 5-HT(4) receptor ligand. Furthermore, RS23597-190 possessed marked agonist activity as did cisapride, whereas LY353433 did not relax the rat esophagus in concentrations up to 10(-5) M. LY353433 (up to 10(-5) M) did not possess appreciable affinity for adrenergic, dopaminergic, histaminergic, muscarinic or GABAergic receptors and, thus, was a highly selective 5-HT(4) receptor antagonist. In addition, LY353433 only slowly associated with an dissociated from the 5-HT(4) receptor, an attribute that conferred long-lasting 5-HT(4) receptor antagonist activity, in contrast to RS23597-190, which rapidly dissociated from the 5-HT(4) receptor. LY353433 dose-dependently inhibited the 5-HT(4) receptor-mediated ex vivo relaxation in the rat esophagus after either i.v. (0.1, 0.3 and 1.0 mg/kg) or p.o. (0.1, 0.3, 1.0 and 3.0 mg/kg) administration. Furthermore, the p.o. to i.v. dose ratio was approximately one, suggesting that LY353433 was well absorbed with excellent pharmacodynamics in the rat. LY353433 (0.3 mg/kg p.o.) blocked esophageal 5-HT(4) receptors ex vivo through 6 hr after p.o. dosing with responses returning to control by 16 hr, indicative of long duration receptor blockade. Lastly, in rats LY353433 was exceptionally safe because acute doses up to 300 mg/kg p.o. did not result in either symptoms or deaths. Thus, LY353433 is a potent, selective, orally effective, long-acting and safe 5-HT(4) receptor antagonist that is highly suitable for clinical use.

Topics: Adamantane; Administration, Oral; Aminobenzoates; Animals; Cisapride; Esophagus; Female; In Vitro Techniques; Indazoles; Male; Muscle Relaxation; para-Aminobenzoates; Piperidines; Rats; Rats, Inbred F344; Rats, Sprague-Dawley; Rats, Wistar; Serotonin Antagonists

Recent findings have suggested a relationship between 5-hydroxytryptamine (5-HT)4 receptors and sigma binding sites. To test this idea, the affinity of 5-HT4 receptor ligands for sigma binding sites was examined. In contrast to the 5-HT4 receptor ligands BIMU-1 [endo-N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-2,3- dihydro-3-ethyl-2-oxo-1H-benzimidazole-1-carboxamide hydrochloride] and BIMU-8 [endo-N-(8-methyl-8-azabicyclo[3.2.1]oct-3- yl)-2,3-dihydro-(1-methyl)ethyl-2-oxo-1H-benzamidazole-1-carbox ami de hydrochloride], DAU 6215 ]N-(endo-8-methyl-8-azabicyclo[3.2.1.]oct-3-yl)-2,3-dihydro-2-oxo-1H- benzimidazole-1-carboxamide hydrochloride], 5-HT and 5-methoxytryptamine had low affinity for sigma binding sites (pKi < 6). Conversely, the sigma ligands haloperidol and pentazocine had low affinity for 5-HT4 receptors. Thus, no relationship was found between the affinity of ligands at 5-HT4 receptors and sigma binding sites. However, one potent 5-HT4 receptor antagonist, RS-23597-190 [3-(piperidine-1-yl)propyl-4-amino-5-chloro-2-methoxybenzoate hydrochloride], had high affinity for sigma-1 (pKi = 8.4) but not sigma-2 (pKi = 6.2) binding sites. [3H]RS-23597-190 bound to a saturable site with the pharmacology of a sigma-1 binding site: (pIC50) haloperidol (9.0) > (+)-pentazocine (8.8) > (+)-3-(hydroxyphenyl)-N-(1-propyl)piperidine (8.2) > 1,3-di-o-tolyl-guanidine (8.0) > (-)-pentazocine (7.8) = (+)-SKF 10,047 [N-allylnormetazocine] > (-)-SKF 10,047 (6.2) > BIMU-1 (5.3) > 5-HT and 5-methoxytryptamine. The distribution of [3H]RS-23597-190 binding sites was similar to that described for other sigma radioligands, with the greatest binding densities in cranial nerve nuclei, the tegmental nucleus and in the mamillary nucleus. In contrast to (+)-3-(hydroxyphenyl)-N-(1-propyl)piperidine, [3H]RS-23597-190 binding was not allosterically modulated by phenytoin. These studies do not support the notion of an obvious relationship between sigma and 5-HT4 receptors, but they provide additional insight into the structure/affinity relationship of ligands at specific sigma binding sites, and they uncover a novel sigma-1 receptor ligand whose binding is insensitive to the action of phenytoin.

Topics: Aminobenzoates; Animals; Binding Sites; Brain; Guinea Pigs; Male; para-Aminobenzoates; Piperidines; Receptors, Serotonin; Receptors, sigma; Serotonin Antagonists

1. The pharmacological properties of RS 23597-190 (3-(piperdine-1-yl)-propyl-4-amino-5-chloro-2-methoxy benzoate hydrochloride) have been studied in vitro and in vivo. 2. RS 23597-190 competitively antagonized 5-HT4 receptor-mediated relaxations of rat, carbachol precontracted oesophageal muscularis mucosae, (pA2 = 7.8 +/- 0.1; Schild slope = 1.2 +/- 0.2). Affinity estimates (-log KB) at 5-HT4 receptors using either renzapride or SC-53116 as agonists yielded a -log KB value of 8.0 +/- 0.01. In contrast, RS 23597-190 failed to antagonize contractile responses to 5-HT of guinea-pig ileal 5-HT3 receptors, even at concentrations up to 10 microM. 3. Increases in short-circuit current, induced by 5-HT, were studied in guinea-pig ileal mucosal sheets. Concentration-response curves to 5-HT were biphasic, with the high potency phase to 5-HT inhibited by RS 23597-190 and mimicked by 5-methoxytryptamine. The -log KB value for RS 23597-190 at the high potency phase was 7.3 confirming that 5-HT4 receptors mediated the high potency phase. 4. In rat isolated vagus nerve, 5-HT elicited a slow, maintained depolarization at low concentrations and a rapid, transient depolarization at higher concentrations. The high potency, slow depolarizing phase to 5-HT was abolished selectively in the presence of 1 microM RS 23597-190 and the low potency phase was abolished selectively in the presence of 1 microM ondansetron. These data confirm that 5-HT4 and 5-HT3 receptors mediated slow and fast depolarization responses, respectively. 5. At 5-HT3 binding sites in membranes from NG 108-15 cells, labelled by [3H]-quipazine, RS 23597-190 exhibited an apparent affinity (- log Ki) of 5.7 +/- 0.1. At 5-HT3 receptors in membranes from rat cerebral cortex, labelled by [3H]-RS 42358-197, the apparent affinity (- log Ki) of RS 23597-190 was also 5.7 +/- 0.1. In both studies, Hill coefficients were not significantly different from unity. At 5-HT1A, 5-HT2,muscarinic M1, M2, M3, M4 and dopamine D1 and D2 receptors, RS 23597-190 exhibited low apparent affinities, with all - log Ki values less than 5.5.6. Intravenous infusion of RS 23597-190 in the conscious, restrained rat antagonized the von Bezold Jarisch reflex induced by 2-methyl 5-HT, with an ID50 of 300 microg kg-1 min-1, i.v. In the anaesthetized,bilaterally vagotomized micropig, RS 23597-190 (6 mg kg-1, i.v.) antagonized 5-HT-induced tachycardia with a half-life of 77 (63-99) min. Transient arrhythmic effects were noted after administration

Topics: 4-Aminobenzoic Acid; Aminobenzoates; Animals; Blood Pressure; Electrophysiology; Female; Guinea Pigs; Heart Rate; In Vitro Techniques; Intestinal Mucosa; Male; Metoclopramide; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; para-Aminobenzoates; Piperidines; Radioligand Assay; Rats; Reflex; Serotonin; Serotonin Antagonists; Swine; Swine, Miniature; Vagus Nerve