Vincent Patrick Rocco

Pharmacologic Characterization of the Cloned Human Trace Amine-Associated Receptor1 (TAAR1) and Evidence for Species Differences with the Rat TAAR1

The hemagglutinin-tagged human trace amine-associated receptor1 (TAAR1) was stably coexpressed with rat Gαs in the AV12-664 cell line, and receptor activation was measured as the stimulation of cAMP formation. After blockade of endogenously expressed α2- and β-adrenoceptors with 2-[2-(2-methoxy-1,4-benzodioxanyl)]-imidazoline hydrochloride (2-methoxyidazoxan, RX821002) and alprenolol, respectively, the resulting pharmacology was consistent with that of a unique receptor subtype. β-Phenylethylamine (β-PEA), the putative endogenous ligand, gave an EC50 of 106 ± 5 nM in the assay. For a series of β-PEA analogs used to explore the pharmacophore, small substituents at ring positions 3 and/or 4 generally resulted in compounds having lower potency than β-PEA, although several were as potent as β-PEA. However, small substituents at ring position 2 resulted in a number of compounds having potencies as good as or better than β-PEA. A number of nonselective antagonists known to share affinity for multiple monoaminergic receptors were evaluated for their ability to inhibit β-PEA stimulation of the human TAAR1. None had an IC50 <10 μM. For comparison, the rat TAAR1 receptor was expressed in the AV12-664 cell line. A number of agonist compounds had significantly different relative potencies between the rat and human TAAR1, demonstrating a significant species difference between the rat and human TAAR1. The TAAR1 receptor exhibits a pharmacologic profile uniquely different from those of classic monoaminergic receptors, consistent with the structural information that places them in a distinct family of receptors. This unique pharmacologic profile suggests the potential for development of TAAR-selective agonists and antagonists to study their physiologic roles.

Advances toward new antidepressants beyond SSRIs: 1-aryloxy-3-piperidinylpropan-2-ols with dual 5-HT1A receptor antagonism/SSRI activities. Part 3

A series of 1-aryloxy-3-piperidinylpropan-2-ols possessing potent dual 5-HT(1A) receptor antagonism and serotonin reuptake inhibition was discovered. 1-(1H-Indol-4-yloxy)-3-(4-benzo[b]thiophen-2-ylpiperidinyl)propan-2-ols exhibited selective and high affinity at the 5-HT(1A) receptor and serotonin reuptake inhibition at nanomolar concentrations for dual activities.

Synthesis and 5α-reductase inhibitory activity of 8-substituted benzo[ƒ]quinolinones derived from palladium mediated coupling reactions

Benzoquinolinones have been shown to be potent, selective inhibitors of the Type I 5 alpha-reductase enzyme, which is responsible for the production of dihydrotestosterone from testosterone localized in the scalp. In an effort to identify compounds that demonstrate inhibition of both 5 alpha-reductase isozymes, we have employed 8-bromobenzoquinolinone as an advanced intermediate for participation in a variety of palladium mediated carbon-carbon bond forming reactions. By varying the 8-substituent it is possible to alter the selectivity profile of the series.

Kinetic analysis of LY320236: competitive inhibitor of type I and non-competitive inhibitor of type II human steroid 5α-reductase

Type I and type II steroid 5alpha-reductases (5alpha-R) catalyze the conversion of testosterone (T) to dihydrotestosterone (DHT). LY320236 is a benzoquinolinone (BQ) that inhibits 5alpha-R activity in human scalp skin (Ki(typeI)=28.7+/-1.87 nM) and prostatic homogenates (Ki(typeII)=10.6+/-4.5 nM). Lineweaver-Burk, Dixon, and non-linear analysis methods were used to evaluate the kinetics of 5alpha-R inhibition by LY320236. Non-linear modeling of experimental data evaluated V(max) in the presence or absence of LY320236. Experimental data modeled to the following equation 1v=+ fixing the In0c value equal to 1.0 or 0 are consistent with non-competitive or competitive inhibition, respectively. LY320236 is a competitive inhibitor of type I 5alpha-R (In0c=0, Ki=3.39+/-0.38, RMSE = 1.300) and a non-competitive inhibitor of type II 5alpha-R (In0c=1, Ki=29. 7+/-3.4, RMSE = 0.0592). These data are in agreement with linear transformation of the data using Lineweaver-Burk and Dixon analyses. These enzyme kinetic data support the contention that the BQ LY320236 is a potent dual inhibitor with differing modes of activity against the two known human 5alpha-reductase isozymes. LY320236 represents a class of non-steroidal 5alpha-R inhibitors with potential therapeutic utility in treating a variety of androgen dependent disorders.

Chapter 1. Recent Progress in Serotonin (5-HT)1A Receptor Modulators

Publisher Summary Serotonin (5-hydroxytryptamine; 5-HT) is a biogenic indolamine found in the blood, the girstro-intestinal tract, and the central nervous system (CNS). In the blood, 5-HT plays a role in the vascular tone and platelet function, while in the gastro-intestinal system it has strong effects on the intestinal motility and gastric-acid secretion. In the brain, 5-HT is synthesized and released as a neurotransmitter from specific cells that form a discrete brain system. 5-HT has been hypothesized to play a role in a myriad number of physiological processes, behaviors, and disease states. The many actions of 5-HT in the body are mediated through at least fourteen different receptor subtypes. Except for the 5-HT 3 receptor, which is a ligand-gated ion channel, all 5-HT receptor subtypes interact with G-proteins. One of these receptor subtypes, the 5-HT 1A receptor, is found in high concentrations in the limbic system where it is thought to play a role in emotional processes. 5-HT has also been hypothesized to play a role in anxiety. This has been supported, in part, by the clinical efficacy of compounds that alter serotonergic transmission. For example, the 5-HT 1A partial agonist buspirone has anxiolytic effects in generalized anxiety disorder and 5-HT reuptake blockers are effective treatments for panic disorder. Recently, the 5-HT 1A full agonists flesinoxan and S 20499 have been reported to display anxiolytic-like activity in several animal models of anxiety. Indeed, preliminary clinical trials indicate that flesinoxan is effective in the treatment of generalized anxiety disorder but not panic disorder, in human. Indirect modulation of serotonergic neurotransmission, with selective 5-HT reuptake inhibitors (SSRls) (for example, fluoxetine), has important therapeutic effects in a number of neuropsychiatric disorders. Selective 5-HT 1A agonists and antagonists shows efficacy for anxiety and depression and are beneficial in depression, anxiety, Alzheimers disease, and prostate cancer. The progression of 5-HT 1A agonists and antagonists through preclinical trials, and ultimately to the clinical tests is anticipated that leads to a greater understanding of the basic working of the brain and potentially to an important class of therapeutics.