[125I]-1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane: an iodinated radioligand that specifically labels the agonist high-affinity state of 5-HT2 serotonin receptors.
Explore the source record for details and available documents.
Amphetamines↗
Biomedical subjects
R A Lyon
Publications and source records attributed to R A Lyon.
N,N-di-n-propylserotonin: binding at serotonin binding sites and a comparison with 8-hydroxy-2-(di-n-propylamino)tetralin.
8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) is a serotonergic agonist with high affinity and selectivity for a particular population of central serotonin (5-HT) binding sites (i.e., 5-HT1A sites). Because the selectivity of 8-OH-DPAT may be due to the terminal amine substituents, the di-n-propyl analogue of 5-HT (i.e., 4) and of 5-methoxytryptamine (i.e., 5) were prepared and compared with 8-OH-DPAT with respect to their binding profile. Unlike 8-OH-DPAT, neither compound 4 nor 5 displays selectivity for 5-HT1A vs 5-HT2 sites. Consistent with these results, stimulus generalization occurs with 5 both in rats trained to discriminate 8-OH-DPAT from saline and in rats trained to discriminate the 5-HT2 agonist DOM from saline. The results of this study suggest that it is not the N,N-dipropyl groups that account for selectivity, but, rather, it is some feature associated with the pyrrole portion of the indolylalkanamines that is important.
8-Hydroxy-2-(di-n-propylamino)tetralin↗
Selectivity of serotonergic drugs for multiple brain serotonin receptors. Role of [3H]-4-bromo-2,5-dimethoxyphenylisopropylamine ([3H]DOB), a 5-HT2 agonist radioligand.
The affinities of putative serotonin receptor agonists and antagonists for 5-HT1A, 5-HT1B, 5-HT1C, and 5-HT2 receptors were assayed using radioligand binding assays. The 5-HT1 sites were labeled with the agonist radioligands [3H]-8-hydroxy-2-(di-n-propylamino)-tetralin [3H]-8-OH-DPAT, [3H]-5-HT, and [3H]mesulergine. The 5-HT2 receptor was labeled with the antagonist radioligand [3H]ketanserin or the agonist radioligand [3H]-4-bromo-2,5-dimethoxyphenylisopropylamine ([3H]DOB). The apparent 5-HT1 receptor selectivity of agonist compounds was found to be 50- to 100-fold higher when the 5-HT2 receptor affinity was determined using the antagonist radioligand [3H]ketanserin than when the agonist radioligand [3H]DOB was used. Quipazine, a putative specific 5-HT2 agonist, appeared to be only 3-fold more potent at 5-HT2 than at 5-HT1A receptors when [3H]ketanserin was used as the 5-HT2 radioligand. When [3H]DOB was used as the 5-HT2 radioligand, quipazine was determined to be 100-fold more potent at 5-HT2 receptors than at 5-HT1A receptors. 1-(3-trifluoromethylphenyl)piperazine (TFMPP), a putative specific 5-HT1B receptor agonist was apparently 10-fold more potent at 5-HT1B receptors than at 5-HT2 receptors when [3H]ketanserin was used as the 5-HT2 radioligand. When [3H]DOB was used as the 5-HT2 radioligand, TFMPP was found to be equipotent at 5-HT1B and 5-HT2 receptors. Using the 5-HT2 antagonist radioligand [3H]ketanserin, a similar pattern of underestimating 5-HT2 receptor selectivity and/or overestimating 5-HT1A or 5-HT1B receptor selectivity was observed for a series of serotonin receptor agonists. Antagonist receptor selectivity was not affected significantly by the nature of the 5-HT2 receptor assay used. These data indicate that, by using an antagonist radioligand to label 5-HT2 receptors and agonist radioligands to label 5-HT1 receptors, the 5-HT1 receptor selectivity may be overestimated. This may be an especially severe problem in serotonin drug development as drugs that interact potently with 5-HT2 receptors have been reported to be psychoactive and/or hallucinogenic.
DOM 2,5-Dimethoxy-4-Methylamphetamine↗
N-methyl derivatives of the 5-HT2 agonist 1-(4-bromo-2,5-dimethoxyphenyl)-2-aminopropane.
1-(4-Bromo-2,5-dimethoxyphenyl)-2-aminopropane (DOB) is a serotonin (5-HT) agonist that displays a high affinity and selectivity for a certain population of central 5-HT binding sites (i.e., 5-HT2 sites). In the present study, (a) an enantiomeric potency comparison was made for the optical isomers of DOB and (b) the activity of N-monomethyl-,N,N-dimethyl-, and N,N,N-trimethyl-DOB was examined. (R)-(-)-DOB (Ki = 0.39 nM) was found to have 6 times greater affinity than its S-(+) enantiomer at [3H]DOB-labeled (rat cortical homogenates) 5-HT2 sites; N-methylation of racemic DOB resulted in a decrease in affinity that was at least 1 order of magnitude per methyl group. Similar results were obtained in an in vivo drug discrimination paradigm with rats as subjects and (R)-(-)-DOB (0.2 mg/kg) as the training drug. Thus, the R-(-) isomer of DOB is more active than its S-(+) enantiomer and than any of the possible N-methyl derivatives of DOB, both with respect to affinity at central 5-HT2 binding sites and with respect to potency in the behavioral (i.e., stimulus generalization) studies.
Animals↗
D2 dopamine receptors on bovine chromaffin cell membranes: identification and characterization by [3H]N-methylspiperone binding.
Although dopamine-containing cells are known to be present in sympathetic ganglia, the site of action and the role of dopamine in ganglion function remain obscure. In the present work, we evaluated the interaction of dopamine receptor ligands with particulate membrane fractions from bovine chromaffin cells and adrenal medullary homogenates using the D2 dopamine receptor radioligand [3H]N-methylspiperone ([3H]NMSP). Scatchard analysis of [3H]NMSP saturation experiments revealed a Bmax of 24.1 +/- 1.6 fmol/mg of protein and a KD of 0.23 +/- 0.03 nM in the particulate fraction from adrenal medulla homogenates and a Bmax of 26.5 +/- 2.7 fmol/mg of membrane protein and a KD of 0.25 +/- 0.02 nM in the particulate fraction prepared from isolated adrenal chromaffin cells. There were approximately 1,000 receptors/cell. There were no detectable levels of specific [3H]NMSP binding in the particulates prepared from adrenal cortical or capsular homogenates. Competition studies with the nonradioactive D2 receptor antagonists spiperone, chlorpromazine, and (-)-sulpiride revealed KI values of 0.28, 21, and 196 nM, respectively. The (+) isomer of butaclamol displayed a 604-fold higher affinity than the (-) isomer. Competition studies with the dopamine receptor agonists dopamine and apomorphine revealed affinities of 3,960 and 417 nM, respectively. A correlation coefficient of 0.96 was obtained in studies comparing the potencies of drugs in inhibiting specific [3H]NMSP binding in bovine adrenal medullary homogenates and in inhibiting specific [3H]NMSP binding to brain D2 dopamine receptors. In summary, radiolabeling studies using [3H]NMSP have revealed the presence of D2 dopamine receptors on bovine adrenal chromaffin cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
3H-DOB (4-bromo-2,5-dimethoxyphenylisopropylamine) labels a guanyl nucleotide-sensitive state of cortical 5-HT2 receptors.
3H-(+/-)-4-Bromo-2,5-dimethoxyphenylisopropylamine (3H-DOB), a putative agonist radioligand, was synthesized and used to label 5-HT2 receptors in a particulate fraction prepared from rat frontal cortex tissue homogenates. The specific binding (defined by the difference in 3H-DOB binding in the presence and absence of 10(-6) M cinanserin, a potent and specific 5-HT2 antagonist) displayed high affinity (KD = 4.1 X 10(-10) M) and saturability with a Bmax of 17.9 fmol/mg of protein. The distribution of specific 3H-DOB binding in nine brain regions correlated closely with the distribution of 3H-ketanserin (an antagonist radioligand)-labeled 5-HT2 receptors. Competition studies in frontal cortex homogenates using a variety of compounds revealed a distinct 5-HT2 receptor pharmacology. A series of 5-HT2 antagonists exhibited high affinities in competition studies for specific 3H-DOB binding. The absolute potencies of these antagonists as well as their order of potencies closely correlated with their potencies in competing for 3H-ketanserin-labeled brain 5-HT2 receptors. A series of 5-HT2 agonists also exhibited high affinities in competition studies for specific 3H-DOB binding. Although the order of potencies of these agonists was similar to their order in competing for 3H-ketanserin-labeled brain 5-HT2 receptors, the agonists displayed 10-100-fold higher affinities for the 3H-DOB-labeled sites than for the 3H-ketanserin-labeled sites. The level of specific 3H-DOB binding in the frontal cortex homogenates was approximately 5% of the levels of 3H-ketanserin-labeled 5-HT2 receptors (358 fmol/mg of protein). Taken together, these results indicate that 3H-DOB labels a subset of brain 5-HT2 receptors that has high affinity for agonists as well as antagonists); 3H-ketanserin appears to label both subsets of brain 5-HT2 receptors. Antagonists apparently do not discriminate between these two subsets of 5-HT2 receptors. 3H-DOB specific binding to 5-HT2 receptors was potently inhibited by guanosine 5'-(beta, gamma-imido)triphosphate and guanosine 5'-O-(3-thio)triphosphate (nonhydrolyzable derivatives of GTP) with IC50 values of 42 and 21 nM, respectively, whereas adenosine 5'-(beta, gamma-imido)triphosphate and adenosine 5'-O-(3-thio)triphosphate (nonhydrolyzable derivatives of ATP) had no effect. In summary, 3H-DOB specific binding displays the pharmacological characteristics of a 5-HT2 receptor.(ABSTRACT TRUNCATED AT 400 WORDS)
DOM 2,5-Dimethoxy-4-Methylamphetamine↗
Asymmetry in D-2 binding in female rat striata.
An asymmetry in D-2 receptor densities (Bmax) measured by [3H]N-methyl spiperone binding was found in striata from female Sprague-Dawley rats. The D-2 Bmax on the right side was on average 40% greater than the D-2 Bmax on the left side. This asymmetry is greater in magnitude and opposite in direction to that reported for males and is independent of directional preference exhibited during nocturnal circling.
Animals↗
3,4-Methylenedioxymethamphetamine (MDMA): stereoselective interactions at brain 5-HT1 and 5-HT2 receptors.
3,4-Methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxy-amphetamine (MDA), and their optical isomers, were assayed for their affinities at radiolabeled brain serotonin (5-HT1, 5-HT2) and dopamine (D2) binding sites. (R(-)-MDA and R(-)-MDMA displayed moderate affinities for 3H-ketanserin-labeled 5-HT2 sites (Ki = 3425 and 3310 nM, respectively) whereas the affinities for their S(+)-enantiomers were lower (Ki = 13,000 and 15,800 nM, respectively). Similar absolute and relative affinities were obtained at 3H-serotonin-labeled 5-HT1 sites; binding at D2 sites was very low (Ki greater than 25,000 nM in each case). The (-) greater than (+) order of potency at 5-HT2 sites is consistent with the observation that R(-)-MDA is a more potent psychoactive agent than its S(+)-enantiomer, but contrasts with the reported finding that S(+)-MDMA is more potent than R(-)-MDMA in humans. These results suggest that MDMA, unlike MDA and other hallucinogenic phenylisopropylamines, does not work primarily through a direct interaction at 5-HT sites.
3,4-Methylenedioxyamphetamine↗
5-HT1 and 5-HT2 binding characteristics of 1-(2,5-dimethoxy-4-bromophenyl)-2-aminopropane analogues.
1-(2,5-Dimethoxy-4-bromophenyl)-2-aminopropane (DOB; 1a) is a purported serotonin (5-HT) agonist that binds selectively to central 5-HT2 binding sites. Systematic removal of any or all of the aromatic substituents had relatively little effect on 5-HT1 binding but reduced 5-HT2 binding by approximately 2 or more orders of magnitude. Demethylation of the 2-methoxy group of 1a, or introduction of an N-n-propyl group, doubled 5-HT1-site affinity but decreased 5-HT2-site affinity by 3- and 30-fold, respectively. In tests of stimulus generalization, using rats trained to discriminate DOM from saline, the 2-demethyl and N-propyl derivatives were found to produce stimulus effects similar to those of DOB. In addition, the S-(+) isomer of the iodo analogue of 1a was found to possess one-third the affinity of its R-(-) enantiomer at 5-HT2 sites and also resulted in DOM-stimulus generalization. Of the DOB analogues examined, DOB (1a) possesses optimal selectivity for 5-HT2 binding.
Animals↗
Synthesis and evaluation of phenyl- and benzoylpiperazines as potential serotonergic agents.
The binding of a series of phenylpiperazines (3) and benzoylpiperazines (4) to central serotonin (5-HT) sites was investigated. Several derivatives of 3 displayed nanomolar affinities for 5-HT1 sites, whereas derivatives of 4 were essentially inactive both at 5-HT1 and 5-HT2 sites. 1-(2-Methoxyphenyl)piperazine (2-MPP, 3a) was found to possess an affinity (Ki = 35 nM) for 5-HT1 sites comparable to that of the recognized 5-HT agonist 1-[3-(trifluoromethyl)phenyl]piperazine (TFMPP) (Ki = 20 nM); 3a also displayed a 100-fold selectivity for 5-HT1 sites (as compared to 8-fold for TFMPP). In tests of stimulus generalization using rats trained to discriminate TFMPP (ED50 = 0.17 mg/kg) from saline, 3a was found to be nearly equipotent (ED50 = 0.22 mg/kg) with the training drug. These results suggest that 3a may be a novel and more selective 5-HT1 agonist than TFMPP.
Animals↗
5-HT1 and 5-HT2 binding characteristics of some quipazine analogues.
Arylpiperazines, such as 1-(3-trifluoromethylphenyl)piperazine (TFMPP) and its chloro analogue mCPP, are 5-HT1 agonists, whereas quipazine, i.e., 2-(1-piperazino)quinoline, appears to be a 5-HT2 agonist. Radioligand binding studies using rat cortical membrane homogenates and drug discrimination studies using rats trained to discriminate a 5-HT1 agonist (i.e., TFMPP) or a 5-HT2 agonist (i.e., 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM)) from saline reveal that quipazine and its 1-deaza analogue 2-naphthylpiperazine (2-NP) bind at 5-HT1 and 5-HT2 sites but produce stimulus effects similar to those of DOM. A structurally related compound, 1-naphthylpiperazine (1-NP), possesses a high affinity for 5-HT1 (Ki = 5 nM) and 5-HT2 (Ki = 18 nM) sites. 1-NP produces stimulus effects similar to those of TFMPP and is able to antagonize the stimulus effects produced by DOM. The present results suggest that the unsubstituted benzene ring of quipazine, and of its 1-deaza analogue 2-naphthylpiperazine, makes a significant contribution to the binding of these agents to 5-HT2 sites and, more importantly, may account for their 5-HT2 agonist properties.
DOM 2,5-Dimethoxy-4-Methylamphetamine↗
Determining staffing requirements in a community hospital pharmacy department.
A community hospital pharmacy did a study to determine staffing requirements. The ability to predict staffing requirements using a standard indicator of workload was sought. The department measured the volume of routine activities over a 4-week period. The service hours performed equaled the volume applied to standard target times. Correlation and multiple regression techniques were used to determine the ability of various workload indicators to predict staffing requirements. The study failed to identify a reliable indicator of workload that would prove useful in predicting staffing requirements. The results facilitated redistribution of workload as a method to improve the use of employees.
Florida↗
3H-3-N-methylspiperone labels D2 dopamine receptors in basal ganglia and S2 serotonin receptors in cerebral cortex.
Detailed studies of the properties of 3H-3-N-methylspiperone (NMSP) binding in rat and human brain homogenates were performed at 37 degrees C. In homogenates of rat striatum and frontal cortex and human caudate and frontal cortex tissues, the specific binding was found to be saturable. Rat caudate contained 33.2 pmol/gm wet-weight tissue and displayed an equilibrium dissociation constant (Kd) of 8.7 X 10(-11) M; rat frontal cortex contained 18.5 pmol/gm wet-weight tissue and displayed a Kd of 1.5 X 10(-10) M. Human caudate contained 8.96 pmol/gm wet-weight tissue and displayed a Kd of 1.1 X 10(-10) M; human frontal cortex possessed 9.8 pmol/gm wet-weight tissue and a Kd of 4.4 X 10(-10) M. Kinetic studies revealed a very rapid rate of association in all the tissues studied. The rate of dissociation was relatively slow in all 4 tissue preparations; the dissociation rate was somewhat slower in rat striatum and human caudate relative to rat and human frontal cortex. This was consistent with the somewhat higher affinity, relative to frontal cortex, displayed by 3H-NMSP in rat striatal and human caudate tissue. The pharmacological properties of the specific binding in rat striatal and human caudate tissues were very similar and indicated the presence of brain D2 dopamine receptors. In rat and human frontal cortex tissue homogenates, the pharmacological characteristics of the specific binding indicated the presence of 5-HT2 receptors.
Animals↗
[3H]DOB: a specific agonist radioligand for 5-HT2 serotonin receptors.
Explore the source record for details and available documents.
DOM 2,5-Dimethoxy-4-Methylamphetamine↗
Drug information roots: the influence of education and training on the philosophy and activities of hospital- and pharmacy school-based drug information services.
The objective of this project was to assess influences of past and present educational and training experiences on the development of drug information services. A questionnaire was used to collect information concerning the respondent's location, educational background, and relationship to others in the field. Next, demographic characteristics of the service were collected. The final section had respondent's rank 26 activities for both current scope of activities and the individual's philosophy of practice. Respondent's were asked to prioritize each activity according to contribution, directly or indirectly, to patient care. This study did not identify a major potential source of educational or training influence. However, despite the apparent lack of a major educational or training influence on the profession there is evidence to suggest that such influences can affect the scope of activities within services or the philosophy of practice of individuals. The differences in rankings commonly observed for the scope of activities support the observation of lack of equivalence in earlier studies.
Drug Information Services↗
Adverse drug effects: evaluation of four secondary reference sources.
Four adverse drug effect abstracting services, Adverse Drug Reaction Index, Clin-Alert, Current Drug Experience Literature, and Reactions were evaluated. Each service was evaluated in terms of the total number of articles cited, cost per citation, lag time, and time requirements for searches. The Adverse Drug Reaction Index was found to retrieve the most total and unique citations. Its potential disadvantages included the longest lag time and a high overall cost for the system. Reactions provided an alternative to this service, although it provided fewer total and unique citations. However, its overall costs is less, and the lag time is shorter. Clin-Alert ad Current Drug Experience Literature provided significantly fewer citations than the other services. Both services did retrieve unique citations.
Abstracting and Indexing↗
Effect of a P & T committee newsletter on anti-infective prescribing habits.
P & T newsletters are commonly employed as a way in which to educate the medical staff. However, studies suggest that a newsletter is an ineffective method of education. This study describes the effects of a newsletter and direct in-service education on altering prescribing habits of physicians in a university-based teaching hospital. The newsletter and in-service recommended that physicians switch from a commonly used anti-infective to a more cost-effective alternative that had recently been added to the formulary. Prescribing patterns were altered and sustained for at least 3 months. The newsletter was at least as effective as direct in-service education.
Drug Utilization↗
Biomedical literature retrieval: comparison of on-line and manual system.
Various data bases available for searching the biomedical literature were evaluated in terms of literature coverage, cost, and lag time. Five drug-disease topics were searched using on-line and manual data bases. With the exception of International Pharmaceutical Abstracts, on-line systems contained more citations than the corresponding manual versions. Of the manual data bases, Index Medicus contained the most citations. Lag times ranged from 66 to 673 days for the various data bases. The manual versions were less expensive per citation to search than the corresponding on-line data bases. On-line searching may actually increase the costs of literature retrieval, but the increase in the number of articles retrieved suggests that on-line literature retrieval is more cost-effective than manual searches.
Abstracting and Indexing↗