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Biomedical subjects

G M Anderson

Publications and source records attributed to G M Anderson.

At least 235 records · Page 13Linked to original sources
PubMed1981

Effects of bromocriptine in developing rat pups after 6-hydroxydopamine.

The effects of low (0.5 mg/kg) and high (2.0 mg/kg) doses of bromocriptine (BCR) on activity and escape performance were examined during the first month of postnatal life in normal developing rat pups and littermates treated at 5 days of age with a combination of desmethylimipramine and 6-hydroxydopamine (6-OHDA). Such a procedure resulted in significant reductions in brain dopamine to concentrations 10-20% of vehicle controls while norepinephrine was unaffected. BCR increased general motor activity in vehicle pups at 13 and 19 days but had little effect on more mature animals. Pups who had not received BCR exhibited a decline in activity over the hour long observation period (habituation of activity) but this decline was abolished by both low (0.5 mg/kg) and high (2.0 mg/kg) doses of the agent. Stereotyped activity, particularly at 19 days was increased by BCR in 6-OHDA pups but not in vehicle animals, an effect suggesting denervation supersensitivity. Head dips in a hole box at 30 days of age were not influenced by BCR in vehicle pups but significantly reduced by BCR in 6-OHDA pups, suggesting that BCR might be acting to stimulate inhibitory dopaminergic mechanisms. Escape learning in a T-maze at 20 days and shuttle box at 28 days was disrupted by high doses of BCR in vehicle pups and both doses of BCR in 6-OHDA animals. The similarity with the behaviors observed in the clinical syndrome of attention deficit disorder with hyperactivity prompted a number of investigative groups including our own to suggest that the 6-OHDA model might serve as a useful and convenient paradigm to evaluate pharmacological agents that offer potential in the treatment of this most common disorder. From this perspective we would predict that BCR would have little clinical utility since it both failed to attenuate 6-OHDA induced hyperactivity and tended to disrupt performance in an avoidance learning task.

Animals↗
PubMed1981

Photoelectron spectra of psychotropic drugs. 6. Relationships between the physical properties and pharmacological actions of amphetamine analogues.

The valence ionization potentials of seven additional members of a series of 2,4,5-trisubstituted amphetamines (1-phenyl-2-aminopropanes) were measured by UV photoelectron spectroscopy. These and previously published data provide experimental measures of the gross electron-donor ability of the aromatic rings of 23 amphetamines. Analogues bearing the 2,5-dimethoxy orientation were found to possess the lowest ionization potentials (IPs); for the analogously X-substituted compounds, the IPs increased in the order of 2,5-(OMe)2-4-X less than 2,4-(OMe)2-5-X less than 4,5-(OMe)2-2-X. Relationships between human psychotomimetic activity (MU), rabbit hyperthermia (SRU), serotonergic receptor affinity (pA2), and charge-transfer complex stabilities (KDNB) were evaluated statistically. A good correlation (r2 = 0.92) was established between the human and rabbit potencies, but poorer correlations were obtained between animal potencies and pA2's (r2 = 0.68-0.69) or KDNB's (r2 = 0.03!). Analysis of the regression relationships between these pharmacological measures and two physical properties, IP and lipid solubility (as modeled by log P), were explored. In general, greater potency is associated with decreasing IP and increasing log P. However, numerous exceptions to single parameter regressions are found. The unusually great potency of the 2,5-(OMe)2-4-X analogues, while qualitatively related to the physical properties, is quantitatively underestimated by these predictors. However, inclusion of a parameter (pi 4) which explicitly acknowledges the type of the 4-substituent leads to much improved correlations. These results support previous suggestions that 4-substituents interact directly with the receptor.

Amphetamines↗
PubMed1981

Urinary free catecholamines determined by liquid chromatography--fluorometry.

Free norepinephrine, epinephrine, and dopamine are determined in urine after purification on a small ion-exchange column and concentration on alumina. The catecholamines are separated by reversed-phase ion-pair chromatography and are quantitated by measuring their native fluorescence (lambda ex 285 nm, lambda em 305 nm). The internal standard is dihydroxybenzylamine. Within-day CVs for the compounds ranged from 1.6 to 5.6%; between-day CVs were 6.6 to 9.8%.

Chromatography, High Pressure Liquid↗
PubMed1980

Environmental influences on body weight and behavior in developing rats after neonatal 6-hydroxydopamine.

There is less hyperactive motor activity and better avoidance performance in rat pups treated with 6-hydroxydopamine as neonates and reared with vehicle-treated littermates than in pups reared in litters composed solely of other 6-hydroxydopamine-treated animals. Thus, in this experimental model of hyperactivity, an environmental manipulation provides an alternative to pharmacologic agents in reducing activity and improving learning performance.

Animals↗
PubMed1980

Serotonin receptor affinities of psychoactive phenalkylamine analogues.

Employing a rat fundus model, the serotonin (5-HT) receptor affinities of 45 phenalkylamine analogues were determined. Phenethylamine and phenylisopropylamine possess relatively low receptor affinities; in general, mono-, di-, and trimethoxylation enhance affinity. Of the disubstituted compounds, methoxyl groups at the 2 and 5 positions are optimal for imparting a high affinity. 4-Methylation, 4-ethylation and 4-bromination also enhance receptor affinity, while N,N-dimethylation of the terminal amine decreases affinity. alpha-Methylation of phenethylamines has little effect on affinity when racemates are examined. Introduction of a benzylic keto group can either increase or decrease affinity, depending upon the presence of other aromatic substituents. The most behaviorally active compounds were found to possess the highest 5-HT receptor affinities, while less active compounds were found to possess lower affinities.

Amines↗
PubMed1980

Tryptophan, 5-hydroxyindoleacetic acid and indoleacetic acid in human cerebrospinal fluid: interrelationships and the influence of age, sex, epilepsy and anticonvulsant drugs.

Tryptophan, 5-hydroxyindoleacetic acid and indoleacetic acid were measured in cerebrospinal fluid, taken during pneumoencephalography, from a large series of patients, the majority of whom were epileptics, most of them receiving anticonvulsants. CSF indoleacetic acid reflects CNS tyrptamine metabolism in the same way that CSF 5-hydroxyindoleacetic acid reflects CNS 5-hydroxytryptamine metabolism. Our data suggest that (i) the brain tryptophan content is an important factor in the control of both 5-hydroxytryptamine and tryptamine synthesis (ii) brain 5-hydroxytryptamine metabolism exhibits a U-shaped relationship with age (iii) the mean brain tryptophan content and rate of 5-hydroxytryptamine metabolism are greater for women than men (iv) indoleamine metabolism is unaffected in untreated epileptics compared with non-epileptics, but anticonvulsant drugs decrease the rate of 5-hydrosytryptamine metabolism.

Adult↗
PubMed1978

Quantitative structure-activity relationships in the 2,4,5-ring substituted phenylisopropylamines.

The potency of a series of 2,4,5-ring substituted phenylisopropylamines was examined using the rabbit hyperthermia assay. An excellent correlation (r = 0.99) was found between the rabbit hyperthermic and human psychotomimetic potencies. In the hyperthermic model, the 4-X-substituted-2,5-dimethoxyphenylisopropylamines were found to be one to two orders of magnitude more potent than the 2-X- or 5-X-substituted positional isomers (X = -H, -CH3, -SCH3, -Br). Conformational perturbations induced by substituents ortho to the ethylamine side chain were studied with the PCILO and ab initio molecular orbital methods. The variations in the biological activities could not be rationalized in terms of the ability of the ortho substituents to stabilize conformations which mimic LSD. The electronic structures of the positional isomers were examined in the corresponding toluene analogues using the CNDO/2 method. A reasonable correlation (r = 0.98) was found between the Highest Occupied Molecular Orbital (HOMO) energy and the ionization potentials reported from photoelectron spectroscopy studies. In the case of the positional isomers, the HOMO energies were ordered as follows: 4-X greater than 5-X greater than 2-X. However, the regression analysis of the relationship between these orbital energies and Log Biological Activity (B.A.) was not impressive. Examination of the partition coefficients (octanol/water) of the positional isomers indicated that the 4-X- and 5-X-substituted compounds have almost equivalent Log P's, but that the 2-X-substituted-4,5-dimethoxyphenylisopropylamines are unusually hydrophilic. The regression of Log H.P. to the HOMO energies resulted in a marginally significant relationship; addition of the Log P's resulted in no significant improvement. Qualitative models based on both regiospecific lipophilicity or electron densities and also metabolic conversion to reactive intermediates are presented.

Animals↗
PubMed1975

Quantitation of tryptophan metabolites in rat feces by thin-layer chromatography.

Indole, skatole, indole-3-acetic acid, indole-3-propionic acid, tryptamine, and free tryptophan have been extracted from rat fecal samples and quantitated by thin-layer chromatography. Additional tryptophan metabolites have been recovered in yields of 87-97% from supplemented fecal samples. Detection limits for all the compounds studied were in the 0.1 mug/g feces range. Quantitation was possible in the mug/g range with an estimated accuracy of plus or minus 10%.

Animals↗
PubMed1975

Formation of indoleacetic acid by intestinal anaerobes.

Indoleacetic acid was produced from tryptophan by only three of 23 intestinal anaerobes studied. Evidence is presented to show that the formation of indoleacetic acid proceeds through the intermediate, indolepyruvic acid, via transamination with alpha-ketoglutarate rather than by tryptamine pathway.

Anaerobiosis↗