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Biomedical subjects

J E Barrett

Publications and source records attributed to J E Barrett.

At least 73 records · Page 4Linked to original sources
PubMed1990

Interactions of corticotropin-releasing factor with antidepressant and anxiolytic drugs: behavioral studies with pigeons.

A number of studies have shown significant interactions between neuronal systems involved with corticotropin-releasing factor (CRF) and either the clinical manifestations of depression and anxiety or the effects of antidepressant or anxiolytic drugs. In the present study, effects of CRF were studied alone and in combination with imipramine and with the sedative-hypnotic/anxiolytic drugs pentobarbital and chlordiazepoxide. Interactions of CRF with the novel, atypical anxiolytic buspirone were also examined. Interactions were evaluated through the use of schedule-controlled responding, responding suppressed by punishment, and drug discrimination procedures using the conditioned key-pecking response of pigeons. Effects of CRF were significantly enhanced when given in combination with imipramine with low noneffective imipramine doses potentiating the rate-reducing effects of CRF. Similarly, in pigeons trained to discriminate imipramine from saline, noneffective doses of CRF shifted the imipramine dose-response curve more than twofold to the left. Low doses of imipramine that produced saline key responding, produced imipramine-key responding when coadministered with CRF. The CRF antagonist alpha-helical CRF9-41 did not alter the rate-decreasing effects of imipramine. Effects of CRF on schedule-controlled responding were, however, antagonized by the administration of chlordiazepoxide and pentobarbital but not by buspirone, suggesting that CRF interacts with the GABA/benzodiazepine receptor mechanism complex but not with those systems involved in mediating the effects of buspirone. These results suggest that CRF interacts in significant ways with specific neurotransmitter systems subserving depression and anxiety.

Animals↗
PubMed1990

5-HT1A agonist effects on punished responding of squirrel monkeys.

Buspirone and other drugs that act as 5-HT1A agonists appear to be clinically effective anxiolytics in humans, yet their anticonflict effects, though robust in pigeons, are equivocal in rodents. In the present study we examined the effects of the benzodiazepine midazolam and a series of 5-HT1A agonists on punished responding of squirrel monkeys. Lever presses were reinforced according to a fixed-interval 3-min schedule; in addition, each thirtieth lever press was punished. Midazolam produced large increases in response rates, whereas none of the 5-HT1A compounds produced any increases in responding. Most of these drugs decreased response rates at the higher doses examined. Although the reasons for the discrepancy between species in the anticonflict effects of serotonergic anxiolytics cannot be specified, the different anatomical distribution of 5-HT1A binding sites across species may suggest a different functional role for this receptor.

Animals↗
PubMed1990

Symptomatology of late-life minor depression among primary care patients.

Patients of four general internists and four family physicians were interviewed by two psychiatrists to identify those suffering from depressive disorders. Nineteen elderly (60 years of age and older) patients and 22 younger (between 18 and 59 years of age) patients met Research Diagnostic Criteria (RDC) for minor depressive disorder, and 73 elderly and 79 younger patients had no psychiatric disorder. In general, the elderly depressed medical outpatients and the younger depressed medical outpatients had similar symptomatology, as did the elderly and nonelderly medical outpatients without psychiatric disorders.

Adult↗
PubMed1990

Trace element nutrition status and dietary intake of children with phenylketonuria.

The trace element status (copper, iron, zinc, manganese, chromium, and selenium) of 20 dietetically treated phenylketonuric (PKU) children was assessed. Significantly higher intakes of copper (p = 0.002) and iron (p = 0.005) were noted in PKU children compared with their siblings. No significant differences were found for zinc, manganese, or chromium. Intake of selenium was significantly lower (p = 0.0001) in PKU children (8.4 +/- 3.9 micrograms/d) than in siblings (41.6 +/- 9.4 micrograms/d). Plasma and urine selenium and erythrocyte glutathione peroxidase activity (GSHpx) were significantly lower (p = 0.001) in PKU children (0.38 +/- 0.11 mumol/L, 58.0 +/- 34.5 nmol/d, and 14.2 +/- 5.5 U/g Hb, respectively) than in siblings (0.82 +/- 0.15 mumol/L, 165.2 +/- 49.4 nmol/d, and 22.7 +/- 5.2 U/g Hb, respectively). No differences were found in plasma and urine concentrations of other elements. Intake of selenium was significantly correlated with erythrocyte GSHpx (r = 0.87, p = 0.0001) and plasma selenium (r = 0.71, p = 0.0001) for the combined groups. The need and possible procedures, including dietary manipulation, for increasing selenium intake in PKU subjects are discussed.

Adolescent↗
PubMed1989

Behavioral and neurochemical effects of the serotonin (5-HT)1A receptor ligand spiroxatrine.

The effects of spiroxatrine, a putative antagonist with selectivity for the serotonin (5-HT)1A receptor, were compared with compounds believed to function as agonists at the 5-HT1A receptor. Schedule-controlled responding of pigeons was maintained under a multiple 30-response fixed-ratio (FR), 3-min fixed-interval (FI) schedule or under a schedule in which responding was suppressed by electric shock ("conflict" procedure). Under the multiple schedule, spiroxatrine (0.3-1.0 mg/kg) decreased FR responding but did not affect FI responding; responding was decreased in both schedule components at 3.0 mg/kg. When administered alone, buspirone, a compound believed to produce its anxiolytic effects through 5-HT1A agonist actions, produced effects similar to those of spiroxatrine; in combination, the two drugs produced greater effects than when either was administered alone. As with 5-HT1A agonists such as buspirone and 8-hydroxy-2(di-n-propylamino)tetralin (8-OH-DPAT) in the pigeon, spiroxatrine (0.01-1.0 mg/kg) increased punished responding. Spiroxatrine and buspirone were potent inhibitors of [3H]8-OH-DPAT binding to pigeon cerebral membranes with IC50 values in the nM range. Neurochemical analyses of metabolite changes produced by spiroxatrine in pigeon cerebrospinal fluid showed buspirone-like effects, with increases in MHPG, DOPAC and HVA at doses that decreased 5-HIAA levels. Spiroxatrine dose-dependently blocked the behavioral effects of the dopamine agonist piribedil indicating that, like buspirone, it also is a potent dopamine antagonist. Spiroxatrine most likely functions as an agonist at the 5-HT1A receptor. As with buspirone, however, spiroxatrine has a prominent dopamine antagonist component.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1989

Behavioral effects of (+-) 3,4-methylenedioxyamphetamine (MDA) and (+-) 3,4-methylenedioxymethamphetamine (MDMA) in the pigeon: interactions with noradrenergic and serotonergic systems.

The effects of three amphetamine analogs were assessed in pigeons key pecking under a multiple 3-min fixed-interval (FI), 30 response fixed-ratio (FR) schedule of food presentation. At doses between 0.1 and 10.0 mg/kg, (+-) 3,4-methylenedioxyamphetamine (MDA), (+-) 3,4-methylenedioxymethamphetamine (MDMA), and (+-)-N-ethyl-3,4-methylenedioxyamphetamine (MDE) either had no effect or decreased response rates in both components of the multiple schedule in a dose-dependent manner. MDA was at least 1 log unit more potent than the other two compounds. Metergoline (0.1-1.0 mg/kg), a serotonin (5-HT) antagonist with comparable affinity for the 5-HT1 and 5-HT2 receptor subtypes, blocked the rate-decreasing effects of 3.0 mg/kg MDA in both components of the multiple schedule, but did not affect the MDMA dose-response curve. The 5-HT2 receptor antagonist ketanserin (0.1-3.0 mg/kg) also restored FI and FR responding that was decreased by 3.0 mg/kg MDA, but had no effect on responding suppressed by MDMA. The noradrenergic alpha-1 antagonist prazosin (0.3-3.0 mg/kg) blocked the behavioral effects of 3.0 mg/kg MDMA at doses that did not attenuate MDA's rate-decreasing effects. These results indicate that although MDA and MDMA are structurally similar and have similar behavioral effects, their actions appear to be mediated through different neurotransmitter systems.

3,4-Methylenedioxyamphetamine↗
PubMed1989

Neurochemical changes in pigeon cerebrospinal fluid during chronic administration of buspirone or 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT).

Cerebrospinal fluid (CSF), collected repeatedly from White Carneau pigeons chronically implanted with guide cannulae located in the lateral ventricles, was analyzed for metabolites of serotonin, dopamine and norepinephrine after acute and chronic administration of buspirone or 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Following the acute administration of 3.0 mg/kg buspirone, levels of 5-hydroxyindoleacetic acid (5-HIAA) decreased, while increases occurred in the dopamine metabolites homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC). Decreases in 5-HIAA persisted throughout the chronic dosing regimen (36 days), while dopamine metabolites returned to control levels within 8 days. When chronic buspirone was discontinued, levels of 5-HIAA were restored to predrug control levels, while levels of HVA, DOPAC and 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) decreased. All metabolites returned to predrug control levels within one week following buspirone discontinuation except for MHPG, which remained depressed. When the acute effects of buspirone were reexamined, levels of 5-HIAA were again significantly decreased, while HVA and DOPAC levels, as well as those of MHPG, increased significantly. Acute administration of the 5-HT1A receptor ligand 8-OH-DPAT (3.0 mg/kg) resulted in large decreases in 5-HIAA levels that persisted throughout the period of chronic administration. Neither acute nor daily administration of 8-OH-DPAT changed levels of HVA, DOPAC or MHPG. Large increases in 5-HIAA occurred when chronic 8-OH-DPAT was discontinued but declined within one week to control levels. Following a two-week drug-free period, 8-OH-DPAT again caused a significant reduction in 5-HIAA levels.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Physostigmine-insensitive behavioral excitatory effects of atropine in squirrel monkeys.

Lever press responses of squirrel monkeys were maintained under a multiple schedule in which the first response after 3 min produced either food or electric shock depending on the prevailing stimulus. Atropine sulfate (0.3-3 mg/kg, IM) given immediately before experimental sessions disrupted the temporal pattern of responding and produced dose-related decrease in rates of food- and shock-maintained responding. Increases in responding occurred when 1 mg/kg atropine was given 1 to 12 hr prior to experimental sessions. A maximal increase of 200% of control rates was seen following the 2-hr pretreatment. Qualitatively similar effects were obtained with scopolamine suggesting that the time-dependent increases may be a general consequence of muscarinic receptor blockade. Response patterning changes and response rate increases were also produced by coadministration of atropine and physostigmine both given immediately before the session. Increases in rates of responding have also been observed previously after administration of atropine with rate-decreasing doses of the direct-acting muscarinic agonist oxotremorine. Physostigmine did not reverse the rate increases or the alteration in temporal patterning produced by the 2-hr atropine pretreatment; rate decreases induced by immediate pretreatment with atropine were blocked by physostigmine. Thus, the response rate-decreasing effects of atropine were distinct from its rate-increasing effects. Whereas the rate-decreasing effects of atropine appear to involve muscarinic receptors, increases in responding may not. Such nonmuscarinic behavioral excitatory actions of atropine may be expressed when the muscarinic-related decreases are blocked by physostigmine or oxotremorine, or when the decreases are overridden by excessive nonmuscarinic stimulation, perhaps triggered by time-dependent changes in acetylcholine turnover associated with atropine.

Animals↗
PubMed1989

Acute and chronic effects of corticotropin-releasing factor on schedule-controlled responding and neurochemistry of pigeons.

Key pecking by pigeons was maintained under various schedules of food presentation. Acute i.c.v. administration of corticotropin-releasing factor (CRF) (3.0-30.0 micrograms/kg) decreased responding in both components of a multiple 3-min fixed-interval, 30-response fixed-ratio schedule and under a multiple fixed-ratio schedule in which responding during one component was punished by shock delivery. The rate-decreasing effects of intermediate doses of CRF were blocked by the CRF antagonist alpha-helical CRF9-41 under the multiple fixed-internal fixed-ratio schedule, with 10.0 micrograms/kg of the antagonist producing a more complete reversal than 30.0 micrograms/kg. The rate-reducing effects of 10.0 and 30.0 micrograms/kg of CRF disappeared rapidly when CRF was administered daily, with complete restoration of responding occurring by the 4th day of chronic administration. Acute effects were recovered when CRF administration was discontinued for 7 to 14 days. Analyses of cerebrospinal fluid revealed that behaviorally active doses of CRF produced large, dose-dependent increases in levels of the serotonin metabolite 5-hydroxyindoleacetic acid and in the dopamine metabolites dihydroxyphenylacetic acid and homovanillic acid; smaller increases also occurred in the levels of 3-methoxy-4-hydroxyphenylethylene glycol, the metabolite of norepinephrine. Chronic administration of 30 micrograms/kg of CRF for a 4-day period did not reveal any change in metabolite levels when compared to those obtained after acute administration, with the exception of 3-methoxy-4-hydroxyphenylethylene glycol which approached control levels after chronic CRF. These results indicate that, as is the case with mammals, CRF has potent behavioral and neurochemical activity in avian species and that tolerance occurs rapidly to the behavioral effects.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Behavioral studies with anxiolytic drugs. VI. Effects on punished responding of drugs interacting with serotonin receptor subtypes.

The effects of drugs that bind selectively to different serotonin (5-HT) receptor subtypes were assessed in pigeons. Keypecking was maintained by a multiple fixed-ratio schedule of reinforcement in which responding also was punished during one component. The greatest increases in punished responding were produced by the buspirone analogs BMY 7378 and ipsapirone, which act at the 5-HT1A receptor. RU 24969, with high affinity for both 5-HT1A and 5-HT1B receptors, and 1-(2-methoxyphenyl)piperazine, a 5-HT1 compound, increased punished responding to a lesser extent, as did the 5-HT2 antagonists ketanserin and ritanserin. The 5-HT3 antagonists GR 38032F, ICS 205930 and MDL 72222 showed little systematic effect, and the mixed 5-HT1B/5-HT1C compound 1-(3-chlorophenyl)piperazine produced only decreases in punished responding. Levels of neurotransmitter metabolites in cerebrospinal fluid were assessed across a wide dose range of representative drugs used in the behavioral studies. Levels of the 5-HT metabolite 5-hydroxyindoleacetic acid were decreased significantly by BMY 7378 and ipsapirone, were not changed by ritanserin and were increased at one dose by MDL 72222. The results are consistent with suggestions that decreased 5-HT neurotransmission is involved in the effects of novel nonbenzodiazepine anxiolytics such as buspirone. Behavioral and neurochemical data also indicate that the effects of these drugs on other neurotransmitter systems do not play a significant role in their anxiolytic actions.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

The prevalence of psychiatric disorders in a primary care practice.

Using a two-stage case identification process, patients from a rural primary care practice were assessed for psychiatric disorders (Research Diagnostic Criteria [RDC] categories) over a 15-month period. The prevalence of all psychiatric disorders was 26.5%; 10.0% were specific RDC depressive disorders, and 5.3% were disorders without depression, usually anxiety related. Another 11.2% of patients were thought to have a disorder with significant depressive symptomatology that could not be classified into a specific depressive disorder category, a finding that suggests restricted usefulness of specialty-based categories for the range of clinical presentations in primary care. The relationship of demographic variables to specific disorders was examined; there were age, sex, and marital status differences in the rates for certain disorders, although these findings need replication using large patient samples. The prevalence findings emphasize the need for research on outcome and treatment response for depression presentations in primary care.

Adolescent↗
PubMed1988

Antagonism by ketanserin of the behavioral effects of quipazine but not l-5-hydroxytryptophan in squirrel monkeys.

The serotonin agonist quipazine maleate (1-10 mg/kg, IM) and the serotonin precursor l-5-hydroxytryptophan (5HTP, 3-30 mg/kg, IM) produced dose-dependent decreases in responding (lever-pressing) of squirrel monkeys maintained under a fixed-ratio 30 schedule of food presentation. The classical serotonin antagonist methysergide antagonized the behavioral effects of both quipazine and 5HTP. The behavioral effects of quipazine but not 5HTP were antagonized by the selective serotonin-2 receptor antagonist ketanserin. These results suggest that decreases in food-maintained responding may be produced independently by stimulation of either serotonin-1 or serotonin-2 receptor subtypes.

5-Hydroxytryptophan↗
PubMed1988

Effects of buspirone differ from those of gepirone and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on unpunished responding of pigeons.

Under several behavioral procedures, such as punished responding and drug discrimination, the effects of the atypical anxiolytic buspirone are similar to those of its analogue gepirone, and to those of the 5-HT1A receptor agonist 8-OH-DPAT. Similarities in the effects of these compounds occur despite the fact that buspirone produces strong dopaminergic actions, whereas both gepirone and 8-OH-DPAT effects mainly appear to be serotonergically mediated. When keypeck responding of pigeons was maintained under a multiple 3-min fixed-interval, 30-response fixed ratio schedule of food presentation, responding under both the fixed-interval and fixed-ratio schedules was decreased over a range of buspirone doses (0.3-5.6 mg/kg). As has been reported with many antipsychotic compounds, performance under the fixed-interval schedule was more sensitive to the rate-decreasing effects of buspirone. In contrast, both gepirone (0.03-3.0 mg/kg) and 8-OH-DPAT (0.03-1.0 mg/kg) increased responding under the two schedules. Differences in the effects of buspirone from the other compounds in this study, compared to the similar effects of these drugs obtained using other procedures, emphasize the importance of the specific behavior as a determinant of drug action. The multiple fixed-interval, fixed-ratio schedule may be useful for delineating the relative balance of dopaminergic and serotonergic effects produced by drugs that are less apparent using other behavioral procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1988

Behavioral studies with anxiolytic drugs. V. Behavioral and in vivo neurochemical analyses in pigeons of drugs that increase punished responding.

Behavioral and neurochemical effects of several drugs that increase punished responding were studied in pigeons. Key pecking was established under a schedule of reinforcement in which periods of food-maintained responding alternated with periods in which behavior also was suppressed by the presentation of electric shock. Buspirone (0.1-10.0 mg/kg), gepirone (0.1-1.0 mg/kg), 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.1-3.0 mg/kg), chlordiazepoxide (3.0-30.0 mg/kg) and to a lesser extent clozapine (0.1-1.0 mg/kg) all produced increases in punished responding at doses having little effect on or decreasing the rate of unpunished responding. Neurochemical analyses on samples of cerebrospinal fluid after administration of several doses of each compound were performed for the dopamine metabolites homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC), the noradrenergic metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA). Gepirone, 8-OH-DPAT and the novel anxiolytic buspirone produced decreases in 5-HIAA at doses that increased punished responding in the behavioral studies. Buspirone increased levels of HVA and DOPAC, whereas its structural analog gepirone and the 5-hydroxytryptamine1A agonist 8-OH-DPAT had little effect on or decreased levels of these metabolites. Chlordiazepoxide, a prototypic benzodiazepine anxiolytic, produced only modest decreases in each of the metabolites studied. Clozapine, an atypical antipsychotic drug, produced increases in each of the metabolites studied, although only the 5-HIAA effect occurred at doses that were not behaviorally disruptive. Haloperidol (0.03-1.0 mg/kg) produced only decreases in punished and unpunished responding, whereas eliciting increases in the appearance of MHPG, DOPAC and HVA; levels of 5-HIAA were relatively unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Psychiatric symptoms in the elderly in a primary care practice.

During a 15-month period in a rural group medical practice 1063 patients of four general internists completed a 49-item version of the Hopkins Symptom Check List (HSCL). This version of the HSCL measured symptoms of depression, anxiety, phobic anxiety, hostility, and interpersonal sensitivity. In comparison to younger groups, the elderly patients reported decreased symptomatology on all HSCL scales except the phobic anxiety scale. These differences could be due to a reporting effect, selective migration or mortality, a cohort effect, or they could reflect a true age effect, the view favored by the authors.

Aged↗
PubMed1987

Behavioral studies with anxiolytic drugs. IV. Serotonergic involvement in the effects of buspirone on punished behavior of pigeons.

Interactions of the nonbenzodiazepine anxiolytic, buspirone, with serotonin (5-HT) were studied using behavioral and neurochemical procedures. Punished responding was studied in pigeons as this behavior is a generally acknowledged preclinical predictor of anxiolytic activity and because buspirone increases punished responding of pigeons with greater potency and efficacy than in other species. Keypeck responses were maintained under either fixed-interval or fixed-ratio schedules of food presentation; every 30th response produced a brief electric shock and suppressed responding (punishment). Buspirone (0.1-5.6 mg/kg i.m.) produced dose-related increases in punished responding which reached a maximum at 1 mg/kg. A serotonin agonist, MK-212 (0.01 mg/kg), antagonized whereas the 5-HT antagonist, cyproheptadine (0.01 mg/kg), potentiated the effects of buspirone without having behavioral effects of their own. The characteristics of [3H]-5-HT binding in pigeon brain membranes were similar to results reported in mammalian brain. Neither buspirone, MJ-13805 (gepirone, a related analog), nor MJ-13653 (a buspirone metabolite), significantly affected [3H]-5-HT binding and none of the compounds appreciably inhibited uptake of [3H]-5-HT into pigeon cerebral synaptosomes. Hill coefficients significantly less than unity for all drugs except 5-HT suggested multiple serotonergic binding sites for buspirone and analogs. Buspirone and MJ-13805 (1 nM) inhibited [3H]ketanserin binding (a measure of 5-HT2 binding sites) in pigeon cerebrum with Ki values above 10(-6) M. The number of [3H]ketanserin binding sites was estimated to be 109 fmol/mg of protein in pigeon cerebrum compared to 400 fmol/mg of protein in rat cerebrum.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1987

Discriminative stimulus properties of buspirone in the pigeon.

The novel anxiolytic buspirone was administered to pigeons in a two-key drug discrimination task in an effort to characterize the stimulus properties of the drug and thereby aid in isolating the pharmacologic basis for its anticonflict effect. Key pecking was maintained by a schedule of reinforcement in which every 30th injection-appropriate response was reinforced by the presentation of food. Subjects were first trained to discriminate buspirone (1.0 mg/kg) from saline, and then generalization tests were conducted using a cumulative dosing procedure. Cumulative doses of buspirone (1.0-3.0 mg/kg), the buspirone analog MJ 13805 (1.0 mg/kg) and the 5-hydroxytryptamine-1A ligand 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (0.3-1.0 mg/kg) produced in excess of 90% buspirone-appropriate responding, whereas midazolam (0.03-1.0 mg/kg), haloperidol (0.03-1.7 mg/kg), apomorphine (0.03-1.0 mg/kg), clozapine (0.1-3.0 mg/kg), methysergide (0.1-3.0 mg/kg) and the 5-hydroxytryptamine-1B ligand 1-[3-chlorophenyl]piperazine (0.3-10.0 mg/kg) produced little or no buspirone-appropriate responding up to those doses that markedly decreased response rate. These findings support recent behavioral and receptor binding studies suggesting that serotonin receptors, and 5-hydroxytryptamine-1A receptors in particular, may be responsible for mediating the anticonflict effects of buspirone and other atypical anxiolytics. The results also corroborate other behavioral work showing that the anxiolytic effects of buspirone are most likely not mediated by the dopaminergic system.

Animals↗