An uptake system for dietary alkaloids in poison frogs (Dendrobatidae).

The skin of poison frogs (Dendrobatidae) contains a wide variety of alkaloids that presumably serve a defensive role. These alkaloids persist for years in captivity, but are not present in captive-raised frogs. Alkaloids fed to poison frogs (Dendrobates, Phyllobates, Epipedobates) are readily accumulated into skin, where they remain for months.

Depressive mania versus agitated depression: biogenic amine and hypothalamic-pituitary-adrenocortical function.

The existence of mixed affective states challenges the idea of specific biological abnormalities in depression and mania. We compared biogenic amines and hypothalamic-pituitary-adrenocortical (HPA) function in mixed manic (n = 8), pure manic (n = 11), agitated bipolar depressed (n = 20), and nonagitated bipolar depressed (n = 27) inpatients (Research Diagnostic Criteria). Mixed manics met Research Diagnostic Criteria for primary manic episodes and also met criteria for major depressive episodes except for duration.

Expressive characteristics of anxiety in depressed men and women.

This study was aimed at identifying the expressive, movement, and social behaviors associated with anxiety in the syndrome of major depression. The sample consisted of 97 hospitalized male and female depressed patients. Expressive and social behaviors were evaluated prior to treatment in a structured videotaped interview.

Specificity of mixed affective states: clinical comparison of dysphoric mania and agitated depression.

To investigate the clinical specificity of mixed affective states, we compared clinical characteristics of mixed (dysphoric) manics to those of agitated depressed patients. The subjects were inpatients studied in the NIMH Clinical Research Branch Collaborative Study on the Psychobiology of Depression, Biological Studies. Behavior and symptom ratings for depressive and manic symptoms were obtained during a 15-day placebo washout period.

Structure-activity relationships for 2-substituted adenosines at A1 and A2 adenosine receptors.

A series of 55 2-alkyloxy-, 2-aryloxy- and 2-aralkyloxy-adenosines was screened as inhibitors of the binding of [3H]R-phenyl-isopropyladenosine to A1 adenosine receptors in rat cerebral cortical membranes, and of the binding of [3]N-ethylcarboxamidoadenosine to A2 adenosine receptors in rat striatal membranes and as agonists at A2 adenosine receptors coupled to adenylate cyclase in rat pheochromocytoma PC12 cell membranes. The activities are consonant with a hydrophobic binding site in the A2 receptors at a distance from the 2-position of the adenine ring corresponding to a spacer chain of -O-CH2-CH2-. These is little lateral steric tolerance in the region occupied by the spacer chain.

Variability in alkaloid profiles in neotropical poison frogs (Dendrobatidae): genetic versus environmental determinants.

Dendrobatid frogs produce a diverse set of alkaloids, whose profiles appear characteristic of frogs of each species or, in the case of variable species, of each population. In the case of one widespread species, Dendrobates auratus, alkaloid profiles in extracts of skin are markedly different in three populations, one from a Pacific island, Isla Taboga, Panama, one from central mountains in Panama, and the third from the Caribbean coast in Costa Rica. The first contains three major classes of dendrobatid alkaloids, the histrionicotoxins, the pumiliotoxin-A class and the decahydroquinolines.

Hypothalamic-pituitary-adrenocortical function in mixed and pure mania.

There is little information about hypothalamic-pituitary-adrenocortical (HPA) axis function in mania, particularly in mixed states. We therefore investigated HPA function and its relationship to clinical state in 19 hospitalized manic patients meeting Schedule for Affective Disorders and Schizophrenia - Research Diagnostic Criteria for acute manic episodes, compared patients with and without a mixed presentation, and examined correlations between HPA activity and behavior. Data were available from 13-16 patients.

Activity of N6-substituted 2-chloroadenosines at A1 and A2 adenosine receptors.

Radioligand binding studies of N6-substituted adenosines at the A1 and A2 adenosine receptors of rat brain cortex and rat brain striatum, respectively, show that a 2-chloro substituent does not consistently change the affinity or the selectivity of these analogues for the A1 receptor. A 2-chloro substituent lowers the characteristic stereoselectivity of the A1 receptor toward the R diastereomer of N6-(1-phenyl-2-propyl)adenosine. A 2-chloro substituent consistently increases potency of N6-substituted adenosines as agonists at an adenosine A2 receptor stimulatory to adenylate cyclase in PC12 cell membranes.

N6,9-disubstituted adenines: potent, selective antagonists at the A1 adenosine receptor.

N6-Substituted 9-methyladenines are potent antagonists of the activation of A1 adenosine receptors. The present study assessed the effect of N6 and N-9 substituents on the binding of adenines to the A1 and A2 receptors, respectively, of rat brain cortex and striatum and also on the antagonism of the A2 receptor mediated stimulation of the adenylate cyclase of PC12 cells by N-ethyladenosine-5'-uronamide. The potency ranking of 9-substituted adenines varied directly with the hydrophobicity of the substituent: cyclopentyl greater than phenyl greater than tetrahydrofuryl greater than ethyl greater than methyl greater than 2-hydroxyethyl.

Identifying the specific clinical actions of amitriptyline: interrelationships of behaviour, affect and plasma levels in depression.

Despite increasing knowledge of the neurochemical bases of the action of the tricyclic drugs, little is known about the sequence of psychological effects which precede recovery in drug-responsive patients. This research was aimed at identifying the specific behavioural effects associated with the therapeutic action of amitriptyline in depression. The design involved measurement (post-hoc) of weekly changes in a severely depressed placebo-resistant group who recovered with drug treatment, compared with a group of similar patients treated for the equivalent four weeks, who showed minimal to no clinical response.

Mania: sympathoadrenal function and clinical state.

We investigated sympathoadrenal and sympathetic nervous system activity, catecholamine disposition, and clinical state in 19 hospitalized manic patients. Severity of the core manic syndrome, anxiety, and hostility correlated with 24-hour urinary excretion of epinephrine relative to its metabolites, but only weakly with norepinephrine. Agitation, however, correlated most strongly and significantly with norepinephrine.

Cardiovascular actions of adenosines, but not adenosine receptors, differ in rat and guinea pig.

This study compared the structure-activity relationships of 16 analogues at the A1 and A2 adenosine receptors (A1AR, A2AR) of rat and guinea pig. Radioligand binding studies revealed no marked differences in the affinities of each analogue at the A1AR of brain cortex or the A2AR of brain striatum. Bioassay employing Langendorff heart preparations showed that the guinea pig is more sensitive than the rat to A1AR-mediated slowing of conduction through the atrioventricular node and, in some instances, to A2AR-mediated coronary vasodilation.

Pumiliotoxin alkaloids: a new class of sodium channel agents.

Pumiliotoxin B (PTX-B) and a variety of congeneric alkaloids and synthetic analogs stimulated sodium flux and phosphoinositide breakdown in guinea pig cerebral cortical synaptoneurosomes. The effects of PTX-B and active congeners and analogs on sodium flux in synaptoneurosomes were potentiated markedly by scorpion venom (Leiurus quinquestriatus). In neuroblastoma cells, PTX-B and active congeners had no effect on sodium flux unless synergized by alpha-scorpion toxin or scorpion venom.

Response to treatment with antidepressants of patients with severe or moderate nonpsychotic depression and of patients with psychotic depression.

Hospitalized patients were divided into nonpsychotic severely depressed (N = 53), nonpsychotic moderately depressed (N = 54), and psychotic depressed (N = 25) groups and treated with either imipramine or amitriptyline, up to 250 mg/day, for 4 weeks. Good response occurred in 39% of the 38 severely depressed, 67% of the 49 moderately depressed, and 32% of the 19 psychotic depressed patients who completed treatment. The response of the patients with nonpsychotic severe depression did not differ significantly from the response of those with psychotic depression, and both groups fared worse than the group with nonpsychotic moderate depression.

Lithium distribution in mania: single-dose pharmacokinetics and sympathoadrenal function.

We examined lithium distribution after a single dose of 25 mEq in 14 drug-free manic patients. Lithium concentrations were measured in plasma, red blood cells, and urine. Maximum concentrations of lithium, times at which they were attained, and influx and efflux rate constants for extracellular fluid, red blood cell, and muscle-like compartments were estimated using a three-compartment pharmacokinetic model.

Stress, depression, and mania: relationship between perceived role of stressful events and clinical and biochemical characteristics.

We investigated the perceived role of stressful events in episodes of major affective disorder in patients studied in the NIMH Clinical Research Branch Collaborative Program on the Psychobiology of Depression (Biological Studies). Using items from the Schedule for Affective Disorders and Schizophrenia (SADS), episodes were divided into environment-sensitive (high perceived role of stressful events) and autonomous (minimal or no perceived role of stressful events). Patients with environment-sensitive episodes had fewer previous episodes and a longer index episode.

Sulfur-containing 1,3-dialkylxanthine derivatives as selective antagonists at A1-adenosine receptors.

Sulfur-containing analogues of 8-substituted xanthines were prepared in an effort to increase selectivity or potency as antagonists at adenosine receptors. Either cyclopentyl or various aryl substituents were utilized at the 8-position, because of the association of these groups with high potency at A1-adenosine receptors. Sulfur was incorporated on the purine ring at positions 2 and/or 6, in the 8-position substituent in the form of 2- or 3-thienyl groups, or via thienyl groups separated from an 8-aryl substituent through an amide-containing chain.

Pyrethroids: involvement of sodium channels in effects on inositol phosphate formation in guinea pig synaptoneurosomes.

The effects of pyrethroids were studied on phosphoinositide breakdown in guinea pig synaptoneurosomes. Similar to other agents that activate voltage-dependent sodium channels, type I and type II pyrethroids stimulated phosphoinositide breakdown. Type II pyrethroids, like deltamethrin and fenvalerate, were more potent and, at least for deltamethrin, more efficacious than type I pyrethroids, like allethrin, resmethrin and permethrin.

Sociodemographic and prior clinical course characteristics associated with treatment response in depressed patients.

A sociodemographic and clinical picture is presented of 82 depressed subjects who had an unequivocal response or lack of response to treatment with amitriptyline or imipramine. Patients with less severe depressive illness were found more likely to respond to treatment, while those with psychotic features were more likely to be treatment resistant. Sociodemographic and other prior and current clinical course variables were not predictive of treatment response in depressed patients.

Lithium carbonate treatment of mania. Cerebrospinal fluid and urinary monoamine metabolites and treatment outcome.

Treatment of manic patients with lithium carbonate was associated with significant decreases in cerebrospinal fluid (CSF) 3-methoxy-4-hydroxyphenylglycol (MHPG) and urinary norepinephrine excretion. These measures, before treatment, were higher in manic patients than in either depressed or normal subjects and correlated significantly with severity of mania. Levels in CSF of homovanillic acid and 5-hydroxyindoleacetic acid did not correlate with severity or with change during lithium carbonate treatment.

Diagnosis and treatment of mixed mania.

In a study of 19 manic patients, the authors found that eight suffered from mixed mania, a condition in which depressive symptoms are found in the context of classic manic features. The presence of a mixed manic state predicted at least a slower and possibly a poor response to lithium therapy. The authors suggest that the delineation of a subgroup of mixed manic patients might help to identify potential lithium-resistant patients.

Lithium distribution in mania: plasma and red blood cell lithium, clinical state, and monoamine metabolites during lithium treatment.

We examined red blood cell (RBC) and plasma lithium concentrations and RBC/plasma lithium ratios in 14 manic patients during lithium treatment as part of the National Institute of Mental Health's Collaborative Program on the Psychobiology of Depression, Biological Studies. All of the lithium measures increased during treatment, especially RBC lithium. There were positive correlations between the RBC lithium concentration and the RBC/plasma lithium ratio and their maximal values in a single-dose pharmacokinetic experiment before treatment.

Lithium treatment of mania: clinical characteristics, specificity of symptom change, and outcome.

The effects of lithium treatment and prediction of response in 18 manic patients were studied as part of the National Institute of Mental Health Collaborative Study of the Psychobiology of Depression. Patients were rated using the Mania Diagnostic and Severity Scale (MADS) and an additional battery of behavioral constructs developed for measurement of state and drug response in depressed patients. About 67% of the patients had good treatment outcome after 26 days of lithium treatment.