NIMH clinical research branch collaborative program on the psychobiology of depression.

This is a report on the history and implications of the collaborative effort that evolved from the 1969 National Institute of Mental Health conference on the psychobiology of depression. The major issues identified at that time were the need to (1) assess relative validities of current systems of nosology and (2) retest critical biological hypotheses concerning the etiology and nature of the depressive disorders. Research was required that would be multidisciplinary and involve clinical settings treating diverse types of depression. The objectives and the nature of the biological and clinical collaborative programs that were designed to address these problems are described. These unique programs, initiated in the early 1970s, currently span research on nosology, genetics, neurochemistry, neuroendocrinology, and psychosocial factors. Although these studies are still in the early stages, they have resulted in significant methodologic developments in diagnosis, descriptive psychopathology, and biological measurements.

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. Responders (about 70% of the patients) did not differ from nonresponders in pretreatment mania ratings or neurotransmitter measures. The CSF MHPG and urinary norepinephrine excretion were reduced during lithium carbonate treatment in both responders and nonresponders. Unlike the case before treatment, urinary MHPG excretion was higher during treatment in nonresponders than in responders and correlated with several indexes of symptom severity. These results support a relationship between mania and increased noradrenergic function. Treatment outcome, however, was not related exclusively to the reduction of noradrenergic indexes by lithium carbonate since reductions were similar in both responders and nonresponders. Reduced noradrenergic activity may therefore be necessary but not sufficient for successful outcome during lithium carbonate treatment.

Biochemistry and suicidal behavior in depressed patients.

The present study was undertaken in order to further explore the relationship between monoamine levels and hypothalamic-pituitary-adrenocortical (HYPAC) functioning and suicidal behavior in depressed patients. One hundred and thirty-two depressed inpatients participated in the NIMH Collaborative Study on the Psychobiology of Depression. Similar to previous reports, our suicide attempters were younger, more likely to be bipolar, had an earlier age at onset, and displayed more psychotic features. No correlation between cortisol hypersecretion or Dexamethasone Suppression Test (DST) nonsuppression and suicide attempts were found. Only the pre-DST evening plasma cortisol distinguished the groups, being lower in the attempter group. We were unable to confirm the previously reported correlation between cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) and suicide attempts. Of the monoamines examined, only urinary and plasma 3-methoxy-4-hydroxphenylglycol (MHPG) differed between suicide attempters and nonattempters, showing lower levels in the attempter group. There was a trend for CSF MHPG in the same direction. This latter reduction was restricted to the bipolar group.

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. The norepinephrine metabolite methoxyhydroxy phenthylene glycol (MHPG) was higher in cerebrospinal fluid from mixed manic than from agitated depressed patients, consistent with differences previously reported between the overall samples of depressed and manic patients. Similarly, patients in a mixed state had higher urinary excretion of norepinephrine (NE) and elevated output of NE relative to its metabolites. HPA activity was similar in mixed manic and agitated depressed patients. These data suggest that mixed manics combine certain biological abnormalities considered to be characteristic of mania and of depression.

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.

CSF monoamine metabolites in mania.

As part of the National Institute of Mental Health Clinical Research Branch Collaborative Program on the Psychobiology of Depression, the authors compared concentrations of CSF monoamine metabolites (the norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol [MHPG], the dopamine metabolite homovanillic acid [HVA], and the serotonin metabolite 5-hydroxyindoleacetic acid [5-HIAA]) from 14 hospitalized manic patients with concentrations from 62 healthy comparison subjects. The manic patients had significantly higher levels of MHPG. Levels of 5-HIAA and HVA did not differ between the manic patients and the comparison male subjects, but they were elevated in the female manic patients. MHPG was the only metabolite that correlated significantly with mania symptom ratings. These data are consistent with findings that have shown abnormal, perhaps excessive, central noradrenergic activity in patients with mania, but not with those suggesting deficits in serotoninergic function.

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.

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. The 9-substituted adenines showed little selectivity for either receptor and the R enantiomer of N6-(1-phenyl-2-propyl)-9-methyladenine was only 4-fold more potent than the S enantiomer at the A1 receptor. An N6-cyclopentyl substituent increased potency at the A1 receptor and decreased potency at the A2 receptor, resulting in selectivity for the A1 receptor of up to 39-fold. The N6-cyclopentyl group completely overshadowed the effect of the hydrophobicity of the 9-substituent. A 2-chloro substituent did not alter the potency of an N6-substituted 9-methyladenine.

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.

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. The feasibility of using the thienyl group as a prosthetic group for selective iodination via its Hg2+ derivative was explored. Receptor selectivity was determined in binding assays using membrane homogenates from rat cortex [( 3H]-N6-(phenylisopropyl)adenosine as radioligand] or striatum [3H]-5'-(N-ethylcarbamoyl)adenosine as radioligand] for A1- and A2-adenosine receptors, respectively. Generally, 2-thio-8-cycloalkylxanthines were at least as A1 selective as the corresponding oxygen analogue. 2-Thio-8-aryl derivatives tended to be more potent at A2 receptors than the oxygen analogue. 8-[4-[(Carboxy-methyl)oxyl] phenyl]-1,3-dipropyl-2-thioxanthine ethyl ester was greater than 740-fold A1 selective.

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. Certain inactive congeners, lacking hydroxyl groups in the 6-alkylidene side chain, inhibited sodium flux elicited by PTX-B, scorpion venom, or the sodium channel activator batrachotoxin. Such inhibition appeared different from inhibition by local anesthetics, since pumiliotoxins, unlike local anesthetics, had little or no effect on binding of [3H]batrachotoxinin A benzoate to sodium channels. Thus, it appears likely that some "inactive" congeners bind to the PTX-B binding site, but do not activate sodium channels. In the absence of scorpion venom the stimulation of phosphoinositide breakdown in synaptoneurosomes was consonant with the stimulatory effects of these compounds on sodium flux through voltage-dependent sodium channels.

Effective short-term treatment of generalized anxiety disorder with trifluoperazine.

The effectiveness of trifluoperazine in daily doses of 2 to 6 mg in the short-term treatment of generalized anxiety disorder was evaluated in 415 outpatients in a double-blind, placebo-controlled, multicenter trial. Efficacy and side effects were assessed by a number of psychiatric rating scales for anxiety. All efficacy measurements of anxiety were significantly improved (p less than .001) with trifluoperazine compared to placebo by the end of the study. The side effects profile of trifluoperazine and placebo were similar during the 4-week treatment period.

A comparative study of bupropion and amitriptyline in depressed outpatients.

A double-blind controlled trial comparing a standard antidepressant drug, amitriptyline, with a new compound, bupropion, was conducted at six centers. There was a placebo washout, after which patients were assigned in a randomized fashion to one of the two treatments. No significant difference was found in therapeutic response to the two drugs after 4 weeks of treatment. Anticholinergic and cardiovascular side effects were less common in the bupropion-treated patients.

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.

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. The effects of type II pyrethroids could be partially inhibited by the sodium channel blocker tetrodotoxin. The effects of allethrin and resmethrin were not affected by 5 microM tetrodotoxin. Stimulation of phosphoinositide breakdown by fenvalerate was additive to the stimulation elicited by the receptor agonists carbamylcholine and norepinephrine, but not to the stimulation elicited by sodium channel agents (batrachotoxin, scorpion venom and pumiliotoxin B). Stimulation by allethrin was not additive to the stimulation elicited either by receptor agonists or sodium channel agents. A submaximal concentration of allethrin, a type I pyrethroid, did not greatly affect the dose-dependent stimulation elicited by a type II pyrethroid, deltamethrin, while a higher concentration of allethrin prevented further stimulation by type II pyrethroids. A local anesthetic, dibucaine, which inhibits sodium channel activation, inhibited phosphoinositide breakdown induced by type II, but not by type I pyrethroids, except at higher concentrations. Thus, type II pyrethroids appear to stimulate phosphoinositide breakdown in synaptoneurosomes in a manner analogous to other sodium channel agents, while type I pyrethroids elicit phosphoinositide breakdown by a different mechanism, probably not involving sodium channels.

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. The second contains mainly histrionicotoxins, pumiliotoxin-A class alkaloids and one indolizidine. The third contains histrionicotoxins, a homopumiliotoxin, one decahydroquinoline, and a variety of indolizidines, quinolizidines and pyrrolizidines. Frogs from Isla Taboga or a nearby island were introduced into the Manoa Valley, Oahu, Hawaii, in 1932. Remarkably, although alkaloids of the pumiliotoxin-A class and one decahydroquinoline are still major constituents in skin extracts of Hawaiian frogs descended from the 1932 founding population, histrionicotoxins are absent and a novel tricyclic alkaloid is present. Offspring of wild-caught parents from Hawaii, Panama or Costa Rica raised in indoor terrariums on a diet of crickets and fruit flies do not contain detectable amounts of skin alkaloids. Offspring raised in large outside terrariums in Hawaii and fed mainly wild-caught termites and fruit flies do contain the same profile of alkaloids as their wild-caught parents in Hawaii, but at reduced levels. The genetic, environmental and dietary determinants of alkaloid profiles in dendrobatid frogs remain obscure, in particular the underlying cause for total absence in terrarium-reared frogs.

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. The process can be selective; an ant indolizidine is accumulated, while an ant pyrrolidine is not. Frogs (Colostethus) of the same family, which do not normally contain alkaloids, do not accumulate alkaloids. Such an alkaloid uptake system provides a means of maintaining skin alkaloids and suggests that some if not all such 'dendrobatid alkaloids' may have a dietary origin.

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. Anxiety was measured using a multi-vantaged approach including doctor's rating, nurse's rating, patient self-report, and a separate video rating. Results indicate that anxiety was significantly associated with agitation, distressed facial expression, bodily discomfort, and poor social interaction in both sexes. Men and women differed in certain respects: anxiety was highly related to motor retardation in women only, and to hostility in men only. Differences in the pattern of expressive behavior between high and low anxious, depressed patients were clearly significant, and several were large enough to serve as clinical indicators. These findings help to characterize the expressive features of anxiety in the context of severe depression, and add to the growing literature on sex differences in depression.

Plasma and erythrocyte electrolytes in affective disorders.

Plasma and erythrocyte sodium (Na+), total and free (ultrafiltrable) plasma magnesium (Mg2+) as well as erythrocyte magnesium were measured in patients with affective disorders and in healthy control subjects. Depressed and manic patients had higher total plasma Mg2+ than did hospitalized healthy control subjects, but concentrations of ultrafiltrable Mg2+ did not differ. Although erythrocyte Mg2+ was significantly elevated in the depressed subjects in comparison with that found in the non-hospitalized healthy controls, this difference was not seen between the depressives and the hospitalized healthy controls. Depressed, manic or healthy control subjects did not differ with respect to either plasma or erythrocyte.

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. Patients with agitated depression were compared to those in acute manic episodes with and without prominent depressive symptoms. Mania ratings clearly distinguished agitated depressed from mixed manic patients. Concerning depression and general psychopathology, mixed manics had more severe agitation, hostility and cognitive impairment than did agitated depressed patients. Depressed mood and anxiety did not differ significantly between the two groups. Nurse ratings for depression and anxiety, based on ward behavior, were similar for mixed manics and agitated depressed patients, while physician-interview rated depression and anxiety were higher in agitated depressed patients. These data support the existence of superimposed depressive and manic syndromes in mixed manics.