Behavioral neurochemistry: neuroregulators and behavioral states.

There is compelling evidence that behavioral events after neurochemical function and that altered neurochemical function can change behavior. Such processes have been related both to neurotransmitters and to neuromodulators, together termed neuroregulators. Available research tools and theoretical constructs have begun to permit studies of certain types of behavior, primarily those related to emotional states and drives. This work is changing long-held concepts about severe mental disorders and the treatment of them.

Tryptoline formation by a preparation from brain with 5-methyltetrahydrofolic acid and tryptamine.

An enzymatic preparation from human brain converts tryptamine to tryptoline (9H-1,2,3,4-tetrahydropyrido[3,4-b]indole) in the presence of 5-methyltetrahydrofolic acid. Similarly, N-methyltryptamine and 5-hydroxytryptamine yield 1-methyltryptoline and 5-hydroxytryptoline, respectively. Neither in vitro nor in vivo formation of these compounds by human tissues has been described.

Changes in resident rat peritoneal macrophage eicosanoid release, induced by altering the buffer K+/Na+ ratio, are Ca2+ dependent.

Altering the buffer K+/Na+ ratio ([K+]o/[Na+]o) resulted in a biphasic change in the basal release of prostaglandin E2, 6-ketoprostaglandin F1 alpha (the stable breakdown product of prostaglandin I2) and thromboxane B2 (the stable metabolite of thromboxane A2), from resident rat peritoneal macrophages. Changing the [K+]o (at the expense of [Na+]o) from 15 mM to 0 mM or 75 mM (combined concentration of [K+]o and [Na+]o was maintained at 150 mM) resulted in a stimulation of 6-ketoprostaglandin F1 alpha and thromboxane B2 release. Prostaglandin E2 synthesis was also stimulated when the [K+]o was decreased from 15 mM to 0 mM. When the [K+]o was increased to 45 mM, prostaglandin E2 formation was inhibited but returned to values observed at 15 mM K+ when the [K+]o was further increased to 75 mM. Prostaglandin E2 synthesis at 75 mM K+ was still only 40% of that measured in the absence of K+, however. When cells were incubated in a Ca2+-free medium (+EDTA) eicosanoid release was drastically reduced and the changes in arachidonic acid metabolite release observed on changing the buffer [K+]o/[Na+]o were abolished. Total release of radiolabel ([14C]arachidonic acid and its radiolabelled metabolites) from macrophages prelabelled with [14C]arachidonic acid followed the same pattern as basal eicosanoid release, suggesting that changing [K+]o influenced phospholipase A2 activity, and hence, substrate availability. At all [K+]o values, from 0 mM to 75 mM, cicletanide reduced the release of radioactivity from macrophages prelabelled with [14C]arachidonic acid (by about 15%). In the presence of [K+]o, cicletanide had a stimulatory effect on the metabolism of the free fatty acid which masked the decrease in eicosanoid release expected due to inhibition of arachidonic acid release from phospholipid. In the presence of 5 mM K+, cicletanide inhibited the basal release but enhanced the arachidonic acid-stimulated synthesis of eicosanoids from resident macrophages in a dose-related fashion, confirming the dual action of the drug, i.e., the inhibitory effect on arachidonic acid release and the stimulation of arachidonic acid metabolism. The possible in vivo significance of these results is discussed.

Platelet methylene reductase activity in schizophrenia.

A case of a folate-responsive psychosis that was associated with a defect in N5-10-methylenetetrahydrofolate reductase (methylene reductase) suggested the need to examine whether abnormally low activity of this enzyme might be of etiological importance in schizophrenia. We now report that there were no statistically significant differences in the platelet methylene reductase activity of chronic schizophrenics, compared with either hospitalized or nonhospitalized age-matched control subjects. Although it is possible that a larger survey might reveal a subpopulation of schizophrenics who are characterized by abnormal methylene reductase activity, this study suggests that chronic schizophrenia is not generally associated with such changes.

beta-Endorphin and schizophrenia.

To study the effects of beta-endorphin in chronic schizophrenia, nine male patients participated in a double-blind crossover comparison of a single intravenous 20-mg injection of beta-endorphin and saline. Bolus injection of beta-endorphin from an albumin-coated syringe produced markedly higher plasma concentrations than did slow intravenous infusion from a non-albumin-coated syringe. Beta-endorphin intravenously injected in nine patients produced a statistically significant increase in serum prolactin levels. In one patient, both 10 mg of morphine sulfate and 20 mg of beta-endorphin produced similar increases in the alpha power of the EEG. In eight patients, beta-endorphin administration was associated with a statistically significant but not clinically obvious improvement in schizophrenic symptoms.

Maintenance of donor phenotype after full-thickness skin transplantation from mice with chronic proliferative dermatitis (cpdm/cpdm) to C57BL/Ka and nude mice and vice versa.

Chronic proliferative dermatitis is a spontaneous mutation in C57BL/Ka mice (cpdm/cpdm) and is characterized by epithelial hyperproliferation, infiltration by eosinophils and macrophages, and vascular dilatation. To elucidate whether these pathologic features are the result of a local (skin) process or a consequence of a systemic disorder, transplantations were performed of full-thickness grafts of affected skin from cpdm/cpdm mice and normal skin from control (C57BL/Ka) mice on the back of cpdm/cpdm, C57BL/Ka and athymic nude mice. After 3 months, the grafts maintained the histologic phenotype of the donor animal. Intercellular adhesion molecule-1 continued to be expressed by basal keratinocytes of the cpdm/cpdm grafts after transplantation. In contrast, the basal keratinocytes of the C57BL/Ka grafts onto cpdm/cpdm mice remained negative for intercellular adhesion molecule-1 3 months after transplantation. An increased number of proliferating keratinocytes was present in the cpdm/cpdm skin-graft transplanted to nudes or to C57BL/Ka mice based on short-term bromodeoxyuridine labeling. The bromodeoxyuridine incorporation in the keratinocytes of the control C57BL/Ka skin grafts transplanted to cpdm/cpdm, nude, or C57BL/Ka mice was the same as in the keratinocytes of normal C57BL/Ka mice. This study demonstrates that the pathologic features found in the cpdm/cpdm mice are the result of a disorder in the epidermis or dermis and not due to a systemic defect.

N5,10-methylenetetrahydrofolate reductase activity in autopsied brain parts of chronic schizophrenics and controls and in vitro tryptoline formation.

We and others have shown that in vitro tryptoline (tetrahydro-beta-carboline) formation accounts for the apparent-N-methylating activity of a brain enzymatic preparation using 5-methyltetrahydrofolic acid (5-MTHF) as a cofactor and tryptamines or catecholamines as substrates. This paper demonstrates that N5,10-methylenetetrahydrofolate reductase (methylene reductase) is responsible for this in vitro tryptoline formation with human brain enzymatic preparations. Others have described a folate-responsive psychosis which was associated with markedly reduced methylene reductase activity. Therefore, we also have examined this enzymatic activity in autopsied brains from chronic schizophrenics and controls. There were no statistically significant differences between activities for schizophrenics and controls in the six brain regions studied. Thus, although it is possible that some subgroup of schizophrenics may be characterized by abnormal methylene reductase activity, there does not appear to be a general association between the two.

The interface between borderline personality disorder and affective disorder.

The authors review the available literature on the interface between borderline personality disorder and affective disorder. Three competing hypotheses have been offered to explain the substantial overlap between these diagnostic categories; they postulate that borderline disorder arises from affective disorder, that affective disorder arises from borderline disorder, or that the two are independent and overlap coincidentally. None of these hypotheses satisfactorily explains the existing data. The authors propose a fourth hypothesis focusing on the multiple etiologies of the signs and symptoms used to diagnose both affective and borderline disorders and suggesting that some patients in the resulting heterogeneous population have symptom clusters that fit both syndromes.

S-adenosylmethionine-dependent N-methyltransferase activity in autopsied brain parts of chronic schizophrenics and controls.

The transmethylation hypothesis of schizophrenia proposes that the disease results from excessive accumulation of methylated derivatives of biogenic amines. To test the hypothesis that an abnormality in S-adenosylmethionine-dependent N-methyltransferase (SAM enzyme) might play a role in schizophrenia, the authors compared SAM enzyme activity of in vitro preparations of 6 brain regions obtained at autopsy from chronic schizophrenics and nonschizophrenic controls. An analysis of variance demonstrated statistically significant differences among brain regions but not between schizophrenics and controls.

Enhanced prostaglandin E2 and thromboxane B2 release from resident peritoneal macrophages isolated from morphine-dependent rats.

Resident peritoneal macrophages from morphine-addicted rats (4 days) released more prostaglandin (PG) E2 and thromboxane (Tx) B2, but not 6-keto-PGF1 alpha, than cells from control animals. This effect, which was due to an enhancement of endogenous AA turnover, was not related to any changes in cAMP synthesis or lysosomal enzyme secretion. [D-Ala2]-Met-enkephalin had no effect on eicosanoid release in vitro. Both morphine and PGE2 have been shown to depress macrophage functions. We suggest that morphine-stimulated macrophage PGE2 synthesis, and the consequent inhibition of phagocytosis, could contribute to the decreased resistance to infections associated with opiate addiction.

An automated method for the quantification of immunostained human Langerhans cells.

Allergic contact dermatitis is a frequent and increasing health problem. For ethical reasons, the current animal tests used to screen for contact sensitizers should be replaced by in vitro alternatives. Contact sensitizers have been shown to accelerate Langerhans cell (LC) migration from human organotypic skin explant cultures (hOSECs) more rapidly than non-sensitizers and it has been proposed that the hOSEC model could be used to screen for sensitizers. However, chemically induced decreases in epidermal LC numbers need to be accurately quantified if the alterations in epidermal LC numbers are to form the basis of an alternative system for screening contact sensitizers in vitro. As manual counting of LCs is labour intensive and subject to intra- and inter-personal variation we developed an image analysis routine, using the Leica QWin image analysis software, to quantify LCs in situ using immunohistochemically stained skin sections. LCs can be identified using antibodies against the membrane molecule CD1a or the Lag antibody, which recognises cytoplasmic Birbeck granules. Quantification of epidermal LC number using the image analysis software had a much lower inter-person variation than when the same specimens were counted manually, using both the anti-Lag and CD1a antibodies. The software-aided quantification of epidermal LCs provides an accurate method for measuring chemically-induced changes in LC numbers.

Aerosol penetration ratio: a new index of ventilation.

Superimposition of nuclear medicine scintigrams and standard radiographs provides a unique opportunity for merging functional information intrinsic to nuclear medicine images with the high resolution anatomic detail of radiographs. A newly developed image processing system allows the merging of two separate films of greatly varying sizes to form a single composite image. Subsequent quantitative analysis of the composite image may be performed. Using the superimposition technique, [99mTc]DTPA aerosol ventilation scans (4.5 X 4.5 cm) were superimposed upon chest radiographs (35.6 X 43.2 cm) in 17 cystic fibrosis (CF) patients. Subsequent quantification of the area of nuclear scan ventilation and the radiographic lung area was then performed. A new quantitative radiologic index of ventilation, the aerosol penetration ratio (APR), was defined. Linear correlation of aerosol penetration ratio with residual volume (RV) as percent of total lung capacity (TLC) measured by body plethysmography was good. We conclude that the APR has validity as a physiologic parameter which localized regional excessive residual volume and correlates well with RV/TLC, the "gold standard" pulmonary function index of obstructive airway disease.

Prostaglandin E2 inhibits and indomethacin and aspirin enhance, A23187-stimulated leukotriene B4 synthesis by rat peritoneal macrophages.

1. The calcium ionophore, A23187, stimulated leukotriene B4 (LTB4), thromboxane B2 (TxB2) and prostaglandin E2 (PGE2) synthesis by 4 day carrageenin-elicited rat peritoneal macrophages. 2. At concentrations of 2 x 10(-7)-2 x 10(-5) M indomethacin and aspirin enhanced A23187-stimulated LTB4 synthesis and inhibited PGE2 and TXB2 formation. 3. PGE2 inhibited A23187-stimulated LTB4 and TXB2 formation as well as the augmentation of LTB4 release caused by aspirin and indomethacin. However, PGE2 was ineffective when the cells were challenged with arachidonic acid (AA). 4. Dibutyryl adenosine 3':5'-cyclic monophosphate (db-cyclic AMP) partially inhibited A23187-stimulated LTB4 production. 5. Our results suggest that PGE2 inhibits macrophage LTB4 synthesis by limiting the availability of AA. Indomethacin and aspirin, possibly by removing the regulatory effect of PGE2, promote the synthesis of the pro-inflammatory LTB4.

Stereotypy and hyperactivity in rats receiving ethanol and a monoamine oxidase inhibitor.

The combined administration of tranylcypromine (TCP) and ethanol to rats produced both a marked increase in general locomotion such as walking and running and the appearance of repetitive stereotyped head and trunk weaving, forepaw padding, and circling movements. Pretreatment with p-chlorophenylalanine (pCPA) abolished the stereotyped behaviors. In contrast, animals pretreated with alpha-methyl-p-tyrosine (AMPT) were virtually indistinguishable from those receiving only TCP + ethanol, except for a decrease in running behaviors. The above results are consistent with a serotonergic mediation of these specific stereotypes. The mechanisms by which TCP + ethanol might produce these effects are discussed.

Comparative in vitro-in vivo percutaneous absorption of the pesticide propoxur.

In vitro and in vivo skin absorption of the pesticide propoxur (2-isopropoxyphenyl N-methyl carbamate, commercially Baygon(TM) and Unden (TM); log Po/w 1.56, MW 209.2) was investigated. In vivo studies were performed in rats and human volunteers, applying the test compound to the dorsal skin and the volar aspect of the forearm, respectively. In vitro experiments were carried out in static diffusion cells using viable full-thickness skin membranes (rat and human), non-viable epidermal membranes (rat and human) and a perfused-pig-ear model. Percutaneous penetration of propoxur in human volunteers was measured by analysis of its metabolite (2-isopropoxyphenol) in blood and urine; in all other studies radiolabeled propoxur ([ring-U-(14)C]propoxur) was used. In order to allow for direct comparison, experimental conditions were standardized with respect to dose (150 microg propoxur per cm(2)), vehicle (60% aqueous ethanol) and exposure time (4 h). In human volunteers, it was found that approximately 6% of the applied dose was excreted via the urine after 24 h, while the potential absorbed dose (amount applied minus amount washed off) was 23 microg/cm(2). In rats these values were 21% and 88 microg/cm(2), respectively. Data obtained in vitro were almost always higher than those obtained in human volunteers. The most accurate in vitro prediction of the human in vivo percutaneous absorption of propoxur was obtained on the basis of the potential absorbed dose. The absorbed dose and the maximal flux in viable full-thickness skin membranes correlated reasonably well with the human in vivo situation (maximal overestimation by a factor of 3). Epidermal membranes overestimated the human in vivo data up to a factor of 8, but the species-differences observed in vivo were reflected correctly in this model. The data generated in the perfused-pig-ear model were generally intermediate between viable skin membranes and epidermal membranes.

The adenylate cyclase of rheumatoid synovial fluid macrophages is more sensitive for dl-5E, 19,14-di dehydro-carbo-prostacyclin, a stable prostacyclin analogue, than for prostaglandin E2.

dl-5E, 19,14-di dehydro-carbo-prostacyclin (DDH-carbo PGI2), a stable prostacyclin (PGI2) derivative, but not prostaglandin (PG) E2, stimulated the adenylate cyclase of synovial fluid macrophages, isolated from rheumatoid patients with an active synovitis, in a dose dependent manner (10-1000 ng/ml). DDH-carbo PGI2 also stimulated synovial macrophage cAMP synthesis when injected into the knee joint. Exogenous arachidonic acid (AA) had little effect on cyclic-AMP (cAMP) formation or PGI2 release (assayed as 6ketoPGF1 alpha). It stimulated, however, the release of PGE2 and, to a lesser extent, thromboxane (Tx) A2 (measured as TxB2).

Specific lipoxygenase inhibition reverses macrophage cytotasis towards P815 tumor cells in vitro induced by the calcium ionophore A23187.

A23187-stimulated cytostatic activity of peritoneal macrophages towards P815 tumor cells served as a model for macrophage activation: a macrophage enriched preparation, separated on the basis of cell size in a discontinuous FCS gradient column, expressed cytostatic activity when stimulated by A23187. This was inhibited dose-dependently, by AA-861 but not by nordihydroguaiaretic acid (NDGA). AA-861 inhibited 5-lipoxygenase specifically, NDGA inhibited both 5-lipoxygenase- and cyclooxygenase activity. The ratio cyclooxygenase/lipoxygenase products increased with AA-861 but not with NDGA. These results show that lipoxygenase products are necessary for expression of cytostatic activity of these arachidonic acid metabolite-producing macrophages and that the ratio cyclooxygenase/lipoxygenase metabolites plays an important role in macrophage activation.

The use of signal detection theory to assess DSM-III-R criteria for autistic disorder.

Sixty cases from the DSM-III-R field trials for autistic disorder (AD) were studied to derive an optimally sensitive and specific combination of scoring criteria based on the 16 DSM-III-R criteria for AD. Signal detection theory, a statistical method new to psychiatric research, was applied. Two of the sixteen criteria tested with this methodology yielded a sensitivity of 0.82, a specificity of 0.89, and a total predictive value of 0.91 relative to clinical diagnosis. Excluded criteria were redundant; unrelated to diagnosis; or highly correlated with degree of mental retardation, mental age, and/or chronological age.

Cardiovascular effects of desipramine in children.

The effect of desipramine hydrochloride was studied in children who were treated for eating disorders (5), attention deficit disorder (13), or affective disturbance (3). Serial heart rate, blood pressure, ECG, and 24-hour ambulatory monitoring were recorded before treatment and at 4 and 8 weeks during treatment. Maximum dose of desipramine was 5 mg/kg/day, average 4.25. A 21% increase in heart rate and 2.5% increase in QTc at 4 weeks were sustained at 8 weeks. No dysrhythmias or clinically significant changes in blood pressure occurred. Desipramine is safe in children who have normal cardiovascular examinations and ECGs when used within the limits of the study design. The cardiovascular effects of desipramine should be kept in mind and monitored when patients are starting tricyclic antidepressant therapy such as desipramine.