Prenatal benzodiazepine immunosuppression: possible involvement of peripheral benzodiazepine site

Possible immunosuppressive effects of drug exposure and environmental and nutritional effects on infection and vaccination

A variety of drugs which are not primarily considered to be immunosuppressive agents have been described to modulate the humoral and cellular immune response in humans or animals. Thereby they may have an influence on the effectiveness and possible side effects of vaccines. This mini review lists some of the different substance classes and also some of endogeneous, infectious, nutritional, and environmental influences with suspected capability to interfere with immunizations. Studies in most cases focused on substances with known immunosuppressive functions, but there is growing evidence for immunomodulatory effects also of commonly used drugs with wide distribution. In particular combinations of those antiproliferative and antiphlogistic side effects of different substance classes have not been studied in detail but may substantially interfere with the development of a functional humoral and cellular immune response. The drugs of importance include antipyretics, anticoagulants, tranquilizers, and substances influencing lipid metabolism but also commonly used drugs of abuse like alcohol or cannabinoids. Additional substances of environmental, nutritional, or microbiological origin may also play a role but their combinatory/synergistic effects have been disregarded so far due to the lack of systematic data and the complex study designs necessary to elucidate those complex epidemiologic questions.

Delayed developmental immunotoxicity of prenatal benzodiazepines

Treatment of pregnant rats with low doses of classical benzodiazepines (BDZ, e.g. 1.25 mg diazepam/kg body weight) or a peripheral type BDZ receptor (PBR) agonist between gestational days 14 and 20 has been shown to result in a long-lasting depression of cellular and humoral immune responses in the offspring. Considerable alterations in mitogen-stimulated cytokine production in rats exposed to diazepam prenatally have now been observed: TNF-alpha liberation by splenocytes of diazepam-exposed rats was reduced at 2 wk of age and increased above control values at 8 wk, and interleukin (IL)-6 was depressed in the offspring at 2 and 8 wk of age. IL-1 was diminished during post-weaning and adult periods in male offspring but only in adult life in female offspring. In contrast, T-cell derived IL-2 was decreased during the postnatal period and normalized in adulthood. Prostaglandin E(2) (PGE(2)), which is known to down-regulate tumour necrosis factor-alpha (TNF-alpha) was increased and interferon-gamma (IFN-gamma), which stimulates TNF-alpha release, was depressed in 2-wk-old offspring that had been treated prenatally. Release of PGE(2) and IFN-gamma was still altered in young adulthood. While the initial action on the foetal immune system remains unknown, an interaction of the drugs with the PBR is suggested by the effectiveness of the PBR agonist and by altered characteristics of PBR (i.e. a decreased B(max) of [(3)H]PK 11195 binding to macrophage membranes of 8-wk-old offspring and an increased Kd of spleen cell membranes of 2-wk-old offspring).

Effects of different doses and schedules of diazepam treatment on lymphocyte parameters in rats

Benzodiazepines (BZD) are widely used for the treatment of anxiety. They enhance GABA-ergic neurotransmission through the binding on specific BDZ recognition sites, within the GABA(A) receptor-ion channel complex. However, recent studies showed that BZD also act on peripheral benzodiazepine receptor sites (PBR) or translocator protein 18 kDa (TSPO). Evidence for a direct immunomodulatory action for BZD emerged from studies that demonstrated the presence of TSPO on immune/inflammatory cells. The present study was designed to analyze the effects of diazepam on rat lymphocyte parameters, specifically on phenotype, cell proliferation and cell death. The effects of both acute and long-term (21 days) diazepam (1 and 10 mg/kg/day) administrations were evaluated. Results showed that diazepam (1 mg/kg) treatment did not change the immune parameters analyzed. However, both diazepam (10 mg/kg) acute and long-term treatments decreased the number of apoptotic cells; they also increased the percentage of T cytotoxic cells; decreased the percentage of B cells and increased the corticosterone serum levels. The induction of functional tolerance was suggested for the highest dose of diazepam (10 mg/kg), but not for the smaller dose (1 mg/kg) used, at least for diazepam effects on corticosterone serum levels. Diazepam effects were discussed as being related to the number of TSPO sites present on immune cells and/or to the increased levels of serum corticosterone observed after the treatments used.

Diazepam leads to enhanced severity of orthopoxvirus infection and immune suppression

Benzodiazepines are drugs widely used as tranquilizers and in various other indications. We treated Balb/c mice with diazepam and infected them with cowpox (CPXV) and vaccinia virus (VACV). Disease index, weight loss and the antibody response were determined. Additionally the influence of different benzodiazepines on the mitogen response of human peripheral blood lymphocytes and spleen cells was tested. Diazepam led to earlier disease onset, prolonged duration of symptoms, higher weight loss and overall disease index in VACV infected mice. CPXV infected mice developed poxviral skin lesions only after drug administration and a significant decrease in the specific antibody response was also observed. Diazepam and alprazolam also inhibited the proliferative response of human lymphocytes/spleen cells in vitro but did not show noteworthy apoptotic effects. It is surprising that even a single dose of diazepam has a profound influence on the immune system, sufficient to facilitate symptomatic infectious disease. These data provide first evidence that commonly used drugs like Valium^® may augment severity of rare poxvirus infections such as CPXV or monkeypox. As VACV is still used as life vaccine against smallpox there is also a risk of enhanced side effects or possible interference with the success of vaccination.

The comparative immunotoxicity of five selected compounds following developmental or adult exposure

It is well established that human diseases associated with abnormal immune function, including some common infectious diseases and asthma, are considerably more prevalent at younger ages. Although not established absolutely, it is generally believed that development constitutes a period of increased immune system susceptibility to xenobiotics, since adverse effects may occur at lower doses and/or immunomodulation may be more persistent, thus increasing the relative risk of xenobiotic exposure to the immunologically immature organism. To address this issue, a brief overview of immune maturation in humans is provided to demonstrate that functional immaturity alone predisposes the young to infection. Age-dependent differences in the immunotoxic effects of five diverse compounds, diethylstilbestrol (DES), diazepam (DZP), lead (Pb), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and tributyltin oxide (TBTO), which have undergone adult and developmental immunotoxicity testing in rodents, are then reviewed, as are human data when available. For all five chemicals, the developing immune system was found to be at greater risk than that of the adult, either because lower doses produced immunotoxicity, adverse effects were more persistent, or both.

Human peripheral blood mononuclear cells express GABAA receptor subunits

The polymerase chain reaction was used to screen human peripheral blood mononuclear cells (PBMC) and Jurkat cells for the presence of GABAA receptor subunit mRNAs. Positive signals were detected for the alpha1, alpha3, beta2, beta3, delta and epsilon subunit mRNAs in both cell populations, with the Jurkat cells giving a positive signal for some additional species. Real-time PCR was used to confirm that PBMC, lymphocytes and monocytes contained significant levels of the alpha1 subunit mRNA and that PBMC and lymphocytes contained low levels of beta2 mRNA. The alpha1 subunit was detected in PBMC and fractionated T-cell populations, as well as Jurkat and HL-60 cell lines, by Western blotting and immunofluorescence using a specific antibody. The application of 1mM GABA reduced the specific increase in intracellular PBMC Ca2+ levels produced by addition of 1 nM fMLP: this effect was mimicked by muscimol, but not glycine, and was blocked by bicuculline. The inhibitory effect of GABA was limited to a subset of PBMC. We conclude that cells within the human PBMC population, including lymphocytes, express functional GABAA receptors and these receptors may modulate immune responses.

Effects of treatment with amphetamine and diazepam on Mycobacterium bovis-induced infection in hamsters

Tuberculosis is an example of an infection with an intracellular bacterium in which sensitivity is determined mainly by the host response. Macrophages are the architectural and functional units of the granulomas described in tuberculosis. Treatment with amphetamine (AMPH) and diazepam has been reported to decrease macrophage activity. The present experiment was undertaken to investigate the effects of AMPH and/or diazepam given alone or in combination on hamster resistance to Mycobacterium bovis. The effects of these treatments on serum cortisol levels were also studied. Adult hamsters were treated i.p. with AMPH (group E1 = 1.0 or 2.0 mg/kg/day), with AMPH (group E2 = 1.0 or 2.0 mg/kg/day) plus diazepam (2.0 mg/kg/day), with diazepam (group E3 = 2.0 mg/kg/day), or with control vehicles (1.0 ml/kg/day) for 40 days. Six days after the beginning of the treatments, the animals received identical inoculum concentrations of M. bovis. Hamsters treated with AMPH plus diazepam exhibited: 1) increased weight loss; 2) increased mortality; 3) increased scores of M. bovis colony forming units (CFU) isolated from liver, lung and spleen; 4) increased granuloma areas measured in the liver, lung and spleen. These effects were not induced by AMPH (1.0 or 2.0 mg/kg/day) given alone and were produced by diazepam (2.0 mg/kg/day) treatment per se. Furthermore, AMPH (2.0 mg/kg/day) and diazepam (2.0 mg/kg/day) given alone or in combination for 20 days increased the serum levels of cortisol in relation to control hamsters, with the effect being higher in the animals treated with both drugs. The present data, which demonstrate an impaired defense against M. bovis in hamsters treated with AMPH plus diazepam or with diazepam alone, were tentatively explained on the basis of a direct and/or indirect action of the drugs on macrophage/lymphocyte activity. In the former case, the effects may be related to stimulation of peripheral benzodiazepine receptor sites (PBR) present on macrophages/lymphocytes and/or to a direct effect of ACTH on immune cells, while in the latter they may be mediated by cortisol via PBR and ACTH stimulation of the adrenals.

Diazepam effects of peritoneal macrophage activity and corticosterone serum levels in Balb/C mice

In the present experiment we investigate the effects of diazepam on macrophage activity and serum corticosterone levels in mice. Adult mice were treated with diazepam (1.5 mg/kg/day - group E) or with control solution (group C1) for 7 days; some animals were only handled, receiving no treatment (group C2). Oral onco-BCG was used for peritoneal macrophage activation. Diazepam treatment: 1-decreased macrophage spreading and phagocytosis; 2-decreased the concentrations of H2O2 spontaneously but not phorbol myristate-acetate-induced release. In relation to mice of group C1, diazepam treatment increased the serum levels of corticosterone. No differences were detected between data of groups C1 and C2 both for macrophage activity and serum corticosterone levels. The present data were explained on the basis of a synergistically action for diazepam through peripheral type binding sites (PBR) present in both adrenals and macrophages, stimulating adrenal glucocorticoid production and altering the macrophage cytokine network.

Benzodiazepine receptors and avian macrophage activity: diazepam decreases spreading and phagocytosis

The complex interrelations between the nervous system and the immune system have led to the creation of a new research area denoted neuroimmunology. The effects of stress on the immune response have long been observed in chickens. Since benzodiazepine receptors are involved in the stress reaction, we proposed to assess the importance of these receptors in the activity of chick peritoneal macrophages. We used 420 viable embryonated eggs of the commercial Hubbard broiler line treated through the chorioallantoid membrane on the 11th day of incubation: falsely manipulated (Sham group), with 40% propyleneglycol (PG) in simple Ringer solution (Vehicle group), and treated with diazepam (DZ), 8 mg/kg (DZ group). After hatching, the chicks were housed in metal rearing cages of the "battery" type for 5 weeks. At 36 days of age, 24 chicks from each treated group were divided at random into two groups of 12 animals each which were treated with DZ (2 mg/kg) or with 40% PPG in an equal volume once a day by the oral route for 4 days. Peritoneal macrophages were collected and submitted to the spreading an phagocytosis tests. Data were analyzed statistically using the SAS software (p < 0.05). Administration of DZ in ovo did not cause a significant decrease in egg hatchability, birth weight or performance parameters during the 5 weeks of assessment. However, the rate of macrophage spreading and phagocytosis was reduced. When administered at 40 days of age, DZ did not change the spreading rate but reduced the phagocytosis rate. There was no interaction between treatments. These results indicate that benzodiazepine receptors seem to be important for macrophage activity also in birds, as previously observed in rodents and primates. Since benzodiazepine receptors are involved in the response to stress, it is possible that the effects of stress on avian immunity may be mediated in part by these receptors.

Effects of diazepam on Mycobacterium bovis-induced infection in hamsters

The in utero exposure of hamsters to low doses of diazepam results in impaired host defense against Mycobacterium bovis during adulthood. Delayed developmental immunotoxicity, however, represents a specific situation that might not be general. The present experiment was undertaken to investigate the effects of diazepam on hamster resistance to M. bovis using adult animals. The effects of diazepam treatment on serum cortisol levels were also studied. Adult hamsters (N = 10 for each group) were treated with diazepam (E1 = 1. 0, E2 = 2.0 or E3 = 3.0 mg kg-1 day-1 subcutaneously) or with control solution (C) for 30 days. Seven days after the beginning of the treatment, the animals received identical inoculum concentrations of M. bovis. Hamsters treated with the higher (2.0 and 3.0 mg kg-1 day-1) doses of diazepam exhibited: 1) increased granuloma areas in the liver (C = 1.81 +/- 1.39, E2 = 10.29 +/- 4.64 and E3 = 15.80 +/- 4.82) and lung (C = 0.54 +/- 0.55, E2 = 6.28 +/- 3.85 and E3 = 6.31 +/- 3.56) and 2) increased scores of M. bovis colony-forming units isolated from liver (C = 2.0, E2 = 3.0 and E3 = 3.5), lung (C = 1.0, E2 = 3.0 and E3 = 3.5) and spleen (C = 1.0, E2 = 2.5 and E3 = 4.0). These effects were dose dependent, and were not detected or were less severe in animals treated with the lowest (1.0 mg/kg) dose of diazepam as well as in those of the control group. Furthermore, diazepam treatment (3.0 mg kg-1 day-1 for 30 days) increased (E3 = 71.32 +/- 2.99; N = 10) the serum levels of cortisol compared to control hamsters (C = 22.61 +/- 2.75; N = 10). The present data, that demonstrate an impaired defense against M. bovis in adult hamsters treated with diazepam, were tentatively explained on the basis of a direct and/or indirect action of diazepam on the cytokine network. The effects may be related to stimulation of peripheral benzodiazepine receptor binding sites (PBR) by macrophages and/or lymphocytes, or they may be mediated by PBR stimulation of the adrenals.

Developmental, neuro and immunotoxic effects of perinatal diazepam treatment in rats

In utero exposure of rats to low dosages of diazepam (1.0-2.0 mg/kg) has been found to result in depression of the cellular and humoral immune responses during adulthood. Behavioral dysfunctions were also reported in infants from mothers with high benzodiazepine (BDZ) intake during pregnancy. The present experiment was undertaken to reconsider the potential action of diazepam during ontogeny in order to obtain further information about developmental processes using a refined methodology. Time-pregnant rats were treated subcutaneously with diazepam (2.0 mg/kg/day,: group E1) or with diazepam vehicle (group C1) from gestational day 14 to 20. Other dams (group E2) received the same BDZ dose from the 1st to the 21st day of lactation (weaning) or were not treated, remaining undisturbed in their home cages (group C2). The following results were obtained for animals perinatally treated with diazepam compared to groups C1 and C2: 1--increased time for testis descent and decreased time for vaginal opening (group E2); 2--no changes in the dates for ear end eye opening, or incisor tooth eruption (groups E1 and E2); 3--increased locomotor activity in the open-field (group E2) and/or in the plus maze (groups E1 and E2); 4--decreased levels of anxiety measured in the plus maze (groups E1 and E2); 5--decreased macrophage spreading and phagocytosis (groups E1 and E2). These results, which occurred in the absence of overt signs of maternal or fetal toxicity, demonstrate developmental, neuro- and immunotoxic effects of perinatal diazepam treatment in rats.

Effects of prenatal diazepam treatment on Mycobacterium bovis-induced infection in hamsters

In utero exposure of rats to low dosages of diazepam has been found to result in depression of cellular and humoral immune responses during adulthood, with marked changes in macrophage spreading and phagocytosis. The present experiment was undertaken to investigate the resistance of adult hamsters to Mycobacterium bovis after prenatal exposure to diazepam. Time-pregnant hamsters were exposed to diazepam (1.0 or 1.5 mg kg(-1) day(-1) subcutaneously) or vehicle from gestational day 9 to 15. A total of 36 different litters (12 of them control and 12 for each experimental group) born after a 16/17-day gestation were used. One male from each litter was infected twice with identical inoculum concentrations of M. bovis at 75 and 107 days of age. This infection model involves the participation of macrophages and T and B cell populations. The animals prenatally exposed to the higher (1.5 mg/kg) dose of diazepam exhibited: (1) increased weight loss, (2) increased mortality, (3) increased granuloma areas measured in the liver, lung and spleen, (4) increased spleen weight, and (5) increased scores of M. bovis colony forming units (CFU) isolated from liver, lung and spleen. These effects were dose-dependent, and were not detected or were less severe in animals treated with the lower (1.0 mg/kg) dose of diazepam as well as in those of the control group. The present data demonstrate an impaired defence against M. bovis in adult hamsters after in utero exposure to a dosage of 1.5 mg/kg of diazepam.

Benzodiazepine receptor agonists modulate thymocyte apoptosis through reduction of the mitochondrial transmembrane potential

Peripheral-type benzodiazepines have been shown to exert immunological effects. In this study, we examined the effects of the peripheral-type benzodiazepines on murine thymocytes. Murine thymocytes that were incubated with the peripheral-type benzodiazepines underwent apoptosis associated with the collapse of mitochondrial transmembrane potential (delta psi(m)). The drugs stimulated dexamethasone- and etoposide-induced apoptosis with the enhanced collapse of delta psi(m). The central-type benzodiazepines had no effect on either the delta psi(m) or apoptosis. The reduction of delta psi(m) depended on protein synthesis and protein phosphorylation. These results suggest that the immunomodulating effect of benzodiazepines is in part due to the modulation of thymocyte apoptosis associated with the collapse of delta psi(m).

Ontogeny of diazepam binding inhibitor/acyl-CoA binding protein mRNA and peripheral benzodiazepine receptor mRNA expression in the rat

The Diazepam Binding Inhibitor/Acyl-CoA Binding Protein (DBI/ACBP) has been implicated in different functions, as acyl-CoA transporter and as an endogenous ligand at the GABA(A) receptor and the peripheral benzodiazepine receptor (PBR). The latter is thought to be involved in control of steroidogenesis. We studied the ontogeny of DBI/ACBP and PBR mRNA expression in embryos and offspring of time-pregnant Long Evans rats by in-situ hybridization with 33P-endlabelled oligonucleotides. Both mRNAs were present in embryo and placenta at gestational day (G)11, the earliest stage studied. DBI/ACBP mRNA was strongly expressed from embryonic through mid-foetal stages in central nervous system (maximum in neuroepithelium), cranial and sympathetic ganglia, anterior pituitary, adrenal cortex, thyroid, thymus, liver and (late foetal) brown adipose tissue, moderately in testis, heart, lung and kidney. In brain, a late foetal decrease of DBI/ACBP mRNA was followed by an increase at postnatal day 6. Peripheral benzodiazepine receptor mRNA expression started very low and increased to moderate levels in adrenal cortex and medulla, testis, thyroid, brown adipose tissue, liver, heart, lung, salivary gland at mid- to late-foetal stages. Data suggest a significant role of DBI/ACBP at early developmental stages. Both proteins may be involved in the control of foetal steroidogenesis. However, differences in developmental patterns indicate that additional functions may be equally important during ontogeny, such as the involvement in lipid metabolism in the case of DBI/ACBP.

Peripheral-type benzodiazepine receptors

1. The pharmacological effects of benzodiazepines are mediated through a class of recognition sites associated with the gamma-aminobutyric acid A receptor. A second class of benzodiazepine binding sites is found in virtually all mammalian peripheral tissues and is therefore called the peripheral type benzodiazepine receptor (PBR). 2. The first section of this review describes the tissue and subcellular distribution of the PBR in mammalian tissues and analyzes its many putative endogenous ligands. 3. The next section deals with the pharmacological, structural and molecular characterization of the PBR that has taken place in the past few years. 4. The final section describes the possible physiological role(s) of the PBR and identifies future work that would help deepen our understanding of the PBR and its function.

Immune response of adult rats is altered by administration of diazepam in the first postnatal week

The potential immunotoxic risk of perinatal treatment with diazepam was investigated using early postnatal administration of the drug to the rat and monitoring the immune response until the age of 24 months. Rats given a single dose of diazepam 10 mg/kg SC on the seventh postnatal day revealed at the age of 6 months a depression of cell-mediated immune response, and at the age of 12 months significant decrease of humoral immune response. The latter persisted until senescence (age 24 months). Also, a repeated dosage of diazepam (3 x 5 mg/kg/day SC on postnatal days 5 to 7) induced a significant depression of humoral immune response in 7-month-old rats. The results demonstrate that both the humoral and cell-mediated immune response of adult rats can be altered by administering diazepam in early postnatal life.

Impaired host resistance to Trichinella spiralis as a consequence of prenatal treatment of rats with diazepam

In utero exposure of Long Evans rats to low dosages of diazepam has previously been found to result in depression of cellular and humoral immune responses until adulthood, with marked changes in cytokine release by splenocytes and splenic macrophages. In order to assess the significance of these alterations in immune cells with regard to host resistance, we investigated the resistance of adult offspring towards Trichinella spiralis. Time-pregnant rats were treated with diazepam (1.25 mg/kg/day) or vehicle from gestational day 14 to 20. Male offspring were infected with T. spiralis at 2 months of age. This infection model tests the participation of T- and B-cell populations and of macrophages. Prenatally diazepam-exposed animals exhibited an impaired defence towards T. spiralis. The number of muscle larvae was increased as determined in digested carcasses and by morphometric analysis of the tongue. Moreover, antibody titers were altered, i.e., IgG was decreased and IgA was elevated in the prenatally diazepam-exposed group. These results demonstrate an impaired defense towards T. spiralis in adult rats after prenatal exposure to diazepam.

Early postnatal diazepam treatment of rats and neuroimmunocompetence in adulthood and senescence

Functional teratogenic risk of perinatal diazepam (D) treatment was studied in animal model experiments using early postnatal D administration in rats (single dose of 10 mg/kg sc in 7-day-old pups) and long-term follow-up till the age of 18 months with monitoring of behavior, reproductive functions, brain biochemical variables, and immune system reactivity. Behavioral tests carried out at the age of 6, 12, and 18 months indicated higher emotionality and deviations of novelty reaction in D rats in comparison with controls, and these differences decreased with aging. However, no deficits were found in memory testing. D rats revealed some transitional alterations of monoamine neurotransmission in the hypothalamus (5-HT) and striatum (DA) and minor defects in reproductive functions (irregular estrous cycles in females). Significant depression of immune response in D rats persisting for the whole life may be considered as a serious risk of neonatal D treatment.

Diazepam treatment of pregnant rats differentially affects interleukin-1 and interleukin-2 secretion in their offspring during different phases of postnatal development

Treatment of pregnant Long Evans rats with benzodiazepines was found to cause alterations in cellular immune responses in their offspring. We now report on changes in interleukin-1 (IL-1) and IL-2 secretion which were analyzed in rats from birth until 12 weeks. Time-pregnant rats were treated with diazepam (1.25 mg/kg/day subcutaneously) from gestational day 14 to 20. Lipopolysaccharide-stimulated release of macrophage-derived IL-1 by spleen cells, determined on D10.G4.1 cells, remained in the control range during the preweaning period (postnatal day 6-28), then decreased in prenatally diazepam-exposed offspring, significantly in males during the postweaning period (postnatal day 34-61) and in both sexes in adults (postnatal day 62-83). Concanavalin A-stimulated release of T lymphocyte-derived IL-2 from spleen cells, determined on CTLL-2 cells, was reduced in male and female offspring during preweaning (postnatal day 3-28) and postweaning (postnatal day 33-55) periods and normalized in adulthood (postnatal day 60-84). The percentage of IL-2 receptor expressing (CD25+) cells was unaffected. From these and our earlier data it is evident that prenatal exposure to low doses of benzodiazepines can result in long-lasting alterations of the cytokine network, as indicated by reduced release of TNF-alpha, IL-1, IL-6, IL-2 and interferon-gamma. The concomitant reduction of peripheral type benzodiazepine receptors on macrophages is discussed as a possible link between prenatal treatment and disturbed function.

Prenatal exposure to diazepam causes sex-dependent changes of the sympathetic control of rat spleen

Prenatal exposure to low doses of benzodiazepines has been found to affect immune functions (25,26). Because the immune system is controlled by the autonomic nervous system, we investigated the sympathetic activity in the spleen for a possible contribution to impaired immune function. Twenty-eight-day-old offspring of prenatally diazepam- or vehicle-treated Long-Evans rats (diazepam 1.25 mg/kg/day SC, gestational day 14-20) were injected IP with sheep red blood cells (SRBC) to evoke an immune reaction. Baseline splenic noradrenaline (NA) turnover was higher in females than in males. Prenatal diazepam treatment resulted in reduced NA turnover in the spleen of SRBC-stimulated female, but not male, offspring. beta-Adrenergic binding sites in spleen membrane fractions, studied with 3H-dihydroalprenolol, showed no differences, indicating that changes in NA turnover were not compensated by changes in receptor expression. Sex-specific developmental effects of diazepam have been described earlier, e.g., in selective effects on perinatal corticosterone levels in female offspring (26).

In vitro inhibition of cellular immune responses by benzodiazepines and PK 11195. Effects on mitogen- and alloantigen-driven lymphocyte proliferation and on IL-1, IL-2 synthesis and IL-2 receptor expression

In vitro mitogen-driven lymphocyte proliferation tests (Con A, LPS) on murine lymph node and spleen cells revealed inhibition of T and B cell stimulation by different benzodiazepines and by PK 11195, with IC50 values in the low micromolar range. T cell responses as a consequence of recognition of alloantigens, as measured in mixed lymphocyte cultures (MLC), were affected in an analogous way. In all systems, agonists at peripheral type benzodiazepine receptors (Ro 5-4864 and the non-benzodiazepine compound PK 11195) and diazepam which acts on both, central and peripheral type benzodiazepine receptors, were most potent; clonazepam, a central type agonist, proved about half as active. The central type antagonist Ro 15-1788 failed to antagonize the action of diazepam and clonazepam. Variations among cells from several congenic strains of mice were modest. Cytotoxicity could not be made responsible for drug effects. The most susceptible stage of mitogen-triggered T and B lymphocyte proliferation was found to be at incipience. Radioresistant, adherent spleen cells, upon LPS-stimulation formed only small amounts of the cytokine IL-1. Its release was affected only at very high drug concentrations. Similar small amounts of IL-1 were generated during MLC; in this case, the drugs were about 10 times less potent than in mitogen-induced proliferation assays. Peripheral agonists were more active on IL-1 synthesis. Spleen cells stimulated with Con A and cultivated with the highest concentration of diazepam and clonazepam formed markedly greater amounts of IL-2 than those cultivated in medium, while at this concentration PK 11195 allowed no formation of the lymphokine.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in interleukin-6 production by LPS- and Con A-stimulated mixed splenocytes, spleen macrophages and lymphocytes in prenatally diazepam-exposed rats

Prenatal exposure to diazepam leads to a suppression of mitogen or allogen-induced lymphocyte proliferation as well as to a reduced production of tumour necrosis factor (TNF)-alpha from rat splenocytes during postnatal development of rats. We analysed the secretion of interleukin (IL)-6 which occurs at a later stage of the cytokine cascade. Splenocytes of male offspring from Long Evans rats, treated with a daily dose of diazepam (1.25 mg/kg) from gestational day 14 to 20, were stimulated with lipopolysaccharide (LPS) and concanavalin A (Con A). In response to LPS, IL-6 liberation was significantly lower in mixed splenocytes and spleen macrophages of 2 and 8 week old prenatally diazepam-treated rats than in controls. Spleen lymphocyte preparations of prenatally treated animals exhibited a reduction of IL-6 release at 12 h and an increase at 24 h of incubation. At 2 weeks of age, Con A-induced IL-6 production could only be detected in mixed splenocytes; prenatally treated rats were releasing significantly less IL-6 than controls. In 8 week old rats, IL-6 liberation from mixed splenocytes and spleen macrophages was significantly lower in prenatally treated animals than in controls. Spleen lymphocytes presented a complex response picture depending upon incubation conditions. Our data indicate that in prenatally diazepam-exposed rats, the disturbance of cytokine release also extends to cytokines which play an important role in the later phases of immune responses.

Changes in free amino acids in peripheral blood (PB) lymphocytes and polymorphonuclear (PMN) leukocytes after treatment with diazepam

The effect of single and chronic (15 days) i.p. injections (1.0 and 8.0 mg/kg) of diazepam (DZ) on free amino acid profile in peripheral blood (PB) lymphocytes and polymorphonuclear (PMN) leukocytes of male Wistar Albino rats were investigated. Depletion of some free amino acids was observed in the lymphocytes (mixed T- and B-lymphocytes) and PMN leukocytes (91-95%) neutrophils especially after chronic DZ-treatment. A dose-dependent depletion in the lymphocyte amino acids, Tau, Gly, Ala, Met and Ile, was found after both acute and chronic DZ-treatment. A similar depletion of Tau, Asp, Glu and Met appeared in the PMN leukocytes after single doses as well as chronic DZ-treatment. These results suggest that administration of 1.0-8.0 mg/kg of DZ in single dose or after chronic administration may interfere with the transport of certain important amino acids and/or protein turnover in PB lymphocytes and PMN leukocytes. On the other hand, the basic amino acids Lys, His and Arg were significantly increased in PMN leukocytes after chronic administration of 1.0 mg/kg DZ. It was suggested that the increased levels of the basic amino acids in the neutrophils may interact with the intracellular changes in pH that normally accompany the respiratory burst.

Peripheral-type benzodiazepine receptors and diazepam binding inhibitor-like immunoreactivity distribution in human peripheral blood mononuclear cells

Peripheral-type benzodiazepine receptors (pBZr) in human lymphocytes have been detected only in mixtures of peripheral blood mononuclear cells (PBMC). The present investigation was designed to describe precisely the location of pBZr in the various sets and subsets of PBMC, purified using monoclonal antibodies to specific PBMC surface markers. Site densities and affinities of pBZr were measured in the intact cells by conventional binding, using 3H-PK 11195 as a ligand. Moreover, we used a specific radioimmunoassay to identify in these cells the presence of the polypeptide diazepam binding inhibitor (DBI), a putative endogenous ligand for various benzodiazepine receptors including the peripheral type. Two major findings are derived from these studies: first, the coexistence of pBZr and DBI, or closely related immunoreactive material, in all major lymphocyte sets and subsets, as well as in monocytes. And second, the significant correlation (r = 0.87, p < 0.001) observed between the density of pBZr in a given cell type and its abundance of DBI like-immunoreactivity (DBI-LI). For both pBZr and DBI-LI content the cell distribution was monocytes > B cells and large granular lymphocytes > T cells (CD3+ set or CD4+ and CD8+ subsets) (ANOVA: pBZr: F = 114.11, p < 0.001; DBI-LI: F = 20.79, p < 0.001). The results are discussed in terms of the possibility that DBI and pBZr might share a relevant interaction in immunocompetent elements, thereby contributing to a new route of connection between the immune and the nervous systems.

The effect of prenatal diazepam exposure on TNF-alpha production by rat splenocytes

Prenatal exposure to diazepam and other benzodiazepines (BDZ) has been found to result in a marked reduction of T-lymphocyte proliferation during postnatal development of rats. In search for pathogenic changes underlying this effect, we investigated the mitogen lipopolysaccharide (LPS) and concanavalin A (ConA) stimulated release of tumour necrosis factor (TNF)-alpha by mixed splenocytes of male offspring from Long Evans rats treated with 1.25 mg/kg per day diazepam from gestational day 14 to 20. In response to LPS, TNF-alpha release was found to be significantly lower in mixed splenocytes of two- and four-week-old treated than in control offspring. However, at eight weeks of age, prenatally diazepam-treated animals showed a significantly higher LPS-induced TNF-alpha release than control rats. Since monocytes/macrophages represent a major source of TNF-alpha, additional experiments were performed on purified spleen macrophages and lymphocytes stimulated with LPS. TNF-alpha release was only detectable in supernatants of adherent spleen macrophages and not in supernatants of lymphocytes. Thus, our data indicate that a disturbance in TNF-alpha release from macrophages is involved in the deficient immune response of prenatally diazepam-exposed rats.

Prenatal diazepam induced persisting downregulation of peripheral (omega 3) benzodiazepine receptors on rat splenic macrophages

Prenatal treatment with a low dose of diazepam (1.25 mg/kg/d, gestational day 14-20) has previously been found to cause longterm impairment of cellular immune responses in rat offspring. A possible site of action of diazepam, i.e., the peripheral-type (omega 3) benzodiazepine receptor, was characterized on splenic macrophages as well as on a rat splenic cell preparation containing mainly lymphocytes. In membranes of both preparations, [3H]PK 11195 bound to a single site which in competition experiments exhibited characteristics of the (omega 3) site. Prenatal exposure to diazepam was followed, at 8 weeks of life, by a marked decrease in maximal binding capacity (Bmax) of spleen macrophage membranes in offspring of both sexes, while membranes of the splenic cell preparation exhibited an increase of the dissociation constant of [3H]PK 11195 at 2 and 8 weeks of life. Both types of delayed effects may reduce the metabolic capacity of these immune cells, in which we have also observed deficits of cytokine release.

Characterization of peripheral-type benzodiazepine binding sites on human lymphocytes and lymphoma cell lines and their role in cell growth

Peripheral-type benzodiazepine binding sites (PBRs) are ubiquitous in mammalian tissues. However, the physiological role of PBRs has not yet been clarified. In this study we characterized a saturable and high affinity binding site for [3H]Pk 11195 (isoquinoline carboxamide derivative) on human lymphocytes and different lymphoma cell lines. Binding parameters of the human T-lymphoma cell line CCRF-CEM came closest to values for lymphocyte binding. Thus, the CCRF-CEM cell line appears to be a suitable lymphocyte cell model for further study of PBRs. To evaluate the pharmacological specificity of binding to human lymphocytes and CCRF-CEM cells we investigated the potency of different ligands to displace [3H]Pk 11195 from its binding site. Pk 11195 was found to be the most potent inhibitor followed by 4'-chlorodiazepan (Ro5-4864) and diazepam (range of inhibition constants from 6.7 x 10(-9) M to 3.6 x 10(-7) M), whereas ligands specific for the central-type receptor like clonazepam and flumazenil had no displacing potency in the tested concentration range (10(-10)-10(-4) M). Since it was assumed that PBRs might be involved in the regulation of cell growth and differentiation, we studied the influence of PBR ligands on cell growth and survival using a quantitative colorimetric assay (MTT). Ligands which bind selectively to PBRs inhibited cell multiplication in vitro. However, half-effective concentrations (EC50) were in the micromolar range and above therapeutic in vivo concentrations (range of EC50 values from 2.4 x 10(-5) M to 1.5 x 10(-4) M). Clonazepam and flumazenil had no inhibiting potency in the tested concentration range (10(-10)-10(-4) M). Although the difference between values for displacing potency and ability to inhibit cell multiplication cannot be explained as yet, it is interesting that all PBR-ligands followed the same sequence in displacing [3H]Pk 11195 and inhibiting cell multiplication and that central type ligands were ineffective in both assays. This association suggest a mediating role of PBR binding in cell growth.