Interleukins-1 and -6 stimulate the release of corticotropin-releasing hormone-41 from rat hypothalamus in vitro via the eicosanoid cyclooxygenase pathway

It has previously been shown that interleukin-1 (IL-1) directly stimulates the release of CRH-41 from rat hypothalamus in vitro, suggesting that cytokines may mediate the effects of changes in immune state on the hypothalamo-pituitary adrenal axis (HPA). However, it is likely that several cytokines can cause changes in neuroendocrine function, and we have now investigated a series of others for central activity on the HPA: IL-2, IL-6, IL-8, tumor necrosis factor (cachectin), interferon-alpha 2, and interferon-gamma. The static rat hypothalamic incubation system used involves fresh hypothalamic explants with consecutive 20-min incubation, and estimation of CRH-41 concentrations in the medium by a specific RIA; the acute effects of cytokines on ACTH release from rat dispersed pituitary cells were also measured. IL-6 increased hypothalamic CRH-41 secretion in the range 10-100 U/ml, but had no effect on isolated median eminences incubated in vitro under the same conditions. IL-6 (1-1000 U/ml) also had no effect on the secretion of ACTH from freshly dispersed rat anterior pituitary cells when administered in 10-min pulses. The effects of both IL-1 and IL-6 were antagonized by blockade of the eicosanoid cyclooxygenase pathway, but not by lipooxygenase blockade. Neither IL-2 (1-10000 U/ml), IL-8 (0.1-10 nM), tumor necrosis factor (10-1000 U/ml), interferon-alpha 2 (10-1000 U/ml) nor interferon-gamma (10-1000 U/ml) had any effect on hypothalamic CRH-41 release or pituitary ACTH release. It is therefore concluded that IL-6, like IL-1, can exert a potent enhancing effect on the HPA by acutely stimulating the secretion of CRH-41 from the hypothalamus at a site above the level of the median eminence, at concentrations known to occur in human plasma and cerebrospinal fluid. These effects are probably mediated by cyclooxygenase products. Acute stimulatory effects of the other cytokines investigated on the HPA are unlikely to be exerted through changes in either CRH-41 or ACTH directly.

Targeted inhibition of transcription elongation in cells mediated by triplex-forming oligonucleotides

Triple-helix-forming oligonucleotides (TFOs) bind in the major groove of double-stranded DNA at oligopyrimidine small middle dotoligopurine sequences and therefore are candidate molecules for artificial gene regulation, in vitro and in vivo. We recently have described oligonucleotide analogues containing N3'-P5' phosphoramidate (np) linkages that exhibited efficient inhibition of transcription elongation in vitro. In the present work we provide conclusive evidence that np-modified TFOs targeted to the HIV-1 polypurine tract (PPT) sequence can inhibit transcriptional elongation in cells, either in transient or stable expression systems. The same constructs were used in transient expression assays (target sequence on transfected plasmid) and in the generation of stable cell lines (target sequence integrated into cellular chromosomes). In both cases the only distinguishable feature between the cellular systems is the presence of an insert containing the wild-type PPT/HIV-1 sequence, a mutated version with two mismatches, or the absence of the insert altogether. The inhibitory action induced by np-TFOs was restricted to the cellular systems containing the complementary wild-type PPT/HIV-1 target, and consequently can be attributed only to a triple-helix-mediated mechanism. As a part of this study we also have applied an imaging technique to quantitatively investigate the dynamics of TFO-mediated specific gene silencing in single cells.

Acute inhibition of nitric oxide synthesis induces anxiolysis in the plus maze test

The involvement of nitric oxide (NO) in anxiety was investigated in rats, using the elevated plus maze test. Acute, but not chronic, systemic treatment with N omega-nitro-L-arginine methyl ester (L-NAME, 10 and 60 mg.kg-1), an inhibitor of NO synthase, increased the time spent by the rats in the open arms. Both the acute and chronic treatments with L-NAME inhibited NO synthase in endothelial cells and in the central nervous system, as shown by the increase in mean arterial pressure and decreased NO synthase activity in brain tissue. Chronic treatment with L-NAME also decreased the serum nitrate levels. The anxiolysis induced by acute L-NAME treatment is unlikely to be due to hypertension, since two-kidney one-clip hypertension in non-L-NAME-treated rats failed to significantly change exploratory behaviour in the elevated plus maze. These results indicate that acute inhibition of NO synthesis decreases anxiety in rats.

Phosphoramidate oligonucleotides as potent antisense molecules in cells and in vivo

Antisense oligonucleotides are designed to specifically hybridize to a target messenger RNA (mRNA) and interfere with the synthesis of the encoded protein. Uniformly modified oligonucleotides containing N3'-P5' phosphoramidate linkages exhibit (NP) extremely high-affinity binding to single-stranded RNA, do not induce RNase H activity, and are resistant to cellular nucleases. In the present work, we demonstrate that phosphoramidate oligonucleotides are effective at inhibiting gene expression at the mRNA level, by binding to their complementary target present in the 5'-untranslated region. Their mechanism of action was demonstrated by comparative analysis of three expression systems that differ only by the composition of the oligonucleotide target sequence (HIV-1 polypurine tract or PPT sequence) present just upstream from the AUG codon of the firefly luciferase reporter gene: the experiments have been done on isolated cells using oligonucleotide delivery mediated by cationic molecules or streptolysin O (SLO), and in vivo by oligonucleotide electrotransfer to skeletal muscle. In our experimental system phosphoramidate oligonucleotides act as potent and specific antisense agents by steric blocking of translation initiation; they may prove useful to modulate RNA metabolism while maintaining RNA integrity.

Fetal movement patterns: a possible means of defining neurologic developmental milestones in utero

Phased-array ultrasonography provides a means for continuous observation of moving structures. This method can be used for assessing fetal movements from the middle of the first trimester. Eleven separate spontaneous movement patterns were defined in 40 examinations of clinically normal women (6 weeks to term). A trend of increasingly complex movement with advancing gestational age was noted with indication that discrete developmental events such as isolated body extension, thumb sucking, or repetitive chest wall excursions can be recognized. Fetal movement responses to a simple pressure stimulus were noted.

Triplex-forming molecules: from concepts to applications

The ability to specifically manipulate gene expression has wide-ranging applications in experimental biology and in gene-based therapeutics. The design of molecules that recognise specific sequences on the DNA double helix provides us with interesting tools to interfere with DNA information processing at an early stage of gene expression. Triplex-forming molecules specifically recognise oligopyrimidine-oligopurine sequences by hydrogen bonding interactions. Applications of such triplex-forming molecules (TFMs) are the subject of the present review. In cell cultures, TFMs have been successfully used to down- or up-regulate transcription in a gene-specific manner and to induce genomic DNA modifications at a selected site. The first evidence of a triplex-based activity in animals has been provided recently. In addition, TFMs are also powerful tools for gene-specific chemistry, in particular for gene transfer applications.

Diagnosis and management of hyperprolactinemia: results of a Brazilian multicenter study with 1234 patients

OBJECTIVE

The aim of the study was to evaluate clinical and laboratorial features of 1234 patients with different etiologies of hyperprolactinemia, as well as the response of 388 patients with prolactinomas to dopamine agonists.

DESIGN, SETTING, AND PATIENTS

A total of 1234 hyperprolactinemic patients from 10 Brazilian endocrine centers were enrolled in this retrospective study.

MAIN OUTCOME MEASURE

PRL measurement, thyroid function tests, and screening for macroprolactin were conducted.

RESULTS

Patients were subdivided as follows: 56.2% had prolactinomas, 14.5% drug-induced hyperprolactinemia, 9.3% macroprolactinemia, 6.6% non-functioning pituitary adenomas, 6.3% primary hypothyroidism, 3.6% idiopathic hyperprolactinemia, and 3.2% acromegaly. Clinical manifestations were similar irrespective of the etiology of the hyperprolactinemia. The highest PRL levels were observed in patients with prolactinomas but there was a great overlap in PRL values between all groups. However, PRL>500 ng/ml allowed a clear distinction between prolactinomas and the other etiologies. Cabergoline (CAB) was more effective than bromocriptine (BCR) in normalizing PRL levels (81.9% vs 67.1%, p<0.0001) and in inducing significant tumor shrinkage and complete disappearance of tumor mass. Drug resistance was observed in 10% of patients treated with CAB and in 18.4% of those that used BCR (p=0.0006). Side-effects and intolerance were also more common in BCR treated patients.

CONCLUSION

Prolactinomas, drug induced hyperprolactinemia, and macroprolactinemia were the 3 most common causes of hyperprolactinemia. Although PRL levels could not reliably define the etiology of hyperprolactinemia, PRL values >500 ng/ml were exclusively seen in patients with prolactinomas. CAB was significantly more effective than BCR in terms of prolactin normalization, tumor shrinkage, and tolerability.

Evaluation of cDNA libraries from different developmental stages of Schistosoma mansoni for production of expressed sequence tags (ESTs)

A comparative study of the gene expression profile in different developmental stages of Schistosoma mansoni has been initiated based on the expressed sequence tag (EST) approach. A total of 1401 ESTs were generated from seven different cDNA libraries constructed from four distinct stages of the parasite life cycle. The libraries were first evaluated for their quality for a large-scale cDNA sequencing program. Most of them were shown to have less than 20% useless clones and more than 50% new genes. The redundancy of each library was also analyzed, showing that one adult worm cDNA library was composed of a small number of highly frequent genes. When comparing ESTs from distinct libraries, we could detect that most genes were present only in a single library, but others were expressed in more than one developmental stage and may represent housekeeping genes in the parasite. When considering only once the genes present in more than one library, a total of 466 unique genes were obtained, corresponding to 427 new S. mansoni genes. From the total of unique genes, 20.2% were identified based on homology with genes from other organisms, 8.3% matched S. mansoni characterized genes and 71.5% represent unknown genes.

Influence of parasite encoded inhibitors of serine peptidases in early infection of macrophages with Leishmania major

Ecotin is a potent inhibitor of family S1A serine peptidases, enzymes lacking in the protozoan parasite Leishmania major. Nevertheless, L. major has three ecotin-like genes, termed inhibitor of serine peptidase (ISP). ISP1 is expressed in vector-borne procyclic and metacyclic promastigotes, whereas ISP2 is also expressed in the mammalian amastigote stage. Recombinant ISP2 inhibited neutrophil elastase, trypsin and chymotrypsin with K(i)s between 7.7 and 83 nM. L. major ISP2-ISP3 double null mutants (Deltaisp2/3) were created. These grew normally as promastigotes, but were internalized by macrophages more efficiently than wild-type parasites due to the upregulation of phagocytosis by a mechanism dependent on serine peptidase activity. Deltaisp2/3 promastigotes transformed to amastigotes, but failed to divide for 48 h. Intracellular multiplication of Deltaisp2/3 was similar to wild-type parasites when serine peptidase inhibitors were present, suggesting that defective intracellular growth results from the lack of serine peptidase inhibition during promastigote uptake. Deltaisp2/3 mutants were more infective than wild-type parasites to BALB/c mice at the early stages of infection, but became equivalent as the infection progressed. These data support the hypothesis that ISPs of L. major target host serine peptidases and influence the early stages of infection of the mammalian host.

Leishmania inhibitor of serine peptidase 2 prevents TLR4 activation by neutrophil elastase promoting parasite survival in murine macrophages

Leishmania major is a protozoan parasite that causes skin ulcerations in cutaneous leishmaniasis. In the mammalian host, the parasite resides in professional phagocytes and has evolved to avoid killing by macrophages. We identified L. major genes encoding inhibitors of serine peptidases (ISPs), which are orthologs of bacterial ecotins, and found that ISP2 inhibits trypsin-fold S1A family peptidases. In this study, we show that L. major mutants deficient in ISP2 and ISP3 (Δisp2/3) trigger higher phagocytosis by macrophages through a combined action of the complement type 3 receptor, TLR4, and unregulated activity of neutrophil elastase (NE), leading to parasite killing. Whereas all three components are required to mediate enhanced parasite uptake, only TLR4 and NE are necessary to promote parasite killing postinfection. We found that the production of superoxide by macrophages in the absence of ISP2 is the main mechanism controlling the intracellular infection. Furthermore, we show that NE modulates macrophage infection in vivo, and that the lack of ISP leads to reduced parasite burdens at later stages of the infection. Our findings support the hypothesis that ISPs function to prevent the activation of TLR4 by NE during the Leishmania-macrophage interaction to promote parasite survival and growth.

Inhibition of CRH-41 release by substance P, but not substance K, from the rat hypothalamus in vitro

Substance P is one of a series of tachykinins which is present throughout the central nervous system, and has potent effects on neuroendocrine function. Recent studies have suggested that it inhibits pituitary-adrenal activity at a site above the level of the pituitary. We have therefore used a well-validated rat hypothalamic incubation system to investigate the effects of substance P on the release of the principal corticotrophin-releasing hormone, CRH-41. Substance P caused a dose-dependent inhibition of the 28-mM KCl-stimulated release of CRH-41, with a maximum effect at 100 nM (P less than 0.01). This effect was attenuated by 10 microM of the substance P antagonist (D-Pro2,-D-Trp7,9)-substance P. No statistically significant effect of substance K was seen at 1 or 100 nM. Substance P, at a dose of 100 nM, did not alter the 28-mM KCl-stimulated release of CRH-41 from isolated median eminences in vitro. It is concluded that substance P is a potent inhibitor of the stimulated release of CRH-41, probably acting at a site within the hypothalamic paraventricular nucleus.

Fetal exomphalos at 11 to 14 weeks of gestation

In an ultrasonographic screening study at 11 to 14 weeks' gestation involving 9885 singleton pregnancies, the prevalence of exomphalos was 0.11% (11 cases) and the prevalence of trisomy 18 or 13 was 0.35% (35 cases). The mean maternal age of the screened population was 35 years (range, 15 to 47 years) and a significant association was found between maternal age and both the prevalence of trisomies and the prevalence of exomphalos. Because the frequency of exomphalos in fetuses with trisomy 18 or 13 was 17% and in those with no evidence of these trisomies it was 0.05%, the risk for trisomies in fetuses with exomphalos is 340 times higher than in those without exomphalos.

A comparison of the clearance of ovine and human corticotrophin-releasing hormone (CRH) in man and sheep: a possible role for CRH-binding protein

A specific binding protein for human corticotrophin-releasing hormone (hCRH), which does not bind to the ovine hormone (oCRH), has recently been demonstrated in human plasma. No such binding protein has been found in sheep plasma. We have investigated the half-life of human and ovine CRH in man and in sheep. Peptides were measured directly in plasma with two-site immunoradiometric assays, as these assays are unaffected by the presence of inactivated peptide fragments. In man, the half-life of hCRH (30.5 +/- 3.3 min; mean +/- S.E.M.) was significantly (P less than 0.001) less than that of oCRH (42.8 +/- 6.4 min). In sheep, there was no significant difference between the half-life of hCRH (46.5 +/- 7.2 min) and that of oCRH (39.8 +/- 10.1 min); these half-lives were also significantly (P less than 0.001) longer than that of hCRH in man. One possible explanation for the shorter half-life of hCRH in man is that the clearance of hCRH is enhanced by CRH-binding protein, although other binding proteins often have the opposite effect. Peak ACTH and cortisol responses occurred earlier in sheep than in man, although no differences were found in the response times to oCRH or hCRH within either species. The responses were more sustained in sheep than in man, and the previously reported biphasic response was only seen in some of the sheep and not in man. Absolute responses to either peptide were greater in sheep than in man; however, in man an 8.1-fold rise in ACTH was measured in response to oCRH, while hCRH gave a significantly (P = 0.043) smaller 4.4-fold response.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of midazolam-induced anxiolysis in the plus-maze Trial 2 is dependent on the length of Trial 1

The influence of the first exposure length upon the effect of midazolam (MDZ) administration prior to the second exposure in the elevated plus-maze (EPM) was investigated. Drug-free rats were assigned to freely explore the EPM for 1, 2 or 5 min (Trial 1). Twenty-four hours later, each group was subdivided in two further groups, which were retested in the EPM for 5 min, 30 min after either saline or MDZ (1.5 mg kg(-1)) administration (Trial 2). The data showed that during Trial 2, the percentage of entries (%Open arm entries) and time spent in the open arms (%Open arm time) were decreased if rats were pre-exposed to the EPM for 2- or 5-min Trial 1, while the group submitted to 1-min Trial 1 length displayed decreased %Open arm time only. The anxiolytic effect of MDZ prior to Trial 2 was present in the group submitted to 1-min, impaired in the group submitted to 2-min and absent in the group submitted to 5-min Trial 1 length. Data are analyzed taking into account the emotional learning which underlies the exploratory behavior during the EPM Trial 2.

Role of ventral hippocampal nitric oxide/cGMP pathway in anxiety-related behaviors in rats submitted to the elevated T-maze

The L-arginine/nitric oxide (NO)/cGMP pathways have been implicated in the control of a variety of physiological mechanisms and are believed to participate in the modulation of anxiety in the CNS. The aim of this study was to investigate the effects of N(G)-nitro-L-arginine-methyl-ester (L-NAME), a non-selective inhibitor of NO synthase (NOS); 7-nitroindazole (7-NI), a preferential inhibitor of neuronal NOS; and sodium nitroprusside (SNP), an NO donor, administered into the ventral hippocampus (VH) of rats submitted to the elevated T-maze (ETM). The ETM, an animal model derived from the elevated plus-maze, allows the measurement of two defensive behavioral responses in the same rat: inhibitory avoidance and escape. Results showed that L-NAME and 7-NI impaired the acquisition of inhibitory avoidance and prolonged escape latency in the ETM, suggesting an anxiolytic-like and panicolytic-like effect, respectively. SNP facilitated the acquisition of inhibitory avoidance without interfering with escape performance, suggesting an anxiogenic-like effect. Treatment with methylene blue did not alter per se any of the behavioral responses measured in the ETM, but blocked the effect promoted by SNP. Thus, altogether these results suggest that NO in the VH is critically involved in the modulation of defensive behavior of rats exposed to the ETM.

Fetal mild hydronephrosis and chromosomal defects: relation to maternal age and gestation

The presence of multiple ultrasonographic abnormalities is associated with a significantly increased risk of chromosomal defects, while for isolated abnormalities, the association is less clear. In a study of 1,177 fetuses with mild hydronephrosis at 16-26 weeks of gestation, the fetal karyotype was abnormal in 86 (7.3%) of the cases and the most common chromosomal defects were trisomies 21, 18 and 13. The frequency of chromosomal defects increased with the number of additional abnormalities and for each chromosomal defect there was a characteristic pattern of associated abnormalities. However, in the 805 fetuses with apparently isolated hydronephrosis there were 5 (0.62%) with trisomy 21. On the basis of the maternal age and gestational age distribution of the population the expected frequency of trisomy 21 was 0.40%, which was not significantly different from the observed (0.62%). To demonstrate that such a difference is significant, it would be necessary to investigate at least 1 million pregnancies. In the meantime, parents could be counselled that the presence of mild hydronephrosis does not increase significantly the risk that the fetus has trisomy 21. Alternatively, the risk is 1.6 times higher than the maternal age and gestational age-related risk.

Role of protein kinase R in the killing of Leishmania major by macrophages in response to neutrophil elastase and TLR4 via TNFα and IFNβ

In cutaneous leishmaniasis, Leishmania amazonensis activates macrophage double-stranded, RNA-activated protein kinase R (PKR) to promote parasite growth. In our study, Leishmania major grew normally in RAW cells, RAW-expressing dominant-negative PKR (PKR-DN) cells, and macrophages of PKR-knockout mice, revealing that PKR is dispensable for L. major growth in macrophages. PKR activation in infected macrophages with poly I:C resulted in parasite death. Fifty percent of L. major-knockout lines for the ecotin-like serine peptidase inhibitor (ISP2; Δisp2/isp3), an inhibitor of neutrophil elastase (NE), died in RAW cells or macrophages from 129Sv mice, as a result of PKR activation. Inhibition of PKR or NE or neutralization of Toll-like receptor 4 or 2(TLR4 or TLR2) prevented the death of Δisp2/isp3. Δisp2/isp3 grew normally in RAW-PKR-DN cells or macrophages from 129Sv pkr^−/−, tlr2^−/−, trif^−/−, and myd88^−/− mice, associating NE activity, PKR, and TLR responses with parasite death. Δisp2/isp3 increased the expression of mRNA for TNF-α by 2-fold and of interferon β (IFNβ) in a PKR-dependent manner. Antibodies to TNF-α reversed the 95% killing by Δisp2/isp3, whereas they grew normally in macrophages from IFN receptor–knockout mice. We propose that ISP2 prevents the activation of PKR via an NE-TLR4-TLR2 axis to control innate responses that contribute to the killing of L. major.—Faria, M. S., Calegari-Silva, T. C., de Carvalho Vivarini, A., Mottram, J. C., Lopes, U. G., Lima, A. P. C. A. Role of protein kinase R in the killing of Leishmania major by macrophages in response to neutrophil elastase and TLR4 via TNFα and IFNβ.

Transcription inhibition induced by modified triple helix-forming oligonucleotides: a quantitative assay for evaluation in cells

Oligonucleotides can bind to double-stranded DNA in a sequence-specific manner to form triple helices. Uniformly modified, pyrimidine-rich oligodeoxyribonuclotides containing internucleosidic N3'-P5' phosphoramidate linkages are known to form very stable triplexes with their DNA target. Psoralen-conjugated triple helix-forming oligonucleotides (Pso-TFOs) can additionally be photo-induced to become irreversibly bound to their targeted DNA sequence. Here, we have examined the ability of various 15-mer phosphoramidate TFOs targeted to the HIV-1 polypurine tract (PPT) sequence to prevent transcription elongation in cell cultures; the PPT sequence has been cloned in the transcribed region of a reporter firefly luciferase gene (luc) and transient expression experiments performed. We show that the level of transcription inhibition of the reporter gene in cells perfectly correlates with the amount of covalent triplex at the PPT site. The efficacy of non-covalent triplexes (either omitting the irradiation step with the psoralen conjugate, or using the unsubstituted oligonucleotide) has been studied in our expression system; the oligonucleotides were introduced into living cells by cationic lipid-mediated delivery or directly into the cell nucleus by microinjection. This experimental approach allowed us to evaluate the intrinsic activity of triplexes as transcriptional inhibitors; transcription elongation was inhibited in cells in a sequence-dependent and concentration-dependent manner. This experimental system is convenient for quantitative and fast evaluation of new chemistries of antigene oligonucleotides as inhibitors of gene expression in cells and in vivo.

The role of nitric oxide in the emotional learning of rats in the plus-maze

The present study evaluated the role of nitric oxide (NO) in the transfer latency (TL) paradigm in the elevated plus-maze. Male Wistar rats received i.p. injections of either 0.9% Saline, N(omega) Nitro-L-arginine-methyl-ester (L-NAME, an inhibitor of NO synthesis), d-NAME (inert isomer), scopolamine (SCO, antagonist of muscarinic receptors), or MK-801 (antagonist of NMDA receptors) and, after 30 min, were submitted to TL procedure. In an independent experiment, the ability of the same L-NAME treatments in changing the arterial pressure and blood glucose level (BGL) was evaluated in conscious rats. The treatment with SCO (1 mg kg(-1)), MK-801 (0.15 mg kg(-1)) and L-NAME (10 and 50 mg kg(-1)), but not with D-NAME, impaired the TL learning. The L-NAME-induced TL deficit was counteracted by L-ARG (100 and 200 mg kg(-1)), while the co-administration of sub-effective doses of L-NAME and MK-801 failed to impair the TL learning. The L-NAME (50 mg kg(-1)) treatment failed to alter the BGL. All treatments with L-NAME induced hypertension, but the rats treated with L-NAME (5 mg kg(-1)) were still able to learn the TL task. The data indicate that the TL deficit induced by L-NAME (10 and 50 mg kg(-1)) is not due to either hypertension or changes in the BGL. It is also possible to establish that NO production is important for emotional learning underlying the TL procedure in rats.

Nitric oxide may underlie learned fear in the elevated T-maze

The present study evaluated the role of nitric oxide (NO) in learned and innate fear in rats submitted to the elevated T-maze (ETM). Learned and innate fear were evaluated through the inhibitory avoidance and escape behaviour from the open arms, respectively. Rats treated with the inhibitor of NO synthesis N(omega)-nitro-L-Arginine methyl ester (L-NAME; 5, 10, and 50 mg. kg(-1)) were able to learn the inhibitory avoidance. However, L-NAME (50 mg. kg(-1)), but not its inert isomer N(omega)-nitro-D-arginine methyl ester (D-NAME, 50 mg. kg(-1)), impaired the inhibitory avoidance 2 with no change in the baseline values, thus suggesting an anxiolytic-like effect without locomotor impairment. All treatments with L-NAME were able to induce increased mean arterial pressure (MAP), measured indirectly through the animal's tail. The treatment with L-NAME (5 and 10 mg. kg(-1)) failed to induce anxiolysis but significantly increased the MAP of the animals, which indicates that hypertension per se, did not underlie anxiolysis induced by L-NAME. L-Arginine, the precursor molecule for NO synthesis, facilitated the inhibitory avoidance and counteracted the L-NAME (50 mg. kg(-1))-induced anxiolysis. Neither previous treatment was able to change the escape behaviour. The results indicate that NO may underlie learned, but not innate, fear in the ETM.

Temporal analysis of the rat's behavior in the plus-maze: effect of midazolam

The aim of the present study was to carry out a temporal analysis of the midazolam (MDZ)-induced anxiolysis in rats submitted to the elevated plus-maze (EPM) test. Male Wistar rats received either MDZ (0.5, 1.0 and 1.5 mg.kg(-1)) or saline (0.9%) and were submitted to the EPM test. Temporal analysis revealed that the group receiving MDZ (1.5 mg.kg(-1)), as well as the group treated with saline, displayed low %Open arm entries, which suggests increased anxiety over the test period. Motor activity, evaluated by the enclosed arm entries, was also decreased in both experimental groups, thus suggesting locomotor habituation. The treatment with MDZ (1.5 mg. kg(-1)) induced a clear anxiolysis during the first 3 min, but not at the end of the test, since only the %Open arm time remained increased. The data are discussed with reference to the lack of the test's sensitivity to alterations in the level of anxiety over time and with respect to a qualitative shift in the experimental anxiety at the end of the session.

CYP2A6 and CYP2E1 polymorphisms in a Brazilian population living in Rio de Janeiro

Cytochrome P450 (CYP) is a superfamily of enzymes involved in the metabolism of endogenous compounds and xenobiotics. CYP2A6 catalyzes the oxidation of nicotine and the activation of carcinogens such as aflatoxin B1 and nitrosamines. CYP2E1 metabolizes ethanol and other low-molecular weight compounds and can also activate nitrosamines. The CYP2A6 and CYP2E1 genes are polymorphic, altering their catalytic activities and susceptibility to cancer and other diseases. A number of polymorphisms described are ethnic-dependent. In the present study, we determined the genotype and allele frequencies of the main CYP2A6 and CYP2E1 polymorphisms in a group of 289 volunteers recruited at the Central Laboratory of Hospital Universitário Pedro Ernesto. They had been residing in the city of Rio de Janeiro for at least 6 months and were divided into two groups according to skin color (white and non-white). The alleles were determined by allele specific PCR (CYP2A6) or by PCR-RFLP (CYP2E1). The frequencies of the CYP2A6*1B and CYP2A6*2 alleles were 0.29 and 0.02 for white individuals and 0.24 and 0.01 for non-white individuals, respectively. The CYP2A6*5 allele was not found in the population studied. Regarding the CYP2E1*5B allele, we found a frequency of 0.07 in white individuals, which was statistically different (P < 0.05) from that present in non-white individuals (0.03). CYP2E1*6 allele frequency was the same (0.08) in both groups. The frequencies of CYP2A6*1B, CYP2A6*2 and CYP2E1*6 alleles in Brazilians are similar to those found in Caucasians and African-Americans, but the frequency of the CYP2E1*5B allele is higher in Brazilians.

Impairment of ATP hydrolysis decreases adenosine A1 receptor tonus favoring cholinergic nerve hyperactivity in the obstructed human urinary bladder

This study was designed to investigate whether reduced adenosine formation linked to deficits in extracellular ATP hydrolysis by NTPDases contributes to detrusor neuromodulatory changes associated with bladder outlet obstruction in men with benign prostatic hyperplasia (BPH). The kinetics of ATP catabolism and adenosine formation as well as the role of P1 receptor agonists on muscle tension and nerve-evoked [(3)H]ACh release were evaluated in mucosal-denuded detrusor strips from BPH patients (n = 31) and control organ donors (n = 23). The neurogenic release of ATP and [(3)H]ACh was higher (P < 0.05) in detrusor strips from BPH patients. The extracellular hydrolysis of ATP and, subsequent, adenosine formation was slower (t (1/2) 73 vs. 36 min, P < 0.05) in BPH detrusor strips. The A(1) receptor-mediated inhibition of evoked [(3)H]ACh release by adenosine (100 μM), NECA (1 μM), and R-PIA (0.3 μM) was enhanced in BPH bladders. Relaxation of detrusor contractions induced by acetylcholine required 30-fold higher concentrations of adenosine. Despite VAChT-positive cholinergic nerves exhibiting higher A(1) immunoreactivity in BPH bladders, the endogenous adenosine tonus revealed by adenosine deaminase is missing. Restoration of A1 inhibition was achieved by favoring (1) ATP hydrolysis with apyrase (2 U mL(-1)) or (2) extracellular adenosine accumulation with dipyridamole or EHNA, as these drugs inhibit adenosine uptake and deamination, respectively. In conclusion, reduced ATP hydrolysis leads to deficient adenosine formation and A(1) receptor-mediated inhibition of cholinergic nerve activity in the obstructed human bladder. Thus, we propose that pharmacological manipulation of endogenous adenosine levels and/or A(1) receptor activation might be useful to control bladder overactivity in BPH patients.

Ecotin-like serine peptidase inhibitor ISP1 of Leishmania major plays a role in flagellar pocket dynamics and promastigote differentiation

Leishmania ISPs are ecotin-like natural peptide inhibitors of trypsin-family serine peptidases, enzymes that are absent from the Leishmania genome. This led to the proposal that ISPs inhibit host serine peptidases and we have recently shown that ISP2 inhibits neutrophil elastase, thereby enhancing parasite survival in murine macrophages. In this study we show that ISP1 has less serine peptidase inhibitory activity than ISP2, and in promastigotes both are generally located in the cytosol and along the flagellum. However, in haptomonad promastigotes there is a prominent accumulation of ISP1 and ISP2 in the hemidesmosome and for ISP2 on the cell surface. An L. major mutant deficient in all three ISP genes (Δisp1/2/3) was generated and compared with Δisp2/3 mutants to elucidate the physiological role of ISP1. In in vitro cultures, the Δisp1/2/3 mutant contained more haptomonad, nectomonad and leptomonad promastigotes with elongated flagella and reduced motility compared with Δisp2/3 populations, moreover it was characterized by very high levels of release of exosome-like vesicles from the flagellar pocket. These data suggest that ISP1 has a primary role in flagellar homeostasis, disruption of which affects differentiation and flagellar pocket dynamics.

Atrial natriuretic peptide in physiological doses does not inhibit the ACTH or cortisol response to corticotrophin-releasing hormone-41 in normal human subjects

Whilst it has been postulated that atrial natriuretic peptide (ANP) may modulate pituitary hormone release, several investigations in non-human species have reported conflicting results when looking for an effect on the hypothalamo-pituitary-adrenal axis. However, in a recent study significant inhibition of corticotrophin-releasing hormone (CRH)-stimulated ACTH in cultured rat anterior pituitary cells occurred only with the complete peptide alpha-ANP(1-28). We have therefore investigated whether this form of ANP can inhibit CRH-stimulated ACTH and cortisol release in human subjects. Six healthy male volunteers received human alpha-ANP or placebo, and human CRH or placebo, on four separate occasions. ANP was infused at a rate of 0.01 micrograms/kg per min in order to achieve levels in the high physiological range. CRH was given as a bolus dose of 100 micrograms 30 min into the ANP infusion. Cortisol and ANP were measured by radioimmunoassay, the latter after extraction. ACTH was measured by immunoradiometric assay. The data were analysed by Student's paired t-test on basal, peak and incremental levels. Basal levels of ANP were within the normal range (2-5 pmol/l). With ANP infusion, mean +/- S.E.M. peak ANP levels were 29.6 +/- 3.1 pmol/l. There were no significant differences in mean basal cortisol and ACTH levels on each of the 4 study days. Mean peak cortisol and ACTH levels after CRH and ANP did not significantly differ from those achieved with CRH and placebo ANP. We thus conclude that at high physiological doses, circulating ANP does not inhibit CRH-stimulated ACTH or cortisol release.