Oral health knowledge of Spanish breastfeeding mothers.

INTRODUCTION: The aim of this study is to evaluate the knowledge of infant oral health in mothers who have breastfeeding for a period longer than 6 months. METHODS: A descriptive, observational and cross-sectional study was carried out in 1126 mothers who had breastfed for more than 6 months, using a validated questionnaire. RESULTS: 57% of the mothers surveyed had a high or very high level of knowledge about oral health during pregnancy and breastfeeding; a statistically significant association (p < 0.05) was found between this and the variables of mother's age, duration of breastfeeding, level of education and previous information received about oral health. CONCLUSIONS: The age of the mothers is positively related to the level of oral health knowledge, the elder the mothers the higher the knowledge. Mothers with a longer duration of breastfeeding beyond 24 months have a higher degree of oral health knowledge compared to the rest of the respondents, while their level of educations was also positively related to their degree of knowledge. There is a direct relationship between mothers having received previous information on oral hygiene and their surveyed degree of knowledge.

Microvesicles: ROS scavengers and ROS producers.

This review analyzes the relationship between microvesicles and reactive oxygen species (ROS). This relationship is bidirectional; on the one hand, the number and content of microvesicles produced by the cells are affected by oxidative stress conditions; on the other hand, microvesicles can directly and/or indirectly modify the ROS content in the extra- as well as the intracellular compartments. In this regard, microvesicles contain a pro-oxidant or antioxidant machinery that may produce or scavenge ROS: direct effect. This mechanism is especially suitable for eliminating ROS in the extracellular compartment. Endothelial microvesicles, in particular, contain a specific and well-developed antioxidant machinery. On the other hand, the molecules included in microvesicles can modify (activate or inhibit) ROS metabolism in their target cells: indirect effect. This can be achieved by the incorporation into the cells of ROS metabolic enzymes included in the microvesicles, or by the regulation of signaling pathways involved in ROS metabolism. Proteins, as well as miRNAs, are involved in this last effect.

Prevalence and risk factors for intestinal parasitic infections in a rural community in "consolación del sur" municipality, cuba.

Intestinal parasites are very common infections worldwide and they are responsible for significant public health problems. The World Health Organization estimates that one-third of the world population is infected and some epidemiologic factors related to the transmission have been identified. The purpose of this investigation was to study the prevalence of intestinal parasitic infections in people living in the rural community of "El Canal", Consolación del Sur municipality and the association with some epidemiologic risk factors. All participants were subjected to three methods of parasitological examinations on the stool samples and by immunodiagnostic tests which allow the detection of excretory-secretory antigens of adults with Fasciola hepatica. The global prevalence rate of intestinal parasitic infections (IPIs) was 18%, and 16.7% for protozoan infections, while the rate of helminth infection was lower (5.3%) in the population studied. The univariate analysis identified three factors associated with intestinal pathogenic protozoan infections which include livestock work, drinking water from well\river and eating unwashed fruits\vegetables. The multivariate analysis using introduction test logistic regression ratified the association of these risk factors. Contrary to what have been published in the majority of Cuban studies carried out in rural places, a higher prevalence of protozoan than helminth infection was found. This discrepancy may be explained because the majority of the workers in this rural community were stock-breeders and they are not involved in other agricultural work. The identification of risk factors is important in order to design appropriate strategies for control of IPIs in communities.

Susceptibilidad in vitro de candida spp: aisladas de la cavidad oral de pacientes VIH/Sida a itraconazol, clotrimazol y ketoconazol / In vitro susceptibility of candida ssp: isolated fromthe oral cavity of HIV/AIDS patientes to itraconazole, clotrimazole and ketoconazole

La candidiasis orofaríngea (COF) permanece como una de las principales infecciones oportunistas en pacientes infectados con el virus de la inmunodeficiencia humana (VIH) y con el síndrome de inmunodeficiencia adquirida (sida), y aunque su incidencia ha disminuido con la introducción de la terapia antirretroviral de alta eficacia, continúa siendo una afección característica en estos pacientes. En el presente trabajo se realizó un estudio de susceptibilidad in vitro mediante la metodología del CLSI, frente a itraconazol, ketoconazol y clotrimazol de 144 aislamientos clínicos de Candida, aisladas de la cavidad oral de pacientes infectados con el VIH/sida con cuadros clínicos de COF. La identificación de los aislamientos demostró que más del 90% pertenecían a Candida albicans. Al determinar el patrón general de susceptibilidad frente a los azoles estudiados mediante el método de microdilución en caldo del documento M27-A2 del Clinical and Laboratory Standard Institute, C. albicans exhibió valores de concentración mínima inhibitoria (CMI) en un rango de 0,01 a 8µg/mL para el itraconazol y el ketoconazol y de 0,01 a 2 g/mL para el clotrimazol. Sólo el 2,1 % de los aislamientos mostró franca resistencia frente al itraconazol, en tanto que el 3,5 % quedó clasificado dentro de la categoría “susceptible dosis-dependiente” para este triazol. La mayoría de los aislamientos de C. albicans mostraron valores de CMI frente al ketoconazol y al clotrimazol menores a 0.06 g/mL, siendo de un 96,9% (129 aislamientos) y de un 97,7% (129 aislamientos), respectivamente. El clotrimazol tuvo una mejor actividadin vitro comparado con los restantes azoles frente a los aislamientos estudiados. Candida spp. Mostró una elevada sensibilidad in vitro a los azoles estudiados. Se hace necesario continuar realizando estudios epidemiológicos para determinar los patrones de susceptibilidad y tasas de resistencias frente a los agentes...

The oropharyngeal candidiasis (OFC) remains as one of the principal opportunistic infections in patients infected with the human immunodeficiency virus (HIV) and with the acquired immunodeficiency syndrome (aids), and although his incidence has declined with the introduction of the highly active anti-retroviral therapy (HAART), remains as a typical complaint in these patients. A study of antifungal in vitro susceptibility testing, following the CLSI methodology, was realized against itraconazole, ketoconazole and clotrimazole of 144 clinical isolations of Candida, isolated from the oral cavity of patients infected with HIV/aids, with clinical pictures of OFC. The isolation’s identification, demonstrated that more than 90% belonged to Candida albicans. The determination of the general pattern of susceptibility, following the document M27-A2 of the Clinical and Laboratory Standard Institute, against to the studied azoles by means of the method of microdilution in liquid medium, show that the majority of C. albicans isolates showed values of MIC against ketoconazole and clotrimazole lower than 0.06 g/mL, representing a 96,9% (129 isolations) and a 97,7% (129 isolations), respectively. C. albicans exhibited the widest range of minimal inhibitory concentration (MIC). Only 2.1% of the isolations showed resistance against to itraconazole, while 3.5 % remained classified in the category “sensible dose - dependent” for this triazole. The majority of the strains showed values of MIC against ketoconazole and clotrimazole below 0.06 g/mL. The clotrimazole had a better in vitro activity compared with the remaining azoles opposite to the isolations. Candida spp. showed a high in vitro sensibility to the azoles studied. It becomes necessary the maintenance of epidemiologic studies for the determination of susceptibility patterns and of resistances rates against to the antifungal agents

Diagnóstico micológico en pacientes infectados por el virus de la inmunodeficiencia humana / Mycological diagnosis in patients infected with human immunodeficiency virus

Con el descubrimiento del virus de la inmunodeficiencia humana (VIH) en 1981, la frecuencia de las infecciones oportunistas en pacientes inmunodeprimidos, especialmente los infectados por el VIH, ha experimentado un notable incremento. Dentro de éstas se encuentran las de etiología fúngica, las cuales presentan un alto grado de mortalidad si no son diagnosticadas y tratadas a tiempo. En nuestro país con la instauración de la terapia antirretroviral altamente efectiva a partir del año 2001, se ha notado una reducción significativa en la morbilidad y la mortalidad por infecciones oportunistas, en particular por las micosis, muy comunes en este tipo de pacientes. En el presente estudio se realizó el diagnóstico micológico procedente de pacientes infectados por el VIH/sida, durante el período comprendido entre enero 2005 y diciembre de 2009. De un total de 1173 muestras biológicas procesadas, solamente resultaron positivas 324 para un 27,6% de positividad. La candidiasis orofaríngea y la meningoencefalitis criptococóccica fueron las infecciones diagnosticadas con una mayor incidencia. En las muestras analizadas la concordancia en la positividad entre el examen directo y el examen por cultivo micológico fue de un 56,2%, lo que confirma la importancia del empleo del examen directo en la visualización de estructuras fúngicas a partir de muestras clínicas

With the discovery of the human immunodeficiency virus (HIV) in 1981, the frequency of the opportunistic infections in the immunosuppressed patients, especially the infected ones by the HIV, it has experienced a notable increase. Inside these there are those of micotic aetiology, which present a high grade of mortality, if they are not diagnosed and treated on time. In our country with the instauration of the highly effective antirretroviral therapy since the year 2001, a significant reduction has been seen in the morbidity and the mortality of the opportunistic infections, specialle those caused by fungus, in this type of patients. In the present study the positividad was analyzed in the mycological diagnosis realized by conventional methods of the different clinical samples received in the National Laboratory of Reference of Mycology, from patients infected with HIV/aids during the period between January 2005 and December 2009. Of a whole of 1173 biological samples processed only 324 turned out positive, for 27, 6 % of positivity, being the oropharingeal candidiasis and the cryptococcal meningoencefalitis, those of major incidence observed. In the clinical samples analyzed, a concordance of 56,2 % was obtained in the positividad of the samples studied by means of direct examination and mycologycal cultures, which confirms the importance of direct preparations of clinical samples for the visualization of fungal elements from clinical samples

Processing of rat preprocortistatin in mouse AtT-20 cells.

Preprocortistatin (PPCST) has been recently identified as a novel somatostatin (SST)-related gene expressed only in brain. PPCST shares 11 of 14 residues with SST-14 at its C-terminal segment, where it features Lys-Lys and Lys-Arg basic sites for cleavage to putative cortistatin (CST)-14 and CST-29 peptides, respectively. Although synthetic replicates of the two putative CST peptides interact with SST receptors, they also display novel effects suggesting independent biological functions. Nothing is currently known about the naturally occurring mature cleavage products of PPCST posttranslational processing. Here we have cloned rat PPCST cDNA, stably expressed it in AtT-20 pituitary cells, and characterized the cellular and releasable products of PPCST processing by HPLC and radioimmunoassay using a SST-14 antibody that recognizes synthetic CST-14 and CST-29. Transfected cells released 120 +/- 21 pg of total CST-LI per plate basally, with an increase to 204 +/- 33 pg per plate with forskolin stimulation (p < 0.05). HPLC chromatograms of cell extracts revealed three peaks corresponding to CST-14, CST-29, and unprocessed PPCST (ratio, 41:55:4.5). CST was released preferentially as CST-14 (63-70%) compared with CST-29 (30-37%) under basal and forskolin-stimulated conditions. These studies demonstrate efficient processing of PPCST to both CST-14 and CST-29 through putative cleavage at both C-terminal dibasic sites of PPCST. Although the two peptides are synthesized approximately equally, CST-14 is released preferentially via the regulated secretory pathway.

Effect of nitric oxide on the somatostatinergic system in the rat exocrine pancreas.

Nitric oxide (NO) and somatostatin (SS) are two important mediators of the exocrine and endocrine pancreas, exerting opposite effects on this organ. There is strong evidence suggesting an interaction between pancreatic NO and SS. The aim of this study was to determine whether L-arginine (L-Arg), the substrate for NO synthase (NOS), and Nomega-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, regulate pancreatic somatostatin-like immunoreactivity (SSLI) content and the SS mechanism of action in pancreatic acinar cell membranes. L-Arg (150 mg/kg, intraperitoneally (i.p.)), L-NAME (50 mg/kg, i.p.) or L-NAME plus L-Arg were injected twice daily at 8 h intervals for 8 days. L-Arg decreased pancreatic SSLI content as well as the number of SS receptors in pancreatic acinar cell membranes whereas L-NAME increased both parameters. The stable SS analogue SMS 201-995 induced a significantly lower inhibition of forskolin-stimulated adenylyl cyclase activity in pancreatic acinar cell membranes from L-Arg-treated rats whereas an increased inhibition was observed in pancreatic acinar membranes from L-NAME-treated rats. These results indicate that the NO system may contribute to the regulation of the pancreatic somatostatinergic system.

Differential regulation of somatostatin receptor types 1-5 in rat aorta after angioplasty.

Treatment of restenosis after angioplasty with octapeptide somatostatin (SST) analogs has met with variable success. These analogs bind with high affinity to only two SST receptor (SSTR) subtypes (2 and 5), display moderate affinity for SSTR3, and low affinity for SSTR1 and 4. To optimize the vasculoprotective effect of SST, we have investigated the pattern of expression of all five SSTRs in rat thoracic aorta in the resting state and at 15 min, 3, 7, and 14 days after balloon endothelial denudation. SSTR1-5 were analyzed as mRNA by semiquantitative reverse transcriptase-polymerase chain reaction and as protein by immunocytochemistry. All five SSTRs were expressed in rat aorta both as mRNA and protein and displayed a time-dependent, subtype-selective response to endothelial denudation. mRNA for SSTR1 and 2 increased acutely (SSTR1 > SSTR2) on days 3 and 7, coincident with smooth muscle cell (SMC) proliferation, and declined to basal levels by day 14. SSTR3 and 4 displayed a different pattern with a delayed, more gradual increase in mRNA beginning at days 3-7 and continued to increase thereafter. SSTR5 mRNA was constitutively expressed at a low level and showed no change during the 2 wk postinjury period. By immunohistochemistry, SSTR1-5 antigens were localized predominantly in SMC that were present in the media or had migrated into the intima; antigen expression correlated with receptor mRNA expression. Notably, only SSTR1,3,4 were expressed in the intima: SSTR1 and 4 during the proliferative burst and SSTR3 and 4 after proliferation, when SMC migration into the intima continues. These results demonstrate dynamic changes in SSTR1-5 expression after vascular trauma localized to areas of vascular SMC migration and replication. In view of their early and prominent induction, SSTR1 may be the optimal subtype to target for inhibition of myointimal proliferation, and SSTR3 and 4 for migration and remodeling.

Polymorphism in the 5' flanking region of the human somatostatin receptor subtype 5.

The human somatostatin receptor subtype 5 (hSSTR5) gene has previously been cloned and localized to chromosome 16 p13.3. This region is evolutionarily conserved in all vertebrate genomes from the puffer fish (Fugu rubripes) to human, and also contains loci for genes associated with two common multisystemic disorders, adult polycystic kidney disease (PKD1) and tuberous sclerosis (TSC2). Analysis of the 5' flanking region of the hSSTR5 gene has revealed consensus sequences for a number of transcription factors as well as Alu-like repeat elements. In the present study, genomic DNA from 53 unrelated individuals was analysed by PCR and Southern blots probed with radiolabeled fragments generated from different segments of the hSSTR5 gene. We have identified two restriction fragment length polymorphisms (RFLP) with high heterozygosity values at the 5' flanking region of the hSSTR5 gene. These RFLP markers will be useful for determining the allelic loss of genetic material from this region. The observed polymorphism in the promoter region may affect the function of the hSSTR5 gene.

Influence of fluoxetine and p-chloroamphetamine on the somatostatin receptor-adenylyl cyclase system in the rat frontoparietal cortex.

There is evidence that suggests a reciprocal functional link between the serotonergic and the somatostatinergic system in the rat frontoparietal cortex. However, to date, the role of endogenous 5-hydroxytryptamine (serotonin) on the regulation of the somatostatin (SS) receptor-adenylyl cyclase (AC) system remains unclear. In the present study, the administration of fluoxetine (10 mg/kg i.p.), a 5-hydroxytryptamine uptake inhibitor in a single dose or administered daily for 14 days increased the number of specific [125I]Tyr11-SS receptors, with no change in the receptor affinity, in rat frontoparietal cortical membranes. However, the capacity of SS to inhibit forskolin (FK)-stimulated AC activity in these membranes was lower than in the control groups. The ability of the stable GTP analogue 5'-guanylylimidodiphosphate (Gpp(NH)p) to inhibit FK-stimulated AC activity in frontoparietal cortical membranes was also decreased in rats acutely and chronically treated with fluoxetine. p-Chloroamphetamine (5 mg/kg i.p.), which leads to a lasting reduction of 5-hydroxytryptamine innervation, administered on days 1, 3 and 5 and the rats sacrificed 1 or 3 weeks after the first injection, decreased the number of SS receptors without changing the receptor affinity. In this experimental group, SS also caused a significantly lower inhibition of FK-stimulated AC activity. p-Chloroamphetamine had no effect on the ability of Gpp(NH)p to inhibit FK-stimulated AC activity in frontoparietal cortical membranes at all the time periods studied. The present results suggest that under normal circumstances some SS receptors are under a tonic stimulatory control through the serotonergic system.

Dopamine enhances somatostatin receptor-mediated inhibition of adenylate cyclase in rat striatum and hippocampus.

Although there is evidence that suggests that dopamine (DA) has stimulatory effects on somatostatinergic transmission, it is unknown to date if DA increases the activity of the somatostatin (SS) receptor-effector system in the rat brain. In this study, we evaluated the effects of the administration of DA and the DA D1-like (D1, D5) receptor antagonist SCH 23390 and the D2-like (D2, D3, D4) receptor antagonist spiperone on the SS receptor-adenylate cyclase (AC) system in the Sprague-Dawley rat striatum and hippocampus. An intracerebroventricular injection of DA (0.5 microgram/rat) increased the number of SS receptors and decreased their apparent affinity in the striatum and hippocampus 15 hr after its administration. The simultaneous administration of the DA receptor antagonists SCH 23390 (0.25 mg/kg, ip) and spiperone (0.1 mg/kg, ip) before DA injection partially prevented the DA-induced increase in SS binding. The administration of SCH 23390 plus spiperone alone produced a significant decrease in the number of SS receptors in both brain areas studied at 15 hr after injection, an effect that disappeared at 24 hr. The increased number of SS receptors in the DA-treated rats was associated with an increased capacity of SS to inhibit basal and forskolin (FK)-stimulated (AC) activity in the striatum and hippocampus at 15 hr after injection. This effect had disappeared at 24 hr. By contrast, basal and FK-stimulated enzyme activities were unaltered after DA injection. No significant changes in the levels of the alpha i (alpha i1 + alpha i2) subunits were found in DA-treated rats as compared with control rats. In addition, the immunodetection of the alpha i1 or alpha i2 subunits showed no significant changes in their levels in DA-treated rats when compared with controls. DA injection also induced an increase in SS-like immunoreactive content in the rat striatum but not hippocampus at 15 hr after administration and returned to control values at 24 hr. These results provide direct evidence of a functional linkage between the dopaminergic and somatostatinergic systems at the molecular level.

5-hydroxytryptamine decreases somatostatin receptors and somatostatin-responsive adenylyl cyclase in rat pancreatic acinar membranes.

Pretreatment of pancreatic acini with 5-hydroxytryptamine (5-HT) reduced the binding of the labeled somatostatin (SS) analogue 125I-Tyr3-SMS to pancreatic acinar membranes. This effect was dependent of the dose of 5-HT used and length of pretreatment. This inhibitory effect of 5-HT was abolished when pancreatic acini were pretreated with 5-HT in the presence of the 5-HT1p receptor-antagonist 5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP). Pretreatment of pancreatic acini with 5-HT reduced the inhibition by the stable SS analogue SMS 201-995 of basal and forskolin (FK)-stimulated adenylyl cyclase (AC) activity in pancreatic acinar membranes. There was no statistical difference established between IC50 values for the stable GTP analogue 5'-guanylylimidodiphosphate (Gpp(NH)p) which inhibits ligand binding to SMS receptors in controls and in 5-HT treated pancreatic cells, respectively. In addition, no significant differences were seen in the level of Gi proteins in the control and 5-HT treated pancreatic acini. These data suggest that the decrease of the number of 125I-Tyr3-SMS receptors, would explain the decreased sensitivity of AC to SMS 201-995 in membranes from 5-HT-pretreated acini.

Histamine H1-receptors modulate somatostatin receptors coupled to the inhibition of adenylyl cyclase in the rat frontoparietal cortex.

Since exogenous histamine has been previously shown to increase the somatostatin (SS) receptor-effector system in the rat frontoparietal cortex and both histamine H1-receptor agonists and SS modulate higher nervous activity and have anticonvulsive properties, it was of interest to determine the participation of the H1-histaminergic system in this response. The intracerebroventricular (i.c.v.) administration of the specific histamine H1-receptor agonist 2-pyridylethylamine (PEA) (10 micrograms) to rats 2 h before decapitation increased the number of SS receptors (599 +/- 40 vs 401 +/- 31 femtomoles/mg protein, p < 0.01) and decreased their apparent affinity for SS (0.41 +/- 0.03 vs 0.26 +/- 0.02 nM, p < 0.01) in rat frontoparietal cortical membranes. No significant differences were seen for the basal and forskolin (FK)-stimulated adenylyl cyclase (AC) activities in the frontoparietal cortex of PEA-treated rats when compared to the control group. In the PEA group, however, the capacity of SS (10(-4) M) to inhibit basal and FK (10(-5) M)-stimulated AC activity in frontoparietal cortical membranes was significantly higher than in the control group (34 +/- 1% vs 20 +/- 2%, p < 0.001). The ability of low concentrations of the stable GTP analogue 5'-guanylylimidodiphosphate [Gpp(NH)p] to inhibit FK-stimulated AC activity in frontoparietal cortical membranes was similar in the PEA-treated and control animals. These results suggest that the increased SS-mediated inhibition of AC activity in the frontoparietal cortex of PEA-treated rats may be due to the increase of the number of SS receptors induced by PEA. Pretreatment with the H1-receptor antagonist mepyramine (30 mg/kg, intraperitoneally (IP) prevented the PEA-induced changes in SS binding and SS-mediated inhibition of AC activity. Mepyramine (30 mg/kg, IP) alone had no observable effect on the somatostatinergic system. The in vitro addition of PEA or mepyramine to frontoparietal cortical membranes obtained from untreated rats did not affect the SS binding parameters. Altogether, these results suggest that the H1-histaminergic system modulates the somatostatinergic system in the rat frontoparietal cortex.

Effect of dimaprit and cimetidine on the somatostatinergic system in the rat frontoparietal cortex.

A recent study carried out by this laboratory demonstrated that exogenous histamine increases the somatostatin (SS) receptor/effector system in the rat frontoparietal cortex (Puebla and Arilla, 1995). In the present study we examined the participation of the H2-histaminergic system in this modulation by use of the H2-receptor agonist and antagonist dimaprit and cimetidine, respectively. Dimaprit administration [20 micrograms/rat, intracerebroventricularly (ICV)] to rats 2 hours before decapitation increased the number of SS receptors in the frontoparietal cortex without changing the affinity constant. Pretreatment with cimetidine (20 micrograms/rat, ICV) prevented the dimaprit-induced changes in SS binding in the frontoparietal cortex, whereas cimetidine alone (20 micrograms/rat, ICV) had no observable effect on this parameter. The in vitro addition of dimaprit or cimetidine to frontoparietal cortex membranes from untreated rats did not markedly affect the SS binding characteristics. Somatostatin caused a significantly higher inhibition of basal and forskolin (FK)-stimulated adenylyl cyclase (AC) activity in frontoparietal cortex membranes from dimaprit-treated rats than in controls, an effect that was prevented by pretreatment with cimetidine. No significant differences, however, were detected for the basal or FK-stimulated AC enzyme activity in the control, dimaprit-, and/or cimetidine-treated groups, which suggests no impairment of the AC catalytic subunit. In addition, the functional activity of the guanine nucleotide-binding inhibitory protein Gi, as measured by the capacity of the stable GTP analogue 5'-guanylylimidodiphosphate [Gpp(NH)p] to inhibit FK-stimulated AC activity, was not altered by dimaprit. Thus, the increased SS-mediated inhibition of AC activity observed in the dimaprit-treated rats may be caused by the increase in the number of SS receptors. Neither dimaprit nor cimetidine affected somatostatinlike immunoreactivity (SSLI) content. The present results, together with the fact that SS and histamine have been shown to influence locomotor activity and nociception in a similar manner, suggest that some of the neurotransmitter effects of SS may be modulated by histamine via H2-histaminergic receptors.

Involvement of presynaptic histamine H3 receptors in the modulation of somatostatin binding and its effects on adenylyl cyclase activity in the rat frontoparietal cortex.

Thioperamide (2 mg/kg, l.p.), a histamine H3-receptor antagonist, increased the number of somatostatin (SS) receptors, with no change in the affinity constant, in the rat frontoparietal cortex. This effect was prevented by treatment with (R)-alpha-methylhistamine (3.2 mg/kg, l.p.), a histamine H3-receptor agonist. Thioperamide also induced an increase in SS binding in rats pretreated with mepyramine, a histamine H1-receptor antagonist, or cimetidine, a histamine H2-receptor antagonist. Pretreatment with mepyramine plus cimetidine administered simultaneously antagonized the thioperamide effect on SS binding. The increase in the number of SS receptors was accompanied by a greater SS-mediated inhibition of basal and forskolin-stimulated adenylyl cyclase (AC) activity in frontoparietal cortical membranes in the thioperamide group. Furthermore, the functional activity of the guanine nucleotide-binding inhibitory protein (G1 protein) was not altered by thioperamide or (R)-alpha-methylhistamine administration in frontoparietal cortical membranes. In rats treated with mepyramine plus thioperamide or cimetidine plus thioperamide, the increase in the number of SS receptors was also accompanied by an increased SS inhibition of AC activity. Thioperamide induced a significant increase in SS-like immunoreactivity content in the frontoparietal cortex. Altogether, these results suggest that frontoparietal cortical histamine may play, at least in part, a role in the regulation of the somatostatinergic system.

Glycine increases the number of somatostatin receptors and somatostatin-mediated inhibition of the adenylate cyclase system in the rat hippocampus.

The glycine and somatostatin (SS) neurotransmission systems in the brain have been implicated in the function of sensory, motor, and nociceptive pathways. To investigate a possible relationship between these two components, we studied the influence of glycine on the binding of 125I-Tyr11-SS to its receptors and on SS-like immunoreactivity (SSLI) levels in the rat hippocampus and frontoparietal cortex. An intracerebroventricular (i.c.v.) dose of 16 or 160 nmol of glycine induced an increase in the total number of specific SS receptors in the hippocampus but not in the frontoparietal cortex at 15 min following injection, with no changes in the affinity constant. This effect seems to be mediated by inhibitory strychnine-sensitive glycine receptors since pretreatment with the antagonist strychnine (80 micrograms/100 g body weight, intravenously) abolished this response. No significant changes in SSLI content were detected in either brain region of glycine- and strychnine plus glycine-treated rats as compared to control values. Since SS receptors are coupled via guanine nucleotide-binding G proteins to the adenylyl cyclase (AC) system, we also examined the inhibitory effects of SS and the guanine nucleotide Gpp(NH)p on AC activity in hippocampal membranes of control, glycine- and strychnine plus glycine-treated rats since the increase in SS receptors was observed only in this brain area. No significant differences were observed for the forskolin (FK)-stimulated AC enzyme activities in hippocampal membranes from all the experimental groups studied. In the hippocampus of the glycine- (160 nmol) treated group, however, basal AC activity was significantly lower, and the capacity of SS to inhibit FK-stimulated AC activity was increased as compared to the control group. Pretreatment with strychnine prevented the increase in SS-mediated inhibition of AC activity. The functional activity of the inhibitory guanine nucleotide-binding protein Gi, as determined by the inhibitory effect of the stable GTP analogue Gpp(NH)p on FK-stimulated AC activity, was significantly higher in hippocampal membranes of glycine- (160 nmol) treated rats as compared to controls. This suggests that the increased inhibition of AC activity by SS in the glycine-treated group may be due to the increase in Gi activity and/or the increase in the number of SS receptors observed. Alternatively, the greater Gi activity may be responsible for the increased binding of 125I-Tyr11-SS to its receptors observed after glycine administration. Altogether, these data suggest that the hippocampal somatostatinergic system can be regulated by strychnine-sensitive glycine receptors in the rat.

Hippocampal somatostatin receptors and modulation of adenylyl cyclase activity in histamine-treated rats.

In the present study, the effects of an intracerebroventricular (i.c.v.) dose of histamine (0.1, 1.0 or 10.0 micrograms) on the hippocampal somatostatin (SS) receptor/effector system in Wistar rats were investigated. In view of the rapid onset of histamine action, the effects of histamine on the somatostatinergic system were studied 2 h after its administration. Hippocampal SS-like immunoreactivity (SSLI) levels were not modified by any of the histamine doses studied. SS-mediated inhibition of basal and forskolin (FK)-stimulated adenylyl cyclase (AC) activity was markedly increased in hippocampal membranes from rats treated with 10 micrograms of histamine (23% +/- 1% vs. 17% +/- 1% and 37% +/- 2% vs. 23% +/- 1%, respectively). In contrast, neither the basal nor the FK-stimulated enzyme activities were affected by histamine administration. The functional activity of the hippocampal guanine-nucleotide binding inhibitory protein (Gi protein), as assessed by the capacity of the stable GTP analogue 5'-guanylylimidodiphosphate (Gpp[NH]p) to inhibit FK-stimulated AC activity, was not modified by histamine administration. These data suggest that the increased response of the enzyme to SS was not related to an increased functional activity of Gi proteins. In fact, the increased AC response to SS in hippocampal membranes from histamine (10 micrograms)-treated rats was associated with quantitative changes in the SS receptors. Equilibrium binding data obtained with [125I]Tyr11-SS indicate an increase in the number with specific SS receptors (541 +/- 24 vs. 365 +/- 16 fmol/mg protein, P < 0.001) together with a decrease in their apparent affinity (0.57 +/- 0.04 vs. 0.41 +/- 0.03 nM, P < 0.05) in rat hippocampal membranes from histamine (10 micrograms)-treated rats as compared to control animals. With the aim of determining if these changes were related to histamine binding to its specific receptor sites, the histaminergic H1 and H2 receptor antagonists mepyramine and cimetidine, respectively, were administered 1 h before histamine injection. The pretreatment with mepyramine or cimetidine induced an increase in the number and affinity constant of the SS receptors whereas the simultaneous pretreatment with both histamine antagonists prevented the histamine-induced changes in SS binding to its receptors. Since the hippocampal SS receptor/effector system is modulated by histamine, it is tempting to speculate that in the hippocampus, SS could be involved as a mediator of the histamine effects on behaviors such as learning and memory.

alpha-Fluoromethylhistidine influences somatostatin content, binding and inhibition of adenylyl cyclase activity in the rat frontoparietal cortex.

Slow-wave sleep, wakefulness, locomotor activity and learning and memory are regulated in similar ways by somatostatin (SS) and histamine. To clarify the possible role of endogenous histamine on the somatostatinergic system of the rat frontoparietal cortex, we studied the effect of 50 micrograms of alpha-fluoromethylhistidine (alpha-FMH), a specific inhibitor of histidine decarboxylase, administered intracerebroventricularly (i.c.v.) at 1, 4 and 6 h, on somatostatin-like immunoreactivity (SSLI) content and the SS receptor/effector system. The histamine content in the frontoparietal cortex decreased to about 67, 60 and 72% of control values at 1, 4 and 6 h after alpha-FMH administration, respectively. At 6 h after alpha-FMH injection, there was an increase in SSLI content and a decrease in the number of SS receptors, with no change in the apparent affinity. No significant differences were seen for the basal and forskolin (FK)-stimulated adenylyl cyclase (AC) activities in the frontoparietal cortex of alpha-FMH-treated rats when compared to the control group at all times studied. At 6 h after alpha-FMH administration, however, the capacity of SS to inhibit basal and FK-stimulated AC activity in the frontoparietal cortex was significantly lower than in the control group. The ability of the stable GTP analogue 5'-guanylylimidodiphosphate (Gpp(NH)p) to inhibit FK-stimulated AC activity in frontoparietal cortex membranes was the same in the alpha-FMH-treated (6 h) and control animals. Therefore, the decreased SS-mediated inhibition of AC activity observed in the alpha-FMH-treated rats is not due to an alteration at the guanine nucleotide-binding inhibitory protein (Gi) level but rather may be due to the decrease in the number of SS receptors. Taken together, these data suggest that alpha-FMH influences the sensitivity to SS in the rat frontoparietal cortex.

Exogenous histamine increases the somatostatin receptor/effector system in the rat frontoparietal cortex.

The present study examined the effects of histamine on somatostatin-like immunoreactivity levels, binding of 125I-[Tyr11]somatostatin to its specific receptors, somatostatin inhibition of basal and forskolin-stimulated adenylyl cyclase activity and inhibitory guanine-nucleotide binding protein (Gi) function in the rat frontoparietal cortex. An intracerebroventricular (i.c.v.) dose of 10 micrograms or 1 microgram of histamine induced an increase in the number of specific 125I-[Tyr11]somatostatin receptors (590 +/- 22 vs 358 +/- 12 fmol/mg protein, P < 0.001 and 455 +/- 20 vs. 342 +/- 21 fmol/mg protein, P < 0.01, respectively) together with a decrease in their apparent affinity (0.76 +/- 0.04 vs 0.39 +/- 0.02 nM, P < 0.001 and 0.60 +/- 0.03 vs 0.39 +/- 0.05 nM, P < 0.01, respectively) in rat frontoparietal cortex membranes. This increase in tracer binding was not due to a direct effect of histamine on the somatostatin receptors since no change in binding was produced when histamine was added directly to the incubation medium. No significant differences were seen for either the basal or forskolin-stimulated adenylyl cyclase activity in frontoparietal cortex membranes of histamine-treated rats as compared with the control group. In rats treated with 10 micrograms of histamine, however, somatostatin caused a significantly greater inhibition of basal and forskolin-stimulated adenylyl cyclase activity as compared to the control group (33 +/- 4% vs 19 +/- 1% inhibition, P < 0.05 and 31 +/- 1% vs 21 +/- 3% inhibition, P < 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-2 adrenoceptors modulate the somatostatinergic system and G protein levels in the rat hippocampus.

alpha 2-Adrenoceptor agonists and somatostatin (SS) exert opposite effects on the spike discharge of pyramidal and granule cells in the rat hippocampus. We studied whether clonidine, an alpha 2-adrenoceptor agonist, and yohimbine, an alpha 2-adrenoceptor antagonist, can modulate somatostatin-like immunoreactivity (SSLI) levels, binding of 125I-Tyr11-somatostatin (125I-Tyr11-SS) to its specific receptors, SS-inhibited adenylyl cyclase (AC) activity, and the guanine-nucleotide binding regulatory proteins Gi and G(o) in the rat hippocampus. Clonidine (1 mg/kg, intraperitoneally (IP) or yohimbine (5 mg/kg, IP) injected at both 10 and 16 hours before decapitation did not affect SSLI content in the hippocampus. Clonidine administration decreased the number of specific SS receptors and increased the apparent affinity in hippocampal membranes. This change in SS binding was not the result of a direct effect of clonidine on these receptors because no effect in binding was produced by high concentrations of clonidine (10(-5) M) when added in vitro. Pretreatment with yohimbine prevented the clonidine-induced in SS binding. Yohimbine alone produced a significant increase in the number of 125I-Tyr11-SS receptors and a decrease in its apparent affinity. Clonidine decreased the ADP-ribosylation of a 41- and a 39-kDa G-protein by pertussis toxin (PTX), whereas yohimbine had no effect on the PTX-catalyzed ADP-ribosylation. No significant differences were seen for the basal or for the forskolin (FK)-stimulated AC enzyme activities in the control, clonidine- and/or yohimbine-treated groups. Somatostatin caused a significantly lower inhibition in AC activity in hippocampal membranes of clonidine-treated rats, whereas yohimbine led to an opposite effect.(ABSTRACT TRUNCATED AT 250 WORDS)