The type of fortificant and the leaf matrix both influence iron and zinc bioaccessibility in iron-fortified green leafy vegetable sauces from Burkina Faso.

Leafy vegetable sauces from Burkina Faso were assessed as a potential vehicle for food fortification. First, iron and zinc bioaccessibility were measured by dialysability method in amaranth and Jew's mallow sauces and in traditional whole dishes consisting of maize paste plus leafy vegetable sauces. Iron dialysability and solubility were higher in amaranth than in Jew's mallow sauce, pointing to a marked effect of the matrix. Iron dialysability was hardly affected by the maize paste contrary to zinc dialysability, which was reduced. Second, iron and zinc bioaccessibility was assessed in the same sauces fortified with NaFeEDTA or iron sulfate. Added iron, i.e. iron supplied by fortification, represented 60% of total iron at the low fortification level and 80% at high level. In amaranth sauces with the high level of fortification using NaFeEDTA and iron sulfate, fractional dialysable iron reached respectively 66% and 26% compared to only 8.1% in the unfortified sauce. Similarly, in Jew's mallow sauces, fractional dialysable iron was 57% and 5% respectively with NaFeEDTA and iron sulfate and less than 1% in the unfortified sauce. Concomitantly, fractional dialysable zinc increased by respectively 20% and 40% in amaranth and Jew's mallow sauces fortified with NaFeEDTA whereas it remained unchanged with iron sulfate. Iron fortification could be an efficient way to greatly increase the available iron content of green leafy vegetable sauces and for this purpose NaFeEDTA is more effective than iron sulfate whatever the food matrix.

Adolescent alcohol exposure alters the rat adult hypothalamic-pituitary-adrenal axis responsiveness in a sex-specific manner.

Exposure to alcohol during adolescence exerts long-term effects on the adult brain stress circuits, causing many changes that persist into adulthood. Here we examined the consequences of adolescent intermittent ethanol (AIE, administered from postnatal day (PND) 28-42) on the hypothalamic-pituitary-adrenal (HPA) axis-related brain circuitry of rats challenged with intragastric (ig) administration of alcohol in adulthood (PND 70-71). Both male and female adolescent rats were exposed to alcohol vapors, while controls did not receive the drug, to assess whether AIE alters adult alcohol response in a sex-specific manner. We demonstrated that AIE increased paraventricular nucleus (PVN) Avp mRNA levels during late (PND 42) but not middle (PND 36) adolescence in males. While an alcohol challenge administered to 70-71-day-old rats increased Crf mRNA levels in males and Avp mRNA levels in females, AIE blunted both effects. These results suggest that AIE produced long-lasting changes in the responsiveness of the HPA axis to a subsequent alcohol challenge in a sex-specific manner. Furthermore, AIE altered adrenergic brain stem nuclei involved in stress responses in adulthood, resulting in increased numbers of phenylethanolamine N-methyltransferase (PNMT) neurons in male C2 and female C1 regions. This tended to enhance activation of the male C2 nucleus upon alcohol challenge. Collectively, these results suggest that AIE exerts long-term effects on the ability of the PVN to respond to an alcohol challenge in adulthood, possibly mediated by catecholaminergic input from the brain stem to the PVN.

Adolescent alcohol exposure alters the central brain circuits known to regulate the stress response.

Adolescent alcohol exposure (AAE) may exert long-term effects on the adult brain. Here, we tested the hypothesis that the brain regions affected include the rat hypothalamic-pituitary-adrenal (HPA) axis. Specifically, we examined the consequences of AAE [postnatal days (PND) 28-42] on the HPA axis-related brain circuitry of male rats challenged with an intragastric (ig) administration of alcohol in young adulthood (PND 61-62). Adolescent rats were exposed to alcohol vapors, while controls did not receive the drug. The mean blood alcohol level in adolescence on PND 40 was 212.8±5.7 mg %. Using immunohistochemistry and in situ hybridization procedures, we measured signals for c-fos and corticotropin releasing factor (CRF) in the paraventricular nucleus (PVN) of the hypothalamus, as well as signals for c-fos and phenylethanolamine N-methyltransferase (PNMT) in the adrenergic brain stem regions (C1 and C2). PVN CRF mRNA expression was significantly blunted in AAE rats tested at PND 61-62, compared to their controls. These animals also displayed a significant increase in the mean number of PNMT-ir cells/brain stem section in the C2 area. Collectively, these results suggest that exposure to alcohol vapors during adolescence exerts long-term effects on the ability of the PVN to mount a response to an acute alcohol administration in young adulthood, possibly mediated by medullary catecholamine input to the PVN.

Brain stem catecholamines circuitry: activation by alcohol and role in the hypothalamic-pituitary-adrenal response to this drug.

Although the stimulatory effect of alcohol on the rat hypothalamic-pituitary-adrenal (HPA) axis is well known, the mechanisms underlying this influence remain poorly understood. In the present study, we tested the hypothesis that brain catecholamines play an important role in this response. As expected, the acute intragastric administration of alcohol to adult male rats elevated plasma adrenocorticotrophic hormone (ACTH) levels and activated hypothalamic corticotrophin-releasing factor neurones. Novel findings pertain to the effect of alcohol on, and the role played by, brain adrenergic circuits. We first observed that alcohol up-regulated c-fos signals in the locus coeruleus, the main noradrenergic brain cell group; and that it activated (nor)adrenergic medullary cells (A1-A2/C1-C3). Evidence for the role played by these catecholaminergic circuits then came from the observation that blockade of α(1) -, but not ß-, adrenergic receptors interfered with alcohol-induced ACTH secretion; and that depletion of catecholaminergic input to the paraventricular nucleus (PVN) by the toxin 6-hydroxydopamine significantly decreased the ACTH response to alcohol. Finally, destruction of the A1-A2/C1-C3 region with the immunotoxin anti-dopamine-B-hydroxylase-saporin interfered with the catecholaminergic input to the PVN. Collectively, our work extends our knowledge of the ability of this drug to up-regulate catecholamine circuitry in the rat brain. It also shows that medullary catecholamine innervation of the hypothalamus plays an important role in modulating the stimulatory effect of alcohol on the HPA axis, an effect exerted through activation of α(1) -adrenergic receptors.

Potential of amylolytic lactic acid bacteria to replace the use of malt for partial starch hydrolysis to produce African fermented pearl millet gruel fortified with groundnut.

Fermentation and starch hydrolysis of a pre-cooked pearl millet-groundnut (MG) slurry inoculated with amylolytic lactic acid bacteria (ALAB) or by back slopping was investigated as a substitute for the addition of malt to prepare infant gruels. The ALAB collection strain Lb. plantarum A6, and the endogenous microflora provided by back slopping were more efficient in acidifying and partially hydrolysing starch in the MG slurry than Lb. plantarum 6.1, isolated from the traditional process in Burkina Faso. Large amounts of maltotriose and maltotetraose accumulated in slurry fermented by strain A6. No accumulation of maltose was observed, which could be an advantage to prevent the growth of microbial contaminants such as yeasts. Starch hydrolysis in the MG slurry inoculated with strain A6 or by back slopping enabled preparation of high-energy density gruels (84.7+/-4.4 and 80.4+/-23.8 kcal/100 g of gruel, respectively) of liquid consistency. However variability was higher with back slopping.

Enzyme activities of lactic acid bacteria from a pearl millet fermented gruel (ben-saalga) of functional interest in nutrition.

Lactic acid bacteria responsible for the fermentation of a pearl-millet based fermented gruel, ben-saalga, were investigated for enzyme activity in relation with the nutritional characteristics of gruels used as complementary foods for young children. Thirty pre-selected LAB from a set of 155 isolates were characterized principally for their ability to produce amylase, phytase and alpha-galactosidase. Two Lactobacillus plantarum strains (4.4 and 6.1) and three Lactobacillus fermentum strains (11.11.2, 3.7, 7.4) able to produce one or more of these enzymes were selected. Only weak amylase activity was found in the two Lactobacillus plantarum strains. alpha-amylase activity was associated with cells and was lower than 0.05 Ceralpha Units/ml. Phytase activity was detected in all five strains and was linked to the cell. The highest phytase activity was found in Lb. plantarum 4.4 and 6.1 (348.7 +/- 17.4U/ml and 276.3 +/- 51.4U/ml, respectively) and Lb. fermentum 7.4. (276.3 +/- 13.2U/ml). All strains displayed a cell-linked alpha-galactosidase activity. In a medium containing 2% glucose, the highest cellular activity was found in Lb. fermentum 3.7 (1441.1 +/- 133.7U/ml) and Lb. plantarum 4.4 (1223.1 +/- 148.3U/ml) after 6h of fermentation in the presence of stachyose, and in Lb. plantarum 4.4 (763.3 +/- 23.5U/ml) and Lb. fermentum 7.4 (346.7 +/- 14.8U/ml) after 24h of fermentation with raffinose. These results are consistent with previous observations showing that phytates and alpha-galactooligosaccharides decreased during the natural lactic acid fermentation of pearl millet slurries, and that partial starch hydrolysis can be performed by endogenous microflora provided a pre-gelatinisation step is included in the process.

Novel role of adrenergic neurons in the brain stem in mediating the hypothalamic-pituitary axis hyperactivity caused by prenatal alcohol exposure.

Exposure to alcohol during embryonic development leads to changes in the hypothalamic-pituitary-adrenal (HPA) axis such that adult offspring release more adrenocorticotrophic hormone (ACTH) than controls when exposed to stress. In the present work, we tested the hypothesis that changes in the activity of the catecholaminergic system modulate, at least in part, this upregulation of the HPA axis. Pregnant Sprague-Dawley rats were exposed to alcohol 6 h daily during gestation days 7-18 using the vapor chamber model, which generated mean blood alcohol levels of 188.6+/-10 mg/dl. All experiments were performed on 2 to 3-month-old offspring. We first measured the ACTH response to i.c.v. injection of adrenergic receptor agonists. In rats exposed to footshocks, we then investigated the activity of corticotrophin-releasing factor (CRF) as well as indexes of catecholamine ir, namely tyrosine hydroxylase (TH) immunopositive neurons in the paraventricular nucleus (PVN), TH immunopositive neurons in the locus coeruleus, and phenylethanolamine N-methyltransferase (PNMT) immunopositive neurons in the brain stem. While adult females exposed to alcohol during fetal development (FAE) displayed the expected enhanced ACTH response to stress, there were no significant differences in response to adrenergic receptor agonists or in shock-induced CRF/TH ir and neuronal activity, as determined by c-fos colocalization. In contrast, FAE female offspring exposed to footshocks showed a significant increase in the activity of adrenergic neurons in the C1 region of the brain stem, a population of cells that project to the PVN. Collectively, these results suggest that while FAE-induced hyperactivity of the HPA axis is not accompanied by significant changes in PVN CRF or TH-ir neurons, it is characterized by an upregulation of C1 adrenergic neurons of the brain stem. This novel finding should lead to the functional characterization of this brain region in the FAE model.

Presence of corticotrophin-releasing factor and/or tyrosine hydroxylase in cells of a neural brain-testicular pathway that are labelled by a transganglionic tracer.

Our laboratory has shown that male testosterone levels are not solely controlled by the release of hypothalamic gonadotrophin-releasing hormone and pituitary luteinising hormone, but are also regulated by a multisynaptic pathway connecting the brain and the testis that interferes with the testosterone response to gonadotrophins. This pathway, which is independent of the pituitary gland, is activated by an i.c.v. injection of either the stress-related peptide corticotrophin-releasing factor (CRF) or of beta-adrenoceptor agonists, both of which alter androgen release and decrease levels of the peripheral-type benzodiazepine receptor and the steroidogenic acute regulatory protein within Leydig cells. Our original studies used the retrograde transganglionic tracer pseudorabies virus (PRV) to map progression of the virus from the testes to upper brain levels. The present study aimed to extend this work by identifying the regions where CRF and catecholamine neurones represented components of the stress-activated, brain-testicular pathway that prevents testosterone increases. To this end, anaesthetised adult male rats received an intra-testicular injection of PRV. Using immunofluorescence, we identified co-labelling of PRV and either CRF or tyrosine hydroxylase (TH), the enzyme responsible for biogenic amine synthesis. Co-labelling of PRV and CRF was found in the bed nucleus of the stria terminalis, the paraventricular nucleus of the hypothalamus (PVN) and the central amygdala. Co-labelling of PRV and TH was found in the PVN, substantia nigra, A7/Kölliker-Fuse area, area of A5, locus coeruleus, nucleus of solitary tract, area of C3, area of C2 and the area of C1/A1. These results indicate that most cell groups of the ventral noradrenergic pathway have neurones that are a part of the brain-testicular pathway. This suggests that the stress hormones CRF and catecholamines may act as neurotransmitters that signal the pathway to inhibit increases in plasma testosterone levels.

Study through surveys and fermentation kinetics of the traditional processing of pearl millet (Pennisetum glaucum) into ben-saalga, a fermented gruel from Burkina Faso.

Traditional cereal-based fermented foods are frequently used as complementary foods for infants and young children in Africa. This is the case for ben-saalga, a popular fermented gruel produced from pearl millet (Pennisetum glaucum) in Burkina Faso. Detailed knowledge of traditional processing is a prerequisite for investigating ways to improve both the nutritional and sanitary qualities of the corresponding foodstuff. In this work, the traditional processing of pearl millet into ben-saalga was investigated in 24 production units, and fermentation kinetics were studied in pilot scale experiments. Processing steps include: washing (optional), soaking of the grains (first fermentation step), grinding and sieving of the wet flour, settling (second fermentation step), and cooking. The soaking step was mainly characterized by alcoholic fermentation whereas lactic acid fermentation occurred during the settling step. Fermentation kinetics during settling indicates a temporal variation of metabolic activity. Initially, both homofermentative and heterofermentative pathways were simultaneously active, and later only a homofermentative pathway was active. The paste produced at the end of settling had a low pH (4.0+/-0.4) and its microflora was dominated by lactic acid bacteria (LAB) with an amylolytic LAB/LAB ratio of 12%. Sucrose disappeared in the grains during soaking but was not detected in the soaking water, whereas glucose, fructose and maltose appeared transiently. Glucose and fructose were the main substrates observed for lactic acid fermentation during the settling step; however unbalanced fermentation led to the hypothesis that starch hydrolysis products may also serve as substrates for lactic acid formation. At the end of the processing, a 75% and 83% decrease was observed in phytate (IP6) and raffinose, respectively. The sour gruel ben-saalga resulting from cooking the sour paste had inadequate nutritional characteristics with respect to infants' and young children's requirements; it was characterized by fluid consistency (Bostwick flow: 137 mm/30 s) and low energy density (about 30 kcal/100 g of gruel).

Synthesis and biological activity of GnRH antagonists modified at position 3 with 3-(2-methoxy-5-pyridyl)-alanine.

Degarelix is a potent very long-acting GnRH antagonist after subcutaneous administration. In this paper, we describe the synthesis of two analogs of degarelix incorporating racemic 3-(2-methoxy-5-pyridyl)-alanine (2-OMe-5Pal, 5) at position 3. The two diastereomers were separated by reverse-phase high-performance liquid chromatography (RP-HPLC) and the absolute stereochemistry at position 3 in the peptides was determined by enzymatic digestion with proteinase K. These analogs were tested in vitro for their ability to antagonize the GnRH receptor and in vivo for duration of action in a castrated male rat assay. Analog 7 with D2-OMe-5Pal was potent in vitro (IC50 = 5.22 nM); however, analog 8 with L2-OMe-5Pal at position 3 in degarelix lost potency as an antagonist of the human GnRH receptor (IC50 = 36.95 nM). Both the analogs were found to be short-acting in vivo.

Role of specific adrenergic receptors in mediating the adrenocorticotropic hormone response to increased nitric oxide levels.

We investigated the role played by catecholamine-dependent pathways in modulating the ability of the nitric oxide (NO) donor 3-morpholino-sydnonimine (SIN-1) to release adrenocorticotropic hormone (ACTH) following its intracerebroventricular (i.c.v.) or intravenous (i.v.) injection. We first showed that the nonspecific adrenergic agonist noradrenaline, the alpha- or beta-adrenergic agonists phenylephrine or dobutamine, or the noradrenergic uptake inhibitor desipramine, all significantly stimulated ACTH secretion by freely moving, nonanaesthetized rats. We then observed that destruction of noradrenergic nerve endings with the neurotoxin 6-hydroxydopamine, respectively abolished and significantly decreased the ACTH response to the i.c.v. or i.v. administration of SIN-1. Finally, we sought to identify the type of adrenergic receptor(s) mediating the influence of catecholamines. beta-Adrenergic receptors did not appear to be involved in the stimulatory effect of SIN-1 regardless of its route of injection. By contrast, alpha 2-adrenergic receptors played an important role in the ACTH response to i.v. or i.c.v. administered SIN-1. Collectively, these results indicate that while hypothalamic alpha 1- and beta-adrenergic receptors are important for hypothalamic-pituitary-adrenal (HPA) axis activity, only alpha 2-adrenergic receptors are involved in modulating the ability of NO to release ACTH. Our laboratory and others have previously reported that NO increased hypothalamic noradrenaline levels, while conversely noradrenaline up-regulated levels of NO synthase, the enzyme responsible for NO formation; and that injection of corticotropin-releasing factor into the brain ventricles releases catecholamines and stimulates NO formation. Taken together with these observations, our results point to complex functional relationships between NO, catecholamines and the HPA axis.

Inducible nitric oxide synthase is responsible for nitric oxide release from murine pituicytes.

This study investigated whether pituicytes were able to produce and release nitric oxide (NO), and which type of nitric oxide synthase (NOS) would be responsible for this phenomenon. Lipopolysaccharide (LPS) 1 micro g/ml was used as inflammatory mediator. Because pituicytes are known to secrete interleukin (IL)-6 upon stimulation with LPS, this parameter was also investigated. Cultured pituicytes, from 4-week-old male mice, were stimulated with LPS for 6 h or 24 h. At 24 h, there was a significant increase in accumulated nitrite indicating NO formation. In contrast, IL-6 release was already significantly higher 6 h after stimulation and further increased at 24 h. The correlation between accumulated nitrite and secreted IL-6 was 0.84 after 24 h of incubation with LPS. The expression of inducible NOS (iNOS) mRNA in the pituicytes was significantly higher than the control level after 6 h and 24 h of exposure to LPS, with levels at 6 h being significantly higher than those at 24 h. There was no detected expression of endothelial NOS or neuronal NOS mRNA. Cultured pituicytes were also subjected to immunocytochemistry for iNOS protein at 6, 12, and 24 h after stimulation with LPS. Most cells were positive for iNOS, but there were no observable differences with the time points that we used. Collectively, these results show that pituicytes are able to produce NO, and that the inducible form of NOS is responsible for this production. Furthermore, there is a weak correlation between NO and IL-6 released from pituicytes after 24 h of stimulation with LPS.

Comparison between the influence of the intravenous and intracerebroventricular injection of a nitric oxide donor on adrenocorticotropic hormone release and hypothalamic neuronal activity.

We investigated the ability of the nitric oxide (NO) donor 3-morpholino-sydnonimine (SIN-1) to release adrenocorticotropic hormone (ACTH) and up-regulate hypothalamic neurones following its intravenous (i.v.) injection. i.v. SIN-1 (0.2-1.8 mg/kg) produced dose-related increases in plasma ACTH levels which were blocked by prior neutralization of endogenous corticotropin-releasing factor (CRF) but not by vasopressin antibodies. In contrast, the intracerebroventricular (i.c.v.) injection of 50-microg SIN-1 released significantly larger amounts of ACTH, a response blunted by either CRF or vasopressin antibodies. While i.c.v. SIN-1 markedly up-regulated transcripts of the immediate early gene NGFI-B in the paraventricular nucleus (PVN) of the hypothalamus, no such response was observed following the i.v. injection of up to 2.0 mg/kg SIN-1. Finally, we found no evidence that the influence of the peripheral administration of SIN-1 on ACTH secretion is mediated by altered pituitary responsiveness to CRF or vasopressin. The fact that NO has a profound hypotensive influence in the periphery suggests that it may have released ACTH through this mechanism, although the absence of PVN neuronal response in regions that are activated by decreased blood pressure casts some doubt on this hypothesis. As the systemic injection of arginine derivatives that block NOS activity potently augment the ACTH response to circulating pro-inflammatory cytokines or vasopressin, the present findings indicate that the mechanisms responsible for this phenomenon are distinct from those responsible for ACTH released by i.v. SIN-1.

Microinfusion of a nitric oxide donor in discrete brain regions activates the hypothalamic-pituitary-adrenal axis.

We previously showed that the intracerebroventricular injection of the nitric oxide (NO) donor 3-morpholino-sydnonimine (SIN-1) released adrenocorticotropic hormone (ACTH) and upregulated transcripts for corticotropin-releasing factor (CRF) and vasopressin in the paraventricular nucleus (PVN) of the rat hypothalamus. In the present work, we microinfused SIN-1 into the PVN itself, the amygdala, the hippocampus or the frontal cortex to identify the brain regions that modulate the influence of NO on the hypothalamic-pituitary-adrenal (HPA) axis. Microinfusion into the PVN, which contains most of the CRF and vasopressin neurones that control HPA axis activity, significantly released ACTH. Microinfusion into the amygdala or the hippocampus, areas which also regulate HPA axis activity, similarly increased plasma ACTH levels. However, these responses were smaller and showed a delayed onset, compared to that observed following PVN treatment. In contrast, microinfusion of SIN-1 into the frontal cortex, which is not believed to exert a major direct influence on the HPA axis, was without effect. The observation that compared to microinfusion into the PVN, peak ACTH levels were both smaller and delayed when SIN-1 was microinfused into the amygdala or the hippocampus, and that SIN-1 only increased NO levels when injected into the PVN, suggests that the NO donor injected outside the PVN activates this nucleus by targeting pathways that connect it to these other regions rather than by leakage. Collectively, our results provide important clues regarding the putative role of these regions in modulating the influence of NO on the HPA axis.

Mice that lack corticotropin-releasing factor (CRF) receptors type 1 show a blunted ACTH response to acute alcohol despite up-regulated constitutive hypothalamic CRF gene expression.

BACKGROUND: The purpose of this work was to determine the influence of acute alcohol treatment, injected intraperitoneally, on the hypothalamic-pituitary-adrenal axis of mice that lack type 1 receptor for corticotropin-releasing factor (CRFR1). METHODS: CRFR1-deficient (CRFR1-/-), heterozygous (CRFR1+/-), and wild-type (CRFR1+/+) mice were generated and maintained under standard conditions. Homozygous, heterozygous, and wild-type offspring were identified by polymerase chain reaction analysis of tail DNA. Experiments were performed on 9- to 16-week-old male and female mice. All blood samples were obtained by rapid decapitation of conscious mice conducted between 10 AM-12 PM. Blood sample collection was completed within 20 to 30 sec of disturbing the animals, and all samples were terminal. Preliminary experiments were conducted to determine the time-course of the ACTH and hypothalamic responses to alcohol in all three groups of mice, and a single time point (30 min and 2 hr, respectively), corresponding to peak responses, was chosen to measure the corresponding parameters in all subsequent studies. RESULTS: In vehicle-injected animals, basal ACTH and corticosterone levels were statistically comparable in heterozygotes and mice with a null allele for the CRFR1 gene, although values of this latter hormone were slightly lower in the mutants. Alcohol (4.0 g/kg) elicited the expected significant (p < 0.01) increase in plasma ACTH and corticosterone levels in heterozygous mice. These responses were virtually abolished or markedly decreased, respectively, in CRFR1-deficient animals. As previously reported, constitutive CRF mRNA levels were elevated in the paraventricular nucleus (PVN) of the hypothalamus in mice that lacked CRFR1, compared to wild-type control mice. Interestingly, this was not the case for transcripts of the immediate early gene NGFI-B. When measured 2 hr after alcohol, PVN NGFI-B gene expression was significantly (p < 0.01) increased in both control and mutant mice, as were CRF mRNA levels in mutant mice, but the hypothalamic responses of the mutants were larger (p < 0.01) than those of the control mice. This difference may be due, at least in part, to the lack of steroid feedback in the mutants. CONCLUSION: These results indicate that although the intraperitoneal injection of alcohol remains capable of eliciting PVN CRF neuronal activation in mice that lack CRFR1, the ACTH and corticosterone responses are significantly blunted, a phenomenon believed to be due to the lack of CRFR1 in the pituitary of these animals.

Identification of an RNA-protein complex involved in chloroplast group II intron trans-splicing in Chlamydomonas reinhardtii.

In Chlamydomonas reinhardtii, the psaA mRNA is assembled by a process involving trans-splicing of separate transcripts, encoded at three separate loci of the chloroplast genome. At least 14 nuclear loci and one chloroplast gene, tscA, are needed for this process. We have cloned Raa3, the first nuclear gene implicated in the splicing of intron 1. The predicted sequence of Raa3 consists of 1783 amino acids and shares a small region of homology with pyridoxamine 5'-phosphate oxidases. Raa3 is present in the soluble fraction of the chloroplast and is part of a large 1700 kDa complex, which also contains tscA RNA and the first psaA exon transcript. These partners, in association with other factors, form a chloroplast RNP particle that is required for the splicing of the first intron of psaA and which may be the counterpart of eukaryotic snRNPs involved in nuclear splicing.

Effect of repeated exposure to alcohol on the response of the hypothalamic-pituitary-adrenal axis of the rat: II. Role of the length and regimen of alcohol treatment.

BACKGROUND: Prior exposure to alcohol alters the adrenocorticotropin hormone (ACTH) response to a second drug challenge administered several days later. We used three models of alcohol treatment to investigate the mechanisms that may be involved in this phenomenon. METHODS: Adult male rats were exposed to alcohol vapors daily for 3 days (4-4.5 hr/day) and then were exposed to shocks or an intragastric injection of alcohol 7 days later (group A); were injected daily with alcohol (4.5 g/kg intragastrically) for 3 days and then exposed to shocks or an intragastric injection of alcohol 7 days later (group B); or were exposed to alcohol vapors for 6 days and exposed to shocks or an intragastric injection 24 hr later (group C). Control animals were not exposed to the vapors or received the appropriate vehicle. RESULTS: Compared with animals administered the vehicle, rats of groups A and B that had been exposed to alcohol all exhibited a significantly decreased ACTH response to a second drug challenge. In contrast, their ACTH response to footshocks was statistically comparable to that of vehicle-pretreated animals. Rats of group C that had been exposed to alcohol for 6 days also showed decreased ACTH release when injected with alcohol 7 days later while responding normally to shocks. Measurement of anterior pituitary pro-opiomelanocortin indicated that alcohol pretreatment had produced a 54% increase of these transcripts in group C and a 27% decrease in group A. There were no changes in pituitary receptors type 1 for corticotropin-releasing factor (CRFR1) in any of the groups. CONCLUSION: Regardless of whether they are delivered shortly before an acute alcohol injection or several days earlier, alcohol vapors or injections interfere with the ACTH response to the drug but not to shocks. Our results also suggest that changes in ACTH responses may not be correlated directly with small changes in pituitary pro-opiomelanocortin or CRFR1 mRNA levels.

Effect of repeated exposure to alcohol on the response of the hypothalamic-pituitary-adrenal axis of the rat: I. Role of changes in hypothalamic neuronal activity.

BACKGROUND: Prior (3-12 days) injection of alcohol significantly blunts the response of the hypothalamic-pituitary-adrenal (HPA) axis to a second drug challenge without measurably altering responses to other stressors. We therefore determined whether adaptation in hypothalamic neurons underlies this decreased activity. METHODS: Adult male rats were administered alcohol (4.5 g/kg intragastrically) or vehicle daily for three consecutive days and then were challenged with the vehicle or alcohol 7 days later. Levels of adrenocorticotropin hormone (ACTH) in the circulation, corticotropin-releasing factor (CRF), CRF receptors type 1 (CRFR1) and vasopressin (VP) transcripts in the paraventricular nucleus (PVN) of the hypothalamus, and CRF/VP peptide in the median eminence were measured. RESULTS: Resting PVN levels of CRF, CRFR1, and VP were comparable in all animals on day 7 of recovery, whereas CRF and VP stores in the external zone of the median eminence were decreased in animals previously exposed to alcohol. After the acute alcohol challenge on day 7, rats previously exposed to the drug exhibited a significant (p < 0.01) dampening of their PVN CRF and CRFR1, but not VP neuronal response, compared with vehicle-pretreated rats. CONCLUSION: Blunted neuronal activity of PVN CRF neurons may be responsible for the decreased ACTH response that we previously reported in rats that had been injected with alcohol several days earlier. In addition, and despite comparable PVN VP transcript levels, the lower levels of this peptide in the median eminence also may participate in the blunted ACTH response that we observed.

Relative importance of nitric oxide and carbon monoxide in regulating the ACTH response to immune and non-immune signals.

The present work investigated the effect of nitric oxide (NO) or carbon monoxide (CO) in the ACTH response to an immune signal [the intravenous injection of interleukin-1 ß (IL-1ß)] or to a neurogenic stressor (mild intermittent inescapable foot shocks). The arginine derivative N(ω)-L-arginine methylester (L-NAME), which non-specifically inhibits NO formation induced by all constitutive forms of NO synthase (NOS), significantly augmented the effect of IL-1P,but blockade of CO formation with metalloporphyrins was without effect. On the other hand, L-NAME blunted the effect of shocks on the early phase of ACTH release, while we had reported earlier that metalloporphyrins exerted a similar effect. This effect was mimicked by blockade of neuronal (n) NOS by N(ω)-Propyl-L-arginine (PA), although the resulting decrease in hormone levels was less than that induced by L-NAME. These results indicate that endogenous NO, but not CO, interferes with ACTH released by a peripheral immune signal. In contrast, NO formed by nNOS enhances the ability of shocks to induce ACTH secretion.