Antiulcerogenic and antioxidant activities of Plantago ovata ethanolic extract in rats / Atividade antiulcerogênica e antioxidante do extrato etanólico de Plantago ovata em ratos

This study aimed to determine the antiulcerogenic and antioxidant activities of Psyllium (Plantago ovata Forssk) seed ethanolic extract in rats. We assessed the antioxidant potential using free radical scavenging on DPPH, ß-carotene bleaching activity, ferric reducing power, and hydroxyl radical scavenging activity. In the antiulcerogenic study, pre-treatment with Plantago ovata seeds ethanolic extract (POE) (400 mg/kg b.wt) significantly protected against ethanol-induced gastric ulcer in rats by decreasing the ulcer index value and preserving the integrity of the gastric mucosa. The oxidative stress status in the stomach tissues showed a significant increase in the antioxidant enzyme levels of superoxide dismutase, catalase, and glutathione peroxidase with a significant decrease in lipid peroxidation during pre-treatment with POE. In conclusion, the POE protects against gastric ulcer due to its antioxidant potential and presence of bioactive molecules.

O presente estudo teve como objetivo determinar as atividades antiulcerogênica e antioxidante das sementes de Psyllium (Plantago ovata Forssk) em ratos. O potencial antioxidante foi avaliado utilizando o método do sequestro do radical livre DPPH, autooxidação do ß-caroteno, poder redutor de ferro e atividade de sequestro do radical hidroxila. No estudo antiulcerogênico, o pré-tratamento com o extrato etanólico das sementes de Plantago ovata (POE) (400 mg/Kg b.wt) reduziu a úlcera gástrica induzida pelo etanol em ratos, diminuindo o valor do índice de úlcera e preservando a integridade da mucosa gástrica. O estudo do estresse oxidativo nos tecidos estomacais mostrou um aumento significativo dos níveis das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase, com uma diminuição significativa da peroxidação lipídica enquanto pré-tratamento com POE. Em conclusão, o POE protege contra úlcera gástrica devido aos seus potenciais antioxidantes e à presença de moléculas bioativas.

Antiulcerogenic and antioxidant activities of Plantago ovata ethanolic extract in rats

Abstract This study aimed to determine the antiulcerogenic and antioxidant activities of Psyllium (Plantago ovata Forssk) seed ethanolic extract in rats. We assessed the antioxidant potential using free radical scavenging on DPPH, -carotene bleaching activity, ferric reducing power, and hydroxyl radical scavenging activity. In the antiulcerogenic study, pre-treatment with Plantago ovata seeds ethanolic extract (POE) (400 mg/kg b.wt) significantly protected against ethanol-induced gastric ulcer in rats by decreasing the ulcer index value and preserving the integrity of the gastric mucosa. The oxidative stress status in the stomach tissues showed a significant increase in the antioxidant enzyme levels of superoxide dismutase, catalase, and glutathione peroxidase with a significant decrease in lipid peroxidation during pre-treatment with POE. In conclusion, the POE protects against gastric ulcer due to its antioxidant potential and presence of bioactive molecules.

Resumo O presente estudo teve como objetivo determinar as atividades antiulcerogênica e antioxidante das sementes de Psyllium (Plantago ovata Forssk) em ratos. O potencial antioxidante foi avaliado utilizando o método do sequestro do radical livre DPPH, autooxidação do -caroteno, poder redutor de ferro e atividade de sequestro do radical hidroxila. No estudo antiulcerogênico, o pré-tratamento com o extrato etanólico das sementes de Plantago ovata (POE) (400 mg/Kg b.wt) reduziu a úlcera gástrica induzida pelo etanol em ratos, diminuindo o valor do índice de úlcera e preservando a integridade da mucosa gástrica. O estudo do estresse oxidativo nos tecidos estomacais mostrou um aumento significativo dos níveis das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase, com uma diminuição significativa da peroxidação lipídica enquanto pré-tratamento com POE. Em conclusão, o POE protege contra úlcera gástrica devido aos seus potenciais antioxidantes e à presença de moléculas bioativas.

Potential hepatoprotective effect of Cheatomorpha gracilis extract against High Fat Diet (HFD)-Induced Liver Damage, and its characterization by HPLC / Efeito hepatoprotetor potencial do extrato de Cheatomorpha gracilis contra dano hepático induzido por dieta alta em gordura (HFD), e sua caracterização por HPLC

The current investigation was carried out to estimate the protective effect of aqueous extract of Cheatomorpha gracilis (AEC) against High fat Diet (HFD) induced liver damage in mice. The results of the in vitro study showed that AEC have higher antioxidant capacities in the DPPH and hydroxyl radical-scavenging assays. Indeed, many phenolic compounds (gallic acid, quercetin, naringenin, apigenin, kaempferol and rutin) were identified in the AEC. In the animal studies, during 6 weeks, HFD promoted oxidative stress with a rise level of malonaldehyde (MDA), protein carbonyls (PCOs) levels and a significant decrease of the antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase. Interestingly, the treatment with AEC (250 mg/kg body weight) significantly reduced the effects of HFD disorders on some plasmatic liver biomarkers (AST, ALT and ALP) in addition to, plasmatic proteins inflammatory biomarkers (α2 and β1 decreases / β2 and γ globulins increases). It can be suggest that supplementation of MECG displays high potential to quench free radicals and attenuates high fat diet promoted liver oxidative stress and related disturbances.

A presente investigação foi realizada para estimar o efeito protetor do extrato aquoso de Cheatomorpha gracilis (AEC) contra o dano hepático induzido por dieta rica em gordura (HFD) em camundongos. Os resultados do estudo in vitro mostraram que os AEC têm maiores capacidades antioxidantes nos ensaios DPPH e de eliminação de radicais hidroxila. De fato, muitos compostos fenólicos (ácido gálico, quercetina, naringenina, apigenina, kaempferol e rutina) foram identificados no AEC. Nos estudos em animais, durante 6 semanas, HFD promoveu estresse oxidativo com aumento do nível de malonaldeído (MDA), níveis de proteína carbonil (PCOs) e diminuição significativa das atividades de enzimas antioxidantes como superóxido dismutase, catalase e glutationa peroxidase. Curiosamente, o tratamento com AEC (250 mg / kg de peso corporal) reduziu significativamente os efeitos dos distúrbios de HFD em alguns biomarcadores hepáticos plasmáticos (AST, ALT e ALP), além de biomarcadores inflamatórios de proteínas plasmáticas (reduções α2 e β1 / β2 e γ aumenta as globulinas). Pode-se sugerir que a suplementação de MECG apresenta alto potencial para extinguir os radicais livres e atenua o estresse oxidativo do fígado promovido pela dieta rica em gordura e distúrbios relacionados.

Potential Hepatoprotective Effect of Cheatomorpha gracilis extract against High Fat Diet (HFD)-Induced Liver Damage, and its characterization by HPLC

Abstract The current investigation was carried out to estimate the protective effect of aqueous extract of Cheatomorpha gracilis (AEC) against High fat Diet (HFD) induced liver damage in mice. The results of the in vitro study showed that AEC have higher antioxidant capacities in the DPPH and hydroxyl radical-scavenging assays. Indeed, many phenolic compounds (gallic acid, quercetin, naringenin, apigenin, kaempferol and rutin) were identified in the AEC. In the animal studies, during 6 weeks, HFD promoted oxidative stress with a rise level of malonaldehyde (MDA), protein carbonyls (PCOs) levels and a significant decrease of the antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase. Interestingly, the treatment with AEC (250 mg/kg body weight) significantly reduced the effects of HFD disorders on some plasmatic liver biomarkers (AST, ALT and ALP) in addition to, plasmatic proteins inflammatory biomarkers (2 and 1 decreases / 2 and globulins increases). It can be suggest that supplementation of MECG displays high potential to quench free radicals and attenuates high fat diet promoted liver oxidative stress and related disturbances.

Resumo A presente investigação foi realizada para estimar o efeito protetor do extrato aquoso de Cheatomorpha gracilis (AEC) contra o dano hepático induzido por dieta rica em gordura (HFD) em camundongos. Os resultados do estudo in vitro mostraram que os AEC têm maiores capacidades antioxidantes nos ensaios DPPH e de eliminação de radicais hidroxila. De fato, muitos compostos fenólicos (ácido gálico, quercetina, naringenina, apigenina, kaempferol e rutina) foram identificados no AEC. Nos estudos em animais, durante 6 semanas, HFD promoveu estresse oxidativo com aumento do nível de malonaldeído (MDA), níveis de proteína carbonil (PCOs) e diminuição significativa das atividades de enzimas antioxidantes como superóxido dismutase, catalase e glutationa peroxidase. Curiosamente, o tratamento com AEC (250 mg / kg de peso corporal) reduziu significativamente os efeitos dos distúrbios de HFD em alguns biomarcadores hepáticos plasmáticos (AST, ALT e ALP), além de biomarcadores inflamatórios de proteínas plasmáticas (reduções 2 e 1 / 2 e aumenta as globulinas). Pode-se sugerir que a suplementação de MECG apresenta alto potencial para extinguir os radicais livres e atenua o estresse oxidativo do fígado promovido pela dieta rica em gordura e distúrbios relacionados.

Potential Hepatoprotective Effect of Cheatomorpha gracilis extract against High Fat Diet (HFD)-Induced Liver Damage, and its characterization by HPLC / Efeito Hepatoprotetor Potencial do Extrato de Cheatomorpha gracilis contra Dano Hepático Induzido por Dieta Alta em Gordura (HFD), e sua caracterização por HPLC

The current investigation was carried out to estimate the protective effect of aqueous extract of Cheatomorpha gracilis (AEC) against High fat Diet (HFD) induced liver damage in mice. The results of the in vitro study showed that AEC have higher antioxidant capacities in the DPPH and hydroxyl radical-scavenging assays. Indeed, many phenolic compounds (gallic acid, quercetin, naringenin, apigenin, kaempferol and rutin) were identified in the AEC. In the animal studies, during 6 weeks, HFD promoted oxidative stress with a rise level of malonaldehyde (MDA), protein carbonyls (PCOs) levels and a significant decrease of the antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase. Interestingly, the treatment with AEC (250 mg/kg body weight) significantly reduced the effects of HFD disorders on some plasmatic liver biomarkers (AST, ALT and ALP) in addition to, plasmatic proteins inflammatory biomarkers (α2 and ß1 decreases / ß2 and γ globulins increases). It can be suggest that supplementation of MECG displays high potential to quench free radicals and attenuates high fat diet promoted liver oxidative stress and related disturbances.

A presente investigação foi realizada para estimar o efeito protetor do extrato aquoso de Cheatomorpha gracilis (AEC) contra o dano hepático induzido por dieta rica em gordura (HFD) em camundongos. Os resultados do estudo in vitro mostraram que os AEC têm maiores capacidades antioxidantes nos ensaios DPPH e de eliminação de radicais hidroxila. De fato, muitos compostos fenólicos (ácido gálico, quercetina, naringenina, apigenina, kaempferol e rutina) foram identificados no AEC. Nos estudos em animais, durante 6 semanas, HFD promoveu estresse oxidativo com aumento do nível de malonaldeído (MDA), níveis de proteína carbonil (PCOs) e diminuição significativa das atividades de enzimas antioxidantes como superóxido dismutase, catalase e glutationa peroxidase. Curiosamente, o tratamento com AEC (250 mg / kg de peso corporal) reduziu significativamente os efeitos dos distúrbios de HFD em alguns biomarcadores hepáticos plasmáticos (AST, ALT e ALP), além de biomarcadores inflamatórios de proteínas plasmáticas (reduções α2 e ß1 / ß2 e γ aumenta as globulinas). Pode-se sugerir que a suplementação de MECG apresenta alto potencial para extinguir os radicais livres e atenua o estresse oxidativo do fígado promovido pela dieta rica em gordura e distúrbios relacionados.

Effect of novel curcumin-encapsulated chitosan-bioglass drug on bone and skin repair after gamma radiation: experimental study on a Wistar rat model.

Radiation therapy contributes to a significant increase in bone osteoporosis and skin loss. Various natural health products might be beneficial to reduce bone and skin alterations. Curcumin (CUR) medicines derived from natural plants have played an important role in health care. This study aims at synthesizing and evaluating the performance therapy of CUR-encapsulated bioglass-chitosan (CUR-BG-CH). In vitro, the antioxidant assay was evaluated by using 1,1-diphenyl-2-picrylhydrazyl free-radical (DPPH) scavenging and the nitroblue tetrazolium reduction. The CUR-BG-CH antimicrobial effects were tested in liquid media. In vivo, after rat (60) Co γ-radiation, the tissue wound-healing process was studied by grafting CUR and CUR-BG-CH in femoral condyle and dorsal skin rat tissue. The antioxidant studies indicated that CUR-BG-CH quenches free radicals more efficiently than unmodified CUR and had effective DPPH (91%) and superoxide anion (51%) radical scavenging activities. The CUR-BG-CH biomaterial exhibited an important antimicrobial activity against Staphylococcus aureus. The histomorphometric parameters showed amelioration in CUR-BG-CH-treated rats. An improved mechanical property was noticed (33.16 ± 5.0 HV) when compared with that of unmodified CUR group (23.15 ± 4.9 HV). A significant decrease in tumour necrosis factor-α cytokine production was noted in the CUR-BG-CH rats (90 pg/ml) as compared with that of unmodified CUR group (240 pg/ml). The total amount of hydroxyproline was significantly enhanced (33.5%) in CUR-BG-CH group as compared with that of control. Our findings suggested that CUR-BG-CH might have promising potential applications for wound healing.

Temporal changes in hepatic antioxidant enzyme activities after ischemia and reperfusion in a rat liver ischemia model: effect of dietary fish oil.

This study investigated the hypothesis that administration of tilapia fish oil diet would attenuate warm liver ischemia/reperfusion injury (IRI) and whether fish oil modulates prooxidant/antioxidant status. Male Wistar rats were subjected to 30 min of approximately 70% hepatic ischemia followed by 1, 12, and 24 h reperfusion. Rats were randomly divided into three groups: sham-operated group (SO), control-warm hepatic ischemia (WI) group, and Oil-WI group given tilapia oil for 3 weeks followed by liver IRI. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured in the plasma. Levels of thiobarbituric acid reactive substances (TBARS) and antioxidant enzymes as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were measured in liver fractions. In the sham group, there was no enzymatic or histological change. I/R caused significant increase in serum AST, ALT, and tissue TBARS levels. As compared to the control group, animals treated with tilapia oil experienced a significant decrease (p < 0.05) in AST and ALT levels in reperfusion periods. Tissue TBARS levels in Oil-WI group were significantly (p < 0.05) reduced as compared to control group at 60 min after reperfusion. After ischemia, 1, 12, and 24 h of reperfusion, CAT, SOD, and GPx values were the lowest in the Oil-WI group and highest in the control group and were statistically significant (p < 0.05). Histological analysis also revealed that fish oil provided some protection compared with the control group. Tilapia oil exerts a protective effect during the early phase of reperfusion, and it modulates prooxidant/antioxidant status of rat liver subjected to warm IRI.

Detoxification of rats subjected to nickel chloride by a biomaterial-based carbonated orthophosphate.

Recently, the therapeutic approaches of the detoxification against the metals (nickel) in the body are the use of biomaterials such as carbonated hydroxyapatite. The aim of this study is therefore to analyze the physiological and physicochemical parameters of strain white rats "Wistar" receiving nickel chloride and to study the protective associative of apatite against adverse effects of this metal, and this in comparison with control rats. Our results showed that the nickel induced in rats an oxidative stress objectified by elevated levels of thiobarbituric acid-reactive substances and conjugated dienes associated with inhibition of the activity of the antioxidant defense system such as glutathione peroxidase, superoxide dismutase and catalase in the liver, kidney, spleen and erythrocyte. Disorders balances of ferric, phosphocalcic, a renal failure and a liver toxicity were observed in rats exposed to nickel. As well as a significant increase in the rate of nickel in the bones and microcytic anemia was revealed. However, the implantation of carbonated hydroxyapatite in capsule form protects rats intoxicated by the nickel against the toxic effects of this metal by lowering the levels of markers of lipid peroxidation and improving the activities of defense enzymes. Our implantation technique is effective to correct ferric balance and phosphocalcic equilibrium, to protect liver and kidney function, to reduce the rate of bone nickel and to correct anemia. They clearly explain the beneficial and protective of our biomaterial which aims the detoxification of rats receiving nickel by substituting cationic (Ca(2+) by Ni(2+)) and anionic (OH(-) by Cl(-)) confirmed by physicochemical characterization like the IR spectroscopy and X-ray diffraction. These techniques have shown on the one hand a duplication of OH(-) bands (IR) and on the other hand the increase of the volume of the apatite cell after these substitutions (X-ray diffraction).

Long-term exposure to low lithium concentrations stimulates proliferation, modifies stress protein expression pattern and enhances resistance to oxidative stress in SH-SY5Y cells.

SH-SY5Y cells, derived from a human neuroblastoma, were submitted to short- or long-term exposures to lithium carbonate concentrations ranging from 0.5 to 8 mM. Short-term exposures (4 days) to concentrations higher than 6 mM were found to reduce cell growth rate while exposure to 8 mM resulted in significant cell mortality. These ranges of concentrations induced an overexpression of (1) the HSP27 stress protein, (2) a 108 kDa protein (P108) recognized by an anti-phospho-HSP27(Ser78) antibody, and probably corresponding to a phosphorylated HSP27 tetramer, (3) a 105 kDa protein (P105), possible glycosylated or phosphorylated form of the GRP94 stress protein and (4) a phosphorylated (inactivated) form of glycogen synthase kinase (GSK3alpha/beta) SH-SY5Y cells, when cultured in the presence of 0.5 mM lithium for 25 weeks, displayed interesting features as compared to controls: (1) higher cell growth rate, (2) increased resistance toward the inhibitory effects of high lithium concentrations on cell proliferation, (3) lower basal level of lipid peroxidation (TBARS) and improved tolerance to oxidative stress induced by high lithium concentrations, (5) reduced expression of monomeric HSP27 versus an increase of corresponding tetrameric protein (P108) and (6) overexpression of a 105 kDa protein (P105). In conclusion, our study suggests that chronic treatment (over several months) by therapeutic relevant lithium concentrations could favour neurogenesis, decrease the vulnerability of neuronal cells to oxidative stress and induce posttranslational changes of molecular chaperones.

Oxidative stress and hepatotoxicity in rats induced by poisonous pufferfish (Lagocephalus lagocephalus) meat

This study was undertaken to evaluate the effect of pufferfish (Lagocephalus lagocephalus) meat poisoning on hepatic functions of Wistar rats. For this purpose, groups of rats (Lcr, Lcu+b and Lcu-b) received diet supplemented with 10 percent of raw or cooked meat, respectively, with or without cooking water of L. lagocephalus while groups Mcr and Mcu+b received diet supplemented with 10 percent of raw or cooked meat of Liza aurata, which were used as a negative control. In Lcu+b group, ALT, AST and ALP rates (hepatic enzyme markers) decreased after two months of treatment, indicating liver damage. We also observed an increase of 54 and 65 percent of thiobarbituric acid reactive substances (TBARS) in their livers respectively 48 hours and two months after treatment compared to controls. The catalase (CAT) activity in group Lcu+b decreased (p < 0.05) after two periods of treatment, whereas metallothionein (MT) level significantly increased and decreased, respectively after 48 hours and two months. In fact, in the histological analysis of the livers from Lcu+b treated group, we observed an increase in vacuolisation, necrosis, hepatocytes ballooning and sinusoids dilation. These results indicate that L. lagocephalus meat cooked with water produces hepatotoxicity and oxidative damage.(AU)

Protective effect of 17beta-estradiol on oxidative stress and liver dysfunction in aged male rats.

In aging liver oxidative stress increases due to the decrease in antioxidant bio-molecules such as estrogens which can be modified by hormonal replacement therapy (HRT). With this in mind, we hypothesized that age-related decline in steroidogenesis may be associated with the impairment of the antioxidant defense cells in liver, the increase in lipid peroxidation, hepatic dysfunction and histological changes; estrogens prevent all these changes induced by aging. 17beta-estradiol treatment was initiated in 12 month-old Wistar rats, and continued until 18 months of age. Our results showed that 17beta-estradiol (E2) level in the serum of the aged untreated rats was reduced by -32% in 18 month-old rats compared to the young animals (4-month-old). The superoxide dismutase (SOD), catalase (CAT), and gluthatione peroxidase (GPX) activities were reduced by -47, -46, and -29% respectively in old rat liver. In addition, the TBARs in liver and hepatic dysfunction parameters in plasma such as gamma-glutamyl transferase (GGT), phosphatase alkalin (PAL) as well as bilirubin level increased significantly in old rats, and histological changes were investigated. In E2-treated rats, protective effects were observed. Indeed, 17beta-estradiol attenuates all changes induced by aging. The 17beta-estradiol level was higher in old E2-treated rats compared to the control rats. Moreover, the SOD, CAT and GPX activities were higher by +28, +15, and +11% respectively. This anti-aging effect of estrogens was clarified by a lower level of lipid peroxidation and liver dysfunction parameters as well as by histological observation.

Changes in growth rate and thyroid- and sex-hormones blood levels in rats under sub-chronic lithium treatment.

Lithium therapy, mainly used in curing some psychiatric diseases, is responsible for numerous undesirable side effects. The present study is a contribution to the understanding of the pathophysiological mechanisms underlying lithium toxicity. Male and female mature rats were divided into three batches and fed commercial pellets: one batch was the control and the second and third batches were given 2 g (Li1) and 4 g (Li2) of lithium carbonate/kg of food/day, respectively. After 7, 14, 21 and 28 days, serum levels of free tri-iodothyronine (FT3), thyroxine (FT4), testosterone and estradiol were measured. Attention was also paid to growth rate and a histological examination of testes or vaginal mucosa was carried out. In treated rats, a dose-dependent loss of appetite and a decrease in growth rate were observed, together with symptoms of polydypsia, polyuria and diarrhea. Lithium serum concentrations increased from 0.44 mM (day 7) to 1.34 mM (day 28) in Li1 rats and from 0.66 to 1.45 mM (day 14) in Li2 rats. Li2 treatment induced a high mortality after 14 days, reaching 50-60% in female and male animals. From these data, the LD50 (14 days Li2 chronic treatment) was calculated to be about 0.3 g/day per kilogram of animal, leading to Li serum concentrations of about 1.4 mM. A significant decrease of FT3 and FT4 was observed in treated rats. This effect appeared immediately for the highest dose and was more pronounced for FT3, resulting in an increase of the FT4/FT3 ratio. In males, testosterone decreased and spermatogenesis was stopped. Conversely, in females, estradiol increased in a dose-dependent manner as the animals were blocked in the diestrus phase at day 28. This finding supports a possible antagonistic effect of lithium on the estradiol receptors.

Effects of nickel poisoning on expression pattern of the 72/73 and 94 kDa stress proteins in rat organs and in the COS-7, HepG2, and A549 cell lines.

The present study deals with the effects of Ni on the expression level of three stress proteins, namely, the cytosolic HSP72 and HSP73, and the reticulum-associated GRP94. Experiments were carried out on "Wistar'' female rats daily injected with 4 mg NiCl2 per kg body weight for 1, 3, 5, and 10 days. Another set of experiments were carried out using cell lines, derived from the monkey kidney (COS-7), and from human tumors of the lung (A549) and liver (HepG2). Cells were cultured for 4 days in the permanent presence of 100, 200, or 400 microM NiCl2. In control rats, stress proteins pattern was found to be tissue specific: two protein bands of 96 and 94 kDa were immunodetected with the anti-GRP94 antibody in kidney and liver extracts, whereas only the 96 kDa band was present in ovary extracts. HSP73 was present in kidney, liver, and ovary whereas HSP72 was only found in kidney. In kidney of nickel-treated animals, HSP73 and the 96 kDa proteins were overexpressed whereas HSP72 was strongly down regulated. No such effect was observed in liver or ovary. Similarly, in nickel-treated cell lines, HSP72 was downregulated and GRP94 (96 kDa protein) was overexpressed. HSP73 expression appeared moderately increased in A549 cells but decreased in COS-7 cells. Because long-term caloric restriction was reported to reduce free radical generation in cells, the effect of 1 month food restriction (50%) was tested in rats as a possible way to lower oxidative damages induced by Ni. No significant effect on HSP expression was observed.

[Sequential and ultrastructural study of lactotroph response to stress in rats as a function of age]. / Etude séquentielle et ultrastructurale de la réponse lactotrope a un stress chez le rat en fonction de l'âge.

In adult rats, ether inhalation stress stimulated basal serum prolactin (PRL) significantly, within a maximum delay of one minute. The same pattern was seen with immature animals of 15-20 and 30 days of age. In contrast, in 2 or 6 days old neonates, serum PRL concentrations remained unaffected by stress. This lack of responsiveness suggests the existence of a transient impairment of lactotroph hormones to stressful stimuli during postnatal life. This hypothesis has been controlled by ultrastructural exploration of lactotrophs. The distribution of organites and secretion grains in lactotrophs was similar in unstressed neonates and adult rats, but after ether stress, the distribution of secretion grains became different with age. Adult lactotrophs showed a peripheral secretion grains aspects indicating cells discharge. In the very young rats, the grains were distributed in the totality of the cytoplasm. These results confirm the existence, in the lactotrophs, of a refractory period to stress in the neonate rats.

[Possible implication of TRH and dopamine in postnatal lactotropic hypoactivity in rats]. / Implication possible de la TRH et de la dopamine dans l'hypoactivité lactotrope post-natale chez le rat.

Our results show that pituitary glands of young rats (6 days) incubated in vitro, increase their PRL secretion in presence of TRH, this responses is greater than that in adult glands. Indeed, in presence of TRH 10(-7) M, PRL basal secretion of immature glands passes from 478.70 +/- 67.25 to 952.78 +/- 67.02, versus 5333.29 +/- 75.456 and 6347.15 +/- 75.246 ng/mg protein at mature glands. The same dose of dopamine (DA), weakens the TRH stimulating effect by 60% and 40% respectively by young and adult pituitary glands. These results suggest that lactotroph insensitiveness to TRH injection observed during the first days of postnatal life at the rat, would not be explained by lactotroph failure, but by intervention of central and peripheral multiple modulator factors affecting lactotrophs reactivity, in particular the importance of dopaminergic control.

[Postnatal lactotropic hypoactivity in rats: possible implication of VIP, endogenous opioids, dopamine and glucocorticoids]. / Hypoactivité lactotrope post-natale chez le rat: implication possible du VIP, des opioïdes endogènes, de la dopamine, et des glucocorticoïdes.

In this study, the possible intervention of VIP (Vasoactive Intestinal Peptide), beta-endorphine, glycocorticoids and dopamine, in postnatal lactotrophs hypoactivity at the rat, was investigated. Our results show that the injection of VIP (40 micrograms/kg), beta-endorphine (125 micrograms/kg) or its antagonist, naloxone (2 mg/kg), does not provide a change in serum PRL before or after ether stress at 6-day-old rats. However, after adrenalectomy, 6 day-old neonates became sensitive to ether stress as do adults, while acute treatment with dexamethasone (2 mg/kg) or dopamine (1 mg/kg), abolished this response completely. Sulpiride injection (1 mg/kg), on the contrary potentialized response. This lactotroph insensitiveness to ether stress, TRH, VIP, and beta-endorphine, during the beginning of postnatal life in the rat, might be explained, partially, by the failure of stimulatory factors "PRF" (Prolactin Releasing Factors), together with strength of inhibitory factors "PIF" (Prolactin Inhibitory Factors), such as dopamine and glycocorticoids.

Impairment of stress-induced secretion of prolactin during development: effects of adrenalectomy, TRH and sulpiride.

Ontogeny of serum and anterior pituitary gland PRL contents was investigated. Pituitary PRL concentrations were found to be low in fetus by 19th day of gestation and to rise slowly after birth with no sex differences being apparent until day 30. Adult levels were reached in males on day 15, while in females they were reached beyond this stage. Serum PRL levels exhibited a similar developmental pattern. In adult rats ether stress stimulated basal serum PRL significantly, with maximum effect one minute after onset of stress. The same pattern was seen with immature animals of 15-20 and 30 days of age. In contrast, in 2 or 6 day-old neonates, serum PRL concentrations remained unaffected by stress. This lack of responsiveness suggests the existence of a transient impairment of lactotrophs to respond to stressful stimuli during postnatal life. Adrenalectomy increased PRL release in adult and newborn rats from day 15 onward and potentiated the response of lactotrophs. Moreover, after adrenalectomy, 6 day-old rats became sensitive to ether stress, while acute treatment with dexamethasone abolished completely this response. In adult or 15 day-old neonates administration of TRH or sulpiride resulted in a marked increase in serum PRL levels. However, at 6 days TRH did not affect resting serum PRL concentrations significantly, whereas sulpiride remained efficient. Moreover, at this age, dopamine inhibited stress-induced PRL release and reduced the stimulatory effect of sulpiride.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of exhaust gas on adrenal cortex activity, general growth and variation of intermediate metabolism in the male rate during a period of growth]. / Incidence du gaz d'échappement sur l'activité corticosurrénalienne, la croissance générale et la variation de certains métabolismes intermédiaires chez le rat mâle en période de croissance.

The exhaust gas induces a stressing action, similar to classical type agression: activation of the pituitary adrenal-axis, with increase of relative adrenal weight, and of the rate of corticosterone production. After chronic exposure, deep metabolic changes appear, which reflect an accentuated state of exhaustion of the organism. Moreover perturbation of spermatogenesis with azoospermia is noted. Thus exhaust gas is to be considered as a very potent toxic agent.