Impact of electronic-cigarette refill liquid on rat testis.

Electronic cigarettes (e-cigarettes) are becoming the fashionable alternative to decrease tobacco smoking, although their impact on health has not been fully assessed yet. The present study was designed to compare the impact of e-cigarette refill liquid (e-liquid) without nicotine to e-liquid with nicotine on rat testis. For this purpose, e-liquid with nicotine and e-liquid without nicotine (0.5 mg/kg of body weight) were administered to adult male Wistar rats via the intraperitoneally route during four weeks. Results showed that e-liquid with or without nicotine leads to diminished sperm density and viability, such as a decrease in testicular lactate dehydrogenase activity and testosterone level. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) analysis identified a reduction in cytochrome P450 side-chain cleavage (P450 scc) and 17 beta-hydroxysteroid dehydrogenase (17ßHSD) mRNA level, two key enzymes of steroidogenesis. Following e-liquid exposure, histopathological examination showed alterations in testis tissue marked by germ cells desquamation, disorganization of the tubular contents of testis and cell deposits in seminiferous tubules. Finally, analysis of oxidative stress status pointed an outbreak of antioxidant enzyme activities such as superoxide dismutase, catalase and gluthatione-S-transferase, as well as an important increase in sulfhydril group content. Taken together, these results indicate that e-liquid per se induces toxicity in Wistar rat testis, similar to e-liquid with nicotine, by disrupting oxidative balance and steroidogenesis.

Oxidative damage and histopathological changes in lung of rat chronically exposed to nicotine alone or associated to ethanol.

Smoking is the most important preventable risk factor of chronic obstructive pulmonary disease and lung cancer. This study was designed to investigate oxidative damage and histopathological changes in lung tissue of rats chronically exposed to nicotine alone or supplemented with ethanol. Twenty-four male Wistar rats divided into three groups were used for the study. The nicotine group received nicotine (2.5mg/kg/day); the nicotine-ethanol group was given simultaneously same dose of nicotine plus ethanol (0.2g/kg/day), while the control group was administered only normal saline (1 ml/kg/day). The treatment was administered by subcutaneous injection once daily for a period of 18 weeks. Chronic nicotine administration alone or combined to ethanol caused a significant increase in malondialdehyde (MDA) level, superoxide dismutase (SOD) activity and catalase (CAT) activity in lung tissue compared to control rats suggesting an oxidative damage. However, these increases were mostly prominent in nicotine group. The histopathological examination of lung tissue of rats in both treated groups revealed many alterations in the pulmonary structures such as emphysema change (disappearance of the alveolar septa, increased irregularity and size of air sacs) and marked lymphocytic infiltration in perivascular and interstitial areas. However, the changes characterized in the nicotine group (pulmonary congestion, hemorrhage into alveoli and interstitial areas, edema) were more drastic than those observed in the nicotine-ethanol group, and they can be attributed to a significant degree of capillary endothelial permeability and microvascular leak. Conversely, the ethanol supplementation caused an appearance of fatty change and fibrosis in pulmonary tissue essentially due to a metabolism of ethanol. Finally, the lung damage illustrated in nicotine group was more severe than that observed in the nicotine-ethanol group. We conclude that the combined administration of nicotine and ethanol may moderate the effect of nicotine administered independently by counteractive interactions between these two drugs.

Involvement of nitric oxide in corticosterone release and glucose metabolism in food deprived rats.

This study was performed to investigate the involvement of nitric oxide (NO) in corticosterone, endpoint product of hypothalamo-pituitary-adrenal (HPA) axis activation, and metabolic responses to 3 days of food deprivation. To investigate this aim, we used a nonspecific inhibitor of nitric oxide synthases, N-nitro- L-arginine methyl ester (L-NAME). In food deprived group we have noted a significant increase in plasma corticosterone concentration accompanied by a significant depletion in hepatic glycogen content with concomitant increase in glycogen phosphorylase (GP) activity by 63.72%, key enzyme of glycogenolysis and decrease in hexokinase (HK) activity by 25.16%, leading to significant decrease in glucose concentration. However, L-NAME administration in food deprived rats decreased slightly corticosterone level and GP activity (16.39%) and increased HK activity (11.26%) as compared to food deprived group. Considering these results, we can deduce that in food deprivation nitric oxide is involved in the regulation of corticosterone release and in glucose metabolic responses via glycogenolysis activation by the stimulation of GP activity and the inhibition of HK activity. However, more studies are necessary to further clarify the mechanisms by which NO induces these responses.

Vasopressin and nitric oxide synthesis after three days of water or food deprivation.

Nitric oxide has been suggested to be involved in the regulation of fluid and nutrient homeostasis. In the present investigation, vasopressin and nitric oxide metabolite (nitrite and nitrate) levels were determined in plasma of male Wistar rats submitted to water or food deprivation for three days. Hematocrit and plasma sodium showed marked increase in dehydrated and starved rats. Potassium levels and plasma volume decreased in both treated groups. Plasma osmolality and vasopressin levels were significantly elevated in water deprived (362.8 +/- 7.1 mOsm/kg H2O, 17.3 +/- 2.7 pg/ml, respectively, p < 0.001) rats, but not in food deprived (339.9 +/- 5.0, 1.34 +/- 0.28) rats, compared to the controls (326.1 +/- 4.1, 1.47 +/- 0.32). The alterations observed in plasma vasopressin levels were related to plasma osmolality rather than plasma volume. Plasma levels of nitrite and nitrate were markedly increased in both water and food deprived rats (respectively, 2.19 +/- 0.29 mg/l and 2.22 +/- 0.17 mg/l versus 1.33 +/- 0.19 mg/l, both p < 0.01). There was a significant negative correlation between plasma nitrite and nitrate concentration and plasma volume. These results suggest that both dehydration and starvation increase plasma nitric oxide, probably by activation of nitric oxide synthases. The release of nitric oxide may participate in the regulation of the alteration in blood flow, fluid and nutrient metabolism caused by water deprivation or starvation.

Protective effect of resveratrol on ethanol-induced lipid peroxidation in rats.

AIM: Chronic ethanol treatment induces an increase in oxidative stress. As polyphenolic compounds are potent antioxidants, we aimed to examine whether dietary supplementation of resveratrol may attenuate lipid peroxidation, the major end-point of oxidative damage resulting from chronic ethanol administration. METHOD: Three groups of male Wistar rats were used. The first group served as control and received a daily intraperitoneal injection of 0.9% saline. The second group of rats was daily injected with 35% ethanol at 3 g/kg body weight. The third group was given the same dose of ethanol and supplemented with resveratrol (5 g/kg) in the standard diet. Malondialdehyde (MDA), an indicator of oxidative stress, was measured in the liver, heart, brain, and testis. RESULTS: At the end of a 6 weeks treatment period, MDA levels were significantly increased by 51.5, 53.7, 72.7, and 40.5% in the liver, heart, brain, and testis, respectively. However, when ethanol treated rats were given resveratrol the increase in MDA levels was significantly reduced in all organs to nearly those of control rats. CONCLUSION: Resveratrol is able to inhibit the ethanol-induced lipid peroxidation and have protective effect against oxidative injury.

Vasopressin and A1 noradrenaline turnover during food or water deprivation in the rat.

In the present study, we have examined in Wistar rats the effects of food or water deprivation of 3 days on the hypophyso-adrenal axis, vasopressinergic system and activity of A1 noradrenergic brain stem cell group, which is involved in the control of the hypothalamic neuro-endocrine activity. Levels of adrenocorticotropic hormone (ACTH) and vasopressin (AVP) were determined by radio-immunoassay, and corticosterone level was determined by fluorimetric method. Plasma levels of ACTH and corticosterone were greatly increased in both groups of rats. In water-deprived rats, plasma AVP (13.83 +/- 1.63 vs. 3.03 +/- 0.23 pg/ml) and osmolality levels were significantly elevated with a marked decrease of AVP hypophysis content (272 +/- 65 vs. 1098 +/- 75 ng/mg protein), but not in food-deprived rats in which osmolality did not change and AVP remained stocked (2082 +/- 216 ng/mg protein) in the hypophysis without release in the plasma (1.11 +/- 0.23 pg/ml). These observations indicated that both food-deprivation and water-deprivation stimulated the pituitary adrenal axis thereby suggesting a stress state. AVP production is stimulated both by fluid and food restriction but is secreted with differential effects: during food restriction AVP secretion is limited to supporting the hypothalamic pituitary-adrenal system.

[The effect of age and dehydration on the activity of the vasopressinergic system in rats]. / Effet de l'âge et de la déshydratation sur l'activité de l'axe vasopressinergique chez le rat.

The aim of our work was to study the different blood parameters as well as the activity of the vasopressinergic axis in young and mature male rats under normal conditions and following a 3-day dehydration cycle by water deprivation. Under normal conditions, our study demonstrates higher levels of vasopressin in mature rats as compared to young rats. This could be due in part to the higher blood osmolality in the mature rats. After dehydration, hypovolemia, plasmatic hyperosmolality, hypernatremia and hyperproteinemia cause a stimulation in vasopressin synthesis and release, as seen in results obtained from the hypothalamus, hypophysis and plasma in both young and mature rats. However, the response of the vasopressinergic axis to dehydration is greater in young rats, suggesting a more pronounced sensitivity to osmotic factors.

Tissue norepinephrine turnover and cardiovascular responses during intermittent dehydration in the rat.

We investigated the central and peripheral sympathetic responses to intermittent dehydration in rats. The norepinephrine (NE) turnover, a biochemical index correlated with noradrenergic neuronal activity, was measured. The modification of blood pressure was also determined by telemetry during the different cycles of dehydration. Dehydration caused a decrease of NE turnover in A2, A5 and A6 nuclei and in peripheral organs. The vasopressinergic level of dehydrated rats decreased in hypophysis and hypothalamus, and increased in plasma. A repeated gradual increase of arterial blood pressure during the first three days of dehydration, followed by a sudden drop when the rats were rehydrated on the fourth day was observed. In conclusion, our study revealed an increase in blood pressure and in central sympathetic activity during dehydration.

Effects of acute and chronic starvation on central and peripheral noradrenaline turnover, blood pressure and heart rate in the rat.

When faced with stress, an organism calls upon several mechanisms to maintain biological homeostasis. The cardiovascular system is the first to respond usually with an increase in arterial pressure and tachycardia. Therefore we investigated the central and peripheral sympathetic responses to acute and chronic starvation in Wistar rats. The noradrenaline (NA) turnover rate was determined in different catecholaminergic nuclei (A1, A2, A5, A6) as well as the arterial blood pressure and heart rate modifications. During acute starvation (3 days of starvation), the NA turnover was increased in the A1 and rostral A2 nuclei as well as in ventricles and kidneys and decreased in the A6 nucleus. During chronic starvation (4 consecutive cycles of 3 days of starvation plus 1 day of feeding), the NA turnover was increased in the A5 and caudal A2 nuclei as well as in ventricles and atria and decreased in the A1 nucleus and kidneys. The arterial blood pressure revealed a gradual decrease during the first 3 days of fasting but the heart rate was not modified. We conclude that starvation should be considered as an unusual state of stress because of the absence of locus coeruleus response (A6 nucleus) despite its well-defined role in stress reactions. One of the manifestations of these central and peripheral noradrenergic changes is the change in blood pressure during the starvation-feeding cycles.

[Effect of fasting on glycemia and proteinemia in young and adult rats]. / Effet du jeûne sur la glycemie et la proteinemie chez le rat jeûne et adulte.

The aim of Our work has consisted of studying the effects of a severe three-day fast on the evolution of the body weight, on glycemia and on proteinemia among the young and mature male rats. The decrease in body weight which is more marked among young rats after starvation shows that the loss of body mass due to fasting decreases with the age of the rats. The physiological perturbations of nutritive constants that have been recorded during this period of fast show that the mature rat first attacks its non-protein stocks or glucides, which leads to a decrease in its glycemia and in its lipids; whereas the young rat uses its proteins after only three days of starvation because of its small stock of lipids.

[Adrenal cortex activity in the malnourished newborn rat]. / Activité corticosurrénalienne chez le rat nouveau-né malnutri.

Newborn rats (4 day-old) were subjected to chronic malnutrition through their mothers submitted to an intermittent fasting (one day out of two) during 41 days. These offspring were compared with others undergoing a treatment of a 21 days malnutrition followed by 20 days ad libitum realimentation. Rats whose mothers were nourished ad libitum with a standard diet served as controls. The body growth was hindered by the malnutrition but restored when fasting was followed by realimentation. The weight of the encephalon, the heart and the ovary was unchanged. In contrast, testicle atrophy was observed without correction by realimentation. A corticoadrenal activation characterized by an increase in blood and adrenal corticosterone levels and by an adrenal gland hypertrophy was observed in undernourished animals. A lower response of the adrenal cortex to ether stress (added stress) was also observed. All these perturbations were suppressed when fasting was followed by refeeding.

[Effects of simulated weightlessness on the hypophyseal-cortical-adrenal axis in the pregnant rat]. / Effets de la simulation de la microgravité sur l'axe hypophyso-cortico-surrénalien chez la rate gestante.

The eventual part of stress in the hormonal responses to simulated weightlessness was studied during gestation in the rat. We have compared these responses with the effects of two other situations well-known to provoke stress: ultrasounds and denutrition. An increase of blood and adrenal corticosterone levels was found in mothers after denutrition, neither after ultrasounds nor after simulated weightlessness. In foetuses, a decrease of weight was noted after denutrition and simulated weightlessness. Foetal suprarenal corticosterone remained normal when mothers were submitted to simulated weightlessness. In this group, a decrease in foetal weight was found that could be explained by non suprarenal hormonal factors or by circulation disturbances.

Cortico-adrenal function under simulated weightlessness during gestation in the rat--effects on fetal development.

To examine the effects of simulated weightlessness on cortico-adrenal function and on fetal development, we suspended pregnant rats for 20 days. The levels of adrenal and plasma corticosterone were examined in mothers and in fetuses. The animal control group was kept single in standard cages. Growth of the suspended animals was repressed for the first 8 days of the experiment, but thereafter it increased greatly, as did the daily food intake. By the 18th day of the experiment, the body masses and food intake of the two groups were equal. No modification in circulating corticosterone was found. It appears that there is no stress in pregnant rats submitted to simulated weightlessness.