Chronic ethanol consumption depresses hypothalamic-pituitary-adrenal function in aged rats.

In separate experiments, nine (n = 20) and fifteen (n = 12) month old rats were treated with either 6% ethanol or 12% sucrose (to balance caloric intake) in the drinking water to examine the effect of chronic ethanol consumption on the hypothalamic-pituitary-adrenal axis of aged rats. Rats were maintained on these treatment regimens for thirty days and were killed by decapitation. Blood was collected and plasma concentrations of adrenocorticotropin (ACTH) and corticosterone were determined by radioimmunoassay. Adrenal glands were cleaned, quartered and used to test in vitro responsiveness to ACTH. Anterior pituitary glands from all 15 month old rats and one half of the nine month old rats were collected, frozen and extracted for measurement of tissue ACTH concentration. The remaining anterior pituitary glands from the nine month old rats were challenged with corticotropin releasing hormone (CRH) to test in vitro responsiveness. In nine month old rats, chronic ethanol consumption decreased plasma ACTH and corticosterone (P less than 0.05). Pituitary ACTH concentrations were unchanged in treated nine month old rats, but the amount of pituitary ACTH released in response to CRH was decreased (P less than 0.05) in rats consuming ethanol. In vitro responsiveness of the adrenal gland to ACTH in nine month old rats consuming ethanol was unchanged (P greater than 0.05). Plasma ACTH and corticosterone concentrations were also decreased in 15 month old rats chronically consuming ethanol (P less than 0.05). No differences were noted in responsiveness of the adrenal gland or in the amount of pituitary ACTH due to ethanol consumption in 15 month old rats (P greater than 0.05). The results of these experiments indicate that chronic ethanol consumption decreases hypothalamic-pituitary-adrenal function in aged rats.     

Effect of long-term restriction of protein intake,from gestation onward,on free-choice consumption of ethanol by rats

Long-term (including gestational and lactational) restriction of protein (8% of diet) significantly lowered the absolute and relative consumption of 6% ethanol (EtOH) in a two-bottle, free-choice (H₂O vs EtOH) situation during a 76-day test period. This difference in response between rats fed the low protein diet and those fed an isocaloric normal protein (24%) diet became non-significant in two subsequent 100-day test periods. Statistical analysis of observations on individual performance indicated that regularity, cyclicity, and duration of drinking in each animal was random over all three time intervals for both groups. The early, significantly lower EtOH consumption by the protein-restricted group may be due to a paucity of EtOH-metabolizing enzymes in brain and liver, thereby prolonging the CNS effects of lower doses of EtOH consumed. The disappearance of this difference in subsequent test periods may reflect either a behavioral or metabolic adaptation in the developing protein-deficient rat.     

Effect of isolation stress on ethanol pharmacodynamics in the blood of rats

Head space chromatography was used to study the rate of ethanol excretion as criterion of the activity of the ethanol-oxidizing enzymatic system. Isolational stress was shown to be one of the factors determining induction of the ethanol-oxidizing erzymatic systems. The isolation-induced activity of these systems was reduced by diazepam administration. This fact may evidence the existence of central regulation of the activity of the enzymatic systems that metabolize ethanol.     

Liver necrosis induced by acute intraperitoneal ethanol administration in aged rats

It is generally agreed that the deleterious pathophysiological effects of ethanol are caused, at least partially by an increase in free radical production. However, little attention has been directed to the effects of ethanol upon elderly organisms. Male Wistar rats at ages 3, 6, 12, 18 and 24 months were treated either with a single i.p. dose of 35% ethanol (v/v) at 3 g ethanol/kg body weight or an isovolumetric amount of 0.9% saline solution. We then assessed the plasma levels of transaminases and hepatic levels of oxidative stress-related parameters, followed by liver histological evaluation. The younger rats (3 months old) were not affected by the treatment with ethanol with respect to any of the studied parameters except for a lowering of total hepatic GSH and an increase in hepatic thiobarbituric acid reactants (TBARS) formation, while animals older than 3 months were increasingly more affected by the treatment. Acute ethanol treatment elicited the similar responses to those in the 3 months-old group, plus a decrease in the hepatic and plasma levels of beta-carotene and the plasma level of alpha-tocopherol, as well as an increase in the activity of plasma transaminases. In the 12,18 and 24 months old groups, there was increasing liver necrosis. These findings suggest that liver damage induced by acute ethanol administration in elderly rats may involve a lack of antioxidants.     

The effect of the animals' emotional state on ethanol consumption under free-choice conditions

Voluntary ethanol consumption (20% solution) in mice of C57BL/6J strain with different experience in social agonistic confrontations was studied. It has been shown, that aggressive males daily winning other individuals did not change the level of ethanol consumption, while the submissive mice with daily experience of defeat in intermale encounters dramatically increased that level. Ethanol enhanced the behavioural reactivity of submissive animals to other individuals. It was supposed that emotionally positive or negative states differentiate the ethanol motivations in mice.     

Unpredictable cold-immobilization stress effects on voluntary ethanol consumption in rats

The effects of exposure to a schedule of unpredictable cold-immobilization stress on voluntary ethanol consumption were examined. Following testing for ethanol preference, rats were divided into high, medium and low ethanol consuming groups on the basis of daily ethanol intake (g/kg/day) and exposed to immobilization stress over an 18 day period. Voluntary ethanol consumption was monitored during the stress period and for an additional 36 days post-stress. Results indicated a differential effect of stress on ethanol intake in that low ethanol consuming rats increased their ethanol intake during the stress period and maintained this increase throughout the entire post-stress period as compared to non-stressed controls. High ethanol consuming groups demonstrated a small (marginally significant) decrease in ethanol intake during the stress period as compared to baseline levels. No change in ethanol intake was observed for the medium ethanol consuming groups. The results suggest that unpredictable immobilization stress has a differential effect on ethanol intake depending upon pre-stress levels of ethanol consumption.     

Effects of melatonin on oxidative stress and spatial memory impairment induced by acute ethanol treatment in rats

Melatonin has recently been suggested as an antioxidant that may protect neurons from oxidative stress. Acute ethanol administration produces both lipid peroxidation as an indicator of oxidative stress in the brain and impairs water-maze performance in spatial learning and memory tasks. The present study investigated the effect of melatonin against ethanol-induced oxidative stress and spatial memory impairment. The Morris water maze was used to evaluate the cognitive functions of rats. Thiobarbituric acid reactive substances (TBARS), which are the indicators of lipid peroxidation, and the activities of antioxidative enzymes (glutathione peroxidase and superoxide dismutase) were measured in the rat hippocampus and prefrontal cortex which form interconnected neural circuits for spatial memory. Acute administration of ethanol significantly increased TBARS levels in the hippocampus. Combined melatonin-ethanol treatment caused a significant increase in glutathione peroxidase activities and a significant decrease of TBARS in the rat hippocampus. In the prefrontal cortex, there was only a significant decrease of TBARS levels in the combined melatonin-ethanol receiving group as compared to the ethanol-treated group. Melatonin did not affect the impairment of spatial memory due to acute ethanol exposure, but melatonin alone had a positive effect on water maze performances. Our study demonstrated that melatonin decreased ethanol-induced lipid peroxidation and increased glutathione peroxidase activity in the rat hippocampus.     

Stress-induced consumption of ethanol by rats

The natural aversion of rats to ethanol was overcome by subjecting rats to immobilization stress for a two-week period during which increasing concentrations of ethanol were offered in the drinking water. The rats subjected to this regimen consumed 47% of total calories as ethanol, indefinitely, following removal of the stress. Ethanol was consumed at a rate of 17.1 g/kg body weight along with sufficient stock diet to assure adequate nutrition in the absence of ethanol.     

Stress-induced consumption of ethanol by rats

Rats were maintained in a continuous choice situation for consumption of either 0.1% aqueous saccharin or 10% ethanol- 0.1% saccharin with daily tube position reversal and 24 hour fluid consumption measurement. After a stabilized baseline was achieved, groups were exposed to either no stress, or to an unpredictable schedule of isolation or immobilization stress for 14 days. During baseline and stress-exposure periods, the rats consumed predominantly the saccharin solution. Upon cessation of the stress exposures the isolation and immobilization groups markedly increased their consumption of the ethanol solution, reaching intakes as high as 9.1 g/kg/24 hours in 2-3 weeks. In addition, after 3 weeks of ethanol consumption, placement of saccharin in both tubes resulted in the stressed animals preferentially consuming from the tube that should have contained ethanol. The results suggest that unpredictable exposure to stressful stimuli can, upon cessation of exposure, induce an alcohol consummatory behavior in rats.     

The effect of Hoe-427 (an ACTH4-9 analog) on free-choice ethanol consumption in male and female rats.

Ethanol consummatory patterns of individual male and female rats and the effects of Hoe-427 (Ebiratide), an ACTH4-9 analog, thereon, were studied in a test system using 24 hour, two-bottle free choice consumption between 0.2% saccharin and 10% ethanol in 0.2% saccharin. Single, daily i.p. doses (0.03mg/rat) of either ACTH4-10 or its analog resulted in a significant reduction of daily ethanol consumption with no effects on saccharin consumption. After 4 days of treatment, male rats consistently exhibited a rebound increase in ethanol consumption; this effect was not seen in females. The daily ethanol consummatory patterns of the female animals seemed to exhibit a 4-6 day cyclic rhythymicity, suggesting an interaction with estrous cycles. These results support a role for ACTH4-10 in the initiation of ethanol consummatory behavior in rats and suggests the existence of sex differences in this phenomenon.     

Oxidative stress in rats induced by consumption of saxitoxin contaminated drink water

Saxitoxins (STXs) are neurotoxins produced by cyanobacteria such as Cylindrospermopsis raciborskii. During bloom events, the production of these compounds causes contamination on public water supply sources. STXs block voltage gated sodium channels and can lead to severe poisoning and death of organisms at different trophic levels. Other toxicity mechanism of STX is the generation of reactive oxygen species (ROS). The aim of this study was to investigate the effect of consumption of water contaminated with a C. raciborskii strain (producing variants of Neo-STX and STX) by rats during 30 days through the analysis of oxidative stress biochemical parameters. Total antioxidant capacity (ACAP) and oxidative stress parameters were analyzed at pre-frontal cortex, hippocampus and liver of adult Wistar rats (2–3 months old). Treated animals ingested concentrations of 3 and 9 μg/L of STX equivalents and were compared with a control group (culture medium ASM-1). At the concentration of 3 μg/L, a decrease in ROS production associated with lower ACAP at hippocampus was observed. Furthermore, a decrease of glutamate cysteine ligase (GCL) activity in the cortex and an increase of brain and liver glutathione concentration were also observed. At the highest concentration (9 μg/L), there was an ACAP increase in the hippocampus as well as in the activity GCL and glutathione-S-transferase in the cortex and hippocampus. At both concentrations, lipid peroxidation was registered in the liver. Therefore, chronic ingestion of STXs can alter the antioxidant defenses and induce oxidative stress in brain and liver. The present results point to the values adopted as threshold limit for STXs in potable waters (3 μg/L) shows already significant chronic effects that alter antioxidant defenses and induce oxidative stress at least in two of the organs studied.     

Effects of male silkworm pupa powder on the erectile dysfunction by chronic ethanol consumption in rats

Erectile dysfunction (ED) is a highly prevalent disorder that affects millions of men worldwide. ED is now considered an early manifestation of atherosclerosis, and consequently, a precursor of systemic vascular disease. This study was designed to investigate the effects of male silkworm pupa powder (SWP) on the levels of nitric oxide synthase (NOS) expression, nitrite, and glutathione (GSH); lipid peroxidation; libido; and erectile response of the corpus cavernosum of the rat penis. We induced ED in the study animals by oral administration of 20% ethanol over 8 weeks. The SWP-treated male rats were divided into 3 groups that were orally administered 200, 400, and 800 mg/kg. The libido of the SWP-administered male rats was higher than that of the ethanol control group. In addition, the erectile response of the corpus cavernosum was restored in males on SWP administration, to a level similar to that of the normal group without ED. The testosterone concentration did not increase significantly. The lipid peroxidation in the corpus cavernosum of the male rats administered SWP decreased significantly. In contrast, compared to the ethanol group, SWP-administered male rats showed increased GSH levels in the corpus cavernosum. The level of nitrite and NOS expression in the corpus cavernosum of SWP-administered male rats increased significantly. These results indicated that SWP effectively restored ethanol-induced ED in male rats.     

Suppression of voluntary ethanol consumption in rats by gamma-butyrolactone

The effect of gamma-butyrolactone (GBL) on voluntary ethanol intake was studied in a group of Wistar rats in which a stable preference had been induced by exposure to increasing ethanol concentrations. These rats drank 60% of their daily fluid intake as 15% ethanol solution, corresponding to about 6 g ethanol/kg/day. GBL, injected intraperitoneally at the dose of 200 mg/kg, twice daily for 3 consecutive days, decreased ethanol intake by about 80% on the days of treatment, but did not reduce total fluid intake. Ethanol intake remained significantly reduced up to the 5th day following cessation of GBL administration. GBL, up to a concentration of 10(-3) M, inhibited neither alcohol-dehydrogenase nor aldehyde-dehydrogenase in rat liver homogenates, nor dopamine-beta-hydroxylase in homogenates of adrenal medulla or hypothalamus of rats. It is suggested that inhibition of firing in dopaminergic neurons mediates the suppressant effect of GBL on ethanol preference.     

Involvement of GABA-A receptor chloride channel complex in isolation stress-induced free choice ethanol consumption in rats

The present study revealed the effect of diazepam, a benzodiazepine, and progesterone, a pregnane precursor of neurosteroids, which act via modulating GABA-A chloride channel complex on the isolation stress-induced free choice ethanol consumption in adult rats. Isolation stress for 24 hr over a period of 6 days produced a significant increase in ethanol consumption, which persisted during the 6-day recovery period. Pretreating the animals with diazepam (5 mg/kg, i.p.), or progesterone (5 mg/kg, i.p.), blocked the isolation stress-induced increase in ethanol consumption. Bicuculline (2 mg/kg, i.p.), a GABA-A receptor antagonist significantly attenuated the effect of both diazepam and progesterone on stress-induced modulation of ethanol consumption. Isolation stress also caused an increase in total fluid consumption, which was antagonised by both diazepam and progesterone. Like ethanol consumption, this effect of diazepam and progesterone on isolation stress-induced increase in total fluid consumption was attenuated by bicuculline. Neither diazepam nor progesterone produced an increase in ethanol consumption in non-stressed rats. However, unlike diazepam, progesterone administration to non-stressed rats caused a significant increase in total fluid consumption. Results of the present study thus show that GABAergic mechanisms may be playing an important role in isolation stress-induced increase in ethanol consumption.     

The influence of chronic ethanol consumption on the distribution of thiopental in rats.

Ethanol was administered chronically for 14 days to male Sprague-Dawley rats. Day 15 was ethanol-free. On day 16 the rats received 25 mg of thiopental per kilogram (intravenously). One minute after the injection, the ethanol-treated rats showed lower blood levels of thiopental and higher liver levels of the drug than control rats given sucrose in place of ethanol. Samples of blood drawn 5 and 10 min after injection showed no significant difference in thiopental levels between the ethanol and control groups. The ethanol-treated group slept for a significantly shorter period of time. It is concluded that chronic ethanol consumption for 14 days decreases the pharmacological effects of thiopental and alters its initial distribution in the body.     

Effects of Centella asiatica on ethanol induced gastric mucosal lesions in rats

Centella asiatica is a herbal medicine widely used in China and India for wound healing. The aim of this study was to examine its effects on the prevention of ethanol induced gastric lesions in rats. Gastric transmucosal potential difference (PD) was reduced by the application of 50% ethanol in the gastric ex-vivo chamber model and Centella extract (CE) accelerated its recovery. Oral administration of CE (0.05 g/kg, 0.25 g/kg and 0.50 g/kg) before ethanol administration significantly inhibited gastric lesions formation (58% to 82% reduction) and decreased mucosal myeloperoxidase (MPO) activity in a dose dependent manner. These results suggested that CE prevented ethanol induced gastric mucosal lesions by strengthening the mucosal barrier and reducing the damaging effects of free radicals.     

Effect of chronic ethanol consumption on emotional stress in the white rat

Chronic pain emotional stress (PES), paired action of the white noise and electric skin stimulation and chronic (during 7 months) ethanol consumption in white rats were shown to act in the same direction. Hypertension, decrease of respiratory rate and increase of Hildebrandt index were observed as a result of PES, ethanol consumption, and especially under PES during ethanol consumption. Ethanol consumption by the animals led to their growth retardation and increase of the spleen and heart mass. Accidental thymus involution was noted both under ethanol consumption and PES. Activation of lipid peroxidation and decrease of superoxide dismutase activity (of its mitochondrial form especially) as well as of Na+,K+-ATP-ase activity were observed in brain homogenates of the rats after PES, while the general ATP-ase activity remained unchanged. An increase of triiodothyronine level and the tendency to thyroxine level increase as well as a decrease of superoxide dismutase activity were observed in the blood serum of these animals. A tendency towards lipid peroxidation level decrease and to brain superoxide dismutase activity increase, as well as blood antioxidation activity increase (evaluated by transferrin and coeruloplasmin contents and by serum superoxide dismutase activity) and a decrease of thyroxine level were observed as a result of ethanol consumption. The mechanisms are discussed of the "anti-stress" action of short-term ethanol consumption and of the action of its chronic consumption, additive to PES.     

Effects of ethanol on the decidual cell reaction in rats.

The effects of ethanol on uterine sensitivity to induction of decidualization and deciduoma growth were determined. Rats were ovariectomized, given an oestrogen-progesterone regimen to optimize induction and growth of deciduoma and randomly assigned to one of three ethanol treatment groups: (i) days 1-4 (pre-induction/period of sensitivity), (ii) days 5-9 (post-induction/period of growth), (iii) days 1-9 (periods of sensitivity and growth); or to a control group not treated with ethanol (pair-fed to treated groups). Ethanol (0, 1, 2, or 4 g kg-1) diluted in water was administered by stomach tube on the days prescribed. Decidualization was induced in one uterine horn by intraluminal injection of sodium phosphate buffer. Uterine sensitivity and decidual growth were assessed as cornu weight. Blood alcohol concentrations were measured by gas chromatography. Alcohol treatment reduced uterine sensitivity, but increased deciduoma growth. Blood alcohol concentrations rose to 133 mg% at 30 min, remained high for 90 min and declined to 82 mg% at 120 min. Thus, blood alcohol concentrations sufficient to induce mild intoxication in humans suppressed uterine sensitivity to decidualization and enhanced deciduoma growth in rats. As all ovarian steroid hormone support was exogenous, the effects of ethanol on deciduoma induction and growth were not due to alterations in the hypothalamic-pituitary-ovarian axis.