Effects of chronic diazepam treatments on behavior on individually housed rats

The present study analyzed the effects of chronic treatment with low doses of diazepam on body weight, defecations and urinations, vertical rears, the elevated platform test; and self-grooming in male rats exposed for 21 days to social isolation. The rats were treated for 21 days with diazepam (0.2 mg/kg, i.p) or its vehicle. Social isolation led to decreased body weight and vertical rears, more defecations and urinations, increased reluctance to step down from the test platform, shorter duration of grooming, and longer reluctance to start grooming. Chronic diazepam in individually housed rats produced increase in body weight and vertical rears, decrease in the number of defecations and urinations, and shortening of the time of reluctance to step down from the platform. The number of grooming bouts, their duration, and reluctance to start grooming were not altered by diazepam, but it decreased the percentage of incorrect transitions. The obtained data indicate that chronic diazepam treatment of socially isolated rats changes non-grooming behavior and some grooming, behavior parameters

HNF4alpha Dysfunction as a Molecular Rational for Cyclosporine Induced Hypertension

Induction of tolerance against grafted organs is achieved by the immunosuppressive agent cyclosporine, a prominent member of the calcineurin inhibitors. Unfortunately, its lifetime use is associated with hypertension and nephrotoxicity. Several mechanism for cyclosporine induced hypertension have been proposed, i.e. activation of the sympathetic nervous system, endothelin-mediated systemic vasoconstriction, impaired vasodilatation secondary to reduction in prostaglandin and nitric oxide, altered cytosolic calcium translocation, and activation of the renin-angiotensin system (RAS). In this regard the molecular basis for undue RAS activation and an increased signaling of the vasoactive oligopeptide angiotensin II (AngII) remain elusive. Notably, angiotensinogen (AGT) is the precursor of AngII and transcriptional regulation of AGT is controlled by the hepatic nuclear factor HNF4alpha. To better understand the molecular events associated with cyclosporine induced hypertension, we investigated the effect of cyclosporine on HNF4alpha expression and activity and searched for novel HNF4alpha target genes among members of the RAS cascade. Using bioinformatic algorithm and EMSA bandshift assays we identified angiotensin II receptor type 1 (AGTR1), angiotensin I converting enzyme (ACE), and angiotensin I converting enzyme 2 (ACE2) as genes targeted by HNF4alpha. Notably, cyclosporine represses HNF4alpha gene and protein expression and its DNA-binding activity at consensus sequences to AGT, AGTR1, ACE, and ACE2. Consequently, the gene expression of AGT, AGTR1, and ACE2 was significantly reduced as evidenced by quantitative real-time RT-PCR. While RAS is composed of a sophisticated interplay between multiple factors we propose a decrease of ACE2 to enforce AngII signaling via AGTR1 to ultimately result in vasoconstriction and hypertension. Taken collectively we demonstrate cyclosporine to repress HNF4alpha activity through calcineurin inhibitor mediated inhibition of nuclear factor of activation of T-cells (NFAT) which in turn represses HNF4alpha that leads to a disturbed balance of RAS

Central and peripheral catecholamine stores in spontaneously hypertensive rats under immobilization stress

The effects of increasing duration of immobilization stress (from 30 min to 240 min) on catecholamine stores in some central (hypothalamus, corpus striatum) and peripheral tissues (suprarenal glands, heart auricles) in spontaneously hypertensive rats were investigated. Sufficiently long immobilization induced significant depletion of both central and peripehral catecholamine stores. The greatest depletion occurred in the suprarenal gland(adrenaline) and in the hypothalamus (noradrenaline and dopamine). The corpus striatum (dopamine) and the heart auricles (noradrenaline) were the most resistant to immobilization stress. These data indicate that catecholamine depletion in all investigated structures in spontaneously hypertensive rats depended on the duration of immobilization. If was concluded that after immobilization for more than 30 min the release of catecholamines was stronger that the processes of synthesis and reuptake, thus leading to progressive depletion of catecholamine stores, particularly when imobilization lasted up to 240 min. The present results indicate a difference in the effects of immobilization stress on catecholamine stores between some brain regions and peripheral tissues in spontaneously hypertensive rats

Effect of immobilization and cold stress on sympatho-adrenal system in rats exposed to long-term cold

In the present study we examined changes in plasma levels of catecholamines, corticosterone and adrenomedullary TH gene expression after a short (2 h) and long-term (28 days) cold exposure, as well as in the cold adapted rats exposed to immobilization. Long-term cold produced a significant elevation of basal plasma levels of noradrenaline, but not of adrenaline, corticosterone and adrenal TH mRNA. Cold-adapted rats exposed to immobilization further significantly elevated plasma levels of catecholamines, corticosterone and adrenal TH mRNA, in comparison with repeated short (2 h) exposure to cold. The response of these animals was more pronounced in comparison with naive rats exposed to the same stressor at room temperature. Based on the results obtained it can be concluded that the rats exposed to long-term cold are able to respond to another stressor by a higher activation of the sympatho-adrenal system as compared to the rats kept at room temperature

Behavioural and endocrine responses of socially isolated rats to long-term diazepam treatment

The effects of diazepam (0.2 mg/kg/ during 21 days, i.p.) on behaviour, pituitary-adrenocortical and sympatho-adrenomedullary system of socially isolated and group-housed adult male rats additionally exposed to immobilization, were studied. Social isolation led to a shorter duration of grooming and longer latency to start grooming. Diazepam in social isolated rats reduced incorrect transitions percentage, but the number of grooming bouts, duration and latency to start grooming remained unchanged. Long-term isolation significantly elevated plasma ACTH and corticosterone, while not affecting noradrenaline and adrenaline. Diazepam decreased only plasma ACTH. Social isolation and immobilization significantly elevated all examined hormones. Immobilization of diazepam-treated isolated rats enhanced plasma ACTH, the increase being significantly lower, comparing to isolated vehicle-treated rats. Immobilization significantly increased plasma adrenaline, noradrenaline and corticosterone of diazepam- or vehicle-treated socially isolated rats. No differences in adrenaline, noradrenaline and corticosterone level between these two groups were observed. This indicates that chronic diazepam treatment of socially isolated rats changes some grooming behaviour parameters, but insignificantly affects stress-related adrenomedullary and adrenocortical alterations

Gene Expression of Catecholamine Synthesizing Enzymes in Stellate Ganglia of Stressed Rats

Enhanced activation of sympathetic neurons during stress results in an increased cardiovascular function. Social isolation is a psychological stress which has deleterious effects on health and represents the most relevant cause of diseases in mammalian species. In this study we investigated the changes in catecholamine biosynthetic enzymes tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) gene expression and protein levels in the stellate ganglia of naive controls and chronically socially isolated (12 weeks) adult rats and the response of these animals to additional immobilization stress (2 h) by applying TaqMan RT-PCR assay and Western blot analysis. Psychosocial stress produced a significant increase of both TH mRNA (p LT 0.05) and DBH mRNA (p LT 0.05) levels in stellate ganglia. The exposure of control rats to acute immobilization significantly increased TH mRNA (p LT 0.001) and DBH mRNA (p LT 0.01) levels, while additional immobilization of chronic psychosocially stressed rats expressed no effect on gene expression of these enzymes. Protein levels of TH, and DBH remained unchanged in control and chronic social isolation rats and also after short-term immobilization. The results presented here suggest that psychosocial stress-induced an increase in gene expression of catecholamine biosynthetic enzymes in stellate ganglia and thus may be connected to the increased risk of cardiovascular disease

Effects of chronic ethanol administration on the serotonin-producing cells in rat gastric antral and duodenal mucosa

The present study describes our observations on optical and ultrastructural features of serotonincontaining cells in the rat antral and upper duodenal mucosa, utilizing optic morphometric measurements in a model of experimental chronic alcoholism of rat in which nutrition was well controlled. Male Wistar rats were given ethanol to provide 23 per cent of the total calories, while starch replaced ethanol isocalorically in controls. Twenty-five per cent of the calories were provided by protein in both groups. Blood levels of serotonin were significantly raised after chronic ethanol feeding (0.05910.06 vs. 0.15910.012 pglml, p<0.01). Decrease in the number of immunohistochemicallydetectable serotonin-containing cells was found in the pyloric gland mucosal area specimens of the chronically ethanol-treated rats (68.915.2 vs 43.313.0; p<0.001). The immunohistologically-evaluated number of the same cells in the duodenal mucosa specimens was significantly decreased by alcohol feeding. Although total villi and crypt count per whole circular section, and the number of crypts per villus were not significantly changed either in control animals or in chronically ethanol-fed rats, decreased number of these cells per whole circular section (289121.6 vs. 183f 10.5; p<O.OOI) per villus (2.5210.14 vs. 1.2110.10; p<0.001) and per crypts (0.97kO.08 vs. 0.7910.04; p<0.05) were reported after alcohol consumption. In both control and experimental rats the cells were predominantly found in the basa1 half of the antropyloric mucosa. Alcohol did not lead to any changes in normal distribution of the duodenal serotonin-producing cells. The above quantitative changes in serotonin-producing cells were not accompanied by changes in their subcellular appearance in stomach and duodenal mucosa of alcoholtreated rat

The effects of long-term low-protein intake on gastrin cells of the rat antral mucosa during adulthood

The effect of experimental protein malnutrition on gastrin producing cells in the antral part of the stomach was studied in male Wistar rats. Isoenergetic diets containing 25% (C-25) or 6% (PD-6) were given in isocaloric amounts during a 4-month experiment. All rats were offered drinking water ad libitum. The results showed that the long-term protein diet did not produce changes in the gastrin cell number. At the ultrastructural level G cells exhibited a decreased size of the nucleus. They were found to have an increased total granule volume density but the volume density of dense-cored granules was lower. The serum gastrin levels were significantly lowered by feeding the low protein diet. These changes are compatible with decreased functional activity of G cells under long-term protein deprivation