Adrenalectomy reduces exploratory activity in the rat: a specific role of corticosterone

The effect of chronic adrenalectomy (10 days) and subsequent steroid hormone administration on exploratory activity in male rats was studied. Chronic adrenalectomy significantly decreased ambulatory and rearing activities, while grooming and defecation scores were not affected. Subcutaneous administration of corticosterone (30 μg/100 g body wt) 1 hr before the open-field test restored the decreased exploratory behavior of adrenalectomized rats toward the activity observed in sham-operated control animals. Neither dexamethasone or progesterone were effective. Administration of the synthetic glucocorticoid 1 hr prior to corticosterone substitution of the adrenalectomized rats even resulted in a complete prevention of the normalization of the behavioral response. The observed specific action of corticosterone on exploratory behavior corresponds to the stringent specificity of the neuronal hippocampal corticosterone receptor system.     

Bombesin-induced behavioural changes: Antagonism by neuroleptics

Adult male Sprague-Dawley rats were administered bombesin (BN) intracerebroventricularly (ICV), at a dose of 0.001, 0.01, 0.1, or 1.0 μg, and the behavioural effects monitored longitudinally across time for up to 24 hr. Administration of BN significantly increased the locomotor, rearing and grooming activity at all doses. The time-course of behavioural activation was dose-related (lasting up to 2.5 hr). There was no significant difference in the behavioural response of rats receiving the BN doses in an ascending or descending order. To test the effects of dopamine receptor blockade on the BN-induced behavioural changes, groups of animals were treated with fluphenazine or haloperidol (0.1 to 2.5 mg/kg, IP) 30 min prior to BN (1 μg, ICV) administration. The results revealed that the neuroleptics could effectively antagonize the BN-induced activation of locomotor, rearing and grooming activity. These data are concordant with the view that centrally administered BN stimulates spontaneous exploratory and grooming behaviours in rats, in a time- and dose-related manner. Furthermore, since neuroleptics block these effects, it remains possible that the BN-induced behavioural changes may be mediated, at least in part, through the dopaminergic system(s).     

Characteristics of open field behavior of Wistar and Sprague-Dawley rats

The open field test (OFT) was carried out on Wistar and Sprague-Dawley rats between the ages of 3 to 20 weeks. At that time, the behavior of each naive rat was observed for two 3-minute periods separated by an interval of 24 h (Day). The OFT scores varied depending on the day and the age. Comparatively higher activity was observed in the extent of ambulation and rearing at 5 weeks old, rearing and preening at 7 weeks old, and preening and defecation at 11 weeks old in the Sprague-Dawley rats compared with the Wistar rats.     

ACE activity during the hypotension produced by standardized aqueous extract of Cecropia glaziovii Sneth: A comparative study to captopril effects in rats

To evaluate the effect of the standardized aqueous extract (AE) of Cecropia glaziovii Sneth on the plasma angiotensin I converting enzyme (ACE-EC 3.4.15.1) activity, rats were treated with a single dose of AE (1 g/kg, p.o.) or repeatedly (0.5 g/kg/bid, p.o.) for 60 days. Captopril (50 mg/kg, p.o.) was used as positive control on the same animals. The effects on the blood pressure were recorded directly from the femoral artery (single dose), or indirectly by the tail cuff method (repeated doses) in conscious rats. The plasma ACE activity was determined spectrofluorimetrically using Hypuril-Hystidine-Leucine as substrate. The arterial blood pressure, heart rate and plasma ACE activity were not significantly modified within 24 h after a single dose administration of AE. Comparatively, blood pressure in captopril treated rats was reduced by 7-16% and heart rate was increased by 10-20% from 30 min to 24 h after drug administration. ACE activity after captopril presented a dual response: an immediate inhibition peaking at 30 min and a slow reversal to 32% up-regulation after 24 h. To correlate the drug effects upon repeated administration of either compound, normotensive rats were separated in three groups: animals with high ACE (48.8+/-2.6 nmol/min/ml), intermediate ACE (39.4+/-1.4 nmol/min/ml) and low ACE (23.5+/-0.6 nmol/min/ml) activity, significantly different among them. Repeated treatment with AE reduced the mean systolic blood pressure (121.7+/-0.5 mm Hg) by 20 mm Hg after 14 days. The hypotension was reversed upon washout 60 days afterwards. Likely, repeated captopril administration decreased blood pressure by 20 mm Hg throughout treatment in all groups. After 30 days treatment with AE (0.5 g/kg/bid, p.o.) the plasma ACE activity was unchanged in any experimental group. After captopril (50 mg/kg/bid, p.o.) administration the plasma ACE activity was inhibited by 50% within 1 h treatment but it was up-regulated by 120% after 12 h in all groups. It is concluded that the hypotension produced by prolonged treatment with AE of C. glaziovii is unrelated to ACE inhibition.     

Uterine contractile activity in rats induced by mifepristone (RU 486) in relation to changes in concentrations of prostaglandins E-2 and F-2 alpha.

Pregnant rats were injected with mifepristone (RU 486) on Day 15 of pregnancy. The force and frequency of uterine contractions, recorded by a microballoon technique, were significantly greater at 12, 24 and 36 h in treated than in control rats (11.9 +/- 1.9 vs. 8.9 +/- 1.2 units, 17.7 +/- 3.0 vs. 10.5 +/- 2.3 units and 16.8 +/- 2.9 vs. 8.8 +/- 1.8 units for force and 51.3 +/- 9.1 vs. 29.4 +/- 3.8/h, 35.4 +/- 6.4 vs. 22.1 +/- 4.9/h and 35.6 +/- 3.2 vs. 24.6 +/- 4.6/h for frequency, respectively). There was no significant difference in concentrations of prostaglandin (PG) E-2 or PGF-2 alpha between treated and control rats at 12 h and 24 h after injection. At 36 h, 7 of 12 rats were aborting and uterine PG concentrations in these were significantly greater than in the others (1.5 +/- 0.2 vs. 0.9 +/- 0.2 ng PGE-2/g and 38.6 +/- 19.2 vs. 16.9 +/- 5.4 ng PGF-2 alpha/g), but there was no significant difference between control and treated rats that were not aborting. Concentrations of PGE-2 and PGF-2 alpha were significantly higher at 48 h when abortion had occurred in all animals (6.5 +/- 2.6 vs. 2.4 +/- 1.7 ng PGE-2/g and 30.4 +/- 8.9 vs. 9.3 +/- 5.6 ng PGF-2 alpha/g). Thus, the increase in uterine contractile activity induced by mifepristone preceded significant changes in concentrations of PGE-2 and PGF-2 alpha in the uterus and so could not have been caused by these changes.     

Acute and chronic effects of ethanol on secretion of alpha-tocopherol from primary cultures of rat hepatocytes

Primary cultures of rat hepatocytes were used to study the effect of acute and chronic ethanol exposure on alpha-tocopherol content in cells and media. Cells treated acutely with 60 mM ethanol secreted 74.5 +/- 18.0% (P less than 0.05), and their cellular alpha-tocopherol content was 85.7 +/- 15.4% (not significant) of controls after 20 h incubation. At this time total recovery of alpha-tocopherol was significantly reduced in ethanol-exposed cells (43.1 +/- 8.4%) as compared to control cells (52.8 +/- 5.0%, P less than 0.05). Hepatocytes isolated from chronic ethanol-fed rats (35% of total energy intake as ethanol for 5 weeks) secreted 41.9 +/- 12.7% less alpha-tocopherol than did cells of pair-fed controls during 20 h incubation (P less than 0.05). The amount of alpha-tocopherol secreted was then 15.6 +/- 4.2 and 19.8 +/- 3.8% of cell-associated alpha-tocopherol at start of incubation for chronic ethanol-fed and control rats, respectively (P less than 0.05). When 60 mM ethanol was added to the incubation medium, hepatocytes of control rats secreted significantly less alpha-tocopherol (about 30%, P less than 0.05), whereas alpha-tocopherol secretion was not significantly reduced in hepatocytes of chronic ethanol-fed rats. We conclude that both acute and chronic ethanol exposure reduce alpha-tocopherol secretion from rat hepatocytes.     

Effects of ethanol and NAP on cerebellar expression of the neural cell adhesion molecule L1

The neural cell adhesion molecule L1 is critical for brain development and plays a role in learning and memory in the adult. Ethanol inhibits L1-mediated cell adhesion and neurite outgrowth in cerebellar granule neurons (CGNs), and these actions might underlie the cerebellar dysmorphology of fetal alcohol spectrum disorders. The peptide NAP potently blocks ethanol inhibition of L1 adhesion and prevents ethanol teratogenesis. We used quantitative RT-PCR and Western blotting of extracts of cerebellar slices, CGNs, and astrocytes from postnatal day 7 (PD7) rats to investigate whether ethanol and NAP act in part by regulating the expression of L1. Treatment of cerebellar slices with 20 mM ethanol, 10(-12) M NAP, or both for 4 hours, 24 hours, and 10 days did not significantly affect L1 mRNA and protein levels. Similar treatment for 4 or 24 hours did not regulate L1 expression in primary cultures of CGNs and astrocytes, the predominant cerebellar cell types. Because ethanol also damages the adult cerebellum, we studied the effects of chronic ethanol exposure in adult rats. One year of binge drinking did not alter L1 gene and protein expression in extracts from whole cerebellum. Thus, ethanol does not alter L1 expression in the developing or adult cerebellum; more likely, ethanol disrupts L1 function by modifying its conformation and signaling. Likewise, NAP antagonizes the actions of ethanol without altering L1 expression.     

Effect of ethanol feeding on the urinary histamine level of the pregnant rat

The influence of ethanol feeding during pregnancy on histamine excretion was studied. Pregnant Sprague-Dawley rats (N = 5) were fed a liquid diet containing 30% ethanol-derived calories from gestation-day 7 to 21; control rats (N = 5) were pair-fed with isocaloric sucrose substituted for ethanol. Twenty-four hour urines were collected for histamine analysis. Rats were killed on day 21 of gestation. Food and ethanol intakes averaged 260 kcal and 11 g/kg/day, respectively. No differences were found between ethanol and control rats in maternal weight gain, litter size or in fetal and placental weights. Although urinary histamine increased in all rats with the advance of pregnancy, on day 16, ethanol rats excreted significantly more (47%) than the controls (199.1 +/- 33.9 vs 135.5 +/- 51.4 ug/24 hr); on day 20, it was 123% more (534.6 +/- 114.4 vs 239.5 +/- 99.3 ug/24 hr). Ethanol enhanced urinary histamine did not reflect the histamine content or histidine decarboxylase activity of fetal liver, presumed site of histamine formation; its physiological significance is discussed.     

Effects of maternal-melatonin treatment on open-field behaviors and hypertensive phenotype in spontaneously hypertensive rats' (SHR) offspring.

Effects of maternal-melatonin treatment in spontaneously hypertensive rats (SHR) were investigated in their offspring. Pregnant SHR were given drinking water with/without melatonin (20 micrograms melatonin/ml tap water) during pregnancy and the lactation period. Maternal-melatonin treatment did not cause changes in body weights during 7 to 27 weeks. Melatonin administration up to weaning period via mother caused a decrease in systolic blood pressure (BP) during 11 to 27 weeks in their offspring compared with those of control group. Open-field behaviors in the offspring were observed at 24 weeks age. Both the control and treatment groups had ratios of central and peripheral locomotion of 30% and 70%, respectively. The treatment group exhibited less total locomotor activity and rearing than the control group did, whereas more latency was exhibited in the treatment group compared with that of the control group. These findings suggest that maternal-melatonin administration may modify open-field behaviors as well as the hypertensive phenotype in their progeny.     

Nonspecific grooming in rats during the solution of an extrapolation task

Grooming behavior in laboratory brown rats was analysed in the course of extrapolation task solving. Cases of task solution (correct and incorrect) were compared with those when animal "refused" to turn round the screen during search of food bait. In latter cases grooming episodes were more numerous, their latency and duration being higher than during former cases. At the same time the latest stages of experiment (when 8-13 trials a day twice a week were presented) were characterized by more frequent grooming occurrence as well as by longer latencies and duration of grooming episodes. When rats were given I trial a day with one week intervals grooming incidence as well as "refusals" occurrence decreased. The possible participation of animal grooming in arranging the defense reactions against excessive and inadequate activity is discussed.     

Comparative studies with cyclic and linear somatostatin on active avoidance behaviour and open-field activity in rats

The action of cyclic and linear somatostatin on active avoidance and open-field behaviour was investigated in rats. Both peptides inhibited the extinction of the avoidance behaviour and slightly but not significantly increased the intertrial activity (ITR). Both peptides increased ambulation and rearing activity in a dose related fashion, while the grooming and defecation rates were not changed. Since both peptides are capable of increasing the locomotor performance this action might contribute to the effect exerted on the extinction of active avoidance behaviour.     

Effect of 5 alpha-pregnan-3 alpha-ol-20-one on nitric oxide biosynthesis and plasma volume in rats

Plasma 5 alpha-pregnan-3 alpha-ol-20-one (pregnan) levels and nitric oxide (NO) biosynthesis increase during pregnancy. These factors have independently been implicated in the control of blood pressure and volume. We wished to determine whether pregnan might be responsible both for the increase in NO biosynthesis and for the increase in plasma volume observed during pregnancy. Virgin female Long-Evans rats were implanted with indwelling cannulas and maintained on a low nitrate/nitrite diet. After the rats recovered from surgery, 500 microg of pregnan or vehicle were given daily for 2 days. NO biosynthesis and plasma volume were measured in conscious animals before and after treatment. Pregnan caused a significant increase in NO biosynthesis (1.9 +/- 0.8 micromol/24 h, n = 10) compared with the vehicle-treated control group (0.3 +/- 0.4 micromol/24 h, n = 10, P < 0.05). Similarly, there was a significant increase in plasma volume in the pregnan-treated group (0.7 +/- 0.2 ml/100 g, n = 11) compared with the vehicle-treated control group (0.2 +/- 0.1 ml/100 g, n = 11, P < 0.05). These results confirm that pregnan can mimic pregnancy by its ability to increase both NO biosynthesis and plasma volume.     

Secretin modulation of behavioral and physiological functions in the rat

The effect of secretin on behavioral and physiological functions in the rat was investigated. Secretin injected intracerebroventricularly (ICV) significantly increased defecation and decreased novel-object approaches in rats. The peptide showed no significant effects on stereotypic behavior (gnawing, grooming and rearing), open-field locomotor activity however was significantly decreased, an effect that was probably due to a decreased propensity for the rats to initiate locomotor responses. In addition, secretin showed significant effects on respiration rate in anesthetized rats. When the peptide was injected in the lateral ventricle a decrease in respiration rate occurred, but when the brain was perfused from the lateral ventricle to the cisterna magna increases in respiration rate occurred. These data, combined with the facts that secretin and secretin receptors have been identified in the brain indicate that secretin may play a neurotransmitter or neuroregulator role in the central nervous system.     

Repeated ethanol exposure during late gestation decreases nephron endowment in fetal sheep

Maternal alcohol consumption during pregnancy can affect fetal development, but little is known about the effects on the developing kidney. Our objectives were to determine the effects of repeated ethanol exposure during the latter half of gestation on glomerular (nephron) number and expression of key genes involved in renal development or function in the ovine fetal kidney. Pregnant ewes received daily intravenous infusion of ethanol (0.75 g/kg, n=5) or saline (control, n=5) over 1 h from 95 to 133 days of gestational age (DGA; term is approximately 147 DGA). Maternal and fetal arterial blood samples were taken before and after the start of the daily ethanol infusions for determination of blood ethanol concentration (BEC). Necropsy was performed at 134 DGA, and fetal kidneys were collected for determination of total glomerular number using the physical disector/fractionator technique; at this gestational age nephrogenesis is completed in sheep. Maximal maternal and fetal BECs of 0.12+/-0.01 g/dl (mean+/-SE) and 0.11+/-0.01 g/dl, respectively, were reached 1 h after starting maternal ethanol infusions. Ethanol exposure had no effect on fetal body weight, kidney weight, or the gene expression of members of the renin-angiotensin system, insulin-like growth factors, and sodium channels. However, fetal glomerular number was lower after ethanol exposure (377,585+/-8,325) than in controls (423,177+/-17,178, P<0.001). The data demonstrate that our regimen of fetal ethanol exposure during the latter half of gestation results in an 11% reduction in nephron endowment without affecting the overall growth of the kidney or fetus or the expression of key genes involved in renal development or function. A reduced nephron endowment of this magnitude could have important implications for the cardiovascular health of offspring during postnatal life.     

Antibody labeling with copper-67 using the bifunctional macrocycle 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)methyl]benzoic acid.

The high kinetic stability of the Cu2+ complex of the chelator 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)-methyl]benzoic acid was demonstrated at physiological pH as well as under acidic conditions. The chelating agent was conjugated to AB35, a monoclonal antibody directed against CEA, without a significant loss of immunoreactivity. The conjugate could, under optimal labeling conditions, be labeled with 67Cu in acetate buffer with a full occupancy of ligands within 20 min. This radiolabeled conjugate showed no transfer of radiocopper to serum proteins in human serum over 7 days. The biodistribution in tumor-bearing mice was measured and compared to that of iodinated AB35. Tumor uptake was high with 15 +/- 3% ID (injected dose)/g after 24 h and 32 +/- 7% ID/g after 96 h for the 67Cu-labeled antibody and 13 +/- 4% ID/g after 24 h and 14 +/- 2% ID/g after 96 h for the 125I-labeled antibody. Whereas radioactivity in normal organs decreased with time after 24 h, increased residence time was shown up to 4 days with the 67Cu-labeled AB35.     

Decreased Histamine-Stimulated Phosphoinositide Hydrolysis in the Cerebral Cortex of a Rat Line Selectively Bred for High Alcohol Preference

This study sheds light on the comparative analysis of agonist-stimulated phosphoinositide (PI) hydrolysis in the cerebral cortex of alcohol-naive rats from established lines selectively bred for low alcohol preference (LAP) and high alcohol preference (HAP). The effect of histamine (1.0 mM), but neither norepinephrine (0.1 mM) nor carbachol (0.5 mM), on PI hydrolysis was significantly reduced in HAP rats (0.4 +/- 5.0 fmol/mg protein [3H]inositol phosphates formed over basal) compared with LAP rats (25.5 +/- 10.0 fmol/mg protein). The contents of monoamines (dopamine, norepinephrine, and serotonin) and histamine in the cerebral cortex did not significantly differ between LAP and HAP rats, nor did the contents of their metabolites, except 3-methoxy-4-hydroxyphenylglycol (one of the metabolites of norepinephrine) and N(tau)-methylhistamine, which was not detected in our system. The histamine stimulatory effect was unchanged in the cerebral cortex of an intact Wistar rat that was treated with intraperitoneal injection of alcohol (1.0 g/kg once per day for 14 days). The results of the current study indicate that the decrease in the histamine effect on PI hydrolysis in HAP rats might be attributed to that particular rat line.     

Cysteamine can induce duodenal ulceration in rats without depletion of immunoreactive somatostatin.

Single subcutaneous administration of cysteamine (2-aminoethanethiol, CSH) produces duodenal ulceration in rats within 24 h. Depletion of circulating and tissue somatostatin (SOM), hypergastrinemia and gastric acid hypersecretion have all been postulated as the pathophysiological response to CSH leading to ulceration. The purpose of this study was to analyze the synthesis, storage and secretion of gastrin and SOM as well as structural changes in SOM peptide after CSH treatment. Injection of 300 mg/kg (s.c.) of CSH caused macroscopic duodenal ulcers in seven out of eight rats at 24 h. Hypergastrinemia was seen within 30 min (from 23 +/- 4 to 74 +/- 20 pmol/l), and persisted for 4 h. Antral gastrin content was elevated at 30 min (2539 +/- 114 pmol/g) when compared to saline controls (1589 +/- 101 pmol/g). Plasma SOM did not change over the 24 h but antral SOM increased at 30 min (from 120 +/- 3 to 230 +/- 23 pmol/g) and remained elevated at 2 h (374 +/- 48 pmol/g) and 4 h (357 +/- 37 pmol/g). Fundic and duodenal SOM followed a similar pattern. Antral SOM mRNA was also elevated over the first 4 h (3-fold increase, P less than 0.05). HPLC analysis of antral tissue extracts revealed the presence of additional molecular forms of SOM which, however, differed from the major products of in vitro reduction with either CSH or dithiothreitol. Thus, the in vivo effect of CSH on SOM cannot be solely explained by a reductive opening of the disulphide bond. These results suggest that duodenal ulceration in rats treated with CSH is not related in a simple fashion to depletion of immunoreactive SOM. Early induction of hypergastrinemia may be important in the onset of ulceration. The value of CSH as a SOM depleting tool in gastrointestinal tissue must remain in doubt.     

Acute and chronic ethanol treatment in vivo increases malate-aspartate shuttle capacity in perfused rat liver

The effects of acute and chronic treatment with ethanol on transport of reducing equivalents into mitochondria via the malate-aspartate shuttle were studied in perfused rat liver. The shuttle capacity was estimated from the decrease in rates of glucose production from the reduced substrate sorbitol caused by an increase in the NADH/NAD+ ratio in the cytosol due to metabolism of ethanol. The greater the capacity of the malate-aspartate shuttle, the smaller the inhibition of glucose synthesis by ethanol. Glucose synthesis was decreased about 2-fold less in livers from fasted rats treated acutely 2.5 h earlier with ethanol than in untreated controls. Chronic treatment with ethanol for 3-5 weeks prevented completely the decrease in glucose synthesis from sorbitol due to ethanol oxidation. Rates of ethanol uptake were elevated significantly from 69 +/- 7 mumols/g/h in livers from control rats up to 92 +/- 7 mumols/g/h in livers from SIAM rats. Similarly, rates of ethanol uptake were stimulated by chronic ethanol treatment from 71 +/- 6 to 222 +/- 15 mumols/g/h; this increase was largely sensitive to aminooxyacetate. Taken together, these data indicate that flux of reducing equivalents over the malate-aspartate shuttle is increased by both acute and chronic treatment with ethanol and that movement of reducing equivalents from the cytosol into the mitochondria via the malate-aspartate shuttle is an important rate determinant in hepatic ethanol oxidation.     

Effects of adrenergic blockers on corticotropin-releasing factor-induced behavioral changes in rats

The effects of adrenoreceptor blocking agents on corticotropin-releasing factor (CRF)-induced behavioral changes in rats were examined. The i.c.v. injection of 1 micrograms ovine CRF significantly increased the grooming frequency, number of occurrences of rearing and total distance moved. I.c.v. administered phentolamine at a dose of 10 nmol completely suppressed the increase in rearing and total distance moved induced by CRF without affecting the grooming frequency, whereas 100 nmol phentolamine significantly decreased the grooming frequency as well as the rearing and total distance moved. In contrast, propranolol reduced the increase in rearing induced by CRF only at a dose which induced ataxia in rats. The increases in rearing and total distance moved induced by CRF were reduced by 10 nmol of yohimbine and 100 nmol of prazosin. S.c. injection of caffeine (10 mg/kg) produced a significant increase in grooming frequency, rearing, and total movement. Administration of 10 nmol phentolamine and yohimbine did not affect these behavioral changes induced by caffeine, while 100 nmol prazosin suppressed them. Therefore, prazosin depressed the behavior of rats non-specifically. These results suggest that CRF-induced behavioral hyperactivity is mediated at least in part by alpha-noradrenergic, mainly alpha 2-noradrenergic, systems in the brain.     

Behavioral Modifications Related to Consumption of a “Soft” Adaptogen,Bee Honey,by Rats

Modifications of neurobehavioral activities related to single episodes of consumption of different doses of bee honey were examined in rats under conditions of the hole-board (HB) test (to evaluate the level of anxiety) and open-field (OF) test (where the intensities of locomotion, rearing, and grooming were measured). Animals of all subgroups had free access to normal saline, while rats of the three experimental subgroups consumed bee honey in the doses of 0.5, 1.0, and 2.0 g per 1 kg body mass (in the form of 10, 20, and 40% solutions, respectively). Among the doses tested, only higher ones induced considerable changes in the behavioral indices. The highest dose (2.0 g/kg) provided a more than twofold increase in the number of examined holes in the HB test; in the OF test, it also increased the numbers of crossed squares, rearings, and grooming episodes by 30, 37, and 164%, respectively. Thus, our experiments demonstrated a rather significant ability of the natural product tested to relieve anxiety and intensify motor, research/orientational, and grooming aspects of behavior even upon single acts of consumption. Possible neurophysiological mechanisms underlying the behavioral modifications observed are discussed.