Effect of an anti-substance P serum on prolactin and gonadotropins in hyperprolactinemic rats

The effects of the acute injection of a rabbit anti-substance P serum (ASPS) were studied in normal rats and rats with hyperprolactinemia induced by 5-hydroxytryptophan and estradiol given as a short or chronic treatment. The anti-substance P serum decreased the release of prolactin induced by 5-hydroxytryptophan when this serotonin precursor was injected 24 h, but not 1 h, after the administration of the antiserum. ASPS reduced the hyperprolactinemia induced by short and chronic treatment with estradiol in castrated rats. This effect was observed 24 h after the injection of the antiserum. On the other hand, the injection of ASPS induced a significant decrease in LH levels in serum of intact male rats injected with 5-hydroxytryptophan 24 h after ASPS, and in castrated rats treated with short-term and chronic administration of estradiol, 24 h after the injection of the antiserum. These results suggest that substance P may have a role in the control of prolactin secretion and could play a part in the hyperprolactinemic effects of estradiol. On the other hand, substance P, under certain circumstances, may stimulate LH release.     

Antisera to atrial natriuretic factor reduces urinary sodium excretion and increases plasma renin activity in rats

Although the presence of atrial natriuretic factor in the blood has been demonstrated by radioimmunoassay, its biological activity and physiological significance has not been elucidated. Using specific antiserum against atrial natriuretic factor, we investigated the effect of passive immunization in rats. A significant reduction of urine output and urinary sodium excretion lasted for about 30 min after intravenous administration of antiserum. The effects were more pronounced in rats pretreated with deoxycorticosterone acetate and saline. Plasma renin activity was increased after the administration of antiserum. No significant effects on the urinary sodium excretion was observed following injection of normal rabbit serum. The results of this study provide evidence indicating that endogenous atrial natriuretic factor plays an important role in the regulation of urinary water and sodium excretion and plasma renin activity.     

Some effects of morphine on lipid metabolism in normal,tolerant and abstinent rats

The effects of morphine on lipid levels of plasma and liver were studied in rats. The first injection of morphine induced a decrease in free fatty acids (FFA) and an increase in the plasma triglyceride level. No changes in phospholipid, cholesterol or cholesterol ester concentrations were observed. In chronic morphinized rats the plasma FFA level was unchanged one hour following the injection of morphine and tolerance developed to the depressive effect of the drug. In contrast, the rise in plasma triglycerides persisted, but to a lesser extent. In these animals, the plasma levels of FFA and of triglycerides were lower than in normal rats, when blood was sampled 24 hours after the last injection of morphine. In abstinent rats, a reversal of action of morphine was noticed. Nalorphine induced an increase in plasma FFA levels in normal and abstinent rats but not in chronically morphine-treated animals. In the liver no significant changes occured in lipids in either acute or chronically morphinized rats. The effects of morphine on plasma lipid levels might be linked to the action of the drug on the secretory activity of the adrenals and also to the depressive effect of the drug on the lipolytic activity of adipose tissue which was demonstrated in vitro.     

Involvement of endogenous digitalis-like substance in genesis of deoxycorticosterone-salt hypertension

In an attempt to evaluate the role of endogenous digitalis-like substance in the genesis of deoxycorticosterone (DOCA) -salt hypertension, the effects of intravenous anti-digoxin antibody on the blood pressure response were observed in male Wistar rats that underwent heminephrectomy followed by treatment with DOCA and saline. Administration of anti-digoxin antibody caused a marked decrease in the blood pressure which continued for about an hour. Such a change in the blood pressure was not observed in pertinent control animals. Thus, it seems that endogenous digitalis-like substance plays an important role in the genesis of DOCA-salt hypertension.     

Anti-arrhythmia effect of digoxin antibodies in experimental myocardial infarct (arrhythmogenic action of endogenous digoxin-like factor)]

Suggesting endogenous digoxin-like factor (EDLF) to display arrhythmogenic activities in myocardial ischemia (MI), we studied the effect of anti-digoxin antiserum (ADS) on the ventricular fibrillation threshold (VFT) after the coronary ligation in cats and ventricular arrhythmias caused by MI in rats and chloroform-induced hypoxia in mice. Intravenous administration of ADS (5 mg/kg) enhanced VFT in cats with MI from 11.3 +/- 1.6 to 53.3 +/- 8.1 V (M +/- m; p less than 0.01) and significantly reduced ventricular arrhythmias in rats and mice. Our experiments on the isolated electro-stimulated rat atria demonstrated that EDLF is likely not to be an adrenergic cotransmitter in the heart. Possible mechanisms of the arrhythmogenic action of EDLF are discussed.     

Cardiac performance in the rabbit as affected by the venom of bitis gabonica. (A preliminary report)

The effect of the venom of Bitis gabonica administered intravenously in the rabbit at the dose of 0.125 mg/kg has been compared with that produced by the same dose of the compound in the dog. In the rabbit the effect on total peripheral resistance, aortic blood pressure and stroke volume is less marked and shorter than in the dog. Furthermore in a period included between 5 and 30 min after the injection, in the rabbit a transient increase of stroke work is observed as a result of the ejection of an increased stroke volume against a blood pressure which has already returned to normal. Such a transient inotropic effect of the venom was also observed in other small mammalians and might be attributed to an adrenergic mechanism.     

beta-Endorphin controls vasopressin release during foot shock-induced stress in the rat

This study tested the possibility that beta-endorphin is involved in the regulation of vasopressin release during stress induced by inescapable electric foot shock. To this end, a specific anti-beta-endorphin antiserum or a control serum lacking the specific anti-beta-endorphin antibodies was administered to male rats. Plasma vasopressin concentrations, measured by radioimmunoassay, were not affected by brief foot shock stress in control rats, but were raised significantly by the stress in animals which had received an intracerebroventricular (i.c.v.) injection of the anti-beta-endorphin antiserum. In contrast, when the same volume of the anti-beta-endorphin antiserum was injected into a tail vein, foot shock stress produced only a slight effect on vasopressin release. I.c.v. injection of the antiserum changed neither basal nociceptive threshold nor stress-induced analgesia as revealed by the tail-flick latency. Vasopressin release induced by an osmotic stimulus was not influenced by the anti-beta-endorphin antiserum given i.c.v. The opiate antagonist naloxone or the glucocorticoid dexamethasone raised plasma vasopressin concentration in stressed rats which had received the control serum (i.c.v.); however, after i.c.v. injection of the anti-beta-endorphin antiserum neither naloxone nor dexamethasone elevated the plasma vasopressin concentration beyond the level reached by the anti-beta-endorphin antiserum (i.c.v.) alone. These results suggest that beta-endorphin inhibits the release of vasopressin during foot shock-induced stress in the rat.     

Effect of 41-CRF antiserum on the secretion of ACTH, B-endorphin and alpha-MSH in the rat

In order to elucidate the physiological role of the 41 amino-acid residue corticotropin-releasing factor (41-CRF) on the secretion of ACTH, B-Endorphin and alpha-MSH, plasma levels of these peptides were measured by radioimmunoassay in intact and adrenalectomized rats, two hours after the injection of either 41-CRF antiserum (CRF-AS) or normal rabbit serum for controls. The administration of CRF-AS strikingly lowered the plasma ACTH levels in both intact and adrenalectomized rats. A statistically significant reduction of plasma levels of B-Endorphin was also observed in the same rats. However, the effect of CRF-AS on B-Endorphin release was less pronounced than the effect on ACTH release. No changes in plasma alpha-MSH levels were observed after passive immunization with CRF-AS. We conclude that, in the rat, 41-CRF plays a physiological role in the regulation of ACTH and B-Endorphin secretion, but is not involved in the regulation of alpha-MSH release from the pituitary gland.     

Noradrenergic transmission in isolated guinea-pig intestine following in vivo administration of antibodies to dopamine beta-hydroxylase.

The effectiveness of transmission from noradrenergic nerves supplying the guinea-pig ileum was evaluated in normal preparations and in preparations taken from animals injected 18 h to 4 days previously with antiserum to dopamine beta-hydroxylase. Degeneration of the nerves following the antiserum was monitored histochemically in the same preparations. A decline in the effectiveness of transmission, which paralleled the degeneration of the nerves, was observed. The earliest effects were detected at 18 h and the greatest effect was found at 2-4 days following the administration of antiserum. Binding of the antibodies has been detected as early as 6 h after injection. It is therefore concluded that binding of the antibodies to the nerves, per se, does not significantly compromise transmission, and that histochemical evidence of degeneration can be used to indicate the onset of functional deterioration of noradrenergic nerves following their exposure to antibodies to dopamine beta-hydroxylase.     

Hypermethioninemia Increases Cerebral Acetylcholinesterase Activity and Impairs Memory in Rats

In the present study we investigated the effect of chronic hypermethioninemia on rat performance in the Morris water maze task, as well as on acetylcholinesterase (AChE) activity in rat cerebral cortex. For chronic treatment, rats received subcutaneous injections of methionine (1.34–2.68 μmol/g of body weight), twice a day, from the 6th to the 28th day of age; control rats received the same volume of saline solution. Groups of rats were killed 3 h, 12 h or 30 days after the last injection of methionine to AChE assay and another group was left to recover until the 60th day of life to assess the effect of early methionine administration on reference and working spatial memory of rats. AChE activity was also determined after behavioral task. Results showed that chronic treatment with methionine did not alter reference memory when compared to saline-treated animals. In the working memory task, we observed a significant days effect with significant differences between control and methionine-treated animals. Chronic hypermethioninemia significantly increased AChE activity at 3 h, 12 h or 30 days after the last injection of methionine, as well as before or after behavioral test. The effect of acute hypermethioninemia on AChE was also evaluated. For acute treatment, 29-day-old rats received one single injection of methionine (2.68 μmol/g of body weight) or saline and were killed 1, 3 or 12 h later. Results showed that acute administration of methionine did not alter cerebral cortex AChE activity. Our findings suggest that chronic experimental hypermethioninemia caused cognitive dysfunction and an increase of AChE activity that might be related, at least in part, to the neurological problems presented by hypermethioninemic patients.     

Regional differences in enhanced neurogenesis in the dentate gyrus of adult rats after transient forebrain ischemia

Neurogenesis in the dentate gyrus occurs throughout life. We observed regional differences in neurogenesis in the dentate gyrus of adult rats following transient forebrain ischemia. Nine days after ischemic-reperfusion or sham manipulation, rats were given 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU), a marker for dividing cells. They were killed 1 or 28 days later to distinguish between cell proliferation and survival. Neurogenesis was evaluated by BrdU incorporation as well by identifying neuronal and glial markers in six regions of the dentate gyrus: rostral, middle and caudal along the rostrocaudal axis, each further divided into suprapyramidal and infrapyramidal blade subregions. In control rats BrdU-positive cells in the rostral subregions were significantly lower in the suprapyramidal than in the infrapyramidal blades at both 1 and 28 days after BrdU injection. One day after injection, BrdU-positive cells had increased more in five of the subregions in the ischemic rats than in the controls, the exception being the suprapyramidal blade of the rostral subregion. At 28 days after BrdU injection, numbers of BrdU-positive cells were higher in four subregions in the ischemic group, the exceptions being the rostral suprapyramidal and middle infrapyramidal blades. At 28 days after BrdU injection, the percentages of BrdU positive cells that expressed a neuronal marker (NeuN) were the same in the dentate granule cell layers of ischemic and control rats. Our data thus demonstrate regional differences in enhanced neurogenesis in the dentate gyrus of adult rats after transient forebrain ischemia.     

Effects of melatonin and natural and synthetic analogues of arginine vasotocin on plasma prolactin levels in adult male rats

A significant elevation in plasma prolactin was observed 10 min following the intravenous injection of 100 microgram of melatonin into either estrogen-progesterone (EP) primed or into nonsteroid-treated male rats. 60 min postinjection in the EP primed rat, the groups treated with 100 microgram or 10 mg of melatonin had signficantly elevated plasma prolactin levels while no effect was observed with these same doses in the nonsteroid-treated rats. Compared to diluent-treated controls, a significant elevation in plasma prolactin was observed at 10, 20 and 60 min following the intravenous injection of either 1 microgram arginine vasotocin (AVT) or 1 mg melatonin into EP primed male rats. A consistent rise in plasma prolactin was also evident after the injection of 1 microgram of either arginine vasopressin, lysine vasopressin or AVT. Oxytocin had no effect on plasma prolactin values. The intravenous administration of 1 microgram of (deamino-1,6 dicarba, 8-arginine)-vasotocin caused a significant elevation of plasma prolactin 10 and 20 min after injection. However, the injection of another analogue of AVT, (4-leucine, 8-arginine)-vasotocin, had no effect on prolactin release at the time points measured.     

Hyperargininemia: the rat as a model for the human disease and the comparative response to enzyme replacement therapy with free arginase and arginase-loaded erythrocytes in vivo

Rat erythrocytes lack arginase as do the erythrocytes of human homozygote patients with hyperargininemia due to arginase deficiency. The rat has physiological liver arginase activity and plasma arginine and ornithine levels between the homozygotes and the heterozygotes with hyperargininemia. In rats, one injection of free arginase induces a transient exogenous arginase effect which is abolished after 24 hr. One injection of isoionic arginase-loaded erythrocytes provokes an exogenous arginase effect in physiological "hyperargininemic" rats and pathological "hyperargininemic"-made rats for at least 8 and 5 days respectively. The very transient response in vivo to exogenous free arginase can be considerably prolonged by entrapment of the arginase in isoionic prepared erythrocytes.     

Renal immunolocalization of kallikrein in cisplatin nephrotoxicity in rats

Summary Treatment of rats with cisplatin (4 mg kg^-1body wt i.p. injection) induced variations of urinary kallikrein excretion (UKE). Three phases were observed: a transient increase of UKE one day after injection, followed by a decrease up to 10 days suggesting an altered biosynthesis and a recovery phase with return to normal control values, 21 days after injection. Early morphological lesions were observed in proximal tubule cells on day 1; severe changes and tubular necrosis were observed in the following days. Less marked changes were also present in distal tubules but the vacuolated and desquamated cells appeared in the lumen of the tubules. By immunocytochemical methods, kallikrein was observed in connecting tubule cells, but also in some proximal tubule cells and along the endothelial side of the glomerular basement membrane and urinary space of glomeruli. An intense labelling was present in desquamated epithelial cells in dilated lumen of tubules. This study provides evidence of the presence of immunoreactive kallikrein in the glomerulus, already reported during acute failure, and confirms the use of urinary kallikrein measurements as a useful non-invasive index to assess a possible nephrotoxic effect at the distal level.     

The regulation of ornithine aminotransferase synthesis by glucagon in the rat.

Ornithine aminotransferase (OAT) from rat liver mitochondria was purified to homogeneity. A monospecific antiserum against the enzyme protein was prepared in rabbits. Immunotitrations were performed on OAT present in crude mitochondrial extracts obtained from the livers and kidneys of rats in several hormonal and dietary states. No evidence was found for the existence of an immunologically reactive but enzymatically inactive form of OAT. The relative rate of enzyme synthesis in vivo was studied by pulselabeling rats with [4, 5-³H]leucine, isolating the enzyme protein by immunoprecipitation, and dissociating the immunoprecipitates on sodium dodecyl sulfate-acrylamide gels. Nine hours after a single subcutaneous injection of a glucagon oil emulsion, a 3-fold increase in OAT activity and a 12-fold increase in the synthetic rate of the enzyme were observed. Serine dehydratase activity increased on a time-course very similar to that of OAT following glucagon injection. These increases occurred only on low (0–12.5%) protein diets. At higher levels of dietary protein (30% and up), no further stimulation of OAT synthesis by glucagon was observed. Administration of actinomycin D within the first 2 h after glucagon injection resulted in an inhibition of OAT induction. When the administration of the antibiotic was delayed until 4 h after glucagon, no inhibition of OAT induction was observed. Glucose repression of the glucagon induction of the enzyme in hepatic mitochondria was demonstrated to be the result of a rapid inhibition of OAT synthesis.     

Chronic ethanol treatment alters the biosynthesis of beta-endorphin by the rat neurointermediate lobe

Tolerance to ethanol was induced in male Sprague-Dawley rats (225-250 g) by chronic feeding with a liquid diet containing 6.5% ethanol (v/v). Control rats were pair-fed with a liquid diet in which the ethanol was replaced by an equicaloric concentration of sucrose. Immediately following sacrifice of the animals the neurointermediate lobes (NIL) were removed and incubated with [3H]phenylalanine. The biosynthesized proopiomelanocortin (POMC), beta-lipotropin (beta-LPH), and beta-endorphin (beta-EP) were purified by immunoprecipitation with an antiserum to beta-EP and analyzed by sodium dodecyl sulfate polyacrylamide disc gel electrophoresis. Alcohol treatment for 3 days had no effect on the degree of incorporation of [3H]phenylalanine into POMC, beta-LPH, and beta-EP but treatment for either 15 or 21 days increased the incorporation of [3H]phenylalanine into all three peptides. Ethanol treatment also increased the beta-endorphinlike immunoreactivity (beta-EPLIR) found in the incubation medium, but no significant change was observed in the beta-EPLIR extracted from the NIL either immediately after sacrifice or after 3 h of incubation of the NIL. However, a significant decrease of beta-EPLIR was found in the anterior lobes of rats treated with ethanol for 21 days. Furthermore, the beta-EPLIR in the serum of alcohol-treated rats was significantly higher than in the serum of their corresponding controls. These results indicate an effect of ethanol on the endorphin system and are consistent with the suggestion that endorphins may be mediators of some of the ethanol effects.     

Some behavioural effects of carbamazepine - comparison with haloperidol.

The experiments presented in this paper aimed to investigate the influence of atypical antiepileptic drug carbamazepine (CBZ, CAS 298-46-4) classified also as normothymic drug on spatial memory in Morris water maze test and anxiolytic effect in two-compartment exploratory test in rats. The study also investigated the probably occurring side effects (measuring cataleptic activity and motor coordination) following single and chronic administration of CBZ compared to haloperidol (HAL, CAS 52-86-8), a conventional antipsychotic. All the tests were carried out on male Wistar rats. CBZ 30 mg/kg was administered orally 60 min before the tests and HAL 0.15 mg/kg was administered orally 60 min before the tests. In the Morris test memory improvement only after chronic administration of CBZ on the 7 and 14 day of treatment was observed, whereas after 14 days of HAL treatment spatial memory impairment was noted. In the two-compartment exploratory test 30 mg/kg of CBZ had an anxiolytic effect after 7 and 14 days of treatment, whereas HAL did not show anxiolytic effect after single and chronic treatment. CBZ did not induce catalepsy after single as well as chronic administration. HAL evoked a strong cataleptic effect both after acute and chronic treatment. CBZ had no impact on motor coordination in the chimney test and HAL disturbed motor coordination in rats after single as well as chronic administration. CBZ may be an useful normothymic drug using in bipolar affective disorder treatment with co-occurred anxiety and cognitive deficits. The lack of significant side effects of CBZ may be an alternative way of treatment in comparison with older drugs, such as lithium carbonate.     

Effects of gastrin-releasing peptide 1-27 on taste responses in the rat

Gastrin-releasing-peptide(1-27) (GRP) has been implicated in the regulation of satiety and appetite in numerous paradigms. However, the specific site and mode of action of this gut-brain peptide has not been elucidated. The following experiment examined the effects of GRP on taste responses to sucrose in the behaving rat. A brief-exposure, multi-bottle gustometer was used to provide rats with momentary access to six different concentrations of sucrose in a single test session. This procedure has been used previously, resulting in monotonically increased licking behavior as concentrations of sucrose increase. Differing injection procedures were employed such that rats were tested immediately after i.p. injection or 5 min after i.p. injection of 5 nmol/kg body wt of GRP. Results indicate that GRP does reduce the oral reinforcing properties of sucrose, but the effect is transient, diminishing significantly within 5 min after injection.     

Stress-induced blocking of cell division in the colchicine arrest technique

Previous studies have shown that procedures commonly used in studies of cell population kinetics in laboratory animals cause a transient block of the entrance of cells into mitosis. The purpose of the present study was, therefore, to examine whether the handling of animals in conjunction with the administration of colchicine affects the results obtained by the metaphase arrest technique. Groups of rats were injected with colchicine or saline at 1300 h and sacrificed at regular intervals during the following 140 min. Histological sections of the palatal mucosa were produced and the number of metaphases was assessed in the epithelium. In both the saline-treated and colchicine-treated groups the numbers of metaphases decreased immediately after injection and reached a minimum within 30 min. After that time a transient increase was observed in the saline group, whereas the number of metaphases in the colchicine-treated group increased continuously during the experimental period. These results indicate that colchicine takes effect after a delay period of 30 min and that the handling procedures in conjunction with the administration of colchicine provoke a transient block of the entry of cells into mitosis. The second part of the study was designed in such a way that the number of metaphases collected during a 2 h period under the influence of stress induced by injection of colchicine could be compared with the number of metaphases collected during the same time period without the influence of stress.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microparticle-Induced Coagulation Relates to Coronary Artery Atherosclerosis in Severe Aortic Valve Stenosis

Background

Circulating microparticles (MPs) derived from endothelial cells and blood cells bear procoagulant activity and promote thrombin generation. Thrombin exerts proinflammatory effects mediating the progression of atherosclerosis. Aortic valve stenosis may represent an atherosclerosis-like process involving both the aortic valve and the vascular system. The aim of this study was to investigate whether MP-induced thrombin generation is related to coronary atherosclerosis and aortic valve calcification.

Methods

In a cross-sectional study of 55 patients with severe aortic valve stenosis, we assessed the coronary calcification score (CAC) as indicator of total coronary atherosclerosis burden, and aortic valve calcification (AVC) by computed tomography. Thrombin-antithrombin complex (TATc) levels were measured as a marker for thrombin formation. Circulating MPs were characterized by flow cytometry according to the expression of established surface antigens and by measuring MP-induced thrombin generation.

Results

Patients with CAC score below the median were classified as patients with low CAC, patients with CAC Score above the median as high CAC. In patients with high CAC compared to patients with low CAC we detected higher levels of TATc, platelet-derived MPs (PMPs), endothelial-derived MPs (EMPs) and MP-induced thrombin generation. Increased level of PMPs and MP-induced thrombin generation were independent predictors for the severity of CAC. In contrast, AVC Score did not differ between patients with high and low CAC and did neither correlate with MPs levels nor with MP-induced thrombin generation.

Conclusion

In patients with severe aortic valve stenosis MP-induced thrombin generation was independently associated with the severity of CAC but not AVC indicating different pathomechanisms involved in coronary artery and aortic valve calcification.