The effects of brain monoamine depletion on p-chlorophenyl-alanine-induced hypothermia

Summary I.p. administration of p-chlorophenylalanine produced a fall in rectal temperature in rats. The hypothermia was attenuated after pretreatment of the animals with 5,6-dihydroxytryptamine, but was unaffected after pretreatment of the animals with 6-hydroxydopamine.This work was supported by grants from the National Science Council (Republic of China) and J. Aron Charitable Foundation (USA). The authors are grateful to Dr C.Y. Chai, Dr T.H. Yin, Dr H.H. Lu and Mr C.C. Wei for their advice and support.     

Demonstration of a tryptaminergic mechanism in the rat beta-cell.

Yellow 5-HT fluorescence has been histochemically demonstrated in rat pancreatic islet cells in animals injected with L-5-HTP with or without pretreatment with the monoaminoxidase inhibitor nialamide. This fluorescence was not observed after inhibition of the aromatic amino acid decarobxylase. The results strongly suggest the presence of a tryptaminergic mechanism in the rat islet cells.     

Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.     

Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.     

Numalnarkose und anti-inflammatorische Wirkung von Phenylbutazon

Summary Following pretreatment of rats by thyroid extract or thyroxin, the anti-inflammatory action of phenylbutazone on formalin edema of the rat paw was strongly diminished by simultaneous numal anaesthesia of the animals.      

Re-examination of Rattus norvegicus as an animal model for Aeromonas-associated enteritis in man

We have developed an oral feeding model for Aeromonas hydrophila enteritis using Rattus norvegicus with clindamycin pretreatment. All animals in the clindamycin group developed a self-limited, loose stool by day four of feeding. Intestinal examination revealed evidence of enteritis. Moreover, antibiotic usage may be a predisposing risk factor to infection.     

Does increased gastric mucus play a role in the ulcer-protecting effects of zinc sulphate?

Zinc sulphate pretreatment i.p. produces dose-related reductions in stess ulcer incidence in pylorus-occluded rats. The associated increases in gastric wall mucus, in stressed and nonstressed animals, suggest that a similar effect may contribute to its ulcer-reducing ability in man.     

Does increased gastric mucus play a role in the ulcer-protecting effects of zinc sulphate?

Summary Zinc sulphate pretreatment i.p. produces dose-related reductions in stress ulcer incidence in pylorus-occluded rats. The associated increases in gastric wall mucus, in stressed and nonstressed animals, suggest that a similar effect may contribute to its ulcer-reducing ability in man.     

Effects of dosage and cadmium pretreatment on the binding of cadmium in rat bile.

The effects of dosage and of cadmium pretreatment on the binding of cadmium in rat bile were studied. With increasing dose a higher cumulative biliary excretion of Cd was observed and a higher percentage of the Cd was excreted in a low-molecular-weight form. On the other hand, after cadmium pretreatment, a decrease in the cumulative biliary excretion of cadmium was observed but a greater percentage of that excreted into the bile was bound to high molecular weight compounds.     

Covalent binding of aflatoxin B1 to liver DNA in rats pretreated with ethanol

Male Fischer F-344 rats were given ethanol in the drinking water and/or by single oral administration. Following this, the animals received p.o. 100 ng/kg of the hepatocarcinogen [3H]aflatoxin B1 (AFB1). 24 h later, the level of DNA-bound AFB1 was determined in the liver and was found not to be affected by any type of ethanol pretreatment. A cocarcinogenic effect of ethanol in the liver is therefore unlikely to be due to an effect on the metabolic activation inactivation processes governing the formation of DNA-binding AFB1 metabolites.     

Effects of dosage and cadmium pretreatment on the binding of cadmium in rat bile

Summary The effects of dosage and of cadmium pretreatment on the binding of cadmium in rat bile were studied. With increasing dose a higher cumulative biliary excretion of Cd was observed and a higher percentage of the Cd was excreted in a low-molecular-weight form. On the other hand, after cadmium pretreatment, a decrease in the cumulative biliary excretion of cadmium was observed but a greater percentage of that excreted into the bile was bound to high molecular weight compounds.     

Radioprotective effect of a protein free parathyroid extract on the mitotic index of rat bone marrow cells.

The protective efficacy of an orally administered bovine protein-free parathyroid extract (PF-PTE) was studied on rat bone marrow cells in vivo with the mitotic index after 850 R irradiation. A remarkable decrease was found in the mitotic activity of bone marrow cells after irradiation in the non-protected animals. However, in the animals treated with PF-PTE after irradiation, a significantly smaller decrease and a faster recovery were found in the mitotic activity of the bone marrow cells.     

Radioprotective effect of a protein free parathyroid extract on the mitotic index of rat bone marrow cells

Summary The protective efficacy of an orally administered bovine protein-free parathyroid extract (PF-PTE) was studied on rat bone marrow cells in vivo with the mitotic index after 850 R irradiation. A remarkable decrease was found in the mitotic activity of bone marrow cells after irradiation in the non-protected animals. However, in the animals treated with PF-PTE after irradiation, a significantly smaller decrease and a faster recovery were found in the mitotic activity of the bone marrow cells.     

Prostaglandin E1-induced fever in rabbits pretreated with p-chlorophenylalanine.

The prostaglandin E1-induced fever was neither potentiated nor attenuated at all levels of the ambient temperatures (2, 22 and 32 degrees C) studied after pretreatment of the conscious rabbits with p-chlorophenylalanine, when compared to the untreated control.     

Histochemische Untersuchungen über den Einfluss von Iproniazid (Marsilid) auf die durch Reserpin erzeugte Freisetzung von Adrenalin und Noradrenalin aus dem Nebennierenmark

Summary A single injection of 10 mg/kg reserpine causes marked decrease of catecholamine in the medulla of the adrenal gland of rats. Histochemically, this can be shown by the disappearance of chromaffinity and of the potassium iodate reaction. After pretreatment with 100 mg/kg of iproniazid, reserpine injection induces little or no decrease in the histochemical reactions of adrenalin and noradrenalin. In animals pretreated with equimolar doses of isoniazid, however, histochemical catecholamine reactions are well preserved in all cells of the adrenal medulla. These results suggest that monoamine oxidase plays a part in the reserpine-induced release of catecholamine.     

Extraneuronal serotonin accumulation in peripheral arteries of the rat

Accumulations of serotonin (5-HT) and norepinephrine (NE) were compared in control and 6-hydroxydopamine (6-OHDA) pretreated rat aorta, mesenteric and tail arteries. The distribution of these amines was corrected by subtracting tissue uptake of tritiated sorbitol in the extracellular space. 5-HT greatly accumulated both in control and 6-OHDA pretreated arteries. In contrast, NE accumulation in mesenteric and tail arteries was substantially decreased after 6-OHDA treatment. In the aorta 6-OHDA pretreatment did not affect the accumulation of both amines. These findings suggest that 5-HT accumulation in these arteries is mainly extraneuronal, and NE mainly neuronal. Since the accumulation of 5-HT in the aorta was not influenced by pretreatment with 10 microM NE, the extraneuronal uptake mechanisms for 5-HT and NE appear to be different.     

Abnahme des Cytochroms P450 nach Inkubation mit CCl4 in einem NADPH-regenerierenden System und teilweise Umwandlung in Cytochrom P420

Summary Isolated damage of cytochrome P450 and partial conversion to cytochrome P420 appears after incubation of carbon tetrachloride with a NADPH-regenerating enzyme system and the microsomale fraction. This effect enlarges after phenobarbital pretreatment.     

Sympathectomy enhances the substance P-mediated breakdown of the blood-aqueous barrier in response to infrared irradiation of the rabbit iris

Rabbits were subjected to infrared irradiation of the iris 1 month after unilateral cervical sympathectomy. The resulting breakdown of the blood-aqueous barrier was greatly enhanced on the sympathectomized side. In contrast, the response to intravitreally injected substance P (SP) was the same in both eyes. The enhancement of the response to IR irradiation could be abolished by pretreatment with an SP antagonist, (D-Pro2, D-Trp7,9)-SP.