Dimethylarginines and serotonin in the blood of spontaneously hypertensive rats.

The serotoninergic system and nitric oxide system were studied in spontaneously hypertensive rats SHR and Wistar rats (control). The contents of serotonin, 5-hydroxyindoleacetic acid (serotonin metabolite), L-arginine, monomethylarginine, and asymmetric and symmetric dimethylarginines were measured in blood plasma. Serotonin content in hypertensive animals was much higher than in Wistar rats. No interstrain differences were found in the concentration of 5-hydroxyindoleacetic acid. The concentration of asymmetric dimethylarginine in SHR rats was higher than in Wistar rats. However, the concentration of monomethylarginine in SHR rats was lower than in Wistar rats. Our results and published data on the serotoninergic system indicate that SHR rats serve as a convenient model of hypertension.

Hypothalamic monoamines in cold stress on the background of changes in the activity of the nitric oxide system.

The effects of the NO donor sodium nitroprusside and the NO synthase blocker L-omega-N-nitroarginine (LNA) on body temperature, hypothalamic monoamines, and plasma corticosterone in conditions of cooling were studied in Male Wistar rats. Reductions in body temperature on cooling, both after administration of sodium nitroprusside and LNA, were no different from those seen without treatment. The basal corticosterone level after treatment with sodium nitroprusside increased from 5.3 +/- 2.2 to 29.1 +/- 1.8 microg%. Cooling led to a multiple increase in corticosterone levels in all animals, both in control conditions and after treatment with sodium nitroprusside and LNA. Sodium nitroprusside significantly decreased the basal hypothalamic noradrenaline level, by 37%. Cooling of the animals in these conditions led to an additional drop in the noradrenaline level. Noradrenaline levels 48 h after cold stress applied to animals cooled after treatment with LNA or sodium nitroprusside were significantly higher than in those cooled without treatment. No changes in serotonin and 5-hydroxyindoleacetic acid levels were seen in these experiments. The basal dihydroxyphenylacetic acid and dopamine levels increased after treatment with sodium nitroprusside, by 379% and 239% respectively. No dopamine response to cold was observed, though the dihydroxyphenylacetic acid level in the control group and animals treated with LNA increased. Thus, cold stress did not reveal differently directed directions for the actions of the NO donor and the NO synthase blocker, as seen with other types of stress.

[Hypothalamic monoamines in the cold stress during changes in activity of nitric oxide system]. / Monoaminy gipotalamusa pri kholodovom stresse na fone izmenenii aktivnosti sistemy oksida azota.

Effects of NO-synthase inhibitor N(omega)-nitro-L-arginine (LNA) and donor sodium nitroprusside (SNP) on alteration in body temperature, plasma corticosterone level and hypothalamic monoamines in response to cold exposure, were studied. Drop of the body temperature in cold exposure in rats treated with LNA or SNP was the same as in the control group. Administration of SNP (2 mg/kg i.p.) significantly increased the basal level of corticosterone (CS). Cold exposure elevated CS in all groups of rats. LNA did not markedly alter the hypothalamic noradrenaline (NA) while SNP significantly decreased the NA. Cold exposure resulted in additional decrease of the NA in SNP-treated rats. NA was found to significantly increase within 48 hrs following the cold exposure in the LNA as well as in the SNP groups. SNP significantly increased basal dopamine and DOPAC levels. Cold exposure did not affect hypothalamic dopamine. In the experiments, NO changes of serotonin and 5-hydroxyindoleacetic acid were observed. The findings suggest that antagonistic effects of the NO-synthase inhibitor and NO donor postulated in literature for various kinds of stress do not occur in experiments with cold stress.

[Effect of haloperidol on transmembrane potential and viscosity of thymocyte membrane lipids]. / Vliianie galoperidola na transmembrannyi potentsial i viazkost' lipidov membran timotsitov.

A damaging effect of the neuroleptic haloperidol on thymocytes was studied in vivo. The integral state of energetic processes in the cells was described by the electric transmembrane potential of thymocytes delta psi equal to the sum of potential on the plasmic and mitochondrial membranes. The effect of haloperidol was also evaluated by the content of lipid peroxidation (LPO) products and by the structural and functional characteristics of thymocyte membranes (lipid viscosity, protein-lipid interaction). A single administration of haloperidol (0.4 mg/kg) decreased the delta psi of thymocytes and increases the viscosity of lipids in the cell membranes. The content of LPO products--primary (diene conjugates) and secondary (Schiff bases)--was not affected. The obtained results indicate that the combination of methods employed can be used for analysis of the structural and functional characteristics of blood cell membranes (in leukocytes and lymphocytes) for evaluating the side effects of haloperidol in the human organism.

[Influence of stress and stress-protecting factors on rat tolerance to cold and efficiency of rat adaptation to cold]. / Vliianie stressa i stress-protektivnykh faktorov na kholodovuiu ustoichivost' i éffektivnost' adaptatsii krys k kholodu.

The adaptive characteristics of the body, including the specific features of increased cold resistance upon repeated exposures to cold, are determined not only by the properties of thermogenic structures themselves, but largely depend on the contribution of the central mechanisms which control the processes of habituation and mobilization of functions. The experiments revealed an increase in cold resistance in rats after preexposure to cold. Immobilization stress prior to training cold significantly decreased rapid cold resistance in the animals, but increased the training effect of the first cooling. On the contrary, chlordiazepoxide increased cold resistance during the first cooling. Testing of the untreated animal showed no effect of training. No adaptive changes in cold resistance occurred in rats with impaired amygdaloid complex. Analyzing adrenal catecholamines revealed a significant elevation of dopamine concentrations in the rats exposed to cold. Hypothalamic catecholamines did not change with cold and serotonin in intact rats and 5-hydroxyindoleacetic acid in amygdalectomized rats substantially increased.