Dynamics of nociceptive sensitivity and blood levels of steroid hormones in Wistar rats

Changes in nociceptive sensitivity and the level of steroid hormones (corticosterone and testosterone) in the plasma of male Wistar rats were studied in repeatedly applied painful stimuli. According to the changes in nociceptive sensitivity the animals were divided into 6 groups. A reliable corticosterone increment and testosterone decrement in the plasma were caused by repeatedly applied painful stimuli. The data observed could be used as individual indices characteristic of animals of this strain.     

Seasonal characteristics of the circadian rhythm of peripheral blood leukocyte content in Wistar rats]

In Wistar rats, the seasonal variability of acrophase position, mesor value and circadian rhythm amplitudes of total leukocyte count, as well as of percentage and absolute lymphocyte count was revealed. The leukocyte count and absolute lymphocyte content were found highest in spring, while eosinophils--in autumn, neutrophils and monocytes--in winter.     

Quantitative characteristics of interactions of blood lipoproteins and steroid hormones]

Human and serum lipoproteins interaction with steroid hormones (corticosterone and hydrocortisone) were studied. Methods of fluorescence quenching titration and equilibrium dialysis were used for quantitative evaluation of VLDL, LDL and HDL glucocorticoids binding ability. Association constants were found to be 0.6-2.0 x 10 M for corticosterone and 4.0-8.0 x 10 M for hydrocortisone. The number of binding sites ranged from 3 to 300 for different classes of lipoproteins. Our data suggest high specificity of serum lipoproteins binding with corticosterone and hydrocortisone.     

Diurnal differences in opioid peptide levels correlated with nociceptive sensitivity

An increase in whole mouse brain total opioid levels, determined by mouse was deferens bioassay, was observed in mice sacrified in late afternoon (when they are least responsive to pain) compared to early morning (when they are most responsive to pain). There were no comparable increases in levels of met⁵- or leu⁵- enkephalin measured by RIA methodology. There were differences, however, in the effects of noxious stimuli on met⁵-enkephalin levels in the efternoon compared to the morning. In the afternoon, but not in the morning, the levels of met⁵-enkephalin in mice tested after hot plate stress were significantly increased compared to those of unstressed animals. Thus, there appears to be some correlation between activity in endogenous opioid systems and the ability of mice to withstand noxious stimuli.     

The effect of sex steroid hormones on interhemispheric asymmetry in rats]

The effect of gonadectomy and sex-steroid hormones treatment on functional interhemispheric asymmetry to the reaction of pain cry avoidance of another species (emotional reactions) and motor and exploratory activity of open-field behavior in Wistar rats of 3 months old has been investigated. A spreading depression technique for hemisphere inactivation has been used. The hemispheric asymmetry of the reactions in intact rats was characterized by sex dimorphism; the left hemisphere dominated to a great extent in males than in females under the control of emotional reactions; in motor and exploratory activity in open-field behavior of rats the left hemisphere dominated in males and the right one--in female. In both sexes the neonatal gonadectomy levelled the interhemispheric differences in reactions under investigation. The following treatment of females with estradiol and males with testosterone didn't restore the asymmetry. After the castration at the age of 3 months the correlation between the size and direction of interhemispheric differences became reverse. The treatment of females with testosterone and males with estradiol both castrated in adulthood restored the interhemispheric asymmetry in males and had no effect in females. The treatment of intact rats with hormones of opposite sex led to the enhancement of left hemisphere dominance in motor and exploratory activity in males and levelled the asymmetry in females. It has been shown that in adult rats sex-steroids effect predominantly the right hemisphere.     

Interaction of lipoproteins in blood serum with steroid hormones

Interaction of human and serum lipoproteins with steroid hormones (corticosterone and cortisol) was studied. Methods of fluorescence quenching titration and equilibrium dialysis were used for quantitative evaluation of VLDL, LDL and HDL glucocorticoid-binding ability. Association constants were found to be 0.6-2.0 x 10(6) M-1 for corticosterone and 4.0-8.0 x 10(6) M-1 for cortisol. The number of binding sites varied from 3 to 300 for different classes of lipoproteins.     

Interaction of steroid hormones with glutamate dehydrogenase]

The inhibitory action of sex hormones on the glutamate dehydrogenase activity is due to their binding to the enzyme protein. No binding of sex hormones to glutamate dehydrogenase is observed in the presence of L-amino acids, preventing the enzyme dissociation. Under those conditions the enzyme sensitivity to the inhibitory action of the hormones sharply decreases.     

The cyclic nucleotide content of the blood plasma in rabbits administered izadrin]

The influence of cyclic nucleotides system on the rabbit resistance to injection of exogenic sympathomimetic was studied in this experiment. Absolute concentration value and ratio of cAMP to cGMP in animals with different resistance were determined.     

Humoral factors of the spleen in the regulation of the calcium content in blood plasma of rats]

Introduction of protein-free peptides-enriched spleen extract increases the calcium content in blood plasma of rats. After the effect of stress factor (long swimming) it falls. The value of the index under study increases in the splenectomized rats and remains unchanged after stress and introduction of the spleen factors. The most pronounced increase of the calcium concentration is observed in the case of experimental hypersplenism induced by methylcellulose introduction. The calcium-regulating effects of introduction of the enriched protein-free spleen extract and pharmacopoeial splenin preparation are compared. It is supposed that spleen contains two humoral factors of different chemical nature which are able to influence somewhat differently the calcium content in blood plasma.     

The morphochemical characteristics of the brain in Wistar rats that differ by open-field motor activity]

By cytochemical and biochemical methods it is established that in rats with low motor activity the increased content of proteins of cytoplasma and nuclei of neurones of the sensorimotor cortex, caudate nucleus and n. accumbens, the increased activity of a number enzymes of oxidizing and protein metabolism in them are combined with a low activity of enzymes of mediator exchange. In the studied formations in rats with high motor activity an increased activity of synaptic and membrane forms of acetylcholinesterase appears at the same level of activity of cholineacetyltransferase in these subcortical formations and at high monoamineoxidase activity in cellular structures of the cortex and in subcortical formations. It is shown that in animals of the same line but differing by the behaviour in the open field, brain formations such as the sensorimotor cortex, caudate nucleus and n. accumbens have their own biochemical properties of the studied characteristics.     

Individual characteristics of the nociceptive sensitivity of rats during the formation of a negative emotional reaction

Changes in dynamics of nociceptive sensitivity in male rats of Wistar strain were studied during formation of negative emotional reaction. The procedure of blood's taking from the tail after its tip's amputation was used as negative emotional factor. The animals were divided into six groups by the criterion of individual properties of nociceptive sensitivity dynamics. On the whole it was found to decrease. Besides, one more group (the seventh group) was found with profound hypoalgesia caused by action of the negative emotional factor. It was also shown that formation of negative emotional reaction in two groups was not accompanied by changes of nociception. The data suggest a selective influence of negative emotional factor on nociceptive sensitivity.     

The cyclic nucleotide content of the blood plasma in mice irradiated at different doses]

Cyclic nucleotide content of plasma was shown to increase after irradiation of mice within a wide range of doses. Compared was the dynamics of changes in the cyclic nucleotide content 24 hr following irradiation with supralethal doses.     

Effects of steroid hormones and xenobiotics on the pubertal development of UDP-glucuronosyltransferase activities towards androsterone and 4-nitrophenol in Wistar rats.

Oestradiol benzoate, testosterone propionate, progesterone, corticosterone, 3-methylcholanthrene and phenobarbital were administered to Wistar rats at the pubertal period, and their effects on hepatic UDP-glucuronosyltransferase activities were determined. Pretreatment with oestradiol benzoate had a temporary suppressive effect on androsterone UDP-glucuronosyltransferase activity in rats with the high-activity phenotype of androsterone glucuronidation. The effect was marked in 40-day-old rats, but was not found in older rats. Androsterone UDP-glucuronosyltransferase activity was induced by phenobarbital in rats with the high-activity phenotype, but not in rats with the low-activity phenotype. Foster-feeding experiments showed that breast milk did not alter the genetically determined expression of androsterone UDP-glucuronosyltransferase activity in Wistar rats. In contrast, 4-nitrophenol UDP-glucuronosyltransferase activity was not affected by steroid hormones, but was highly induced by 3-methylcholanthrene.