Sources of cortical,hypothalamic and spinal serotonergic projections: Topical organization in the dorsal raphe nucleus

A study was made of retrograde axon transport of luminescent stains (primulin, fluoro-gold, fast blue, and nuclear yellow) from the spinal cord, the frontal cortex and lateral hypothalamus to various neuron groups of the periventricular gray matter of the midbrain and the dorsal tegmentum of the pons Varolii. Two large groups of serotonergic neurons are localized in the dorsomedial area of the dorsal raphe nucleus where projections to the thoracic segments of the spinal cord originate. Some of these neurons form divergent axon collaterals to the frontal cortex. Our data indicate that the antinociceptive effect of stimulating the "purely analgesic zone" of the midbrain periventricular gray matter may be due to direct involvement of the dorsal raphe nucleus in the descending control of impulsation induced by nociceptive stimulation at the spinal cord level. The neurotransmitter and neuromodulator role of separate cortical and hypothalamic projections of serotonin-containing neurons in the dorsal raphe nucleus is discussed.A. M. Gorky Medical Institute, Donetsk. A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 1, pp. 87–96, January–February, 1992.     

Mechanisms of regulation of intracellular distribution of Ca2+ in adipose tissue

The kinetics of influx and efflux of 45Ca and its accumulation by the subcellular membranes of adipose tissue have been studied. The initial rate of Ca2+ efflux does not depend on the intracellular concentration of Na+ and K+. The rate of exchange between intracellular 45Ca and 40Ca of the incubation medium is independent on concentration of Na+ and K+ in the incubation mixture. This suggests the absence of Na,Ca-transmembrane exchange in the adipocytes. The changes in the ratio of intracellular concentration of Na+ and K+ by the factors inhibiting the activity ofNa,K-ATPase cause redistribution of Ca in the intracellular pools of the adipocytes. The lypolytic agents (adrenalin, adrenocorticotropic hormone, caffeine) but not dibutytyl-3' : 5'-AMP, accelerate Ca2+ efflux from the adipocytes. At physiological concentrations of ATP, succinate and Pi the highest Ca-accumulating activity is observed in adipose tissue mitochondria. The highest initial rate of Ca uptake, as in the case of contractile tissues, is detected in the endoplasmic reticulum membranes. In contrast to the plasma membranes and reticulum, in which the Ca-accumulating capacity is independent of ATP concentration up to 0.5 mM, the Ca-accumulating capacity of mitochondria decreases 8--9-fold with a reduction in ATP concentration from 4 down to 1 mM. The physiological significance of this phenomenon in the action mechanism of lipolytic agents, which reduce the ATP content in the adipocytes, is discussed.     

Transmembrane potential and electrogenicity of thrombocyte Na, K-ATPase in different forms of hypertension in rats

The fluorescent dye 3,3'-dipropylthiadicarbocyanine iodide, dis-C3-(5), was used to study the membrane potential of platelets in rats with renal, DOCA-induced and spontaneous hypertension. The magnitude of the transmembrane potential in platelets combines the activity of electrogenic Na, K-ATPase and the rate of ion diffusion across the plasma membrane. The basal potential is 12 = 14 mB as lowered only in spontaneously hypertensive rats. The decrease of the basal potential is made for electrogenicity of platelet Na, K-ATPase in spontaneously hypertensive rats.     

Utilization of hemoglobin by the plague microbe

Hemin and hemoglobin are found to be adequate sources of iron for growth of Yersinia pestis. The mechanism of their assimilation is similar and consists of absorbtion of the free intact hem molecule.     

Differences in certain immunological indices among persons who have had cholera and among Vibrio carriers]

Blood sera of persons, who sustained cholera of different degree of severity, and of vibrio-carriers, and also chromatographic fractions obtained in separation of the mentioned sera on DEAE-cellulose were investigated in the reaction of agglutination and the indirect hemagglutination test. Immunological response in the vibrio carriers was realized by the microglobulin, and in the convalescents--by the macroglobulin type. There was also revealed an association between the severity of the course of cholera and the prevalence in the blood serum of one or another type of specific antibodies: in severe forms of the disease the antibodies of the IgM-class were detected with the greatest frequency, and microglobulin antibodies--in vibrio carriers. The detected differences in the immunological status of those who sustained cholera and of vibrio-carriers could be used as an additional differential sign in the diagnosis of the mentioned conditions.     

Distribution of lymphocytes according to the cell cycle phases in T, B, D and O populations in human blood and the immune system organs of animals vaccinated against cholera

The work presents the results of the study (carried out by the method of continuous flow cytofluorometry) of changes in the distribution of lymphocytes and their populations (obtained by means of distributing cell electrophoresis) according to the phases of the cell cycle (G0 + G1; S; G2 + M) in the blood and spleen of guinea pigs, as well as in the blood of humans, before and after immunization with cholera vaccine. The results of the determination of DNA-synthesizing lymphocytes in the blood of immunized humans and animals have been shown to serve as an objective characteristic for the complex evaluation of the biological activity of cholera vaccines.     

Limited proteolysis of prolactin in secretory granules from the pituitary gland of estrogenized rats

The LTH-converting proteolytic activity in LTH granules isolated from estrogenized rat hypophysis was studied. Suspensions of granules were incubated at different values of pH for 4 hours at 37 degrees C. The reaction was controlled by SDS electrophoresis. Intensive proteolysis of LTH was observed at pH 6.0 and 3.9, which was accompanied by the formation of fragments with Mr 10, 12 and 17 kD and probably of smaller peptides. An inhibitory analysis revealed that the formation of the 17 kD fragment at pH 3.9 was partly and selectively inhibited by chloroquine, phenanthroline and phenylmethylsulfonyl fluoride. Pepstatin A fully inhibited the proteolysis, whereas leupeptin had no inhibiting influence. The data obtained testify to the presence in the granular fraction of the endopeptidase LTH-converting activity which is sensitive to pepstatin A, an aspartyl proteinase inhibitor as well as to chelators and a serine proteinase inhibitor.