Effect of lamotrigin on the development of neurogenic pain syndrome in rats

Analgesic activity of a new anticonvulsive agent lamotrigin was studied on the model of neurogenic pain syndrome produced in rats by penicillin applied to the dorsal surface of the spinal cord and by dissection of the sciatic nerve. Lamotrigin was shown to have a profound analgesic activity. It can be used as an efficient prophylactic agent for prevention of chronic pain syndromes by suppression of the generators of pathologically enhanced excitation in the nociceptive structures which are the pathophysiological basis of the chronic pain syndromes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 5, pp. 517–521, January, 1998.     

Morphological study of some hypothalamic centers in rats after deafferentation of the mediobasal hypothalamus

The volume of the nuclei and nucleoli of certain hypothalamic centers (SON, PVN, SCN, AN, VMN) was determined in control rats and in rats after deafferentation of the mediobasal hypothalamus. Sex differences were found in the parvocellular formations of the control animals: The volumes of nuclei and nucleoli of neurons of AN and VMN, and also of the nucleolus of SCN neurons were larger in females than in males. After deafferentation of the mediobasal hypothalamus the volume of the cell nuclei was increased, especially in hypothalamic formations located outside the isolated zone. This increase was more clearly defined in rats constantly in a state of estrus after the operation. Statistically significant differences between volumes of both nuclei and nucleoli of the cells in subgroups of rats with permanent estrus and with permanent diestrus were found only in the case of SCN. No such differences were found for AN, despite the considerable difference in the constant of luteinizing hormone in the pituitary of the same rats. It is suggested that gonadotropin releasing factors are not produced by the cells of AN and that control over the succession of phases of the sex cycle may be exerted by SCN.Laboratory of Neuroendocrinology, I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 3, pp. 352–354, March, 1980.     

Study on streptococcus group A antigens common with heart tissue elements

Four different cross-reactive antigens were revealed in cultures of group A streptococci by immunoelectrophoresis using antistreptococcal sera unabsorbed, or absorbed with homogenates of rabbit heart tissue. Preliminary study of these sera by immunofluorescence showed that they react with different elements of the myocardium.

The hypothesis is suggested that the biological (immunizing) action of microbial cross-reactive antigens depends on the presence or absence of immunological tolerance to these antigens in the individual immunized. The mechanism of autoantibody formation by immunization with such common antigens is discussed.

     

Different pathways of neurohormonal hypothalamic control of the adrenal cortex function in young and old rats

The pathways of hypothalamic control of the adrenal cortex function were studied in the experiments on young and old male Wistar rats. Immunohistochemical, morphometric, densitometric and radioimmunoassay methods were used. It was shown that in young rats under stress vasopressin (VP) is released into the portal circulation and probably in this way stimulates ACTH and enhances secretion of corticosterone in the adrenal cortex. In old rats stress-reaction is delayed and less adequate compared to young animals. It seems likely that in old rats VP is secreted into the general circulation mainly via the posterior pituitary lobe (PP), exerting a direct influence on the adrenal cortex. The conclusion is made that in old rats regulation of the adrenal cortex function is realised via the pathway phylogenetically more ancient than in young animals.     

Generators of pathologically enhanced excitation as determinant structures in the spinal cord

With the aid of tetanus toxin, which disturbs various types of inhibition, generators of excitation were created in the left and right anterior horns of the lumbar spinal cord in rats. The regimes of activity of the generators differed: the left-sided generator, formed during the longer action of the toxin, in response to activation by trigger stimulation first produced tonic, and then intermittent activity, or individual spontaneous discharges, whereas the righ-sided generator produced only tonic activity. If one generator was blocked by glycine, the other continued to operate as before. Activation of one generator led to concomitant depression of the effects of the other. During separate activation of each generator, all the spinal and supraspinal motoneuron pools synchronously reproduced the character of activity of the generator functioning at that particular moment. The generator thus played the role of a determinant structure, determining the behavior of the system. The results are examined from the standpoint of the general concept of the role of determinant structures in the activity of the nervous system and the theory of generator mechanisms of neuropathological syndromes characterized by hyperactivity of systems.Laboratory of General Pathology of the Nervous System, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 515–519, May, 1977.