Functional changes in neurosecretory cells of the anterior hypothalamic nuclei after stimulation of the midbrain reticular formation

The functional activity of the neurosecretory cells in the supraoptic and paraventricular nuclei was studied in male Wistar albino rats at various intervals after electric stimulation of the midbrain reticular formation. These studies showed that such stimulation elicits higher functional activity of the neurosecretory cells in the anterior hypothalamic nuclei, characterized by increased secretory synthesis by these cells and rapid transport of the neurosecretion. These changes were most pronounced 1 h after stimulation of the reticular formation. The changes observed were unidirectional in both neurosecretory centers, but their manifestation was different: in the supraoptic nucleus the reaction was more intense but short lived, in the paraventricular it was less intense but lasted longer.A. A. Bogomolets Institute of Physiology, Academy of Sciences, Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 3, No. 4, pp. 394–400, July–August, 1971.     

Parallel analysis of c-Fos protein and interleukin-2 expression in hypothalamic cells under different influence

The objective of this work was to perform a parallel analysis of activation of the rat anterior hypothalamus cells as judged by c-Fos protein expression, and of the expression of interleukin-2 (IL-2) under different influences, i. e., mild stress (handling) and adaptation to it, and intranasal administration of saline and the peptides Vilon (Lys-Glu) and Epithalon (Ala-Glu-Asp-Gly). Changes in the counts of cells positive for c-Fos- and IL-2 proteins were studied in structures of the lateral (LHA) area, anterior (AHN), supraoptic (SO) and paraventricular (PVH) nuclei of Wistar rat hypothalamus. Quantity of the interleukin-2-positive and c-Fos-positive cells was calculated. The findings were: a negative correlation between the activation of cells and the amount of IL-2 in the cells in the hypothalamic structures under study, and the specific patterns of changes in the counts of cells positive for c-Fos and IL-2 under stress and adaptation to stress.     

Serum protein changes in brown trout (Salmo trutta L.) after single injections of soluble and cellular antigens

Brown trout sera were examined by cellulose acetate (CAE) and polyacrylamide electrophoresis (PAE) and the protein concentrations measured by the Lowry method, before and after stimulation with haemocyanin, horse serum, Salmonella typhi 'H' and human group 'O' erythrocytes. Uninjected fish contained 5.l1±0.71 g protein/100 ml. Protein concentration was unaffected by haemocyanin and horse serum but was significantly lowered by S. typhi and human group 'O' erythrocytes. Male and female fish gave similar responses. Uninjected and injected fish showed 8 components on CAE and 16 on PAE. Significant differences were found between injected and uninjected control fish and between antigen stimulated and uninjected controls.     

Tyrosine hydroxylase activation upon electric stimulation of isolated hypothalamic nerve endings in rats]

The effect of electrical stimulation on the membrane-bound tyrosine hydroxylasectivity of the rat hypothalamus synaptosomes was studied. The electrical stimulation caused an elevation of O2 consumption and the elevation of glycolysis indicating synaptosome excitation. The membrane-bound tyrosine hydroxylase activity increased under these conditions. The KM value for tyrosine decreased from 0.091 to 0.026 mM. Noradrenaline inhibition of the enzymatic activity diminished. It is assumed that the effect of depolarization on the catecholamine synthesis velocity in the nerve endings involves tyrosine hydroxylase modification.     

Responses of pyramidal tract and corticorubral neurons to stimulation of lateral hypothalamic structures in cats

Responses of pyramidal tract neurons and corticorubral and unidentified neurons in the pericruciate area of the cortex to electrical stimulation in the posterior, tuberal, and anterior zones of the lateral hypothalamus and also to electrodermal stimulation of all four limbs were studied in cats anesthetized with chloralose. The proportion of pyramidal tract, corticorubral, and unidentified neurons which responded to hypothalamic stimulation was 73.3, 55.7, and 79.1% respectively. Data on the possibility of monosynaptic activation of some pyramidal tract neurons and unidentified cells were obtained. The presence of less stable and longer-latency responses of corticorubral neurons indicated the absence of a monosynaptic pathway for realization of ascending hypothalamic influences on neurons of the cortical extrapyramidal system. Some cortical neurons responded to stimulation of more than one zone of the hypothalamus. Pyramidal tract neurons and corticorubral neurons with axon collaterals running into the region of the hypothalamus were discovered for the first time. It was shown that most neurons of the pericruciate area of the cortex to which the ascending influence of the hypothalamus is directed have a large bilateral receptive field and respond to electrodermal stimulation of several limbs.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 14, No. 3, pp. 298–306, May–June, 1982.     

Repair of the protein structures of ciliated epithelial cells after heat damage

A study has been made of the ability of ciliated pharengial cells of Rana temporaria L. to repair heat injury. The heat injury estimated by cessation of cellular motile activity has been shown to repair, ciliar movements being renewed. The reparation of the ciliar function is due to the restoration of nativity of the intracellular protein structures providing for the ciliar motility. These structures can be repaired only when they are a component of the whole living cell system; they are not capable of spontaneous renativation, however, when isolated as "glycerinized cell models". It is suggested that the reparation of heat injury in these cells is an active process, presumably dependent on the intracellular metabolism.     

Role of dominant motivation in producing the effects of electric stimulation of hypothalamo-limbic structures

The experiments were made on cats with electrodes chronically implanted in the hypothalamus and the amygdala. The effects of electrical stimulation of the points from which the food reactions were initially evoked, were transformed into an avoidance reaction, if stimulation was applied in surroundings where the animals had previously received pain stimuli. Defensive reactions to stimulation of the hypothalamus and amygdala changed to alimentary reactions if the same stimulation was presented to hungry cats in conditions of repetitive feeding. A conclusion has been drawn that the elements of the hypothalamo-limbic structures have plastic properties and may be involved in different forms of behaviour, depending on current motivation and learning.     

Neuronal reactions of the olfactory centers of the forebrain during stimulation of the hypothalamic structures in rabbits]

During stimulation of phylogenetically ancient parts of the hypothalamus (the anterior and lateral), neuronal reactions have been recorded in the prepyriform lobe and tuberculum olfactorium. These reactions are characterized by a short latent period (6-25 msec) and high stability to rhythmic stimulation. Neuronal reactions in the same olfactory centers during stimulation of phylogenetically more recent hypothalamic structures (the posterior and medial) exhibit a long latent period (30-120 msec) and are readily exhausted by rhythmic stimulation.     

Modifications of neuronal activity in the rat hypothalamic supraoptic nucleus after long-lasting vibrational stimulation

We analyzed the background impulse activity (BIA) generated by neurons of the rat hypothalamic supraoptic nucleus in the norm and under conditions of long-lasting vibrational stimulation (exposure 5, 10, or 15 days). Distributions of neurons by the level of regularity, dynamics of discharge trains, form of histograms of interspike intervals (ISIs), as well as distributions of neurons by the BIA frequency ranges, were studied. We also calculated the mean frequency of impulsation of the neurons under study and the coefficient of variation of ISIs. After vibrational influences, we found modifications of both the internal structure of the recorded spike trains and the mean frequency of impulsation within the entire studied group and different frequency subgroups. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 224–230, May–June, 2006.     

Changes in the LHRH-immunoreactivity of hypothalamic structures during late pregnancy and after parturition in the guinea pig

Summary LHRH-immunohistochemistry and radioimmunoassay of the gonadotropins were used to demonstrate changes in the LHRH content of the hypothalamus during late pregnancy and after parturition in the guinea pig. Immediately after parturition a decrease in the amount of LHRH-associated fluorescence was observed in the medial preoptic area. Only 12 h later similar changes were found in the median eminence. In the precommissural region no obvious changes were noted in the quantity of LHRH-immunoreactive terminals and synapses. The radioimmunoassay of the gonadotropins shows an increase of LH shortly after parturition which reaches the level of a preovulatory rise, whereas the amount of FSH does not vary significantly. The role of the medial preoptic area and the OVLT in the regulation of the estrous cycle through LHRH is discussed.This work was performed under a postdoctoral fellowship at the INSERM unité 156, Lab. d'Histologie, Faculté de Médecine, Lille, France