Rat hippocampus and primary immune response.

During immune challenge hippocampal region shows time-dependent changes in neurotransmitter levels. Hence in the present study the effect of electrolytic lesion in the dorsolateral hippocampus (DLH) and ventral hippocampal formation (VHF) (to create a disturbance in neurotransmitter levels) on humoral immunity in albino rats has been studied along with appropriate controls. Haemagglutination titre, IgM and IgG levels were monitored on the 5th day after an immune challenge by sheep red blood cells (SRBC) suspension. Antigen challenged lesioned animals had low circulating antibody titre levels compared with the controls and their site-specific sham lesioned groups. The IgM levels were significantly lowered in both DLH and VHF lesioned and immunized animals compared to their immunized sham groups as well as immunized controls. However, only immunized VHF lesioned group showed a significant decrease in IgG level from their immunized sham group. It was concluded from the results that an intact hippocampal region is essential for the normal humoral immunity for the primary immune response in rats. Probably VHF region may be required for the secondary immune response as indicated by the alteration in IgG levels in these animals.

Effect of acute noise stress on acetylcholinesterase activity in discrete areas of rat brain.

Effect of various stressor agents on the adrenergic system in brain had been studied extensively. However, reports on the effect of stress on various parameters of central cholinergic system are scanty. And very little is known about the effect of noise stress on the cholinergic system in brain. Hence, it was decided to elucidate the effect of acute noise stress on the activity of the enzyme acetylcholinesterase in discrete areas of brain in albino rats. Male albino rats of Wistar strain were subjected to acute noise stress for 30 minutes. The noise of pure sine wave tone was produced by using a function generator and was amplified. The frequency of noise generated was 1 kHz and the intensity was set at 100 dB. The total acetylcholinesterase activity was determined in the tissues of cerebral cortex, corpus striatum, hypothalamus and hippocampus of brain in these rats. The enzyme activity was estimated by colorimetric method using acetylthiocholine iodide as the substrate. The values were compared with the enzyme activity in the control rats. The activity of the enzyme increased significantly in all the four regions of the brain in rats after exposure to noise stress for 30 minutes. The results of the study indicate that the exposure to acute noise stress could modulate the cholinergic system in these areas of brain in rat.

Free radical changes in methanol toxicity.

Role of free radicals in methanol toxicity was evaluated in methanol treated albino rats. Methanol intoxication increased lipid peroxidation and depleted the free radical scavenging enzyme systems. The free radical quenching effect of vitamin E protected the animals from methanol induced free radical damage.

Neuro-immunomodulation by dorsolateral hippocampus--role of macrophages,T and B cells.

In dorsolateral hippocampal lesioned, Sham and control animals, the total number of splenocytes was determined and macrophages, B cells and T cells were isolated and their percentage distribution in total splenocytes were determined. The leukocyte migration inhibition was studied in these groups using different fractions of splenocytes namely whole splenocytes, macrophage removed fraction, and nylon wool eluted T cell population. The same groups were also studied after an antigenic challenge. The results indicate alterations in the macrophages, adherent cell population as well as T cell population in lesioned and Sham animals and also in their immunized groups. These altered cell sub-populations may be responsible for the altered migration.

Acute noise-induced alterations in the immune status of albino rats.

The effect of acute noise induced changes on the immune functions of albino rats was studied. Cell mediated immunity was assessed by Leukocyte migration inhibition index (LMI) and humoral immunity by estimating antibody titre. The organ weight of spleen, thymus, adrenal and lymph node was noted, the cell count of spleen and thymus was enumerated and plasma corticosterone level was estimated. A significant increase in the plasma corticosterone level, thymus weight and cell count along with significant decrease in the antibody titre, spleen weight and cell count was observed in noise stressed animals. No significant changes were observed in the LMI and organ weight of adrenal and lymph node in these animals. Our study shows acute noise to be a potent stressor causing definite alterations in the immune functions of the albino rats.

The effect of acute noise stress on neutrophil functions.

The effect of acute noise stress on albino rats was studied by estimating the plasma corticosterone level, total leukocyte count and differential leukocyte count. Neutrophil function was assessed by Candida phagocytosis and Nitroblue tetrazolium reduction test. The total leukocyte count was significantly decreased. No significant changes were observed in the differential count of the leukocytes. A significant increase in the plasma corticosterone level, Candida phagocytosis and Nitroblue tetrazolium reduction was observed indicating acute noise to be a potent stressor in albino rats.

Effect of Ocimum sanctum Linn on noise induced changes in plasma corticosterone level.

Ethanol extract of leaves of ocimum sanctum was screened for its antistressor actions against acute and chronic noise stress in albino rats by investigating the plasma corticosterone level in these animals. There was a significant elevation of the corticosterone level in plasma of rats subjected to 30 min noise (100 dB) stress. Chromic exposure (4 hr daily for 30 days) to noise with same intensity reduced the hormonal level significantly. Treatment of animals with ethanol extract of Ocimum sanctum prevented the changes in plasma level of corticosterone induced by exposure to both acute and chronic noise stress, indicating the antistressor property of the plant against noise.

Regional specificity seen within hypothalamus in neuroimmunomodulation.

Wistar strain male albino rats lesioned and sham lesioned at Ventromedial hypothalamus (VMH) were used to study the neuroimmunomodulation by this brain region. Except the decrease in thymus weight/body weight ratio (P < 0.01), and its cellularity (P < 0.02) in immunized VMH lesion animals, the rest of the parameters like plaque forming cells (PFC), antibody titre, leukocyte migration inhibition index, foot pad thickness in the lesioned as well as the lesion immunized animals never deviated from their respective sham and immunized sham animals. Sham operated belongs to VMH when compared to control rats, showed marked decrease in spleen weight (P < 0.001), thymus weight (P < 0.02) and decrease in popliteal lymph node weight (P < 0.001) ratios. After immunization, the immunized sham animals showed a marked decrease in antibody titre (P < 0.05), PFC (P < 0.05), spleen (P < 0.05) and thymus (P < 0.001) weight ratios with the significant increase in splenic cell count (P < 0.01) compared to immunized control rats. VMH may be one of the information receiving center. However, from these results, it is inferred that VMH could not be a modulating center for the many of the parameters studied as far as neuroimmunomodulation is concerned.

Peripheral immune response in albino rats following cerebroventricular and intraperitoneal antigen challenge.

Success in neural tissue transplants at central nervous system suggest that the site may be immunologically privileged. However, this experimental study in which an antigen (Sheep Red Blood Cells) was administered into the third ventricle does not support the above concept. The antibody titre and soluble immune complex levels seen in these animals are similar to the levels seen in animals immunized with the same amount of antigen through the intraperitoneal route. Intraventricular immunization is rather a more potent modulator in decreasing the total WBC count (P < 0.05) and neutrophils (P < 0.001). Further a marked increase in lymphocytes (P < 0.01) in peripheral blood was observed in these animals. Intraventricular immunization also increased the killing power (NBT reduction) of the neutrophils (P < 0.05).

Activated charcoal--an antidote to methyl alcohol poisoning.

Every year a considerable number of people die due to methly alcohol poisoning, in which most of them die even before they are given proper treatment. This report gives a simple and cheap first aid measure to those affected by methanol poisoning by the administration of activated charcoal. This study has shown that the mortality of methanol recipient rats have significantly reduced by the administration of activated charcoal.

Potassium channel blockade amplifies cardiac instability numerical studies of torsades de pointes.

Suppression of responses to premature stimulation has been the guiding principle in managing many cardiac arrhythmias. Recent clinical trails revealed that sodium channel blockade increased the incidence of re-entrant cardiac arrhythmias resulting in sudden cardiac death, although the physiologic mechanism remains uncertain. Potassium channel blockade offers an alternative mechanism for suppressing responses to premature stimuli. We have developed a simple model of a 2D sheet of excitable cells. We can initiate re-entrant activation with stimuli timed to occur within a period of vulnerability (VP). Reducing the Na conductance increases the VP while reducing the K conductance increases the collective instability of the array, and arrhythmias similar to torsades de pointes seen in patients subjected to K channel blocked can be readily initiated. Thus, while K channel blockade may suppress excitability by prolonging the action potential duration, it appears to simultaneously exhibit proarrhythmic properties that result in complex re-entrant arrhythmias.

Programme for drawing line graphs on IBM personal computers.

A simple program for drawing line graphs on IBM Personal Computers is described here. This program is written in Basic language and is user friendly. This program allows the operator to plot the line graphs with standard error of each of the observations. After plotting suitable legend can also be added at appropriate places in the graph. In the graphic mode a hard copy can be obtained from a dot matrix printer using print screen command.

Reticuloendothelial function in acute noise stress.

Wistar strain albino rats of either sex were subjected to acute noise stress (3000 Hz at > 97 dB) for 30 minutes. Carbon clearance test was conducted in noise stressed animals immediately after the stress period. Significant (P < 0.001) increase of the clearance constant K was observed in stressed animals compared to the controls, indicating increased phagocytic activity of the reticuloendothelial system.

Effect of acute heat stress on certain immunological parameters in albino rats.

The effect of acute heat stress on certain immunological parameters were studied in male albino rats. The test rats were exposed to an ambient temperature of 40 degrees celsius for 30 minutes and sacrificed immediately. Total WBC count, Differential count, Phagocytic index, NBT reduction, organ weight body weight ratio of spleen, thymus, and popliteal lymph nodes, and soluble immune complex levels were measured in control group and the heat stressed animals. The heat stressed animals show decrease in total WBC count, and neutrophilia, eosinophilia, and lymphocytopenia. The phagocytic index showed a significant increase whereas the avidity index showed a decrease from the control value. NBT reduction was also significant. The soluble immune complex level was not altered. The heat stressed animals showed a decrease in the thymus and spleen weight/body weight ratio while the lymph node/body weight ratio showed an increase compared to the control animals.