Rabbits received either bilateral dorsal or unilateral dorsolateral spinal cord lesions. The duration and incidence of contact defensive immobility (CDI; animal hypnosis) were tested in these rabbits and in intact controls. Neither of the spinal cord lesions affected the number of CDI inductions, but rabbits with lesions of the dorsal spinal cord exhibited significantly shorter durations of CDI than either of the other groups which did not differ from each other. These results are interpreted to indicate that the somesthetic systems that ascend in the dorsal spinal cord are important for the maintenance, but not the initiation, of CDI.

No description available.

An in vitro study was conducted to determine whether indomethacin (IN) and oestradiol (E2) induced decreases in rabbit haematocrit may be related to their effect on erythrocyte fragility (EF). Aliquots of treated rabbit whole blood were assayed as control, IN (9.6 μg/ml), E2 (500 pg/ml) and IN + E2, for changes in EF. Osmotic (OF) and mechanical (MF) fragility in eight experimental replicates were evaluated under approximate physiological conditions by measurement of haemoglobin release. Samples were assayed immediately after drug addition and again 4 hr after incubation at 39.5°C. OF results showed a significant increase in 50% haemolysis between final IN and IN + E2 values when compared with their initial values and with controls. OF haemolysis dispersion was increased over time by IN and IN + E2. MF increased with IN, E2 and IN + E2 was not greater than that from IN alone. The IN induced increases in both OF and MF indicate a difference in degree of interaction with the erythrocyte from that of E2, which affected only MF and the effect of which was neither additive nor synergistic with that of IN.

The first purpose of the present experiments was to make a detailed study of the effects of hippocampal lesions on self-grooming behavior in rats. Hippocampal lesions decreased total grooming time and almost eliminated complete sequential grooming patterns, but increased open-field activity. Both hippocampal and neocortical lesions altered grooming in response to sucrose spray. The second purpose of this study was to compare the effects of the neurotoxin trimethyltin (TMT) with those produced by surgical destruction of the hippocampus. High doses of TMT, which produced extensive cell loss in the hippocampus, increased activity in the open field, but only moderate doses of TMT altered grooming. The results of the present study indicate that surgical removal of a large part of the hippocampus can disrupt a sequential, unlearned behavior. Furthermore, the behavioral effects of TMT cannot always be attributed to its neurotoxic action on the hippocampus.

Bradykinin (BK), a known inflammatory mediator, may induce alterations in the shape of endothelial cells via an intracellular pathway involving protein kinase C (PKC). Endogenous alkylglycerol (AG), a product produced by lipid metabolism, concomitantly with diacylglycerol (DAG), has been shown to reduce the translocation of PKC in various cell types; thus, this study investigates the potential inhibitory role of AG in the BK-induced translocation of PKC. Human endothelial cells (HUVEC) were incubated for 15 min and 3 hr in either control media or BK (1μM), 1-O-dodecyl-rac-glycerol (DDG, a synthetic AG, 30μM), phorbal myristale acetate (PMA, 0.1μM) or BK/DDG or PMA/DDG. Cytosolic and membrane fractions were collected via digitonin (0.5%) and Trilon X-100 (1%) extractions, respectively; then, after measurements of protein content (Pierce BCA), immunoblotting for specific isoforms. PKCα, PKCε, PKCζ, were completed by Western blot and imaging for band intensity was performed. In the control (untreated) HUVEC, PKC isoforms were found in both cytosol and membrane fractions with decreasing particulate levels of PKCε, PKCα, and PKCζ, respectively, while DDG reduced all isoform translocation. BK did not appear to induce translocation at either timepoint; however, with both DDG and BK present, translocation of PKCε and PKCα was increased. PMA induced translocation of PKCα and PKCε with no translocation of PKCζ; treatment with DDG and PMA did not alter the PMA-induced translocation. These results imply that DDG initiates a BK-induced translocation of the DAG-depended PKC isoforms. Therefore, the roles of transcellular signalling systems via DAG and PKC is complex, isoform specific, and can be amplified by DDG/AG.

Intravenous injection of SP increases blood pressure, heart rate and renal nerve activity by stimulating sympathetic ganglia. This effect is greater in SHR than in WKY rats. The present study compared ganglion and cardiovascular responses to the native tachykinin SP and the NK, agonist GR73637 (GR) to determine the receptor type and the response profile in SHR and WKY rats. Anesthetized rats were treated with a ganglion blocker, chlorisondamine (25 μmol/kg), to prevent baroreceptor modulation of ganglion responses to SP and GR. GR (0.1 - 100 nmol/kg) caused dose-dependent effects in the two strains similar to those caused by SP. Maximum responses to SP and GR were: 1 renal nerve firing 1 blood pressure 1 heart rate strain n (mV2/sec) (mmHg) (beats/min) SP GR, SP GR SP GR SHR 8 151±23.9 122±18.0 32±4.2 19±2.6a 82± 9.6 62±7.2a WKY 6 36±11.4b 12± 3.1a,b 4±1.7b 0a,b 56±14.1b 16±4a,b mean±SEM; aGR different from SP; bWKY different from SHR These findings demonstrate that 1) GR has effects on blood pressure, heart rate and renal nerve firing similar to those caused by SP, 2) the magnitude of the responses to GR and SP is less in WKY rats than in SHR and 3) NK1 receptors have a major but not exclusive role in mediating renal nerve and cardiovascular responses to the ganglion action of the native tachykinin SP.

PKC has been linked to functional and morphological changes in endothelial cells which could be involved in their response to inflammation. PKC α, ε, and ζ isotbrms have been shown to be the most prominent in Human Umbilical Vein Endothelial Cells (HUVEC). We hypothesize that: 1) high and low passed cells would have the same isoform distribution, and 2) bradykinin (luM) and PMA (100nM) activate PKC isoforms in high (-20th) and low (4-5th) passed HUVEC. The cells were incubated for 1 and 15 min with either bradykinin or PMA and then scraped, sonicated and fractionated. PKC in the cytosolic and membranebound fractions was assayed by Western blot. These experiments revealed that: • In the control samples, a and Çisoforms were present in cytosolic but not membrane-bound fractions, whereas e was present only in the membranebound fraction. • Bradykinin did not cause a change in a or Çisoform distribution, but the amount of e was attenuated in the membrane bound fraction at 15 min. • PMA activated the DAG-dependent a and e isoforms but not the DAG-independent Çisoform. • All the above results were consistent for both high and low passed cells. This study suggests that bradykinin inhibits a Ca-independent, DAG-dependent PKC isoform (e), potentially by activating an inhibitory G protein. Further, HUVEC clearly display a non-uniform basal distribution of PKC α, ε and ζ in HUVEC.

A simple method for staining nerve cells and fibers of the salamander central nervous system is described. The procedure employs Carnoy's fixation followed by Protargol impregnation and Nissl staining. This technique permits the simultaneous observation of intracellular neurofibrils, neuronal processes and basophilic components of the neuron. In addition, it eliminates the need to stain alternate sections with separate procedures to view the various components of the urodele central nervous system.

To help define the optimal conditions for the preparation of vascular corrosion casts of rat heart, we examined the effect of prefixation with aldehyde fixatives on the perfusion rates of rat heart and on the quality of vascular casts. For these studies, beating hearts were removed from rats, cannulated via the aortic stump, arrested with KCl, perfused retrograde with buffered saline or fixative, and infused with resin to prepare corrosion casts. Fixatives used were 2.5% glutaraldehyde or 2% paraformaldehyde, and the casting resin consisted of a Mercox-methylmethacrylate mixture (4:1). All perfusion pressures were monitored at 80 to 100 mm Hg using a mercury manometer. The perfusion rate of control hearts was 13 to 14 mL/min. Prefixation with glutaraldehyde and paraformaldehyde reduced perfusion to 8.5 and 8.1 mL/min, respectively. Cast quality was observed grossly and with the scanning electron microscope. Control hearts yielded high quality, complete casts with 2570 capillaries/mm2+. Casts from prefixed hearts exhibited areas of incomplete vessel filling and resisted complete tissue maceration, leaving tissue remnants adhering to the vessel replicas. Casts from glutaraldehyde-fixed hearts were of very poor quality. Our results indicate that prefixation is an unnecessary step in the preparation of vascular casts of rat heart and is inconsistent with cast quality. © 1995.

The effects of ozone (O3) and nitrogen dioxide (NO2) on the solubility and proteolytic susceptibility of elastin were examined to better understand how these oxidant air pollutants might damage the lung. In vitro O3 exposures at pH 7.4 resulted in the complete solubilization of elastin, but NO2 had no effect on solubility. The initial solubilization rate was 65 μg/μmol of O3, which increased to 150 μg/μmol in the midregion of a sigmoidal solubilization curve. Peptide fragments of the O3-solubilized elastin ranged in size from 5 to 20 kD. The conversion of insoluble elastin into soluble fragments by O3 was not due to the destruction of desmosine crosslinks. The effect of O3 on the proteolytic susceptibility of elastin was measured using insoluble elastin recovered from exposures that resulted in 5.3%, 12.8%, and 26.3% solubilization. Human neutrophil elastase (HNE) digested the remaining insoluble elastin samples 4.3, 6.0, and 9.8 times faster than unexposed elastin. In contrast, NO2-exposed elastin was no more susceptible to digestion by HNE. Ascorbate, EDTA, and uric acid reduced the proteolytic susceptibility of O3-exposed elastin, but mannitol afforded no protection. These findings indicate that the inhalation of O3 may contribute to lung disease by directly damaging elastin and by increasing its susceptibility to proteolysis, whereas NO2 probably damages lungs via alternative mechanisms.