Dopamine and cerebral cortical blood flow in the rat

Summary Dopamine topically applied to the cerebral cortex (1–20 g/ml) or administered i.v. (0.5–64 g/kg/min) has no effects on cerebral cortical blood flow in the rat.     

May K+ ions stimulate the formation of cyclic AMP in the brain independently on their depolarizing action?

Summary The effect of potassium ions on the formation of adenosine 3,5-monophosphate (cAMP) in the rat cerebral cortex in vivo was studied under conditions where development of spreading depression had been blocked by pretreatment of the cerebral cortex by topically applied magnesium ions. A linear relationship between potassium concentrations applied to the cortical surface and levels of cAMP has been found. Moreover, potentiation of the K⁺-effect by magnesium ions has been observed.     

Immunocytochemical localization of neurons containing ACTH 17-39 in the rat brain]

Immunoreactive neurons and fibers were localized in the Rat brain by immunocytochemistry using an anti-ACTH 17-39 antiserum. Neither adrenalectomy nor water deprivation affected intensity of distribution of reaction of labelled neurons whereas colchicine increased labelling of hypothalamic perikarya. These results support the neuronal origin of cerebral ACTH.     

‘Binding’ of glutamate and aspartate to synaptosomal fractions of six regions of the feline brain

The order of potency of binding of both glutamate and aspartate to synaptosomal fractions of brain regions was: cerebellar cortex caudate nucleus cerebral cortex > medulla pons > corona radiata. Glutamate was bound to a greater extent than aspartate to particles of all regions studied, except for cerebral cortex.     

Regional distribution of thiamin pyrophosphokinase in rat brain

The highest specific activity of thiamin pyrophosphokinase was found in the cerebellum, and lower activity in cerebral cortex and midbrain. The regional difference in the enzyme activity was similar to that in thiamin content and the influx rate in rat brain, suggesting that the enzyme is involved in the thiamin transport.     

Lead distribution in the nervous system of 8-month-old rats intoxicated since birth by lead

Lead levels in the nervous system of rats intoxicated for 8 months by lead acetate (0.2% in drinking water) varied according to the region: the lowest levels were observed in sciatic nerve and the highest in hippocampus and cerebral neocortex, while intermediate levels were observed in pons medulla, cerebellum, midbrain, hypothalamus and striatum.     

Regional distribution of thiamin pyrophosphokinase in rat brain

Summary The highest specific activity of thiamin pyrophosphokinase was found in the cerebellum, and lower activity in cerebral cortex and midbrain. The regional difference in the enzyme activity was similar to that in thiamin content and the influx rate in rat brain, suggesting that the enzyme is involved in the thiamin transport.     

Correlation between acidic phospholipids and serotonin and between lysolecithin and dopamine in ganglia of the marine mussel,Mytilus edulis

Summary These studies have demonstrated a positive correlation between the acidic phospholipids and the serotonin content and between the lysolecithin and the dopamine content in the cerebral, pedal and visceral ganglia ofMytilus edulis. These relationships were further supported by experiments utilizing 6-hydroxydopamine and 5,6-dihydroxytryptamine.This study was partially supported by USPHS grant NS 10845 to Dr E. Aiello of Fordham University.Presently at Medgar Evers College of C.U.N.Y., Brooklyn, N.Y. 11225.     

High K+-induced release of somatostatin from the cortical preparation of rat brain.

Release of endogenous somatostatin (SRIF) from the rat cerebral cortical slices incubated in Krebs-bicarbonate buffer was increased from the basal rate of 3.4 +/- 0.6% of the total SRIF content in 15 min at [K+]o = 5.6 mM, to 13.1 +/- 1.6% upon raising the [K+]o to 56.6 mM. The high-K+ evoked SRIF release was absent when Ca++ in the medium was replaced by Mn++. The isolated synaptosomes from rat cerebral cortex contain 13.2 +/- 3.1 ng SRIF/mg protein compared to 0.33 +/- 0.01 ng/mg protein in the cortical tissue as a whole, suggesting that nerve terminals are the main source of the peptide released upon membrane depolarization.     

Cerebrovascular autoregulation is resistant to calcium channel blockade with nimodipine

Summary In normal baboons cerebrovascular resistance changed along with blood pressure to maintain blood flow constant. This autoregulation was not significantly altered in animals treated with a dose of the calcium channel blocker nimodipine causing selective cerebral vasodilation.     

Insulin stimulates sodium-potassium activated ATPase from rat hippocampus

Summary It is suggested that insulin is capable of activating cerebral NaK-ATPase in a dose-dependent manner.Supported by grants from Ministerium für Hoch- und Fachschulwesen der DDR.     

Effects of cerebral lateral,ventricular infusions of phloridzin on feeding and body weight in Gallus domesticus (L.)

Summary Contrary to earlier findings in rats, cerebral lateral ventricular infusions of 1×10^–3 M or 2×10^–3 M solutions of phloridzin at a rate of 2.5 l/min for 90 min had no significant stimulating effects on food intake and weight gain in hens and cocks. These different responses to intraventricular phloridzin might reflect a difference of sensitivity to the inhibitory action of phloridzin on glucose transport in cerebral cells or certain peculiarities of mechanisms controlling food intake in chickens.     

Bilinear correlation between tissue water content and diastolic stiffness of the ventricular myocardium

Summary In oedematous and dehydrated canine hearts a close bilinear correlation was demonstrated between myocardial water content and diastolic stiffness (characterized by the passive elastic modulus) with an optimal minimum of stiffness at normal myocardial water content.     

Brain ischemia hypertension

Summary Hypertension was produced in anesthetized and conscious dogs when cerebral perfusion was reduced. It lasted up to 19 days in chronic studies, was not abolished by carotid sinus denervation nor with beta receptor blockade, but was absent after removal of brachiocephalic artery constriction (BCAC). The cardiovascular features of this neurogenic hypertension are presented.     

The effect of intraventricular thyroxine administration on body temperature in dogs at rest and during physical exercise

Summary Infusion of 1 g thyroxine into the left cerebral ventricle of the dog did not change body temperature at rest, but it caused significantly higher increases in T_re during physical exercise.     

Pentagastrin induction of acetylcholinesterase activity in cerebral cortex of rats

Summary A single injection of pentagastrin (500 g kg^–1) produced an immediate (within 15 min) and pronounced increment (about 50%) in the activity of acetylcholinesterase (AChE) in the cerebral but not in the cerebellar region of the brain. Pretreatment of rats with either actinomycin-D or cycloheximide did not fully abolish the pentagastrin-mediated stimulation of cerebral AChE activity.Acknowledgments. A.M. Nakhla is recipient of a postdoctoral research fellowship from Danida, Ministry of Foreign Affairs, Denmark. The project was in part supported by grants to A.P.N.M. from The Laegevidenskabelige Forskningsråd and Danida, Denmark.     

The endothelium-dependent relaxation of human middle cerebral artery: Effects of activated neutrophils

Neutrophils, activated by 4-phorbol-12-myristate-13-acetate, decreased acetylcholine-induced relaxation of strips of human middle cerebral artery precontracted with noradrenaline. This effect was prevented by catalase, but not by superoxide dismutase. Nifedipine, propranolol and, less markedly, captopril reduced the decrease in acetylcholine-induced relaxation. Aspirin and dipyridamole did not reduce it.     

A new,rapid and precise method for measuring the intra-cellular water content by gas chromatography and3H-sucrose

Summary A new rapid method for measuring intra-cellular water content by gas chromatography and an isotopic (³H-sucrose) technique is described. Water content of circulating red cells was revealed to be 71.26±0.31%. Intra-cellular water content increased to 102.9% of its original value following addition of 3 volumes of acid-citrate-dextrose (ACD) to 20 volumes of blood.     

Imbalance in the activities of alkaline phosphatase and Na+-K+-ATPase in the brain of experimentally induced phenylketonuric squirrels (Funambulus palmarum)

Summary Phenylketonuric squirrels have shown marked inhibition of alkaline phosphatatase in the olfactory lobes and cerebral hemispheres, whereas the Na⁺-K⁺-ATPase remained less altered. In the pathogenesis of phenylketonuria inhibition of alkaline phosphatase at the level of Blood-Brain Barrier (BBB), leads transport system to impaired functioning.This work was done in the Department of Zoology, University of Udaipur, Udaipur-313001, India.     

Changes to cellular water and element content induced by nucleolar stress: investigation by a cryo-correlative nano-imaging approach

The cell is a crowded volume, with estimated mean mass percentage of macromolecules and of water ranging from 7.5 to 45 and 55 to 92.5 %, respectively. However, the concentrations of macromolecules and water at the nanoscale within the various cell compartments are unknown. We recently developed a new approach, correlative cryo-analytical scanning transmission electron microscopy, for mapping the quantity of water within compartments previously shown to display GFP-tagged protein fluorescence on the same ultrathin cryosection. Using energy-dispersive X-ray spectrometry (EDXS), we then identified various elements (C, N, O, P, S, K, Cl, Mg) in these compartments and quantified them in mmol/l. Here, we used this new approach to quantify water and elements in the cytosol, mitochondria, condensed chromatin, nucleoplasm, and nucleolar components of control and stressed cancerous cells. The water content of the control cells was between 60 and 83 % (in the mitochondria and nucleolar fibrillar centers, respectively). Potassium was present at concentrations of 128–462 mmol/l in nucleolar fibrillar centers and condensed chromatin, respectively. The induction of nucleolar stress by treatment with a low dose of actinomycin-D to inhibit rRNA synthesis resulted in both an increase in water content and a decrease in the elements content in all cell compartments. We generated a nanoscale map of water and elements within the cell compartments, providing insight into their changes induced by nucleolar stress.