Distribution of DNA and RNA in different regions of cat's brain

Résumé Chez le chat normal, la concentration d'ADN est à peu près la même dans les diverses régions examinées du système nerveux central. Par contre, la concentration d'ARN varie considérablement d'une région à l'autre. Ces résultats suggèrent que la distribution de l'ARN correspond à la différentiation morphologique et fonctionnelle des parties du cerveau.     

MEPE evolution in mammals reveals regions and residues of prime functional importance

In mammals, the matrix extracellular phosphoglycoprotein (MEPE) is known to activate osteogenesis and mineralization via a particular region called dentonin, and to inhibit mineralization via its ASARM (acidic serine-aspartate rich MEPE-associated motif) peptide that also plays a role in phosphatemia regulation. In order to understand MEPE evolution in mammals, and particularly that of its functional regions, we conducted an evolutionary analysis based on the study of selective pressures. Using 37 mammalian sequences we: (1) confirmed the presence of an additional coding exon in most placentals; (2) highlighted several conserved residues and regions that could have important functions; (3) found that dentonin function was recruited in a placental ancestor; and (4) revealed that ASARM function was present earlier, pushing the recruitment of MEPE deep into amniote origins. Our data indicate that MEPE was involved in various functions (bone and eggshell mineralization) prior to acquiring those currently known in placental mammals.     

Neurotrophic effects of conditioned media of astrocytes isolated from different brain regions on hippocampal and cortical neurons

The present study was designed to reveal whether astroglial cells from different brain regions produce diffusible factors that differentially support the survival of neurons and the establishment of neuronal morphology. For this purpose, astrocyte conditioned media (ACM) were prepared by conditioning chemically-defined medium with type I astrocyte culture dissociated from cerebral cortex, hippocampus and hypothalamus. Hippocampal and cortical neurons were cultured in ACM or in non-conditioned medium. ACM derived from three brain regions all supported the survival of hippocampal and cortical neurons better than non-conditioned control medium. Of these, hypothalamic ACM was the most effective in supporting the survival of cortical neurons. The ACM also potentiated the elongation of the longest neurite of hippocampal and cortical neurons. However, there were no significant differences in the promoting effects on neurite elongation among ACM from three brain regions.     

Neurochemical correlates of alloxan diabetes: Protein and ribonucleic acid levels in the different regions of the rat brain

Summary The levels of protein and ribonucleic acid in the cerebrum, cerebellum, optic lobes and medulla oblongata of normal and alloxan-diabetic rats were measured. In general, the protein content and levels of ribonucleic acid in the broad compartments of the brain of rat decreased during diabetes.Acknowledgment. The authors thank Dr.A. R. Kasturi Bai, Head of the Department of Zoology, Bangalore University, for providing facilities during the study.     

Developmental characteristics of histamine methyltransferase and phenylethanolamine-N-methyltransferase of rat brain

Summary The specific activity of histamine methyltransferase of rat brain increases rapidly from the 16th until the 25th day of gestation (7 days after birth). The specific activity of phenylethanolamine-N-methyl-transferase shows a rapid incrase during the 1st and the 2nd week after birth, the adult values being obtained by the end of the 2nd week.     

Dipeptidyl aminopeptidase in neonatal rat brain regions

Summary Changes in the activity of dipeptidyl aminopeptidase in rat pituitary gland and various brain regions were examined at 3, 5 and 20 weeks of age. The enzyme activity per g tissue wet weight in pituitary gland was the highest of all tissues studied. Subcellular distribution of the activity was also studied. The highest enzyme activity was found in a crude mitochondrial fraction including synaptosomes.     

The effect of physostigmine on (Na++K+)-ATPase activity in different rat brain regions

Summary The activity of (Na⁺+K⁺)-ATPase and acetylcholine esterase were folloed in rat brain cerebral cortex, caudate, thalamus, hippocampus and medulla after i.v. administration of physostigmine. Both enzymes were found to be inhibited in a dose-dependent manner. The most pronounced inhibition of (Na⁺+K⁺)-ATPase was found in caudate. where the highest activity of acetylcholine esterase is found.These studies were supported by a grant from the Union of Science of Republic Serbia, No. 40404-14.     

The effect of physostigmine on (Na+ + K+)-ATPase activity in different rat brain regions

The activity of (Na+ + K+)-ATPase and acetylcholine esterase were followed in rat brain cerebral cortex, caudate, thalamus, hippocampus and medulla after i.v. administration of physostigmine. Both enzymes were found to be inhibited in a dose-dependent manner. The most pronounced inhibition of (Na+ + K+)-ATPase was found in caudate, where the highest activity of acetylcholine esterase is found.     

Feeding induced by blockade of histamine H1-receptor in rat brain

Summary Histamine antagonists were infused into the third ventricle of the cerebrum in rats. All the H₁-, but none of the H₂-antagonists tested, induced initial feeding during the early portion of the light phase when histamine level was highest. No periprandial drinking was observed. Ambulation increased during feeding. The effect on feeding was attenuated when brain histamine was normally low during the early portion of the dark phase, or was decreased by -fluoromethylhistidine. Hypothalamic neuronal histamine may suppress food intake through H₁-receptors, and diurnal fluctuations of food intake may mirror neuronal histamine levels.     

Feeding induced by blockade of histamine H1-receptor in rat brain

Histamine antagonists were infused into the third ventricle of the cerebrum in rats. All the H1-, but none of the H2-antagonists tested, induced initial feeding during the early portion of the light phase when histamine level was highest. No periprandial drinking was observed. Ambulation increased during feeding. The effect on feeding was attenuated when brain histamine was normally low during the early portion of the dark phase, or was decreased by alpha-fluoromethylhistidine. Hypothalamic neuronal histamine may suppress food intake through H1-receptors, and diurnal fluctuations of food intake may mirror neuronal histamine levels.     

Distribution of glycerophosphorylcholine diesterase in rat brain

Summary The distribution of glycerylphosphorylcholine diesterase in the rat brain has been examined. The enzyme was evenly distributed throughout the brain but was localized in the synaptosome (nerve ending) fraction which was prepared by ultracentrifugation.     

Modulation of Kv7 channels and excitability in the brain

Neuronal Kv7 channels underlie a voltage-gated non-inactivating potassium current known as the M-current. Due to its particular characteristics, Kv7 channels show pronounced control over the excitability of neurons. We will discuss various factors that have been shown to drastically alter the activity of this channel such as protein and phospholipid interactions, phosphorylation, calcium, and numerous neurotransmitters. Kv7 channels locate to key areas for the control of action potential initiation and propagation. Moreover, we will explore the dynamic surface expression of the channel modulated by neurotransmitters and neural activity. We will also focus on known principle functions of neural Kv7 channels: control of resting membrane potential and spiking threshold, setting the firing frequency, afterhyperpolarization after burst firing, theta resonance, and transient hyperexcitability from neurotransmitter-induced suppression of the M-current. Finally, we will discuss the contribution of altered Kv7 activity to pathologies such as epilepsy and cognitive deficits.