Effects of free fatty acids, ethanol and development on gamma-aminobutyric acid and glutamate fluxes in rat nerve endings.

The effects of type A (cis-unsaturated) and type B (trans-unsaturated and saturated) fatty acids, 1% and 3% ethanol (v/v), and development (7 days) on the thermodynamics of glutamate and gamma-aminobutyric acid (GABA) transport into cortical rat brain nerve endings were examined. The effects of the various manipulations, which are known to affect membrane fluidity, may be summarized. Three percent ethanol and oleic acid increased delta S degrees and delta S+ for glutamate transport and decreased delta H degrees and delta H+.

Repeated electroconvulsive shock or chronic morphine treatment increases the number of 3H-D-Ala2,D-Leu5-enkephalin binding sites in rat brain membranes.

Experiments were performed in rats to evaluate the possible mechanisms responsible for the pharmacological cross-sensitization observed between repeated electroconvulsive shock (ECS) and chronic morphine administration. Repeated daily ECS for 9 days as well as chronic morphine pellet implantation resulted in a significant increase in the number of 3H-DADLE binding sites (Bmax values of 231 and 196 fmoles/mg protein, respectively). By contrast, single ECS, repeated sham ECS, and placebo pellet-treated rats all had significantly lower Bmax values (approx.

Effects of naloxone on d-amphetamine- and apomorphine-induced behavior.

The effects of acute naloxone administration on d-amphetamine- and apomorphine-induced behavior were studied. Naloxone, in doses of 0.3-10 mg/kg (s.

Developmental regulation of phospholipid methylation in rat brain synaptosomes.

Phospholipid methylation was studied in cortical synaptosomes prepared from 7 and 14 day and adult rat brain. Using varying concentrations of [3H] S-adenosylmethionine, Km and Vmax values were determined for the formation of [3H] phosphatidylmonomethylethanolamine (PME), [3H] phosphatidyl-dimethylethanolamine and [3H] phosphatidylcholine (PC). At 25 degree C, the Km values for the formation of all three products, significantly decreased with development.

The transport and turnover of phospholipids in the rat nigrostriatal system: effects of d-amphetamine and haloperidol.

the nigrostriatal transport of phospholipids was studied using [3H] glycerol, 32Pi and [3H] choline. [3H] glycerol was rapidly incorporated into phospholipid and significant amounts of labelled phospholipid were found in the striatum one hour after injection into the substantia nigra. In contrast, both 32Pi and [3H] choline were more slowly incorporated into phospholipid and significant amounts of labelled phospholipid were not found in the striatum until 24 hours after injection.

Developmental changes in the fatty acids of synaptic membrane phospholipids: effect of protein malnutrition.

The acyl-linked fatty acid composition of the major phospholipid species in rat cortical synaptic membranes was determined at various stages of development. For most species there was a decrease during development in the short chain saturated fatty acids, 14:0 and 16:0, an increase in 18:0 and 22:6 (n-3) and an increase in ratio of 22:6 (n-3)/22:5 (n-6). Pups were protein deprived by feeding the dams a 12% casein diet as compared to the 24% casein control diet.

Phosphatidate as a molecular link between depolarization and neurotransmitter release in the brain.

Phosphatidate, a neuronal phospholipid, stimulated the uptake of calcium by nerve terminals isolated from the striatum of rat brain. This effect was not produced by other phospholipids or glycolipids. Phosphatidate, but not other phospholipids, evoked the release of [3H] dopamine from striatal synaptosomes.

Membrane fluidity and alcohol actions.

Many studies have demonstrated that the ability of alcohols and other intoxicant-anesthetics to affect biochemical, physiological, and behavioral processes rests in their hydrophobicity. This means that potency is determined by the ability of the drug to move from a water phase into a lipid or membrane phase. In more precise terms, anesthetic effects are correlated with the volume occupied by the anesthetic molecules within the membrane.

Brain locations controlling the behavioral effects of chronic amphetamine intoxication.

Rats were administered D-amphetamine repeatedly for 4 days. After day 1 of treatment, the amphetamine-induced increases in ambulation, rearing, and stereotyped activity were augmented. However, after 4 days treatment, the rearing and ambulatory responses became attenuated while the stereotyped activities remained augmented.

Influence of morphine, beta-endorphin and naloxone on the synthesis of phosphoinositides in the rat midbrain.

The effects of morphine, beta-endorphin and naloxone on the initial incorporation of 32Pi and [3H]glycerol into TPI, DPI and PI were measured in discrete subcellular fractions of the rat midbrain. Morphine and beta-endorphin significantly increased microsomal 32PI incorporation into TPI and PI but not DPI. Although neither morphine nor beta-endorphin significantly affected the levels of [3H]TPI or [3H]DPI, both agents significantly increased [3H]PI levels.

High-affinity GABA and glutamate transport in developing nerve ending particles.

The high-affinity transport of [3H]GABA and [14C]glutamate was measured in discrete nerve ending fractions isolated from the developing rat cortex, beginning on day 7 postpartum and prepared using discontinuous Ficoll-isotonic sucrose gradients. On day 7 the material sedimenting in the lightest gradient fractions contained the highest density of particles capable of high-affinity transport. With increasing age, the transport sites became progressively associated with more dense particles in the gradient.

Effects of some conformationally restricted GABA analogues on GABA membrane binding and nerve ending transport.

By using a series of aminocyclopentane- and aminocyclohexanecarboxylic acids, as well as some naturally occurring amino acids, it was possible to determine some aspects of the spatial topography of the GABA membrane binding and transport sites. The NA-independent GABA binding site was found to have a different spatial topography than the Na-dependent binding site in that trans-3-aminocyclopentanecarboxylic acid (trans-3-ACPC) was 7 times more potent than cis-3-ACPC to inhibit Na-independent binding, but only 1.6 times more potent to inhibit Na-dependent binding.

Effects of withdrawal from chronic amphetamine intoxication on exploratory and stereotyped behaviors in the rat.

Rats were administered 3, 6, and 12 mg/kg of d-amphetamine s.c. twice daily on a weekly increasing staircase schedule.

Influence of morphine on protein synthesis in synaptic plasma membranes of the rat brain.

The effects of acute and chronic morphine treatment on the incorporation of 3H-lysine into synaptic proteins were studied. No changes related to tolerance development were observed in the total incorporation of 3H-lysine into cortical or subcortical synaptic plasma membrane (SPM) or synaptic soluble proteins. Two populations of subcortical SPM were prepared, one from light (L) and one from heavy (H) nerve ending particles.