Dopaminergic and serotonergic function following isolation rearing in rats: study of behavioural responses and postmortem and in vivo neurochemistry.

This series of experiments compared isolation-reared and socially reared rats for their locomotor activity, behavioural stereotypy, and monoamine function both postmortem and in vivo using intracerebral dialysis. In Experiment 1, isolates showed an altered time course of locomotor activity following d-amphetamine sulphate (AMPH) administration (0.5, 2.

Excitatory amino acid-induced phosphoinositide turnover in guinea pig cerebral cortical slices: selective enhancement by spermine of the response to DL-1-aminocyclopentane-trans-1,3-dicarboxylate.

In the presence of 1 mM spermine, accumulations of 3H labelled inositol phosphates elicited by quisqualate (100 microM) and 1-aminocyclopentane-trans-1,3-dicarboxylate (t-ACPD, 300 microM) were significantly enhanced by 21 and 26%, respectively, without a significant alteration in the accumulation elicited by L-glutamate (10 mM) or DL-alpha-amino-3-hydroxy-5-methyl-4-isoxalone propionate (10 microM). Analysis of concentration-response data indicated that the presence of spermine led to an increase in the maximal response to t-ACPD without altering the EC50 value. The stimulatory effect of spermine on the accumulation of t-ACPD-elicited 3H-inositol phosphates was not reversed by ifenprodil or diethylenetriamine (putative polyamine site antagonists), by agents that activate or inhibit protein kinase C, or by calcium channel blockade, but was abolished in the presence of elevated extracellular calcium ion concentration.

Preserved insulin secretion and insulin independence in recipients of islet autografts.

Background: Transplantation of pancreatic islets, rather than whole pancreas, has been introduced as a treatment for diabetes mellitus. We studied five patients ranging in age from 12 to 37 years who had severe chronic pancreatitis for which they underwent total pancreatectomy followed by isolation and hepatic transplantation of their own islets.

Methods: All patients had remained insulin-independent for 1 to 7 1/2 years after transplantation.

Agonist-induced changes in [Ca2+]i in N1E-115 cells: differential effects of bradykinin and carbachol.

The addition of bradykinin to populations of fura-2 loaded N1E-115 neuroblastoma cells produced an increase in intracellular calcium which rapidly reached a peak and returned to baseline within 60 s. The response was concentration dependent and unaffected by removal of extracellular calcium or addition of the inorganic channel blocker Ni2+. Similar transient responses were seen with histamine and angiotensin II and experiments monitoring manganese entry suggest that agonist responses in this cell line involve mainly release of calcium from intracellular stores.

Inhibition of forskolin-stimulated cyclic AMP formation by 1-aminocyclopentane-trans-1,3-dicarboxylate in guinea-pig cerebral cortical slices.

The effects of the selective metabotropic glutamate receptor agonist 1-aminocyclopentane-trans-1,3-dicarboxylate (t-ACPD) on forskolin-stimulated cyclic AMP formation in guinea-pig cerebral cortex slices were determined. t-ACPD inhibited the accumulation of [3H]cyclic AMP by approximately 80%, with an IC50 value of 35 +/- 4 microM. The effect was reversible and stereoselective, with the 1S,3R isomer being approximately 400-fold more potent than the 1R,3S isomer.

Direct and indirect stimulations of cyclic AMP formation in human brain.

1. Adenosine 3':5'-cyclic monophosphate (cyclic AMP) formation, by use of an [3H]-adenine prelabelling assay, was measured in fragments of human cerebral cortex, taken in the course of various neurosurgical procedures. 2.

Signal sequences containing multiple aromatic residues.

Using homopolymeric units of either phenylalanine or tryptophan to replace the natural core segment of the Escherichia coli alkaline phosphatase signal peptide, the hydrophobicity requirements for protein export and processing were further explored. The mutant signal peptide containing polyphenylalanine functioned at least as efficiently as the wild-type, while the signal incorporating polytryptophan was dysfunctional. The transport properties of these mutants confirm our work with sequences rich in aliphatic residues; namely that a high mean hydrophobicity per residue is critical for complete and rapid precursor processing and for translocation of the protein.

Biochemical correlates of alpha 1-adrenoceptor activation.

An impressive body of evidence based on radioligand binding, biochemical, functional and structural data supports the existence of two sub-types of the alpha 1-adrenoceptor (alpha 1a and alpha 1b) in the CNS and in peripheral tissues. Both elevate intracellular Ca2+ concentrations, although by different mechanisms, resulting in a cascade of intracellular events dependent upon the cell type involved.

Do polyamines regulate the NMDA inhibition of muscarinic receptor-induced phosphoinositide turnover in guinea pig brain?

The N-methyl-D-aspartate (NMDA) receptor-induced inhibition of muscarinic receptor-stimulated phosphoinositide turnover in guinea pig cerebral cortical slices was investigated to determine whether polyamines regulate the function of NMDA in this system. None of the polyamines tested produced significant stimulation of phosphoinositide turnover. Neither spermine nor the substituted polyamine philanthotoxin-343 altered the inhibitory effect of NMDA.

Alpha- and beta-adrenoceptor regulation of cyclic AMP accumulation in cultured rat astrocytes. A comparison of primary protoplasmic and mixed fibrous/protoplasmic astroglial cultures.

The effect of noradrenaline and isoprenaline on cyclic AMP accumulation has been investigated in primary rat astrocytes which contain either (a) protoplasmic astrocytes alone or (b) both fibrous and protoplasmic astrocytes. Isoprenaline and noradrenaline stimulated cyclic AMP formation in both astrocyte culture preparations. Combinations of noradrenaline (1 microM) and isoprenaline (1 microM) produced a cyclic AMP response which was 58% and 26% of that produced by isoprenaline alone in protoplasmic and mixed fibrous/protoplasmic cultures, respectively.

Long-term metabolic function of pancreas transplants and influence of rejection episodes.

Pancreas grafts, when not rejected, can sustain an insulin-independent state in type I diabetic recipients for indefinite periods. To what extent the metabolic control achieved approaches that of normal individuals, the relationships between graft endocrine and exocrine function, the effect of reversible rejection episodes on subsequent graft function, and the correlation between the results of serial tests of graft function were determined by studies at 1 month, 1 year, and 2 years in a cohort of 39 recipients (29 females, 10 males; mean age (+/- SD), 33 +/- 5 years; mean duration of diabetes, 22 +/- 6 years) of bladder-drained pancreas transplants performed between November 1984 and December 1988. Fifteen patients received a pancreas transplant alone, 8 a pancreas after a kidney, and 16 a simultaneous pancreas/kidney transplant.

Multilayering and loss of apical polarity in MDCK cells transformed with viral K-ras.

The effects of viral Kirsten ras oncogene expression on the polarized phenotype of MDCK cells were investigated. Stable transformed MDCK cell lines expressing the v-K-ras oncogene were generated via infection with a helper-independent retroviral vector construct. When grown on plastic substrata, transformed cells formed continuous monolayers with epithelial-like morphology.

Functional limits of conformation, hydrophobicity, and steric constraints in prokaryotic signal peptide cleavage regions. Wild type transport by a simple polymeric signal sequence.

These experiments examine the role of conformation, hydrophobicity, and steric constraints in the function of the prokaryotic signal peptide cleavage region. The experimental strategy involves replacement of the wild type Escherichia coli alkaline phosphatase signal peptide cleavage region with a series of idealized model sequences designed to epitomize the particular structural and physical variables under study. By analyzing model sequences whose conformations have been determined by physical studies, we have demonstrated that efficient transport does not depend on the structural preference of the cleavage region.

The glycine antagonist 7-chlorokynurenic acid blocks the effects of N-methyl-D-aspartate on agonist-stimulated phosphoinositide hydrolysis in guinea-pig brain slices.

Despite having no effect on basal phosphoinositide hydrolysis. N-methyl-D-aspartate (NMDA) inhibited carbachol-stimulated accumulation of 3H-inositol phosphates and enhanced that due to noradrenaline in guinea-pig cerebral cortex slices. The glycine antagonist 7-chlorokynurenic acid inhibited the effects of NMDA and this inhibition was reversed by glycine.

Expression of beta 2-adrenoceptors mediating cyclic AMP accumulation in astroglial and neuronal cell lines derived from the rat CNS.

The effect of isoprenaline on cyclic AMP accumulation has been investigated in the rat neuronal cell line B50 and the rat astrocytoma cell line C6. Noradrenaline and isoprenaline stimulated cyclic AMP accumulation in both cell lines. Isoprenaline (0.

Differential effects of elevated calcium ion concentrations on inositol phospholipid responses in mouse and rat cerebral cortical slices.

Inositol phospholipid turnover in cerebral cortical slices from mouse and rat was assessed using a [3H]inositol pre-labelling technique followed by anion exchange chromatography to isolate [3H]inositol phosphates ([3H]InsP chi). In both mouse and rat cerebral cortical slices, elevating the CaCl2 concentration of the Krebs medium from 1.3 to 4 mM did not significantly enhance the accumulation of [3H]InsP chi in the absence of any stimulus, or in the presence of glutamate (3 mM), depolarizing concentrations of KCl (25 mM), 5-hydroxytryptamine (0.

Is the adenosine receptor modulation of histamine-induced accumulation of inositol phosphates in cerebral cortical slices mediated by effects on calcium ion fluxes?

In this report, we show that under conditions designed to provide an initially uniform incorporation of [3H]inositol into mouse and guinea pig cerebral cortical slices prior to agonist stimulation, the accumulation of 3H-inositol phosphates (3H-InsPx, x = 1-4) induced by histamine in mouse and guinea pig cerebral cortical slices increased in a quasilinear manner with increasing added calcium. Raising the ambient calcium ion concentration failed to reduce the adenosine receptor-mediated inhibition of the histamine-induced 3H-InsPx response in mouse cerebral cortical slices. Similarly, the potentiation of the histamine response by adenosine receptor activation in guinea pig cerebral cortical slices was unaffected by lowering the added calcium ion concentration.

Excitatory amino acid-induced formation of inositol phosphates in guinea-pig cerebral cortical slices: involvement of ionotropic or metabotropic receptors?

In cerebral cortical slices from the guinea-pig, quinoxalinedione derivatives antagonised the generation of 3H-inositol phosphates evoked by the excitatory amino acids quisqualate and DL-alpha-amino-3-hydroxy-5-methyl-4-isoxalone propionic acid but were without effect on the trans-DL-1-amino-1,3-cyclopentanedicarboxylic acid and L-glutamate responses. Omission of calcium from the medium reduced the accumulation of 3H-inositol phosphates induced by incubation with trans-DL-1-amino-1,3-cyclopentanedicarboxylic acid (incubation for 45 min) by greater than 50%, whereas the responses to L-glutamate and the two other amino acid analogues were reduced by approximately 20%. Generation of inositol 1,4,5-trisphosphate over a 30-s period by treatment with quisqualate, trans-DL-1-amino-1,3-cyclopentane-dicarboxylic acid, KCl, and carbachol was abolished in the presence of nominally calcium-free medium.

The effects of acute and chronic lithium treatment on pilocarpine-stimulated phosphoinositide hydrolysis in mouse brain in vivo.

1. Measurements were made of the in vivo formation of inositol phosphates in the brains of C57/B1/601a mice treated acutely or chronically with lithium chloride (LiCl). 2.

Lithium amplifies inhibitions of inositol phospholipid hydrolysis in mammalian brain slices.

1. We have examined the effects of lithium chloride (LiCl) on inhibitions of inositol phospholipid hydrolysis in guinea-pig and rat brain slices by assessing the accumulation of [3H]-inositol phosphates ([3H]-InsP), in vitro. 2.

Inositol phospholipid hydrolysis in human brain; adenosine inhibition of the response to histamine.

1. Inositol phospholipid hydrolysis was examined in human cerebral cortex slices by a [3H]-inositol prelabelling assay. 2.

Niguldipine discriminates between alpha 1-adrenoceptor-mediated second messenger responses in rat cerebral cortex slices.

The effect of both isomers of niguldipine, a highly selective alpha 1-adrenoceptor antagonist and dihydropyridine calcium channel blocker, on noradrenaline-stimulated inositol phosphate (IP) accumulation and adenosine 3':5'-cyclic monophosphate (cyclic AMP) potentiation was examined. Both isomers inhibited noradrenaline-stimulated IP accumulation. (+)-Niguldipine was 100 fold more potent than (-)-niguldipine.

Discriminatory effects of forskolin and EGTA on the indirect cyclic AMP responses to histamine, noradrenaline, 5-hydroxytryptamine, and glutamate in guinea-pig cerebral cortical slices.

The effects of forskolin (1 microM) and EGTA (5 mM) on indirect cyclic AMP responses in slices of guinea-pig cerebral cortex were examined. Forskolin had little effect on the direct 2-chloroadenosine-stimulated cyclic AMP response. However, it completely abolished the glutamate-induced augmentation of this response.