Clozapine and haloperidol have differential effects on glutamic acid decarboxylase mRNA in the pallidal nuclei of the rat.

The striatum, and one of its targets, the pallidum (globus pallidus and entopeduncular nucleus) are based ganglia nuclei involved in extrapyramidal movement control. Gamma-aminobutyric acid (GABA)ergic neurons of the pallidum may be important for the expression of the effects of agents which alter striatal neurotransmission. In this study, rats were treated once daily for 28 days with either haloperidol or clozapine, two drugs which respectively, do and do not, induce extrapyramidal movement disorders.

The N- and C-terminal boundaries of myelin basic protein determinants required for encephalitogenic and proliferative responses of Lewis rat T cells.

Highly purified synthetic peptides representing portions of the 68-86 sequence of guinea pig (GP) myelin basic protein (GPMBP) were used to define the N- and C-termini of encephalitogenic determinants that cause experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Each peptide was tested for: (a) induction of EAE, (b)in vitro potentiation of EAE transfer activity by GPMBP-sensitized lymph node cells (LNC), (c) in vitro proliferation of GPMBP-sensitized LNC, and (d) in vitro proliferation of a GPMBP-reactive line of EAE-inducing T cells. In these bioassays, the general rank order of potency was: GPMBP greater than or equal to GP68-86 greater than or equal to GP72-86 greater than [G84]GP68-86 greater than or equal to GP68-84 much greater than GP75-85 greater than or equal to GP75-84 = virtually no activity.

A novel potent non-benzodiazepine anxioselective agent with reduced dependence liability: ICI 198, 256.

ICI 198,256, a member of the cinnoline series, was shown to be a potent anxiolytic agent in several species of animals. In addition, ICI 198,256 exhibited potent activity as an antagonist of both metrazole and bicuculline-induced convulsions. The salient features of ICI 198,256 are that it possesses minimal sedative liability, lower ethanol interaction and possibly lower dependence liability than benzodiazepines (e.

Clonotypic heterogeneity of Lewis rat T cells specific for the encephalitogenic 68-86 region of myelin basic protein.

Experimental autoimmune encephalomyelitis was induced in a Lewis rat by sensitization with synthetic peptide GP68-86, representing the 68-86 sequence of guinea pig myelin basic protein (GPMBP). To delineate T cell determinants of GP68-86, lymph node cells from this rat were activated in culture with GP68-86 and were fused with cells of the mouse thymoma BW5147. The resultant hybrids were cloned by limiting dilution and screened for GP68-86-evoked secretion of IL2 in the presence of rat splenocytes.

Encephalitogenic and proliferative responses of Lewis rat lymphocytes distinguished by position 75- and 80-substituted peptides of myelin basic protein.

The encephalitogenic and proliferative responses of Lewis rat lymphocytes were defined by use of synthetic peptide GP68-84, representing the 68-84 sequence of guinea pig myelin basic protein (GPMBP), and otherwise identical peptides containing substitutions of either A75 or P80 residues. The comparative activities of these peptides were tested in the following bioassays: 1) active induction of experimental autoimmune encephalomyelitis (EAE), 2) potentiation of EAE transfer activity by MBP- or peptide-sensitized lymph node cells (LNC), 3) in vitro proliferation of MBP- or peptide-sensitized LNC, and 4) in vitro proliferation of an encephalitogenic T cell line. The GP68-84 peptide exhibited potent activity in all four bioassays.

Voltage-sensitive calcium channels in differentiated neuroblastoma X glioma hybrid (NG108-15) cells: characterization by quin 2 fluorescence.

Depolarization of differentiated neuroblastoma X glioma (NG108-15) cells with KCl (50 mM) or veratridine (50 microM) stimulated Ca2+ accumulation, was detected by quin 2 fluorescence. Intracellular Ca2+ concentrations ([Ca2+]i) were elevated about threefold from 159 +/- 7 to 595 +/- 52 nM (n = 12). Ca2+ entry evoked by high extracellular K+ concentration ([K+]o) was voltage-dependent and enhanced by the dihydropyridine agonists, BAY K 8644 and CGP 28 392, in a dose-dependent manner.

Preclinical studies with pyrazolopyridine non-benzodiazepine anxiolytics: ICI 190,622.

Tracazolate is a pyrazolopyridine anxiolytic that enhances the binding of [3H]-flunitrazepam [( 3H]FLU) to brain tissue. The discovery that a metabolite of tracazolate, desbutyltracazolate, was a weak inhibitor of [3H]FLU binding led to the synthesis of a series of potent anxiolytics. From this series, ICI 190,622 emerged as a viable drug candidate, being a potent anxiolytic in rats and monkeys.

Heterologous up-regulation of Ni-coupled receptors in cultured neural hybrid cells by a transferable factor, whose expression is inhibited in a cyclic AMP-dependent, cell-specific manner.

Opiate, muscarinic, and alpha 2-adrenergic receptors on NCB-20 and NG108-15 neuroblastoma hybrid cells were up-regulated by treatment of the cells with media (CM) conditioned by previous incubation with either cell type. NG cells treated with CM from both NCB and NG cells (NCB-CM or NG-CM) showed a 2-fold increase in opiate receptor density relative to untreated cells, with no change in ligand affinities. Opiate receptor density on NG cells was also enhanced approximately 2-fold by CM derived from dibutyryl cyclic AMP (dBc)-treated NG cells (NG-dBc-CM) but not by CM from dBc-treated NCB cells, (NCB-dBc-CM).

Calcium mobilization by muscarinic receptors in human astrocytoma cells: measurements with quin 2.

Activation of muscarinic cholinergic receptors on 1321N1 human astrocytoma cells leads to Ca2+ mobilization as measured by quin 2 fluorescence. Acetylcholine and methacholine were full and potent agonists, while carbachol and muscarine, were fully efficacious but 6- and 10-fold less potent than acetylcholine. The carbachol-induced Ca2+ response was also observed in absence of extracellular Ca2+ and was blocked by muscarinic receptor antagonists but not by organic Ca2+ channel blockers, tetrodotoxin (TTX), tetraethylammonium (TEA) or metal cations, suggesting that Ca2+ is mobilized from intracellular storage sites rather than through plasma membrane ion channels.

Heterogeneity of muscarinic receptors coupled to phosphoinositide breakdown in guinea pig brain and peripheral tissues.

Muscarinic receptors coupled to phosphoinositide hydrolysis (PI) are present in guinea pig bladder and colon. Compared to rat cerebral cortex, an extensively studied muscarinic/PI turnover system, all agonists were more potent and efficacious in both bladder and colon. The "M1-selective antagonists", pirenzepine and dicyclomine, were much more potent (Ki = 1-5 nM) and selective (300 to 500-fold) at both rat and guinea pig brain and guinea pig colon receptors, compared to PI-coupled receptors in guinea pig bladder.

Persistence of immunoreactive TRH and GnRH in long-term primary anterior pituitary cultures.

Intact anterior pituitary tissue and primary anterior pituitary cultures were stained with 1:30,000 anti-TRH and 1:10,000 anti-GnRH using the peroxidase antiperoxidase immunocytochemical technique. Stains applied to serial ultrathin sections of intact pituitaries showed that TRH immunoreactivity could be localized in secretory granules of thyrotropes, gonadotropes and corticotropes whereas GnRH immunoreactivity was found only in gonadotropes and corticotropes. Long-term primary pituitary cultures were studied to remove the anterior pituitary cells from hypothalamic influences.

Modulation of agonist and antagonist interactions at kidney alpha 1-adrenoceptors by nucleotides and metal ions.

In order to characterize putative high- and low-affinity states of the renal alpha 1-adrenoceptor, binding sites for the selective antagonist radioligand [3H]prazosin were examined in washed membranes prepared from rat renal cortex and medulla. Norepinephrine competition curves at [3H]prazosin sites were biphasic and were best fit by a two-site model. Na+ and GTP selectively decreased the proportion of sites exhibiting a high affinity for norepinephrine.

Ni-coupled receptors in cultured neural hybrid cells: cell specificity for dibutyryl cyclic AMP-induced down-regulation but not morphological differentiation.

Opiate, muscarinic, and alpha 2-adrenergic receptors and the Ni-coupled response of adenylate cyclase (AC) inhibition were examined in neuroblastoma X glioma NG108-15 (108 CC15) and neuroblastoma X Chinese hamster brain NCB-20 clonal hybrid cells, induced to differentiate with 1.0 mM dibutyryl cAMP (dBcAMP). Scatchard analysis of binding of the opiate agonist 3H-(D-Ala2,D-Leu5)enkephalin (DADLE) and the antagonist [3H] diprenorphine to dBcAMP-treated NCB-20 cell membranes indicated an 80% reduction in opiate receptor density relative to untreated cells (Bmax = 47 +/- 11 fmol/mg of protein versus 220 +/- 48 fmol/mg of protein), with no change in ligand affinities.

Pharmacological profile of adenosine A2 receptor in PC12 cells.

The PC12 cell line, a clone isolated from a pheochromocytoma tumor of rat adrenal medulla, was shown to exclusively contain stimulatory adenosine (A2) receptors linked to adenylate cyclase (AC). AC was stimulated 6-7 fold by several agonists with a rank order of potency of 5'-N-Ethyl carboxamidoadenosine (NECA) greater than 2-Chloroadenosine (2-CADO) greater than (R)-N-Phenylisopropyladenosine (R-(-)-PIA) greater than N6-Cyclopentyladenosine (CPA) greater than N6-Cyclohexyladenosine (CHA) greater than S-(+)-PIA. AC activity was antagonized by a variety of adenosine receptor antagonists with a potency order of 1,3,-Dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX) greater than 1,3,-Diethyl-8-phenylxanthine (DPX) greater than 8-Phenyltheophylline greater than 3-Isobutyl-1-methylxanthine (IBMX) greater than 8-(p-sulfophenyl)theophylline (PST) greater than 7-(beta-chloroethyl)theophylline greater than theophylline = enprofylline = caffeine.

Para-azidoclonidine: a novel photoaffinity ligand for the alpha 2-receptor.

Reversible and irreversible interactions of the photoreactive clonidine analogue p-azidoclonidine (PAZC) with brain alpha 2-adrenergic receptors were examined. In the absence of light, PAZC displayed selective, high affinity, competitive interactions with sites labeled by the alpha 2-agonist 3H-p-aminoclonidine (3H-PAC). Reversible binding characteristics resembled those of other alpha 2-agonists.

Induction of experimental allergic encephalomyelitis in Lewis rats with purified synthetic peptides: delineation of antigenic determinants for encephalitogenicity, in vitro activation of cellular transfer, and proliferation of lymphocytes.

Four highly purified synthetic peptides encompassing segments of the 68-86 region [for the numbering system used, see Eylar, E.H., Brostoff, S.

Characteristics of receptors and enzymes in brains of human alcoholics.

Acute and chronic ethanol administration to animals has been shown to produce changes in the turnover of numerous neurotransmitters, as well as to change the characteristics of certain neurotransmitter receptors. In the present study, brains obtained from human alcoholics and matched control subjects were examined for similar changes. In frontal cortex, the affinity of opiate receptors for dihydromorphine was significantly reduced in brains of alcoholics.

Inheritance of adrenal phenylethanolamine N-methyltransferase activity in the rat.

Phenylethanolamine N-methyltransferase (PNMT) is the enzyme that catalyzes the S-adenosyl-L-methionine-dependent methylation of (-)norepinephrine to (-)epinephrine in the adrenal medulla. Adrenal PNMT activity is markedly different in two highly inbred rat strains; enzyme activity in the F344 strain is more than fivefold greater than that in the Buf strain. Initial characterization of the enzyme in the two inbred strains reveals evidence for catalytic and structural differences, as reflected in dissimilar Km values for the cosubstrate (S-adenosyl-L-methionine) and prominent differences in thermal inactivation curves.

Assessment of the functional role of brain adrenergic neurons: chronic effects of phenylethanolamine N-methyltransferase inhibitors and alpha adrenergic receptor antagonists on brain norepinephrine metabolism.

The potential role of brain adrenergic neurons in regulating noradrenergic neuronal metabolism was assessed using inhibitors of phenylethanolamine N-methyltransferase (PNMT), the enzyme responsible for epinephrine production. Two centrally active PNMT inhibitors (SK&F 64139 and LY134046) were administered over a 6-day treatment period to cause prolonged reductions in epinephrine formation. In brain regions containing endogenous epinephrine (medulla-pons and hypothalamus), chronic treatment with PNMT inhibitors produced: 1) reductions of epinephrine content, 2) elevation of tyrosine hydroxylase activity and 3) elevation of alpha-1 and particularly alpha-2 adrenergic receptor radioligand binding sites; neither norepinephrine turnover nor beta adrenergic receptor binding was affected.

Changes in brain alpha-adrenergic receptors after alpha-methyldopa administration to spontaneously hypertensive rats.

The hypotensive action of methyldopa has been linked to production of the metabolites methyldopamine and methylnorepinephrine in brain. We have studied the effect of long-term (72 hour) intravenous infusions of methyldopa to awake restrained spontaneously hypertensive rats and normotensive Wistar-Kyoto control animals to look for differences in hypotensive effect, differences in concentrations of natural and alpha-methylated catecholamines, and differences in alpha 1 and alpha 2-adrenergic receptor populations. Results described here indicate that hypertensive rats have a greater reduction in blood pressure and a larger increase in hypothalamic and brain stem methylnorepinephrine concentrations than do the normotensive animals.

Binding of the imidazoline UK-14, 304, a putative full alpha 2-adrenoceptor agonist, to rat cerebral cortex membranes.

The aryl imidazoline compound UK-14, 304 (5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline) is a potent and selective alpha 2-adrenoceptor agonist with full intrinsic activity, unlike other imidazolines. We examined the characteristics of high specific activity (84 Ci/mmol) [3H]UK-14, 304 binding to rat cerebral cortex membranes. [3H]UK-14, 304 specific binding was enhanced by Mn2+ ion, and associated and dissociated moderately rapidly at 25 degrees C.

Prenatal exposure to drugs of abuse in humans: effects on placental neurotransmitter receptors.

Recently, the concept of behavioral teratology has evolved. In animal models, prenatal exposure to low doses of psychotropics (e.g.

Brain epinephrine systems: detailed comparison of adrenergic and noradrenergic metabolism, receptor number and in vitro regulation, in two inbred rat strains.

Epinephrine content and PNMT activity in medulla pons and hypothalamus of F344 inbred rats is from 3- to 8-fold higher than that of Buf inbred rats. These strain-dependent differences in brain adrenergic neurons are reciprocally related to altered alpha 1- adn alpha 2-adrenergic receptor density in PNMT-containing brain regions. Radioligand binding indices related to alpha 2-receptor function reveal that receptors may be 'desensitized' as well as 'down-regulated' in the strain with high PNMT activity (F344), and may be 'supersensitive' as well as 'up-regulated' in the strain with low PNMT activity (Buf).