Effect of chlorpromazine on mouse ambulatory activity sensitization caused by (+)-amphetamine

Presenilin 2 N141I mutation induces hyperactive immune response through the epigenetic repression of REV-ERBα

Hyperimmunity drives the development of Alzheimer disease (AD). The immune system is under the circadian control, and circadian abnormalities aggravate AD progress. Here, we investigate how an AD-linked mutation deregulates expression of circadian genes and induces cognitive decline using the knock-in (KI) mice heterozygous for presenilin 2 N141I mutation. This mutation causes selective overproduction of clock gene-controlled cytokines through the DNA hypermethylation-mediated repression of REV-ERBα in innate immune cells. The KI/+ mice are vulnerable to otherwise innocuous, mild immune challenges. The antipsychotic chlorpromazine restores the REV-ERBα level by normalizing DNA methylation through the inhibition of PI3K/AKT1 pathway, and prevents the overexcitation of innate immune cells and cognitive decline in KI/+ mice. These results highlight a pathogenic link between this AD mutation and immune cell overactivation through the epigenetic suppression of REV-ERBα.

Hyperimmunity is associated with Alzheimer disease. Here the authors show that the Presenilin 2 N141I mutation causes overproduction of clock-controlled cytokines and memory deficits through suppression of REV-ERBα gene by hypermethylation.

Potential for targeting dopamine/DARPP-32 signaling in neuropsychiatric and neurodegenerative disorders

INTRODUCTION

Alterations in dopamine neurotransmission has been implicated in pathophysiology of neuropsychiatric and neurodegenerative disorders, and DARPP-32 plays a pivotal role in dopamine neurotransmission. DARPP-32 likely influences dopamine-mediated behaviors in animal models of neuropsychiatric and neurodegenerative disorders and therapeutic effects of pharmacological treatment. Areas covered: We will review animal studies on the biochemical and behavioral roles of DARPP-32 in drug addiction, schizophrenia and Parkinson's disease. In general, under physiological and pathophysiological conditions, DARPP-32 in D1 receptor expressing (D1R) -medium spiny neurons (MSNs) promotes dopamine/D1 receptor/PKA signaling, whereas DARPP-32 in D2 receptor expressing (D2R)-MSNs counteracts dopamine/D2 receptor signaling. However, the function of DARPP-32 is differentially regulated in acute and chronic phases of drug addiction; DARPP-32 enhances D1 receptor/PKA signaling in the acute phase, whereas DARPP-32 suppresses D1 receptor/PKA signaling in the chronic phase through homeostatic mechanisms. Therefore, DARPP-32 plays a bidirectional role in dopamine neurotransmission, depending on the cell type and experimental conditions, and is involved in dopamine-related behavioral abnormalities. Expert opinion: DARPP-32 differentially regulates dopamine signaling in D1R- and D2R-MSNs, and a shift of balance between D1R- and D2R-MSN function is associated with behavioral abnormalities. An adjustment of this imbalance is achieved by therapeutic approaches targeting DARPP-32-related signaling molecules.

Treatment of the psychostimulant-sensitized animal model of schizophrenia

Behavioral sensitization to psychostimulants in rodents is associated with the alteration of dopaminergic neurotransmission, and has been proposed as a useful model of schizophrenia due to its progressively intensifying, easily relapsing, and long-lasting features. Pharmacological treatments that reverse the established sensitization may have potential therapeutic values for schizophrenia. The present aim is to review pharmacological treatments that induce the reversal of established sensitization to psychostimulants. In addition, we discuss possible mechanisms for the reversal of sensitization. Reversal of sensitization is induced by chronic dopamine D1 receptor agonism, D2 or D1/D2 receptor agonism combined with mild N-methyl-D-aspartate (NMDA) receptor antagonism or serotonin (5-HT(2A) or 5-HT(3) ) receptor antagonism, 5-HT(1A) receptor agonism, and 5-HT(2A) or 5-HT(3) receptor antagonism. Chronic treatments with these drugs likely adjust altered dopaminergic neurotransmission in sensitized animals. Especially, chronic dopamine D1 receptor agonism, which may adjust mesolimbic hyperdopaminergic and mesocortical hypodopaminergic functions in sensitized animals, is an attractive therapeutic approach for schizophrenia.

Effects of SKF-38393, a dopamine D1 receptor agonist on expression of amphetamine-induced behavioral sensitization and expression of immediate early gene arc in prefrontal cortex of rats

Repeated administrations of psychostimulants into rodents produce behavioral sensitization. We examined whether a dopamine D1 agonist can reverse behavioral sensitization once established by repeated amphetamine (AMP) administrations and determined the mRNA expression levels of the D1 and D2 receptors, metabotropic glutamate receptor 1 (mGluR1), and activity-regulated cytoskeleton-associated protein (arc) in rats. Rats were pretreated with six intermittent AMP injections. Following a 14-day withdrawal period, the rats were divided into six groups and treated with either SKF-38393 (SKF; dopamine D1 agonist), SCH-23390 (SCH; selective D1 antagonist), YM-09151-2 (YM; selective D2 antagonist), SKF+SCH, SKF+YM or physiological saline once daily for 5 days. Three days or 4 weeks after the reversal treatments, all the rats were rechallenged with AMP. D1 and D2 antagonist treatments produced no significant decreases in locomotor activity or stereotyped behavior rate, respectively. In the SKF treatment group, stereotyped behavior rate decreased markedly after the three-day and four-week withdrawal periods. SKF+SCH treatment inhibited the effect of SKF treatment. The rats in the other groups that received AMP with or without SKF were decapitated 1 h after treatment, and the mRNA levels of the D1 and D2 receptors, mGluR1, and arc were measured by TaqMan real-time reverse transcriptase-polymerase chain reaction (RT-PCR). AMP administration significantly increased arc level. SKF also increased arc level significantly after the first single injection and after repeated injections of AMP during the pretreatment. There was no significant difference in arc expression level between the saline and SKF treatment groups after the AMP challenge, suggesting that arc expression level is not involved in the reversal effects of SKF in AMP sensitization.

Amphetamine-induced locomotor activation in 5-HT(1B) knockout mice: effects of injection route on acute and sensitized responses

Knockout mice lacking serotonin(1B) (5-hydroxytryptamine(1B); 5-HT(1B)) receptors (1BKO) exhibit increased sensitivity to the stimulant and reinforcing effects of indirect dopamine (DA) agonists and are more reactive to mild stressors such as handling and the injection procedures that commonly occur when using the intraperitoneal (i.p.) route of drug administration. Since the intravenous (i.v.) route of administration allows minimal handling and injection-induced stress, the present study was designed to evaluate the effect of the administration route on amphetamine-induced locomotor activation and behavioural sensitization in 1BKO mice. For this purpose, 1BKO and wild-type (WT) control mice were administered i.p. or i.v. amphetamine in a within-session design, which allows evaluation of a complete dose-response curve within a single session. The locomotor stimulant effects of i.p. (0.5-4.0 mg/kg) and i.v. (0.6-1.2 mg/kg) amphetamine were investigated both acutely and following repeated treatments (four treatments at 48 h intervals). The results showed that acute i.p. amphetamine injection induced a significant higher horizontal activity peak effect in 1BKO mice, while this difference was less profound after acute i.v. injection. However, repeated i.p. or i.v. administration of amphetamine induced significantly higher locomotion in 1BKO mice. We conclude that the stimulant effects of amphetamine can be influenced by the route of administration in a genotype-dependent manner, and that route of drug administration (and associated variables) should be considered an important factor in studies of psychostimulant action in knockout mice.

Quantitative analysis of the effects of lithium on the reverse tolerance and the c-Fos expression induced by methamphetamine in mice

To elucidate the mechanism of psychostimulant-induced reverse tolerance [A. Kifune, S. Tadokoro, Modification of stereotype producing and ambulation-increasing effects following repeated administration of methamphetamine in rats, Jpn. J. Psychopharmacol. 11 (1991) 207-214 [11]; N.J. Leith, R. Kuczenski, Chronic amphetamine: tolerance and reverse tolerance reflect different behavioral actions of the dog, Pharmacol. Biochem. Behav. 15 (1981) 399-405 [13]; S. Tadokoro, H. Kuribara, Reverse tolerance to the ambulation-increasing effect of methamphetamine in mice as an animal model of amphetamine-psychosis, Psychopharmacol, Bull. 22 (1986) 757-762 [18]; S. Tadokoro, H. Kuribara, Modification of the behavioral effects of drugs after repeated administration: special reference to the reverse tolerance, Folia Pharmacologica Japonica 95 (1990) 229-238 [19]], the effects of lithium on ambulatory activity [P. Cappeliez, E. Moore, Effects of lithium on an amphetamine animal model of bipolar disorder, Prog. Neuro-Psychopharmacol. Biol. Psychiatry 14 (1990) 347-358 [1]; M. Hirabayashi, M.K. Alam, Enhancing effect of methamphetamine on ambulatory activity produced by repeated administration on mice, Pharmacol. Biochem. Behav. 15 (1981) 925-932 [7]; M. Hirabayashi, S. Okada, S. Tadokoro, Comparison of sensitization to ambulation-increasing effects of cocaine and methamphetamine after repeated administration in mice, J. Pharm. Pharmacol. 43 (1991) 827-830 [8]; T. Miyauchi, K. Kikuchi, S. Satoh, Further studies on the potentiating effect of lithium chloride on methamphetamine-induced stereotypy in mice, Jpn. J. Pharmacol. 31 (1981) 61-68 [14]; H. Ozawa, T. Nozu, H. Aihara, F. Akiyama, M. Sasajima, Pharmacokinetics and general pharmacological actions of lithium salts administered singly or repeatedly, Folia Pharmacologica Japonica 72 (1976) 433-443 [15].] and cerebral c-Fos expression [S. Ceccatelli, M.J. Villar, M. Goldstein, T. Hokfelt, Expression of c-Fos immunoreactivity in transmitter-characterized neurons after stress, Proc. Natl. Acad. Sci. USA 86 (1989) 9569-9573 [2]; L. Giovannelli, P.J. Shiromani, G.F. Jirikoski, F.E. Bloom, Expression of c-fos protein by immunohistochemically identified oxytocin neurons in the rat hypothalamus upon osmotic stimulation, Brain Research 588 (1992) 41-48 [4]; B.T. Hope, H.E. Nye, M.B. Kelz, D.W. Self, M.J. Iadarola, Y. Nakabeppu, R.S. Duman, E.J. Nestler, Induction of a long-lasting AP-1 complex composed of altered Fos-like proteins in brain by chronic cocaine and other chronic treatments, Neuron 13 (1994) 1235-1244 [10]; T. Miyauchi, K. Kikuchi, S. Satoh, Further studies on the potentiating effect of lithium chloride on methamphetamine-induced stereotypy in mice, Jpn. J. Pharmacol. 31 (1981) 61-68 [14]; F.R. Sharp, S.M. Sager, K. Hicks, D. Lowenstein, K. Hisanaga, c-fos mRNA, Fos, and Fos-related antigen induction by hypertonic saline and stress, J. Neurosci. 11 (1991) 2321-2331 [16].] were investigated in mice injected with methamphetamine (2 mg/kg, s.c., one to five times). The ambulatory activity enhanced by either acute or chronic methamphetamine injection was delayed or diminished by lithium chloride (LiCl) pretreatment [R.G. Fessler, R.D. Sturgeon, S.F. London, H.Y. Meltzer, Effects of lithium on behaviour induced by phencyclidine and amphetamine in rats. Psychopharmacology 78 (1982) 373-376 [3].]. How the Li-sensitive c-Fos expression in the dorsolateral geniculate nucleus and striatum is related to methamphetamine-induced behavioral excitation is unclear. This protocol, in combination with c-Fos expression of mouse cerebral regions, may provide a useful tool for quantitation of ambulatory activity during c-Fos expression.

Lithium inhibits the reverse tolerance and the c-Fos expression induced by methamphetamine in mice

To elucidate the mechanism of psychostimulant-induced reverse tolerance, the effects of lithium on ambulatory activity and cerebral c-Fos protein expression were investigated in mice injected with methamphetamine (2 mg/kg, s.c., 1-5 times). The ambulatory activity enhanced by either acute or chronic methamphetamine injection was delayed or diminished by LiCl pretreatment (170 mg/kg, s.c., 1 h before methamphetamine). The c-Fos expression in the dorsal lateral geniculate nucleus and in the striatum was significantly increased by acute but not chronic injection of methamphetamine, and the increases were significantly suppressed by LiCl pretreatment. Although how the Li-sensitive c-Fos expressions in the dorsolateral geniculate nucleus and striatum are related to methamphetamine-induced behavioral excitation is unclear, these results suggest that lithium at least functionally interferes with the formation of the state of reverse tolerance to methamphetamine in the mouse.

Phencyclidine-induced expression of c-Fos-like immunoreactivity in mouse brain regions

For the purpose of studying a role of immediate early genes in psychotomimetic-induced behavioral excitation, we experimentally enhanced the locomotor activity of mice by acute administration of phencyclidine and examined the expression and localization of the c-Fos-like and c-Jun-like immunoreactivities in brain regions. A single injection of phencyclidine (5.0 mg/kg, i.p.) significantly increased not only the locomotor activity but also the expression of c-Fos-like immunoreactivity in several brain regions, particularly in the parietal cortex, hippocampal dentate gyrus, piriform cortex and hypothalamus. Interestingly, the c-Fos-like immunoreactivity in the parietal cortex continued to increase for 1 week after the phencyclidine injection. These results indicate that phencyclidine, even injected only once, can induce the persistent expression of c-Fos or c-Fos-related protein(s) in the mouse brain, and also suggest the possibility that such a c-Fos expression may underlie the behavioral and/or psychotomimetic effects of phencyclidine.