Role of dopamine D1-like receptors in methamphetamine locomotor responses of D2 receptor knockout mice

Behavioral sensitization to psychostimulants manifests as an increased locomotor response with repeated administration. Dopamine systems are accepted to play a fundamental role in sensitization, but the role of specific dopamine receptor subtypes has not been completely defined. This study used the combination of dopamine D2 receptor-deficient mice and a D1-like antagonist to examine dopamine D1 and D2 receptor involvement in acute and sensitized locomotor responses to methamphetamine. Absence of the dopamine D2 receptor resulted in attenuation of the acute stimulant effects of methamphetamine. Mutant and wild-type mice exhibited sensitization that lasted longer within the time period of the challenge test in the mutant animals. Pretreatment with the D1-like receptor antagonist SCH 23390 produced more potent reductions in the acute and sensitized locomotor responses to methamphetamine in D2 receptor-deficient mice than in wild-type mice; however, the expression of locomotor sensitization when challenged with methamphetamine alone was equivalently attenuated by previous treatment with SCH 23390. These data suggest that dopamine D2 receptors play a key role in the acute stimulant and sensitizing effects of methamphetamine and act in concert with D1-like receptors to influence the acquisition of methamphetamine-induced behavioral sensitization, traits that may influence continued methamphetamine use.Fil: Kelly, M. A.. Oregon Health And Science University; Estados UnidosFil: Low, M. J.. Oregon Health And Science University; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Phillips, T. J.. Oregon Health And Science University; Estados Unido

Blockade of Scopolamine Tolerance and Modification of Methamphetamine Sensitivity by Pilocarpine, a Muscarinic Cholinergic Drug, Evaluated in Terms of the Ambulation in Mice

The ambulation-increasing effect of scopolamine (SCP: 2 mg/kg s.c.), a muscarinic anti-cholinergic drug, was inhibited by simultaneously administered pilocarpine (PILO: 1, 3 and 10 mg/kg s.c.) in a dose-dependent manner. The behavioral tolerance to SCP induced by repeated administration at 3-day intervals was protected when PILO (10 mg/kg) was administered at post-scopolamine period of 0 min (simultaneous) and 5 min, but not 20 min or later, although the repeated administrations of PILO alone did not change the sensitivity to SCP. These treatments induced no significant change in the sensitivity to methamphetamine (2 mg/kg s.c.). These results suggest that repeated experience of both the muscarinic anti-cholinergic effect of SCP and the free ambulation during the early post-SCP period of 0-20 min is essential factor for the induction of behavioral tolerance to SCP in mice. It is also suggested that repeated experience of both central and peripheral anti-cholinergic effect may not increase the risk to psychotoxic effect of psychomotor stimulants such as methamphetamine

Block of the Tolerance to Ambulation Stimulant Effect of Scopolamine in Mice by Bethanecol, a Peripheral Cholinergic Drug

A behavioral tolerance to the ambulation-increasing effect of scopolamine (SCP: 2 mg/kg s.c.), a muscarinic anti-cholinergic drug, was induced following the repeated administration to mice at 3-day intervals. The combined administration of SCP + bethanechol (BET: 0.01, 0.03, 0.1 and 0.3 mg/kg s.c.), a peripheral muscarinic cholinergic drug, resulted in sensitization, although the single treatment with 0.03-0.1 mg/kg of BET did not modify the ambulation-increasing effect of SCP at the first administration. In addition, the treatment with BET (0.1 mg/kg) at post-SCP period of 5-20 min also induced the sensitization to SCP after the repeated administration. The post-SCP treatment with BET at 30 min and later produced the tolerance to SCP. The repeated administrations of BET alone did not change the sensitivity to the ambulation-increasing effect of SCP. Furthermore, the mice showing sensitization to SCP + BET, but not tolerance to SCP, demonstrated a cross-sensitization to methamphetamine (2 mg/kg s.c.). These results suggest that the tolerance to SCP is produced by the interaction of the stimulation of central dopaminergic system (reward effect) through the blockade of peripheral muscarinic cholinergic receptors (harmful effect), and that the latter effect overwhelms the former effect of SCP. It is also suggested that the selective inhibition of the peripheral anti-cholinergic effect of SCP increases the dependence liability of SCP, and psychotoxicity of anti-cholinergic drugs including SCP and psychomotor stimulant drugs such as methamphetamine

Interaction of Nicotine and N-cyanomethylmethamphetamine, a Main Pyrolysis Product of Smoking Methamphetamine Mixed with Tobacco, in Terms of the Sensitization to the Ambulatory Stimulant Effect in Mice

N-cyanomethylmethamphetamine (CMA) is a main pyrolysis product of smoking methamphetamine (MA) mixed with tobacco, and it has MA-like central stimulant effects, acceleration of ambulation and production of various types of stereotyped behavior, and induction of sensitization to these behavioral effects following repeated administration in mice and rats. The induction of behavioral sensitization to central stimulants has been considered to be intimately related to the development of the psychotoxic symptoms following repeated abuse of these drugs. Since CMA is inhaled simultaneously with nicotine, the aim of this study was to investigate the modifications by nicotine of induction and expression of sensitization to the ambulation-increasing effect of CMA in mice. During the 5 repeated co-administrations of CMA (3 mg/kg s.c.) with nicotine (0.03, 0.1, 0.3 and 1 mg/kg s.c.) at 3 day intervals, nicotine dose-dependently inhibited the progressive enhancement of CMA-induced ambulatory stimulation. However, such treatments did not modify the induction of sensitization to the ambulatory stimulant effect of MA (2 mg/kg s.c.). The MA-sensitized mice demonstrated significant cross-sensitization to CMA. In both the drug-naive and MA-sensitized mice, nicotine reduced the ambulatory stimulant effect of CMA. These results suggest that, although nicotine acts to reduce the ambulatory stimulant effect of CMA, nicotine does not protect the induction of behavioral sensitization to CMA and MA. The repeated 5 times experience of nicotine (1mg/kg s.c.) alone did not modify the sensitivity of mice to CMA or MA. These results also indicate that nicotine does not modify the psychotoxic liability of MA following repeated smoking MA mixed with tobacco, although nicotine may reduce the reward effect of MA

Induction of the Sensitization to Morphine-induced Ambulatory Stimulation in Mice: Importance of Free Movement in the Early Post-Morphine Period

Morphine (10 mg/kg s.c.) accelerated the ambulatory activity of mice for 3 hr with a peak effect around 1/2-1 hr after the administration. A sensitization to the morphine-induced stimulation was induced when the mice were repeatedly given morphine at 3-day intervals, and they were individually put in activity cages of 20 cm in diameter for 3 hr after each administration. The sensitization attained a plateau by the 4th administration, and the 3-hr overall activity counts at the 4th and later administrations were 2.2-2.4 times as high as that at the first administration. However, neither marked change in the latency to the peak effect nor prolongation of the stimulant effect was demonstrated even in the morphine-sensitized mice. The mice allowed ambulation in the activity cages during post-morphine period of 1/2-1 hr showed a strong sensitization as high as that in the mice given morphine with the free ambulation for 3 hr. Whereas, the limited allowance of ambulation during the post-morphine periods of 0-1/2 and 1-3 hr resulted in only partial or no sensitization. The repeated administrations of saline with free or limited ambulation caused no significant change in the sensitivity to morphine. These results suggest that the repeated experience of both morphine effect and the resultant ambulation during the early post-morphine period of 1/2-1 hr, i.e., immediately before the peak effect, highly contributes to the induction of ambulatory sensitization to morphine in mice. This period may be related to the development of the reward effect of narcotic analgesic drugs such as morphine and heroin which is the main factor of abuse and dependence liability

Time-Dependent Inhibition by Naloxone, an Opiate Receptor Antagonist, of the Sensitization to Morphine-Induced Ambulatory Stimulation

Abstract:A significant sensitization to the ambulation-stimulating effect of morphine (10 mg/kg s.c.), a narcotic analgesic drug with agonistic action on opiate receptors, was produced when mice were repeatedly administered morphine at intervals of 3 days, and their ambulation was measured for 3 hr in an activity cage of 20 cm in diameter after each administration. Naloxone (0.01-1 mg/kg s.c.), an opiate receptor antagonist, blocked the morphine-induced ambulation in a dose-dependent manner. The mice treated with naloxone at post-morphine period of 3/4 hr and later showed a strong ambulatory sensitization as high as that in the mice repeatedly given morphine alone. The treatment with naloxone at post-morphine period of 1/2 hr caused a partial sensitization, and at 0-1/3 hr no significant sensitization. The repeated administrations of naloxone alone or saline caused no significant change in the sensitivity to morphine. These results suggest that experience of morphine effect and the resultant ambulation for 1/2 hr prior to the peak effect is important for induction of the sensitization to the ambulation-increasing effect of morphine in mice. This finding also indicates that the reward effect of morphine appears in the early post-morphine period prior to the peak effect, which is the essential factor for induction and maintenance of the abuse and dependence of narcotic analgesic drugs such as morphine and heroin

Alcohol Intoxication and Drunken Frenzy and/or Hangover Models in Terms of Discrete Shuttle Avoidance Behavior in Mice

The aim of this study was to assess the modification of the behavioral effect of ethanol by antialcoholic drugs, Ca-cyanamide and disulfiram, in terms of discrete shuttle avoidance response in mice. Ethanol (2g/kg p.o.) significantly increased the response rate due to its disinhibitory action. Although the single administration of Ca-cyanamide (1-10 mg/kg p.o.) or disulfiram (3-30 mg/kg p.o.) did not change the response rate, these drugs inhibited the ethanol-induced increase in the response rate. A similar reduction of the response rate was produced by the single administration of acetaldehyde (1-10mg/kg p.o.), and the combined administration of ethanol (2 g/kg) + acetaldehyde (1-10 mg/kg). These results suggest that the combined administration of ethanol and antialcoholic drugs may cause an accumulation of acetaldehyde, and may decrease in the response rate. In summary, it is expected that the present experimental conditions of the discrete shuttle avoidance can be applied to behaviorally investigate not only the disinhibition (alcohol intoxication) but also the drunken frenzy (sickness) and/or hangover induced by ethanol in mice

Alleviation of the Drunken Frenzy/Hangover-like Symptoms by SJS, a Japanese Herbal Medicine, in Mice

A Japanese herbal medicine SJS is made of hot water extract of Chishimazasa leaves (Sasa kurilensis (Ruprecht) Makino et Shibata: SS), and ethanol extracts of Japanese red pine leaves (Pinus densiflora Siebold & Zucc.: RP) and Ginseng roots (Panax ginseng C.A. Meyer: PG). The aim of this study was to assess the modification by SJS of the intoxication and drunken frenzy models in terms of discrete shuttle avoidance behavior in mice. The response rate (number of shuttles) was increased by ethanol (2 g/kg p.o.), but decreased by the combined administration of ethanol + Ca-cyanamide (10 mg/kg p.o.), an anti-alcoholic drug. Although SJS, freely given 10% solution for 4 weeks and longer, or acutely administered at doses of 10 and 20 ml/kg p.o., did not change the ethanol effect, it significantly recovered the decreased response rate by ethanol + Ca-cyanamide. A similar significant recovery of response rate was demonstrated by PR and SS, but not by PG. These results suggest that SJS alleviates the ethanol-induced drunken frenzy and/or hangover without significant effect on the ethanol intoxication (disinhibition)

Modification by Nicotine of the Sensitization to Methamphetamine-induced Ambulatory Stimulation in Mice: Possibility of Increase in Methamphetamine Dose of Abuse and Enhancement of Its Psychotoxicity

Since methamphetamine (MAP) has been frequently inhaled simultaneously with nicotine, i.e., cigarette smoking mixed with MAP, the modification by nicotine of the behavioral sensitization to MAP was evaluated in terms of ambulatory activity in mice. During the 5 repeated co-administrations of MAP (2 mg/kg s.c.) with nicotine (0.03, 0.1, 0.3 and 1 mg/kg s.c.) at 3 day intervals, nicotine dose-dependently inhibited the progressive enhancement of MAP-induced ambulatory stimulation. However, such pre-treatments did not modify the induction of ambulatory sensitization to MAP (2 mg/kg s.c.). In both the drug-naive and MAP-sensitized mice, nicotine reduced the ambulatory stimulant effect of MAP. These results suggest that, although nicotine reduces the expression of ambulatory stimulant effect of MAP, nicotine does not protect, but rather accelerate, the induction of psychotoxic effect of MAP

Enzyme-free release of adhered cells from standard culture dishes using intermittent ultrasonic traveling waves.

Cell detachment is essential in culturing adherent cells. Trypsinization is the most popular detachment technique, even though it reduces viability due to the damage to the membrane and extracellular matrix. Avoiding such damage would improve cell culture efficiency. Here we propose an enzyme-free cell detachment method that employs the acoustic pressure, sloshing in serum-free medium from intermittent traveling wave. This method detaches 96.2% of the cells, and increases its transfer yield to 130% of conventional methods for 48 h, compared to the number of cells detached by trypsinization. We show the elimination of trypsinization reduces cell damage, improving the survival of the detached cells. Acoustic pressure applied to the cells and media sloshing from the intermittent traveling wave were identified as the most important factors leading to cell detachment. This proposed method will improve biopharmaceutical production by expediting the amplification of tissue-cultured cells through a more efficient transfer process