Blockade of morphine-induced place preference by diazepam in mice

We assessed the efficacy of combined laparoscopic and minilaparotomy for outpatient microsurgical reversal of extensive tubal sterilization in 11 women undergoing the procedure and followed for a mean of 24.7 months. All patients desired reversal of extensive tubal sterilization, and had 4 cm or less of the longer oviduct remaining. The mean operating time was 110 minutes, and the mean total cost was $5067. There were no major complications. Two women were treated for uncomplicated cystitis within 1 month of surgery. Five (45%) of 11 women delivered viable infants; one patient had two ectopic pregnancies. These preliminary data suggest that outpatient combined laparoscopy and minilaparotomy may be effective in patients who desire restoration of fertility after extensive tubal sterilization.     

Ibogaine attenuates morphine-induced conditioned place preference.

Ibogaine, a putative anticraving drug in humans, reduces the ability of a single injection of morphine to produce a place preference in rats (Rattus norvegicus). The attenuation of morphine's effect is seen even if ibogaine is administered 24 hr before the opiate. However, after the 4th morphine conditioning trial, ibogaine no longer modified morphine reward. Ibogaine alone is neither reinforcing nor aversive, and ibogaine does not affect place aversions produced by naloxone or lithium chloride. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intra-ventral pallidal glutamate antagonists block expression of morphine-induced place preference.

The role of ionotropic glutamate receptors within the ventral pallidum (VP) in the expression of conditioned place preference (CPP) and motor adaptations to morphine was evaluated. VP-cannulated rats were subjected to 3 days of conditioning in which saline was paired to one distinct chamber in the morning and morphine (8 mg/kg ip or its vehicle) was paired to an alternate chamber in the afternoon. This induced (a) CPP expression in drug-free rats 1 day later, which was blocked by immediate pretreatments with intra-VP injections of a glutamate antagonist cocktail (DL-2-amino-5- phosphonopentanoic acid lithium salt [AP-5] + 6-cyano-7-nitroquinoxaline-2,3-dione disodium salt [CNQX]), and (b) changes in motor function expressed following an acute morphine challenge 18 days later, which were absent if preceded by a 10-day treatment with the glutamate antagonists injected unilaterally once daily in alternating hemispheres. Thus, VP ionotropic glutamate receptors are critical mediators of the expression of place preference and motor adaptations subsequent to repeated morphine exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verapamil suppresses d-amphetamine-induced place preference conditioning

The effect of pretreatment with (+/-)-verapamil (5, 10 or 15 mg/kg, i.p.) on place preference induced with d-amphetamine (1 mg/kg, i.p. 40 min after verapamil) was studied in male rats. Place preference conditioning was performed using two-compartment shuttle boxes and 8 alternating stimulant/saline sessions. Verapamil dose-dependently suppressed amphetamine-induced place preference. No significant changes in place preference were observed following 8 alternating verapamil (no stimulant)/saline sessions, irrespective of whether verapamil injections were paired with the originally less or the originally more preferred compartment. It appears that verapamil effectively suppresses the reinforcing properties of d-amphetamine in the paradigm used.     

Blockade of morphine- and amphetamine-induced conditioned place preference in the rat by riluzole

Three cases of isolated one-and-a-half syndrome with facial nerve palsy related to infarction are presented. Magnetic resonance imaging in cases 1 and 2 was unremarkable, whereas magnetic resonance angiography demonstrated pathophysiologically significant vertebral basilar disease. Case 3 is unique due to its association with giant cell arteritis. Ipsilateral adduction improved to a greater extent than abduction in each case, perhaps providing insight into the exact localization of these lesions or selective vulnerability of the ocular motor structures within the pons. This combination of clinical findings, termed the 8-1/2 syndrome (cranial nerve 7 + 1-1/2), allows precise localization, and magnetic resonance angiography appears to be the imaging study of choice.     

Cocaine-conditioned place preference in young precocial domestic fowl.

Experiment 1 established conditioned place preference (CPP) control procedures for young precocial domestic fowl (test day age?=?13–25 days). Chicks displayed a preference (greater choice time) for white stimulus cards on first exposure to white versus red cards and equivalent preference for these stimulus cards after 6 exposures. Chicks in Experiment 2 displayed a cocaine CPP at each dose (0.5, 1.0, and 2.0 mg/kg intraperitoneally) after 6 cocaine-red card and 6 saline-white card pairings. This CPP decreased and was no longer significant over 2 additional nonreinforced test days. Experiment 3 results replicated the cocaine CPP (2.0 mg/kg) and demonstrated that the CPP did not develop when cocaine was administered several hours after card exposure. To our knowledge, these results are the first to demonstrate drug CPP in a nonmammalian model and support the notion that drug reinforcement processes are highly conserved. This precocial avian model may prove a useful addition to existing altricial models for the study of determinants of human drug use and abuse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Isradipine produces neither a conditioned place preference nor aversion

Isradipine (ISR) has been reported to block cocaine-induced conditioned place preference. Using this procedure, the pairing of this L-type calcium blocker, at doses of 2.5, 5.0 and 10 mg/kg, with a preferred (cue-distinct) environment was investigated. In a separate experiment, ISR injection (10 mg/kg) was paired with the less-preferred environment to determine whether ISR produces a place preference. Testing in the non-drugged state revealed that ISR conditioning failed to affect side preference in both experiments. The neutral affective properties of ISR may be relevant to the development of cocaine use/abuse treatment regimens.     

Sexual behavior regulated (paced) by the female induces conditioned place preference.

The possibility that female-paced coital behavior induces a reward state of sufficient intensity and duration to induce conditioning was evaluated by the conditioned-place-preference paradigm. Ovariectomized female rats, treated with estradiol benzoate and progesterone, regulated (paced) their coital interactions with a stud male through a 2-compartment chamber in which only the female could freely move from one compartment to the other. The females that paced their coital interactions showed a clear place preference. In contrast, no change in preference was observed in the females that could not pace their coital contacts. The change in preference in the females that paced their coital interactions was similar to that produced by an injection of morphine (1 mg/kg). These results suggest that coital interactions in females can induce a reward state when the females can control the pace of the sexual interaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ibogaine interferes with the establishment of amphetamine place preference learning.

The ability of ibogaine, injected 24 hr before amphetamine, to modify the establishment of amphetamine-induced place preference learning was assessed. A single injection of ibogaine blocked the establishment of amphetamine place preference after 1 or 2 conditioning trials, but it was less effective after 4 trials. The reduced effectiveness of ibogaine across multiple conditioning trials appears to be the result of the development of tolerance to ibogaine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Baclofen facilitates the extinction of methamphetamine-induced conditioned place preference in rats.

The powerful, long-lasting association between the rewarding effects of a drug and contextual cues associated with drug administration can be studied using conditioned place preference (CPP). The GABAB receptor agonist baclofen facilitates the extinction of morphine-induced CPP in mice. The current study extended this work by determining if baclofen could enhance the extinction of methamphetamine (Meth) CPP. CPP was established using a six-day conditioning protocol wherein Meth-pairings were alternated with saline-pairings. Rats were subsequently administered baclofen (2 mg/kg i.p. or vehicle) immediately after each daily forced extinction session, which consisted of a saline injection immediately prior to being placed into the previously Meth- or saline-paired chamber. One extinction training cycle, consisted of six once-daily forced extinction sessions, mimicking the alternating procedure established during conditioning, followed by a test for preference (Ext test). CPP persisted for at least four extinction cycles in vehicle-treated rats. In contrast, CPP was inhibited following a single extinction training cycle. These data indicate that Meth-induced CPP was resistant to extinction, but extinction training was rendered effective when the training was combined with baclofen. These findings converge with the prior demonstration of baclofen facilitating the extinction of morphine-induced CPP indicating that GABAB receptor actions are independent of the primary (unconditioned) stimulus (i.e., the opiate or the stimulant) and likely reflect mechanisms engaged by extinction learning processes per se. Thus, baclofen administered in conjunction with extinction training may be of value for addiction therapy regardless of the class of drug being abused. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Differential effects of 7-OH-DPAT on amphetamine-induced stereotypy and conditioned place preference

Cost-effectiveness and cost per successful treatment has been evaluated in 186 outpatients randomised to treat moderate to severe migraine attacks either with subcutaneous sumatriptan 6 mg (n = 97) or with their current therapy (n = 89) during an open, multicentre study of 3 months. Within 2 hours, headache severity decreased to none/mild in 86% of all attacks in the sumatriptan group (STG) compared to 25% in the customary group (CTG). Migraine was alleviated earlier in the STG than in the CTG (median 3.78 vs. 13.39 hours, p < 0.0001). The direct and total cost of treatment was 133 and 2012 BF, respectively, in the CTG and 1400 and 2522 BF, respectively, in the STG. Measuring the effectiveness of earlier pain relief with sumatriptan, the incremental cost-effective ratios for direct and total cost were 132 and 53 BF per hour of relieved pain, respectively. For this price, significantly more sumatriptan patients improved their quality of life by more than 20% (61.6 vs. 20.6% patients, p < 0.001) and less sumatriptan patient consulted a medical professional (11.3 vs. 29.2% patients, p < 0.01), used less medication for adverse events (6.2 vs. 22.5%, p < 0.001) and suffered less from associated migraine symptoms. The median number of hours of diminished work-efficiency (3 vs. 7 hours, p < 0.01) or of suspension of non-professional activity (10 vs. 24 hours, p < 0.001) was also significantly lower in the STG. The total cost per successfully treated patient was lower in the STG. Sumatriptan is more effective, provides a better quality of life, reduces health care resource utilisation, and improves work productivity as compared to the CTG, thereby resulting in a favourable cost-effectiveness ratio.     

Facilitation of ejaculation induced by 8-OH-DPAT does not produce conditioned place preference in male rats.

The serotonin 1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) produces a drastic facilitation of ejaculation characterized by a significant reduction in the number of pre-ejaculatory intromissions and a shortening of ejaculation latency. In the present study, the authors evaluated whether this facilitation of ejaculation can induce a reward state assessed by conditioned place preference. Males treated with 0.1 or 1.0 mg/kg of 8-OH-DPAT showed a clear facilitation of ejaculation but did not develop conditioned place preference. These results clearly indicate that the pharmacological facilitation of ejaculation and the reduction of the number of intromissions does not necessarily make sex rewarding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potentiation of morphine-induced seizure by 6-hydroxydopamine

A retrospective study of sixteen patients with pelvic fractures compounded through the perineum, rectum, or vagina showed a mortality of 50 per cent. The cause of death in seven of the eight patients was sepsis and multisystem failure. The initial surgical management of these patients must include complete diversion of the fecal stream so that pelvic and systemic sepsis may be prevented.     

The NMDA receptor antagonist MK-801 elicits conditioned place preference in rats

(+)-5-Methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate, (MK-801) a potent noncompetitive antagonist of central NMDA receptors, has been hypothesized to have rewarding properties indicative of abuse potential. To test this hypothesis, the effects of MK-801 on the acquisition of a conditioned place preference and on locomotor activity were assessed and compared with d-amphetamine. Both MK-801 (0.03 and 0.1 mg/kg, SC) and d-amphetamine (1.0 mg/kg, SC) administration resulted in the acquisition of a conditioned place preference. However, while both amphetamine and the higher dose of MK-801 produced a behavioral activation during the training period the lower dose of MK-801 did not. These results suggest that MK-801, at doses that produce behavioral activation and below, is rewarding and therefore may have abuse potential.     

Naloxone blocks place preference conditioning after paced mating in female rats.

Sexual behavior in male rats induces a positive affect as evaluated by conditioned place preference (CPP). In addition, when females control or "pace" the rate of sexual interaction, a clear CPP is also observed. The reward state induced by mating in male rats is blocked by the injection of the opioid antagonist naloxone. In the present experiment, a dose of 4 mg/kg of naloxone completely blocked the CPP induced in females by paced mating. It appears that a common opioid system is involved in the positive affect induced by sexual behavior in both male and female rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential involvement of enkephalins in analgesic tolerance, locomotor sensitization, and conditioned place preference induced by morphine.

In this study, the authors investigated the role of enkephalins in morphine-induced conditioned place preference, locomotor sensitization, and analgesic tolerance. Both preproenkephalin wild type (ppENK [+/+]) and knockout (ppENK [-/-]) mice showed similar preference for the morphine-paired chamber over the vehicle-paired chamber, indicating morphine induced comparable conditioned place preference in ppENK (+/+) and ppENK (-/-) mice. Sensitization developed to the motor stimulatory action of morphine after its repeated administration, but the magnitude of this response was not altered in ppENK (-/-) mice. However, as shown previously, ppENK (-/-) mice displayed blunted morphine analgesic tolerance. Taken together, the results suggest that enkephalins may be important for the development of analgesic tolerance but not for conditioned place preference or behavioral sensitization induced by morphine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The place preference task: A new tool for studying the relation between behavior and place cell activity in rats.

This study describes a task that combines random searching with goal directed navigation. The testing was conducted on a circular elevated open field (80 cm in diameter), with an unmarked target area (20 cm in diameter) in the center of 1 of the 4 quadrants. Whenever the rat entered the target area, the computerized tracking system released a pellet to a random point on the open field. Rats were able to learn the task under light and in total darkness, and on a stable or a rotating arena. Visual information was important in light, but idiothetic information became crucial in darkness. Learning of a new position was quicker under light than in total darkness on a rotating arena. The place preference task should make it possible to study place cells (PCs) when the rats use an allothetic (room frame) or idiothetic (arena frame) representation of space and to compare the behavioral response with the PCs' activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned place preference for mating is preserved in rats with pelvic nerve transection.

Female rats exhibit a conditioned place preference (CPP) for a context paired with mating. The present experiment tested the hypothesis that the activation of the pelvic nerve mediates the reinforcing effects of mating for female rats. Rats underwent bilateral pelvic nerve or sham transection and then received paced mating, nonpaced mating, or the control treatment during a CPP procedure. Pelvic nerve transection did not affect the CPP for paced or nonpaced mating. In tests of paced mating behavior, contact-return latencies following intromissions were significantly shorter in rats with pelvic nerve transection than they were in rats with sham transections. These results show that the pathway conveying the reinforcing effects of mating stimulation does not depend on the integrity of the pelvic nerve, but that activation of the pelvic nerve contributes to the display of paced mating behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of the naltrexone implant on rodent social interactions and cocaine-induced conditioned place preference

It is well known that excessive thyroid hormone in the body is associated with bone loss. However, the mechanism by which thyroid hormone affects bone turnover remains unclear. It has been shown that it stimulates osteoclastic bone resorption indirectly via unknown mediators secreted by osteoblasts. To determine if interleukin-6 (IL-6) or interleukin-11 (IL-11) could be the mediator(s) of thyroid hormone-induced bone loss, we studied the effects of 3,5,3'-tri-iodothyronine (T3) on basal and interleukin-1 (IL-1)-stimulated IL-6/IL-11 production in primary cultured human bone marrow stromal cells. T3 at 10(-12)-10(-8) M concentration significantly increased basal IL-6 production in a dose-dependent manner. It also had an additive effect on IL-1-stimulated IL-6 production, but failed to elicit a detectable effect on basal or IL-1-stimulated IL-11 production. Treatment with 17beta-estradiol (10(-8) M) did not affect the action of T3 on IL-6/IL-11 production. These results suggest that thyroid hormone may stimulate bone resorption by increasing basal and IL-1-induced IL-6 production from osteoblast-lineage cells, and these effects are independent of estrogen status.     

Blockade of morphine-induced hindlimb myoclonic seizures in mice by ketamine

Morphine administration can lead to a variety of side-effects, including myoclonus. In an animal model, high morphine doses given intrathecally elicit hindlimb myoclonic seizures which are not influenced by traditional opioid receptor antagonists, such as naloxone. Ketamine prevents this seizure-like activity in a dose-dependent manner. The response is stereoselective, with S-ketamine far more potent than R-ketamine. A competitive NMDA antagonist, NPC17742, also prevents the seizures, although less potently than ketamine. Dextromethorphan has limited activity in this model, while haloperidol and pentothal are without any effect.