Drug abuse in China.

The drug problem in China reappeared in the late 1980s. At that time, most drug abusers used opium only, with heroin accounting for a very small proportion and its use being limited to border areas in the southwest and rural areas in the northwest. Beginning in the early 1990s, drug abuse spread quickly.

Nerve growth factor protects R2 cells against neurotoxicity induced by methamphetamine.

It is well known that methamphetamine is a neurotoxic drug of abuse to cause cell death both in vitro and in vivo. In this study, the protective effect of nerve growth factor on methamphetamine-induced neurotoxicity was examined in R2 cells. Treatment of R2 cells with methamphetamine for 48 h induced apoptotic-like death as determined by cell viability assay, DNA fragmentation on agarose gel and flow cytometric analysis.

L-type Ca(2+) channel blockers inhibit the development but not the expression of sensitization to morphine in mice.

The relationship between opioid actions and L-type Ca(2+) channel blockers has been well documented. However, there is no report relevant to L-type Ca(2+) channel blockers and morphine sensitization, which is suggested to be an analog of behaviors that are characteristic of drug addiction. We now studied systematically the effects of three L-type Ca(2+) channel blockers, nimodipine, nifedipine and verapamil, on morphine-induced locomotor activity, the development and the expression of sensitization to morphine.

Tramadol reduces the 5-HTP-induced head-twitch response in mice via the activation of mu and kappa opioid receptors.

Tramadol, an atypical opioid analgesic, stimulates both opiatergic and serotonergic systems. Here we have investigated the effect of tramadol in mice on 5-hydroxyptrytophan (5-HTP)-induced head twitch response (HTR), which is an animal model for the activation of the CNS 5-HT(2A) receptors in mice. Tramadol attenuated 5-HTP-induced HTR in a dose-dependent manner as morphine.

Buspirone-induced antinociception is mediated by L-type calcium channels and calcium/caffeine-sensitive pools in mice.

Rationale: Previous studies have shown that buspirone, a partial 5-HT(1A) receptor agonist, produces antinociceptive effects in rats and mice; Ca(2+) plays a critical role as a second messenger in mediating nociceptive transmission. 5-HT(1A) receptors have been proven to be coupled functionally with various types of Ca(2+) channels in neurons, including N-, P/Q-, T-, or L-type. It was of interest to investigate the involvement of extracellular/intracellular Ca(2+) in buspirone-induced antinociception.

Peripheral electric stimulation attenuates the expression of cocaine-induced place preference in rats.

The present study was designed to investigate the effect of peripheral electrical stimulation (PES), with high (100 Hz) or low (2 Hz) frequencies, on the expression of cocaine-induced conditioned place preference (CPP). Rats were trained with cocaine (0.1-10 mg/kg, i.

Effect of 7-nitroindazole on drug-priming reinstatement of D-methamphetamine-induced conditioned place preference.

The study investigated the role of nitric oxide (NO) in the relapse to drug-seeking behavior induced by D-methamphetamine. After the induction of D-methamphetamine (1 mg/kg) conditioned place preference, the rewarding effect became extinct 6 weeks later. The extinguished place preference was reinstated by D-methamphetamine (0.

The effect of 7-nitroindazole on the acquisition and expression of D-methamphetamine-induced place preference in rats.

The present study investigated the role of nitric oxide (NO) in the rewarding effects of D-methamphetamine using 7-nitroindazole, a potent inhibitor of neuronal nitric oxide synthase (nNOS), as determined by the conditioned place preference paradigm. Male Sprague-Dawley rats treated with D-methamphetamine (1 mg/kg) or saline every other day for 8 days (four drug and four saline sessions) developed marked place preference for the drug-paired side. The administration of 7-nitroindazole (12.