Biomedical subjects

S L Cappendijk

Publications and source records attributed to S L Cappendijk.

8 recordsLinked to original sources

PubMed1999

A heroin-, but not a cocaine-expecting, self-administration state preferentially alters endogenous brain peptides.

The purpose of the current study was to assess neuropeptidergic alterations during a phase of the drug addiction cycle associated with drug craving as compared to a time period when the drug had been recently self-administered. Male Wistar rats were allowed to self-administer cocaine, heroin or saline for 6 h for 5 consecutive days. Immediately following the last self-administration session ('acute drug on board' state), and just before the next scheduled session ('drug expecting' state), the animals were decapitated and the levels of dynorphin A and B, [Met5]- and [Leu5]-enkephalin and substance P were measured in different brain areas. During the 'acute drug on board' state, peptide levels in animals that self-administered heroin or cocaine were not significantly changed. In contrast, during the 'drug expecting' state, heroin-treated animals had increased levels of dynorphin A, dynorphin B and [Met5]-enkephalin in the caudal striatum as compared to the cocaine- and saline-treated animals, and the level of [Leu5]-enkephalin was increased as compared to the cocaine-treated group. In the septum, an increase of [Met5]-enkephalin and substance P was observed in the animals expecting heroin as compared to the saline- and/or cocaine-treated animals. In the caudal striatum, substance P levels were elevated in the heroin- and cocaine-expecting animals. In conclusion, heroin, as compared to cocaine, appears to have a more pronounced effect on dynorphin, enkephalin and substance P levels in the caudal striatum and septum, especially during periods when self-administration of the drug is expected.

Animals↗

PubMed1995

Comparative study of normotensive and hypertensive nitric oxide synthase inhibitors on morphine withdrawal syndrome in rats.

The effects of the normotensive, mainly centrally active nitric oxide synthase (NOS) inhibitor 7-nitro indazole and the hypertensive drug NG-nitro-L-arginine, which blocks both the endothelial and the central NOS, have been examined on naloxone-precipitated withdrawal in morphine-dependent rats. Both drugs attenuated the same withdrawal signs (teeth-chattering, penile licking, diarrhoea, chewing, wet-dog shakes, grooming), while other signs remained unaffected (rearing, jumping, ptosis, rhinorrhoea, irritability on touch). These findings indicate that mainly central (but not endothelial) nitric oxide is involved in the expression of some opioid withdrawal symptoms.

Amino Acid Oxidoreductases↗

PubMed1994

The inhibitory effect of norharman on morphine withdrawal syndrome in rats: comparison with ibogaine.

Norharman (20 mg/kg, i.p.) and ibogaine (40 mg/kg, i.p.) significantly attenuated naloxone (4 mg/kg, i.p.)-precipitated withdrawal syndrome in morphine-dependent rats. Several withdrawal signs, such as teeth-chattering, chewing, penile licking and diarrhoea, were decreased by both norharman and ibogaine. In addition, norharman reduced also the withdrawal grooming and rearing. It is concluded that both norharman and ibogaine are inhibitors of withdrawal syndrome in morphine-dependent rats.

Animals↗

PubMed1993

Inhibitory effect of nitric oxide (NO) synthase inhibitors on naloxone-precipitated withdrawal syndrome in morphine-dependent mice.

The effect of intraperitoneally administered nitric oxide (NO) synthase inhibitors has been examined on the naloxone-precipitated withdrawal syndrome in morphine-dependent mice. L-NAME (30-200 mg/kg) and L-NOARG (7.5-50 mg/kg) induced a significant decrease of naloxone-precipitated withdrawal jumping and diarrhoea. However, L-NMMA (3.5-100 mg/kg), considered as a less potent NO synthase inhibitor, did not significantly affect the withdrawal signs in mice. Although a specificity of NO synthase inhibitors is not fully established, these results indicate that inhibition of NO synthesis in the central nervous system and periphery may significantly affect the morphine withdrawal phenomena. Accordingly, this study suggests an involvement of NO in morphine withdrawal syndrome.

Amino Acid Oxidoreductases↗

PubMed1993

Inhibitory effects of ibogaine on cocaine self-administration in rats.

In order to determine the potential anti-addictive properties of ibogaine, we used the cocaine self-administration model in rats. The results indicate that a single injection of ibogaine (40 mg/kg i.p.) produced a significant decrease of cocaine intake, which remained unaltered for more than 48 h. Since the half-life time of ibogaine is short, this might suggest the involvement of one or several active metabolites of ibogaine in cocaine intake. Repetitive administration of ibogaine on three consecutive days also induced a pronounced decrease of cocaine intake. However, a more prominent inhibitory effect on cocaine intake was observed in animals treated repeatedly with ibogaine (40 mg/kg i.p.), once each week for 3 consecutive weeks. These results indicate that ibogaine or its metabolite(s) is a long-lasting interruptor of cocaine dependence, which supports similar observations from uncontrolled clinical studies.

Analysis of Variance↗

PubMed1993

Excitatory amino acid receptor antagonists and naloxone-precipitated withdrawal syndrome in morphine-dependent mice.

The effects of the excitatory amino acid (EAA) receptor antagonists MK-801 (non-competitive NMDA receptor antagonist), DNQX (competitive non-NMDA receptor antagonist) and 5,7-DCKA (antagonist of glycine site of NMDA receptor) have been examined on the naloxone (4 mg/kg, i.p.)-precipitated withdrawal jumping behaviour in morphine-dependent mice. The results indicate that withdrawal jumping behaviour in morphine-dependent mice was attenuated by all three EAA receptor antagonists, MK-801, DNQX and 5,7-DCKA. However, MK-801, DNQX and 5,7-DCKA inhibited the jumping behaviour in a relatively narrow dose range.

Animals↗

PubMed1992

The effects of orally active enkephalinase inhibitors on morphine withdrawal syndrome.

Considerable evidence has accumulated to suggest that intracerebroventricular administration of enkephalinase inhibitors, which do not penetrate the blood-brain barrier, significantly attenuates opioid withdrawal syndrome. Therefore, the aim of this study was to examine the effect of intraperitoneal (i.p.) administration of orally active enkephalinase inhibitors, acetorphan (2.5-20 mg kg-1) and SCH 34826 (15-120 mg kg-1). These drugs significantly decreased the severity of the naloxone precipitated withdrawal syndrome in morphine dependent rats and mice. It therefore appears that these orally active enkephalinase inhibitors are promising tools in studying modulation of opioid dependence phenomena.

Administration, Oral↗

PubMed1991

Decrease of beta-endorphin in the brain of rats following nitrous oxide withdrawal.

beta-Endorphin levels in the whole rat brain were not changed during acute (25 min) or chronic (48 h) exposure of rats to N2O. However, a significant decrease of beta-endorphin was found in the whole brain, brain stem and subcortex during the withdrawal from chronic exposure to N2O. It has been suggested that decrease of beta-endorphin levels during N2O withdrawal could be ascribed to unspecific stress accompanying drug withdrawal. Decrease of central beta-endorphin during N2O withdrawal might have a significant modulatory effect on transmitter balance, neuronal excitability and corresponding withdrawal behaviour. Furthermore, the decrease of beta-endorphin levels in the whole brain during N2O withdrawal might contribute to the postanaesthesia N2O-excitatory syndrome in humans. This might explain the known therapeutic effect of the opioid drug, meperidine on the excitatory N2O withdrawal phenomena during recovery from N2O anaesthesia in man.

Animals↗