Effect of ethanol on (R)- and (S)-salsolinol, salsoline, and THP in the nucleus accumbens of AA and ANA rats.

Tetrahydroisoquinolines (TIQ) are active metabolites of dopamine. Intracerebral application stimulates the voluntary ethanol intake. In the present study, the levels of several TIQ's [(S)- and (R)-salsolinol, salsoline and tetrahydropapaveroline (THP)] were measured in the extracellular space of the nucleus accumbens of alcohol-preferring AA and alcohol-avoiding ANA rats. Ethanol (2 g/kg i.p.) caused an increase in dopamine levels in ANA but not in AA rats. Neither (R)- nor (S)-salsolinol concentrations changed after ethanol application, though (S)-salsolinol concentrations were higher in ANA than in AA rats. Ethanol caused an increase in salsoline concentrations in ANA but not in AA rats. THP increased following ethanol, which tended to be stronger in ANA rats. The study revealed differences in the TIQ levels of the nucleus accumbens between AA and ANA rats. In case of changes following ethanol application (dopamine, salsoline, THP), the AA rats were less sensitive. The findings resemble observations in high-risk sons of alcoholics with reduced sensitivity to ethanol in young age and increased risk to become alcoholic.

R- and S-salsolinol are not increased in cerebrospinal fluid of Parkinsonian patients.

Various investigators address an augmented synthesis of tetrahydroisoquinolines, such as salsolinol (SAL), or an increased N-methylation of these compounds as putative pathophysiologic mechanisms in Parkinson's disease (PD). Objectives of this study were (1) the evaluation of a putative elevation of enantiomers (R-, S-) of SAL and (2) the investigation of relations between these metabolic precursors of neurotoxic N-methylated-SAL (NMSAL) and dopamine in cerebrospinal fluid of untreated de-novo Parkinsonian patients and age- and sex-matched healthy controls. Levels of R- and S-SAL and dopamine did not significantly (R-SAL: P = 0.75, S-SAL: P = 0.69, dopamine: P = 0.46) differ and dopamine did not correlate to R-SAL and S-SAL in both groups. We conclude, that central accumulation of R-NMSAL, which is neurotoxic to dopaminergic nigrostriatal neurons, is not due to elevated synthesis of R-SAL and/or S-SAL in PD.

Plasma levels of R- and S-salsolinol are not increased in "de-novo" Parkinsonian patients.

An augmented synthesis of tetrahydroisoquinolines, such as salsolinol (SAL) or an increased N-methylation of these compounds has been addressed by various investigators as putative pathophysiologic mechanisms in Parkinson's disease (PD). Aim of this study was (1) to investigate putative relations between plasma levels of dopamine and R- and S-enantiomers of SAL and (2) whether these metabolic precursors of the neurotoxic N-methylated-SAL (NMSAL) are elevated in untreated "de-novo" Parkinsonian patients compared to age- and sex-matched healthy controls. Plasma levels of R- and S-SAL and dopamine did not significantly (R-SAL: p=0.61, S-SAL: p=0.51, dopamine: p=0.84) differ in both groups. Parkinsonian patients' R-SAL plasma levels were inversely related to intensity (p=0.03, r =-0.42) and duration of PD (p=0.03, r=-0.43) in contrast to S-SAL and dopamine. Dopamine levels were not associated to R-SAL (p=0.88, r2=0.0008) and S-SAL (p=0.088, r2=0.12) neither in Parkinsonian patients nor in controls. We conclude, that an upregulation of N-methylation of tetrahydroisoquinolines takes place in PD by enzymes such as neutral N-methyltransferase specific for R-SAL. The activity of this enzyme has been found elevated in parkinsonian lymphocytes. This increased N-methylation by the N-methyltransferase specific for R-SAL leads to the known augmented levels of neurotoxic R-NMSAL in Parkinsonian patients compared to controls in the cenral nervous system especially in the beginning of PD.

Antisocial tendencies in alcohol-dependent men and their relation to harman, salsolinol and dopamine.

Plasma dopamine, ß-carbolines (norharman, harman) and isoquinolines ((R)- and (S)-salsolinol) were examined for their relationship to antisocial tendencies in 138 drinking men with an alcohol dependence syndrome according to ICD-10 criteria. Antisociality was assessed according to the following criteria: delinquency, involvement in fist-fights and homelessness. The personality structure was documented by the Tridimensional Personality Questionnaire of Cloninger. An early age of onset of alcohol dependence and a high degree of 'novelty seeking' were associated with antisocial tendencies. Of the ß-carbolines and isoquinolines, harman and (S)-salsolinol were significantly decreased among antisocial alcoholics. Norharman, (R)-salsolinol and dopamine were not associated with antisocial personality. The contribution of endogenous alkaloids to the biological characterization of antisocial tendencies in alcoholics is described.