In vitro effect of organic and inorganic mercury on the serotonergic system.
Interactions of organic (methyl mercury) and mineral (acetate, chloride, nitrate: Hg2+) mercury salts with the serotonergic systems were studied in vitro using synaptosomal fractions prepared from rat brain cortex preloaded with [3H]5-HT. In the absence of calcium, mercury salts induced a spontaneous release of the amine corresponding to a total depletion of the synaptosomal content. EC50 for the organic and mineral forms of the ion were 66 +/- 2 microM and 107 +/- 16 microM respectively. In the presence of calcium (2.4 mM) a similar pattern of release was observed except that an additional release was induced by mineral mercury at low concentration (EC50 = 8.4 +/- 1.3 microM) which corresponded to a maximal release of 18.6 +/- 3.5% of the synaptosomal content. Therefore, the latter release appears calcium-dependent. Parallelly, the effects of mercury salts have been examined on the binding of [3H]5-HT to its high affinity 5-HT1 sites; organic and mineral mercury inhibited the binding with IC50 of 27.8 +/- 3.2 microM respectively. These results show that mercury ions interact with the serotonergic system by different mechanisms depending on their concentrations and their ionic forms.
Oudar
P
P
Institut Pasteur, Unit of Neuro-immuno-endocrinological Pharmacology, Paris, France.
Caillard
L
L
Fillion
G
G
D000818:Animals; D004121:Dimethyl Sulfoxide; D066298:In Vitro Techniques; D008297:Male; D008628:Mercury / Q000633:toxicity*; D009941:Organomercury Compounds / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D009941:Organomercury Compounds; D012701:Serotonin; D008628:Mercury; D004121:Dimethyl Sulfoxide