Effects of serotonin depletion by p-chlorophenylalanine, p-chloroamphetamine or 5,7-dihydroxytryptamine on central dopaminergic neurons: focus on tuberoinfundibular dopaminergic neurons and serum prolactin.
Three serotonin (5-HT) neurotoxins, p-chlorophenylalanine (PCPA, 125 and 250 mg/kg, i.p.), p-chloroamphetamine (PCA, 10 mg/kg, i.p.) and 5,7-dihydroxytryptamine (5,7-DHT, 200 microg/rat, i.c.v.) were used to examine whether depletion of central 5-HT has an effect on central dopaminergic (DA) neuronal activities or on prolactin (PRL) secretion. Adult ovariectomized Sprague-Dawley rats primed with estrogen (polyestradiol phosphate, 0.1 mg/rat, s.c.) were treated with one of three neurotoxins and then decapitated in the morning after 3-7 days. Blood sample and brain tissues were collected. The acute effect of PCA (from 30 to 180 min) was also determined. The concentrations of 5-HT, DA and their metabolites, 5-hydroxyindoleacetic acid and 3,4-dihydroxyphenylacetic acid, in the median eminence, striatum and nucleus accumbens were determined by HPLC-electrochemical detection. All three toxins significantly depleted central 5-HT stores by 11-20%. Except for PCPA, neither PCA nor 5,7-DHT had any significant effect on basal DA neuronal activities or PRL secretion. PCA also exhibited an acute effect on the release and reuptake of 5-HT and DA. In summary, depletion of central 5-HT stores to a significant extent for 3-7 days did not seem to affect basal DA neuronal activity and PRL secretion.
Yang
I C
IC
Department of Physiology, School of Life Science, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Pan
J T
JT
D015116:5,7-Dihydroxytryptamine / Q000633:toxicity; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D010134:Fenclonine / Q000633:toxicity; D007700:Kinetics; D008473:Median Eminence / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009498:Neurotoxins / Q000633:toxicity; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000172:deficiency / Q000378:metabolism*; D010133:p-Chloroamphetamine / Q000633:toxicity
D009498:Neurotoxins; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D010133:p-Chloroamphetamine; D011388:Prolactin; D010134:Fenclonine; D004298:Dopamine