Lack of glucocorticoids attenuates the self-stimulation-induced increase in the in vivo synthesis rate of dopamine but not serotonin in the rat nucleus accumbens.
Our previous study demonstrated that intracranial self-stimulation of the medial forebrain bundle can increase the in vivo synthesis turnover rate of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens of adrenal-intact rats. The present study examined using microdialysis whether such increases in DA and 5-HT syntheses are influenced by adrenal hormones, which are also activated following intracranial self-stimulation. A decarboxylase inhibitor, NSD-1015, was perfused through reversed microdialysis which enabled the simultaneous measurement of 3,4-dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) as an index of the in vivo turnover rate of DA and 5-HT syntheses. Adrenalectomy (ADX) attenuated significantly the self-stimulation-induced increase in dialysate levels of DOPA but not 5-HTP. Corticosterone (Cort) replacement reversed the attenuation in DOPA levels in adrenalectomized rats. The finding indicates that activation of DA synthesis in vivo in the nucleus accumbens during intracranial self-stimulation is dependent on, whereas that of 5-HT synthesis is independent of glucocorticoid modulation.
Nakahara
D
D
Departments of Psychology and Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan. nakahara@hama-med.ac.jp
Nakamura
M
M
Oki
Y
Y
Ishida
Y
Y
D006916:5-Hydroxytryptophan / Q000378:metabolism; D000315:Adrenalectomy; D000818:Animals; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D003348:Cortisone / Q000494:pharmacology; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004298:Dopamine / Q000096:biosynthesis*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005938:Glucocorticoids / Q000172:deficiency*; D006834:Hydrazines / Q000494:pharmacology; D006900:Hydroxylation; D008297:Male; D017551:Microdialysis; D009474:Neurons / Q000201:enzymology; D009714:Nucleus Accumbens / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012646:Self Administration; D012653:Self Stimulation / Q000502:physiology*; D012701:Serotonin / Q000096:biosynthesis*; D014364:Tryptophan / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D006834:Hydrazines; D012701:Serotonin; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; D014364:Tryptophan; C004297:3-hydroxybenzylhydrazine; D006916:5-Hydroxytryptophan; D003348:Cortisone; D004298:Dopamine