0 2 - Adrenoceptor modulation of 5 - HT biosynthesis in the rat brain
نویسنده
چکیده
'Fhc purpose of the present study is to clarify the modulation of the biosynthesis ol'serotonin (5-HT) via the ~:-adrcnoceptors in the brain. For this purpose. 5-hydroxytryptophun 15-HTP) accumulation was determined using an HPLC-ECD system in the presence of the inhibition of aromatic I -amino acid decurboxylasc. Administration of :z2-adrenoceptor agonist, clonidine, produced a reduction of the in viw) 5-HTP accumulation in Ihe rat hippocampus and dorsal raphe nucleus. In addition, c~:-adrenoceptor antagonist, idazoxan, increased the 5-HTP accumulation m both the hippocampus and thc dorsal ruphe nucleus. In rats with catecholammergic neurons denervatcd by pretreatment with 6-bydroxydopamme, clonidine failed to produce a reduction of 5-HTP accumulation in the dorsal ruphe nucleus. On Ihe other hand, hippocumpal 5-HTP accumulation was decreased signilicantly. Brain tryptophan levels were unaffected by either clonidine or idazoxun. These results suggest that c~-adrenoceptors might m~,dulatc serotonin biosynthesis and this modulation might be related to the neuroanatomical differences in the rat brain.
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