Investigation of serotonergic regulation of acetycholine release in the cortex (II)

(Exp.1)The role of 5-HT I D 21A D 2 receptors in the serotonergic regulation of cortically projecting cholinergic neurons was studied.8-OH-DPAT(DPAT；1.0 mg/kg，s.c.)Significantly increased cortical ACh output。WAY100-635(WAY；0.1 mg/kg，s.c.)Did not influence the ACh output。Local application of WAY(0.1，10µM for 60min)in the frontal cortex had no effect on the basal ACh output。Locally applied WAY(10µM for 60min)after injection of fenfluramine(FEN；10 mg/kg，i.p.)Or DOI(2.5毫克/千克.I.p.)Did not affect the ACh output。Nevertheless，DPAT(10µM)applied after injection of DOI significantly potentiated DOI‘s ability to increase cortical ACh release.DPAT injected after ketanserin(KET；5 mg/kg，i.p.)Failed to affect the ACh output。These results suggest three possibilities。First，5-HT may not tonically stimulate ACh release via the postsynaptic5-HT I D21AⅡD2 receptors.Second，FEN-induced increase of ACh release may be mediated mainly via the 5-HT I D 22A I D 2 recept…More ors.Third，the stimulatory effect of 5-HT on ACh release via the postsynaptic5-HT I D21AⅡD2 receptors may be increased when the 5-HT I D 22AⅡD2 receptors are activated.(Exp.2)The effects of estrogen on cortically projecting cholinergic neurons were investigated.Nineteen days after ovariectomy rats were implanted a microdialysis probe，and immediately injected subcutaneously with either 17β-estradiol(3.0µg/kg.30µg/kg，300µg/kg)，or sesame oil.Two days later microdialysis experiment was performed。17β-estradiol treatment resulted in a significant difference among the serum estradiol concentrations of each individual animal group。However，it failed to produce a difference in the basal ACh output。In addition，estrogen replacement did not yield a difference in FEN‘s ability to increase cortical ACh release.These results suggest that estrogen replacement for two days is not enough to restore both the functions of cortically projecting cholinergic neurons，and of 5-HT I D22A西耶D2 receptors.Less：Less

〔Exp. 1〕 The role of 5-HTィイD21AィエD2 receptors in the serotonergic regulation of cortically projecting cholinergic neurons was studied. 8-OH-DPAT (DPAT ; 1.0 mg/kg, s.c.) significantly increased cortical ACh output. WAY 100-635 (WAY ; 0.1 mg/kg, s.c.) did not influence the ACh output. Local application of WAY (0.1, 10μM for 60 min) in the frontal cortex had no effect on the basal ACh output. Locally applied WAY (10 μM for 60 min) after injection of fenfluramine (FEN ; 10 mg/kg, i.p.) or DOI (2.5 mg/kg. i.p.) did not affect the ACh output. Nevertheless, DPAT (10 μM) applied after injection of DOI significantly potentiated DOI's ability to increase cortical ACh release. DPAT injected after ketanserin (KET ; 5 mg/kg, i.p.) failed to affect the ACh output. These results suggest three possibilities. First, 5-HT may not tonically stimulate ACh release via the postsynaptic 5-HTィイD21AィエD2 receptors. Second, FEN-induced increase of ACh release may be mediated mainly via the 5-HTィイD22AィエD2 recept … More ors. Third, the stimulatory effect of 5-HT on ACh release via the postsynaptic 5-HTィイD21AィエD2 receptors may be increased when the 5-HTィイD22AィエD2 receptors are activated.〔Exp. 2〕 The effects of estrogen on cortically projecting cholinergic neurons were investigated. Nineteen days after ovariectomy rats were implanted a microdialysis probe, and immediately injected subcutaneously with either 17β-estradiol (3.0μg/kg. 30μg/kg, 300μg/kg), or sesame oil. Two days later microdialysis experiment was performed. 17β-estradiol treatment resulted in a significant difference among the serum estradiol concentrations of each individual animal group. However, it failed to produce a difference in the basal ACh output. In addition, estrogen replacement did not yield a difference in FEN's ability to increase cortical ACh release. These results suggest that estrogen replacement for two days is not enough to restore both the functions of cortically projecting cholinergic neurons, and of 5-HTィイD22AィエD2 receptors. Less