Yang, Yu-Mi Chung, Jun-Mo Rhim, Hyewhon 2024-01-21T01:33:23Z 2024-01-21T01:33:23Z 2021-09-05 2007-02 0918-6158 https://pubs.kist.re.kr/handle/201004/134682 Many behavior studies indicate that cholecystokinin (CCK) is related to nociception and anxiety/panic actions in the midbrain periaqueductal gray (PAG). We previously reported that a sulfated form of CCK octapeptide (CCK-8S) produced excitatory effects at both pre- and postsynaptic loci in PAG neurons using slice preparations and whole-cell patch-clamp recordings. Here, we further examined the detailed mechanism of CCK-8S in acutely isolated PAG neurons of the rat using fura-2-based imaging of intracellular Ca2+ concentration ([Ca2+](i)) and whole-cell patch-clamp recordings. Application of 1 mu ym CCK-8S produced an increase of [Ca2+](i), and its effect did not desensitize. This CCK-8S-induced [Ca2+](i) increase was inhibited by the CCK2 receptor antagonist L-365260 but not by the CCK, receptor antagonist L-364718. In addition, the effect of CCK8S was eliminated by removing extracellular Ca2+, but not by an addition of the intracellular Ca2+ reuptake inhibitor thapsigargin. When simultaneous recordings of [Ca2+](i) imaging and whole-cell patch-clamp were performed, CCK-8S-induced [Ca2+](i) increase was significantly reduced at a membrane holding potential of -60 mV while CCK-8S-induced inward current was still observed. Current-voltage plots revealed that CCK-8S-induced inward current reversed near the equilibrium potential for K+ ions with a decreased membrane conductance. However, CCK-8S produced a significant inhibition on high-voltage-activated Ca2+ channel currents. These results suggest that CCK-8S can excite PAG neurons by inhibiting K+ channels, and CCK-8S-induced [Ca2+](i) increase occurs secondary to depolarization. The evidence presented here expands our understanding of cellular mechanisms for CCK-mediated anti-analgesic and anxiogenic actions in the PAG. English PHARMACEUTICAL SOC JAPAN PROTEIN-KINASE-C MORPHINE ANALGESIA B RECEPTORS IN-VITRO CELLS OCTAPEPTIDE MECHANISMS EXPRESSION TRANSDUCTION POTENTIATION Cholecystokinin-8S-induced intracellular calcium signaling in acutely isolated periaqueductal gray neurons of the rat Article 10.1248/bpb.30.297 1 BIOLOGICAL & PHARMACEUTICAL BULLETIN, v.30, no.2, pp.297 - 302 BIOLOGICAL & PHARMACEUTICAL BULLETIN 30 2 297 302 scie scopus 000245582600017 2-s2.0-33846950389 Pharmacology & Pharmacy Pharmacology & Pharmacy Article PROTEIN-KINASE-C MORPHINE ANALGESIA B RECEPTORS IN-VITRO CELLS OCTAPEPTIDE MECHANISMS EXPRESSION TRANSDUCTION POTENTIATION cholecystokinin (CCK)(2) receptor periaqueductal gray Ca2+ channel depolarization fura-2 patch-clamp recording