大鼠未定核對視丘後內側核傳遞傷害性傳入訊息之調控

Abstract

前人研究顯示大鼠視丘後內側核(POm)會受到未定核(ZI)持續且有力的抑制性調控，因此ZI移除後，才能見到POm神經元對輕觸鬍鬚之刺激產生明顯的反應。本研究目的是檢視ZI被毀壞後，POm調控傷害性傳入訊息的能力。首先利用神經追蹤劑檢視ZI投射至POm的確切區域。而後在ZI經過毀壞的實驗動物上，以16通道－密西根電極進行單一神經元紀錄。本實驗在ZI毀壞同側之POm紀錄到了42顆神經元，在ZI毀壞側之對側與未經手術的動物紀錄了81顆神經元，比較這些神經元對於傷害性機械刺激與熱痛刺激的反應。研究結果顯示：1）ZI被毀壞後，POm中對傷害性刺激有反應的神經元數目顯著高於對照組；2）藉由ZI的調控，POm可能為一傳遞傷害性刺激訊息的區域。本實驗藉由ZI移除的處理，揭開了隱藏於POm傳遞傷害性訊息之能力。然此能力在正常動物中的重要性仍需進一步的研究與探討。

The posterior medial nucleus (POm) is tonically inhibited by Zona Incerta (ZI), so that robust vibrissae evoked responses are revealed after ZI inactivation. The present study was to examine the capability of the POm neurons in processing nociceptive information after removal of ZI inhibition. Incerto-POm terminal zones were delineated by anterograde tracing of Biotinylated Dextran Amine. For electrophysiological studies, unilateral ZI lesion was made by micro-injection of kainic acid into the facial region of ZI. Seven days after lesion, single-unit recordings were made with a 16-channel Michigan probe. Responses to noxious mechanical and thermal stimuli were compared among 42 POm neurons in ZI lesioned sides versus 81 neurons in non-lesioned side and na