安非他命與古柯鹼皆屬心理興奮性藥物(psychostimulants)，在藥理上有很多功能相似的機制，而且兩種藥物濫用成癮的問題一直是臨床及基礎研究所關心的問題。就動物行為模式而言，安非他命與古柯鹼具有影響包括反射性及制約學習性的行為表現的效果。若針對藥物的酬賞性做探討時，制約性場地偏好行為模式的相關研究益發受到重視，本研究實驗一先針對此作業之操弄時間及環境變項做一探討，再研究安非他命與古柯鹼之作用機制。過去的研究發現，週邊注射安非他命或古柯鹼與某環境刺激配對能引發制約性引發場地偏好的傾向，但兩藥的行為現象卻對藥理的操弄呈不一致的結果，隱含兩藥背後的神經機制可能也不同。其中阿控博核是一個值得再驗證的區域。阿控博核被認為是動機系統與運動系統的介面。此部位因其解剖及生化功能的異質性，故實驗二針對其次分區進行中樞藥物注射，於是直接將安非他命(10，15μg)與古柯鹼(50，100μg)分別注射於阿控博核之次級區。結果發現安非他命直接注入阿控博核核區或古柯鹼注入阿控博核殼區可表現顯著的場地偏好效果。基於阿控博核所含有的麩胺酸神經末梢源自內側前額葉皮質，實驗三則發現安非他命或古柯鹼注入內側前額葉皮質可引發制約性場地偏好行為。實驗四將麩胺酸專屬受體抑制劑與安非他命共同注入核區或與古柯鹼共同注入殼區，結果發現不論NMDA或non-NMDA受體抑制劑均減抑了安非他命與古柯鹼注入阿控博核不同區所引發之制約性場地偏好的效果。最後實驗五利用內側前額葉遭破壞的受試，發現古柯鹼注入阿控博核殼區所引發之制約性場地偏好的效果受損，但不影響安非他命注入阿控博核核區所引發之制約性場地偏好的效果。綜觀上述結果顯示安非他命與古柯鹼的酬賞特質所引發行為的神經機制可能不同，腦中之內側前額葉皮質及阿控博核對兩藥的行為效果有不同的涉入。 / The function of the nucleus accumbens (NACC) has been suggestedto play an important role of the rewarding effects of psychostimulants.It is hypothesized that the neural substrates for amphetamine and cocaineto produce behavioral effects can be different. As conducted in Experiment 1, a conditioned place preference (CPP) task with procedures for amphetamine microinjection was established from the manipulation of conditioning environment. In considering the heterogeneity of NACC, Experiments 2 investigated the potentiality of the CPP effects after local infusion of amphetamine (10, 15 μg/site) or cocaine (50, 100 μg/site) into the core and shell subareas of NACC. Amphetamine microinjection into the NACC core significantly produced CPP, whereas such effect only appeared under treatment of the high dose of cocaine into the shell area. Lack of the CPP effects for amphetamine or cocaine infused into the boundary areas of the core and shell regions was seen in Experiment 2 (part B). In Experiment 3, the involvement of the medial prefrontal cortex (mPFC) was challenged for amphetamine and cocaine on the CPP task. Both doses of cocaine and the low dose of amphetamine locally infused in mPFC significantly produced CPP. In Experiment 4, glutamatergic NMDA receptor antagonist APV (0.5, 1 μg/site) and non-NMDA receptor antagonist CNQX (1 μg/site) significantly attenuated the CPP effects of amphetamine infused into the NACC core. This antagonism was also true for the cocaine-induced CPP in the NACC shell. These results implied that the other cortical areas can modulate such CPP effects, in particular the mPFC. In Eperiment 5, lesion of mPFC significantly inhibited the cocaine-induced CPP in the shell area but not for the amphetamine-induced CPP in the core area. Taken together, the NACC is an important neural substrate for mediating the rewarding effects for amphetamine and cocaine on the CPP task, and such effects can be dissociated as drugs locally infused into core and shell areas. Glutamatergic projections originating mPFC may provide some motivational information to the NACC. The mPFC may distinctly be involved in the motive circuit of cocaine- or amphetamine-induced CPP in the NACC. These results highlight that different processes are involved in the acquisition of CPP for microinjection of amphetamine or cocaine into the NACC subareas.

本研究以心理興奮性藥物(psychosimulants)引發之行為致敏化作為探討環境與藥物的配對學習如何影響個體長期使用藥物後對藥物的反應。首先於實驗一建立安非他命引發自發活動致敏化基本模式，以及不同的重複注射情境下致敏化的表現，結果顯示經由本實驗操弄注射情境的程序可有效引發在測試箱、飼養籠，和第三處的安非他命致敏化表現，並且致敏化自發活動表現量在測試箱組顯著高於飼養籠組和第三處組。實驗二對致敏化形成歷程中可能與安非他命配對的刺激進行消除，以釐清致敏化形成歷程中連結學習的要素，結果顯示消除程序沒有降低致敏化活動量的效果。實驗三使用中樞注射麩胺酸受體拮抗劑NBQX於依核以影響致敏化的連結學習歷程，結果顯示該操弄可阻斷在飼養籠重複注射安非他命引發的行為致敏化。測試箱組經過該操弄後其致敏化活動量顯著降低但仍有顯著的致敏化活動量表現。實驗四分別破壞前額葉皮質兩處次級區塊以瞭解其在致敏化連結學習歷程中扮演的角色，結果顯示破壞背側前額葉皮質只阻斷在飼養籠注射安非他命所引起的行為致敏化，破壞腹側前額葉皮質只阻斷測試箱組行為致敏化。綜合上述研究結果顯示安非他命引發致敏化的形成深受藥物配對的環境影響而可區分環境相依與環境獨立之行為致敏化，環境相依行為致敏化的行為機制可由場合建立的觀點加以解釋。在依核內之麩胺酸傳導和前額葉皮質次級區塊之功能在兩種行為致敏化上的差異可以反應環境相依和環境獨立行為致敏化的潛在神經機制可能有所不同。 / The present study investigated the neurobehavioral mechanisms of d-amphetamine (AMP) induced behavioral sensitization, with the aim to elucidate the role of associative learning between the context and drug. Experiment 1 compared the sensitization effects of repeated (AMP) conducted in three different contexts by the measurement of locomotion activity. The results showed that behavioral sensitization of locomotion was significantly induced AMP repeatedly injected in each of the contexts. However, the magnitudes of behavioral sensitization were different among those three conditions. The highest degree of sensitized locomotion was observed in the group with repeated AMP conducted in the test box in comparing to the other two groups with drug administration in the home cage and a third place, Experiment 2 was designed to examine the effects of extinction on the injection procedure and the contextual cue on the behavioral sensitization of AMP induced in the test box, the home cage, and a third place. The resu lts clearly indicate all three types of locomotion sensitization were resistant to the manipulation of extinction. Experiment 3 tested the effects of NBQX, a glutamatergic AMPA receptor antagonist, infused into the nucleus accumbens on the establishment of behavioral sensitization of AMP induced in the test box and the home cage. This intra-accumbens NBQX treatment significantly suppressed the formation of behavioral sensitization of AMP induced in the home cage, but not in the test box. Experiment 4 investigated the lesion effects of medial prefrontal cortex (mPFC) on the establishment of behavioral sensitization of AMP induced in the test box and the home cage. Two subareas of the mPFC, dorsal and ventral parts, were lesioned by ibotenic acid. The findings indicated a double dissociation existing in the mPFC subareas for the behavioral sensitization of AMP induced in different contexts. The lesion of ventral mPFC inhibited the formation of behavioral sensitization of AMP induced in the test box, whereas the lesion of dorsal mPFC attenuated the AMP sensitization induced at the home cage. Together, these data suggest that the association of the repeated drug effects pairing to the context is critical for the development of behavioral sensitization. Such sensitization can further be differentiated into the context-depentdent and context-independent forms based on the uniqueness of contextual cue in the environment where drug is administered. Different neural substrates are involved in the establishment of behavioral sensitization of AMP.

蛋白激酶CK2（Casine kinase 2）為四單體所構成，針對配受質蛋白之絲胺酸或蘇胺酸位置進行磷酸化，先前研究已經發現在紋狀體腦區之CK2的表現量與活性皆高於大腦中其餘腦區，而紋狀體腦區主要神經細胞為-氨基丁酸神經元（GABAergic neurons）的medium spiny neuron（MSN），會受到來自黑質多巴胺神經細胞（dopaminergic neurons）的調控。此外，DARPP-32（dopamine- and cAMP-regulated phosphoprotein, Mr 32 kDA）蛋白亦被發現大量表現於在MSN細胞中，且為CK2之受質蛋白質。雖然CK2已被證實參與多巴胺神經元的神經保護機制，但是否參與MSN細胞對運動行為調控之生理機制仍未清楚。由於已有研究發現施予1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）藥物處理造成黑質-紋狀體腦區受損之老鼠腦內-氨基丁酸（GABA）的生合成酵素─麩胺酸脫羧酵素67（GAD67）表現量與正常老鼠不同，因此本論文研究的主題擬在大鼠實驗模式中利用MPP+造成投射至紋狀體之多巴胺神經細胞受損，探討當多巴胺調控紋狀體神經細胞能力缺失的狀態下，MSN細胞之CK2、DARPP-32和GAD蛋白表現與動物運動行為之相關性。 實驗結果發現，直接於紋狀體給予1-甲基-4-苯基碘化啶 （MPP+ Iodide）皆會造成CK2、DARPP-32以及GAD67之蛋白質含量的減少，多巴胺及其代謝物和GABA等神經化學傳遞物質亦有減少的現象；另外，在MPP+給予前分別操弄CK2或DARPP-32 胺基酸Ser102磷酸化的表現，皆會改變GAD67蛋白質含量與黑質酪胺酸羥化酶（Tyrosine Hydroxylase, TH）蛋白質含量，同時神經化學傳遞物質的含量或代謝亦有改變。由現有之結果推測CK2/DARPP-32/GAD67細胞訊息傳遞機制可能參與巴金森氏症運動行為失常之細胞層面的調控。 / Protein kinase CK2 is a heterotetrameric and serine/threonine protein kinase. Its protein levels and activity are found to be elevated in the striatum when compared to other brain areas. CK2 is known to involve in the neuroprotective effects of dopaminergic neurons, whether it also regulates the neuronal function relative to motor behaviors is still unclear. DARPP-32 protein is known as one of the substrates for CK2 and is highly expressed in the GABAergic medium spiny neurons (MSN) responsible for dopamine stimulation in the striatum. Furthermore, other studies have indicated that the expression of glutamic acid decarboxylase 67 (GAD67) mRNA and protein was different in the striatum of MPTP vs. naïve animals, which is one of the enzymes responsible for the synthesis of neurotransmitter GABA. In the present study, we observed that the parallel changes in protein levels of CK2, DARPP-32 and GAD67 in the striatum and TH in the substantia nigra of MPP+-treated. We also found that manipulation of CK2 or DARPP-32 gene expression aggravated the MPP+-induced neuropathological dificts. The present results suggest that CK2/DARPP-32/GAD67 signaling pathway might involve in the cellular mechanism of motor-deficit in Parkinson’s disease.