安非他命及其相關的衍生物是目前時下年輕人普遍濫用的精神興奮劑，其所帶來社會成本的消耗以及相關的犯罪問題造成社會治安的重大負擔。而目前對於安非他命所造成的成癮理論，猜想可能是透過存在於邊緣系統迴路( mesolimbic circuit )或相關的腦區來達成，經由引起神經細胞中分子層次的適應性( molecular adaptation )而改變該神經細胞的功能，進而造成行為及情緒上的特殊表現。安非他命與鴉片類及酒精類藥物濫用有著顯著的不同，是在於安非他命不易產生身體依賴性，但相對地，安非他命卻對於情緒相關的迴路有著重要的影響。因此，進一步了解安非他命對於情緒作用機轉的調控，是現階段實驗的重點。經多項研究發現，認為腦中杏仁核區域涉及安非他命所誘發、形成的記憶固化作用，因此，探討安非他命之於腦中杏仁核區域神經細胞的作用就愈顯重要。

　　而在本實驗進行中，發現安非他命會引發杏仁核區域神經細胞長期突觸傳導抑制現象( long-term synaptic depression, LTD )，安非他命所引發的長期抑制現象並不受dopamine ( DA )，serotonin 1A ( 5-HT1A )及norepinephrine ( NEa2 )受體拮抗劑的影響，但卻會被cannabinoid CB1受體拮抗劑阻斷。相同地，這個長期抑制現象亦可藉由CB1受體作用劑WIN55212-2來模擬；再則，若施以endocannabinoid uptake inhibitor AM404會加強或部分遮蔽這個現象。不論是安非他命或WIN55212-2誘發的LTD均會上升paired-pulse facilitation ( PPF )的比例，並且會受到P/Q型鈣離子管道阻斷劑所拮抗；另以mEPSCs實驗可進一步證實amphetamine及WIN55212-2之LTD會改變其frequency但不改變amplitude，顯示amphetamine及WIN55212-2所誘發之LTD係透過突觸前機轉。另一方面，這兩者所誘發的抑制作用會互相遮蔽，顯示兩者所產生的突觸塑性改變是透過相類似的作用路徑。若在突觸後神經細胞內給予鈣離子螯合劑BAPTA，則會將部分因安非他命所誘發的長期抑制作用阻斷，而另有一些神經細胞則沒有此項反應；猜想其接續所產生的作用可能是透過鄰近的神經細胞達成；若此項論點正確，則在記錄電極存有BAPTA的情況之下，合併給予AM404，安非他命應仍能誘發產生長期抑制作用；結果確實如此，是故安非他命的作用是透過內生性大麻物質的釋出而來的。綜合以上結果顯示，安非他命誘發內生性大麻物質釋放是必須藉由上升細胞內鈣離子來造成，並改變突觸前P/Q-型鈣離子管道效用，相信將為研究精神刺激劑造成的成癮作用提供一個新的方向。

　　在另一方面，大麻物質具有許多中樞神經生理效應，例如：腦中海馬迴學習與記憶的缺損現象、情緒狀態的調控以及麻醉相關的機制等等，顯示大麻物質在生理作用上具有相當重要的地位。就我們所知，在老鼠的杏仁核中，若活化此區域的CB1 receptors會造成腦區中GABA所媒介的抑制性突觸後電流長期抑制的現象( IPSCs )。再者根據我們先前的研究報導也發現，安非他命能在杏仁核區域，藉由刺激內生性大麻物質的釋放而造成興奮性突觸後電位的長期抑制作用。因此，在本階段的實驗中，將藉由利用在cortico-LA synapses的突觸後神經細胞去極化，引發興奮性突觸後電位的長期抑制作用，經此實驗策略觀測內生性大麻物質在當中所扮演的角色。

　　在一連串的實驗中發現，我們利用在突觸後神經細胞注入正電流的方式( +1.2 nA )，引發突觸後神經細胞去極化，會造成神經突觸長期抑制現象( long-term depression of EPSP )，若此時合併給予CB1 receptor拮抗劑AM251，發現隨著AM251濃度的提高，此拮抗劑的抑制作用會越趨明顯。顯示內生性大麻物質在藉由突觸後神經細胞去極化所誘發的長期抑制現象中有著相當重要的角色；確實如此，在給予CB1 receptor作用劑WIN55212-2之後，隨即遮蔽因去極化所進一步引發的抑制作用；顯示內生性大麻物質會經由突觸後神經細胞去極化而釋出，並造成突觸傳導之長期抑制現象。若於記錄電極內填入鈣離子螯合劑BAPTA，亦會阻斷此長期抑制現象；猜想必有鈣離子參與其間。接下來，利用給予各個型態的鈣離子阻斷劑L-type ( nimodipine )，N-type ( w-conotoxin-GVIA )及P/Q-type calcium channel blocker ( w-agatoxin-TK )，並內鈣離子作用觀測劑( xestospongine, ryanodine )，發現鈣離子的來源為P/Q type Ca++ channels及內鈣的釋放。

　　接下來欲進一步探討的是，究竟內生性大麻物質的作用是透過突觸前亦或突觸後而達成，我們利用一種low-affinity competitive AMPA receptor antagonist g-DGG，間接觀測在paired-pulse protocol及引發LTD之後，突觸效能的變化情形。結果發現，內生性大麻物質的作用係透過突觸前而達成。由此可知，經由突觸後神經細胞去極化會引發內生性大麻物質的釋放，並作用於突觸前造成突觸間長期抑制作用；而此間涉及鈣離子的參與。

　　不論是藉由安非他命亦或突觸後神經細胞去極化，均能在突觸間引發長期抑制作用，使突觸間傳導效能下降。而已知，內生性大麻物質之訊息傳遞在調控LA神經細胞活性中有著相當重要的生理角色；除此之外，相關研究學者亦同時報導，因著內生性大麻物質的出現會下降杏仁核中corticotrophin-releasing hormone的表現程度，並改善因環境刺激所引發的情緒反應不良與壓力的形成。

　　故此，接下來我們希望能夠進一步證實，是否此間所活化釋出出的內生性大麻物質能夠改善或減緩因環境所誘發的恐懼記憶，若確實能夠，其又是參與在哪一個恐懼記憶形成步驟中。恐懼記憶的形成大致上可分為幾個步驟：acquisition，consolidation及extinction。分別在這幾個不同的階段中，施予安非他命及WIN55212-2，並觀察其對恐懼記憶形成的影響為何。此間我們是利用動物恐懼行為模式( Fear-Potentiated Startle )評估動物在活體行為表現上。

　　結果發現，安非他命及WIN55212-2會影響恐懼記憶之acquisition而非consolidation步驟，而此項作用會經由給予CB1 receptor拮抗劑AM251而抵消；並且安非他命的施予有助於恐懼記憶的消除( extinction )。在安非他命影響acquisition的實驗中，我們利用西方點墨法偵測細胞內蛋白質在藥物的作用下所產生的變化，發現mitogen-activated protein kinase ( MAPK )的磷酸化會下降，相同的現象也在安非他命造成extinction作用中發現。

　　由此可知，安非他命及WIN55212-2會下降恐懼記憶的形成，且極可能參與在acquisition步驟中，另外，安非他命亦具有消彌恐懼記憶的效用，此一實驗將可供我們深入探究內生性大麻物質是否亦具有消彌恐懼記憶效用的一個開端。針對安非他命及內生性大麻物質的探究，不僅只作用於突觸效用的調控，更在動物模式中有明確的影響；此舉將有助於未來改善恐懼記憶及情緒壓力的一個新方向。

　　Amphetamine and associated derivatives are the most commonly abused psychostimulant in the young people. Amphetamine is an artificially synthesized psychostimulant. It could activate both central and autonomic nervous system. As we know, amphetamine acts on mesolimbic circuit or associated brain regions and influences on associated emotional circuit. Therefore, to investigate the modulation of amphetamine on emotional circuit is very important for current study.

　　The amygdala is thought to mediate memory consolidation of amphetamine-induced conditioned place preference, a behavioral paradigm that requires memory for an association between environmental cues and the affective state produced by the drug treatment. Here we show that amphetamine induced long-term synaptic depression (LTD) in the amygdala. Amphetamine LTD was not affected by dopamine, serotonin 1A, and norepinephrine a2 receptor antagonists but was blocked by the cannabinoid CB1 receptor antagonist AM251. It was mimicked by the CB1 agonist WIN55212-2 and facilitated and partially occluded by endocannabinoids uptake inhibitor AM404. Both amphetamine and WIN55212-2 LTDs were associated with an increase in the ratio of paired-pulse facilitation and a decrease in the frequency but not the amplitude of miniature EPSCs. They were also sensitively blocked by P/Q type calcium channel blocker and occluded by each other, indicating that these two forms of synaptic plasticity shared a common underlying mechanism. Loading postsynaptic neuron with calcium chelator blocked amphetamine LTD in some but not all neurons tested. However, in the presence of AM404, amphetamine LTD was present in all neurons recorded. These results suggested that amphetamine-induced endocannabinoids release depended on a rise in intracellular calcium and the incomplete blocking of LTD in some neurons. This phenomenon might be attributed to the spillover of endocannabinoid from nearby cells. The finding that endocannabinoids underlie the synaptic actions of amphetamine may open a new avenue for the treatment of psychostimulants addiction.

　　Cannabinoids display a variety of central effects such as impairment of hippocampus-dependent learning and memory, modulation of emotional states and analgesia. Thus, cannabinoids play a very important role in the central nerves system. According to previous finding that endocannabinoids released by amphetamine were capable of inducing LTD of EPSP in the LA. Therefore, in the present study, we aimed to determine a role for endocannabinoids in the LTD of EPSP induced by postsynaptic depolarization at cortico-LA synapses. We injected a positive current ( +1.2 nA ) to postsynaptic neuron and produced a depolarization pattern. This experiment protocol could produce a long-term depression of EPSP. At the same time, if we applied CB1 receptor antagonist AM251, we could find out that AM251 blocked depolarization-induced LTD in a dose-dependent manner. It revealed that endocannbinoids played an important role in depolarization-induced LTD. On the other hand, in appearance of WIN55212-2, depolarization of postsynaptic neuron could not induce further depression. It displayed an occlusion pattern.

　　If we filled electropipette with Ca++ chelator BAPTA, LTD induction could also be blocked. Thus, we suggested that Ca++ must be involved in this phenomenon. According to a series of experiments, we found that postsynaptic depolarization induced LTD that required an elevation of Ca++ though P/Q type Ca++ channels and from releasing of intracellular Ca++ stores.

　　Then, we elucidated possible pre- vs. postsynaptic expression of depolarization LTD by using the low-affinity competitive AMPA receptor antagonist g-D-glutamylglycine ( g-DGG ). The degree of g-DGG inhibition can be used to assess changes in the glutamate transient concentration in the synaptic cleft during paired-pulse protocols and after induction of LTD. No matter all synapses displaying PPF or PPD, g-DGG caused a further inhibition of EPSP after the expression of LTD suggesting that the glutamate concentration in the synaptic cleft was reduced after LTD expression.

　　According to previous experiments, we could conclude that depolarization of postsynaptic neurons could induce LTD by releasing endocannabinoids and acted on presynaptic nerve terminal. In this action process included Ca++ involvement.

　　Either amphetamine or depolarization could induce LTD in the synapses. As we know that the physiological significance of endocannabinoids signaling in the LA is reflected in the activity of LA neurons. Aversive nature of sensory stimuli is processed in the LA, and afferent input from LA to the central nucleus constituted an important pathway for the mediation of stress and fear responses. According to previous findings that cannabinoid exposure decreases corticotrophin-releasing hormone level in the amygdala, positively influences emotional states and removes stress responses to environmental stimuli.

　　Therefore, we tried to further exam whether the releasing of endocannabinoids could relieve the stress and aversive memory which is stimulated by environment. Thus, we applied amphetamine and CB1 receptor agonist WIN55212-2 to observe their effects on the fear memory formation.

　　Our results showed that amphetamine interfered with the steps of acquisition and extinction. It meant that amphetamine and WIN55212-2 application before training would decrease fear level of animal and such an effect might be antagonized by CB1 receptor antagonist AM251. In contrast, amphetamine did not affect the steps of consolidation. On the other hand, amphetamine was able to eliminate fear memory ( extinction ). By western blotting experiments, we found that MAPK was involved in the interference actions of amphetamine and WIN55212-2.

　　By a series of experiments, it is very important for us to know that amphetamine could extinct fear memory. Amphetamine could induce endocannabinoids release and produce long-term depression of synapse. Thus, if we use endocannabinoids agonist directly to monitor whether it could extinct fear memory, it will provide a new insight for improving emotional associated symptoms.

1. Aggleton JP (2000) The amygdala Oxford: Oxford UP.

2. Alger BE (2002) Retrograde signaling in the regulation of synaptic transmission: focus on endocannabinoids. Progress in Neurobiology 68: 247-286.

3. Ameri A (1999) The effects of cannabinoids on the brain. Progress in Neurobiology 58: 315-348.

4. Atkins CM, Selcher JC, Petraitis JJ, Trzaskos JM, Sweatt JD (1998) The MAPK cascade is required for mammalian associative learning. Nature Neuroscience 1: 602-609.

5. Azad SC, Eder M, Marsicano G, Lutz B, Zieglgansberger W, Rammes G (2003) Activation of the cannabinoid receptor type 1 decreases glutamatergic and GABAergic synaptic transmission in the lateral amygdale of the mouse. Learning and Memory 10: 116-128.

6. Bardo MT, Bevins RA (2000) Conditioned place preference: what dose it add to our preclinical understanding of drug reward? Psychopharmacology 153: 31-43.

7. Beltramo M, Stella N, Calignano A, Lin SY, Makriyannis A, Piomelli D (1997) Functional role of high-affinity anadamide transport, as revealed by selective inhibition. Science 277: 1094-1097.

8. Bjijou Y, De Deurwaerdere P, Spampinato U, Stinus L, Cador M (2002) D-Amphetamine-induced behavioral sensitization: effect of lesioning dopaminergic terminals in the medial prefrontal cortex, the amygdala and the entorhinal cortex. Neuroscience 109: 499-516.

9. Blair HT, Schafe GE, Bauer EP, Rodrigues SM, LeDoux JE (2001) Synaptic plasticity in the lateral amygdala: a cellular hypothesis of fear conditioning. Learning and Memory 8: 229-242.

10. Blitzer RD, Wong T, Nouranifar R, Iyengar R, Landau EM (1995) Postsynaptic cAMP pathway gates early LTP in hippocampal CA1 region. Neuron 15: 1403-1414.
11. Bohme GA, Laville M, Ledent C, Parmentier M, Imperato A (2000) Enhanced long-term potentiation in mice lacking cannabinoid CB1 receptors. Neuroscience 95: 5-7.

12. Bouton ME, Bolles RC (1979) Role of contextual stimuli in reinstatement of extinguished fear. Journal of Experimental Psychology 5: 368-378.

13. Bouton ME, King DA (1983) Contextual control of conditioned fear: tests for the associative value of the context. Journal of Experimental Psychology 9: 248-256.

14. Carson G, Wang Y, Alger BE (2002) Endocannabinoids facilitate the induction of LTP in the hippocampus. Nature Neuroscience 5: 723-724.

15. Cassella JV, Davis M (1986) The design and calibration of a startle measurement system. Physiology and Behavior 36: 377-383.

16. Civelli O, Bunzow JR, Grandy DK (1993) Molecular diversity of the dopamine receptors. Annual Review of Pharmacology and Toxicology 32: 281-307.

17. Clausing P, Gough B, Holson RR, Slikker Jr W, Bowyer JF (1995) Amphetamine levels in brain microdialysate, caudate/putamen, substantia nigra and plasma after dosage that produces either behavioral or neurotoxic effects. Journal of Pharmacology and Experimental Therapeutics 274: 614-621.

18. Corcoran KA, Maren S (2001) Hippocampal inactivation disrupts contextual retrival of fear memory after extinction. Journal of Neuroscience 21: 1720-1726.

19. Coutts AA, Anavi-Goffer S, Ross RA, MacEwan DJ, Mackie K, Pertwee RG, Irving AJ (2001) Agonist-induced internalization and trafficking of cannabinoid CB1 receptors in hippocampal neurons. Journal of Neuroscience 21: 2425-2433.

20. Davis M, Rainnie D, Cassell M (1994) Neurotransmission in the rat amygdala related to fear and anxiety. Trends in Neuroscience 17: 208-214.

21. Davis M, Walker DL, Myers KM (2003) Role of the amygdala in fear extinction measured with potentiated startle. Annals of the New York Academy of Sciences 985: 218-232.

22. De Vries TJ, Schoffelmeer AN, Binnekade R, Mulder AH, Vanderschuren LJ (1998) Drug-induced reinstatement of heroin- and cocaine-seeking behavior following ling-term extinction is associated with expression of behavioral sensitization. European Journal of Neuroscience 10: 3565-3571.

23. Dovedova EL (1994) The mechanism of amphetamine action of the neuromediator system of the brain. Voprosy Meditsinskoi Khimii 40: 7-9.

24. Drevets WC, Gautier C, Price JC, Kupfer DJ, Kinahan PE, Grace AA, Price JL, Mathis CA (2001) Amphetamine-induced dopamine release in human ventral striatum correlates with euphoria. Biological Psychiatry 49: 81-96.

25. Elphick MR, Egertova M (2001) The neurobiology and evolution of cannabinoid signalling. Philosophical Transactions of the Royal Society of London B Biological Sciences 356: 381-408.

26. English JD, Sweatt JD (1996) Activation of p42 mitogen-activated protein kinase cascade in hippocampal long-term potentiation. Journal of Biological Chemistry 271: 24329-24332.

27. English JD, Sweatt JD (1997) A requirement for the mitogen-activated protein kinase cascade in hippocampal long-term potentiation. Journal of Biological Chemistry 272: 19103-19106.

28. Fallon JH, Koziell DA, Moore RY (1978) Catecholamine innervation of the basal forebrain. I. Amygdala, suprarhinal cortex and entorhinal cortex. Journal of Comparative Neurology 180: 509-532.
29. Fanselow MS, Gale GD (2003) The amygdala, fear, and memory. Annals of the New York Academy of Sciences 985: 125-134.

30. Finkbeiner S, Greenberg ME (1996) Ca++-dependent routes to Ras: mechanisms for neuronal survival, differentiation, and plasticity? Neuron 16: 233-236.

31. Freund TF, Katona I, Piomelli D (2003) Role of endogenous cannabinoids in synaptic signaling. Physiological Reviews 83:1017-1066.

32. Garattini S, Jori A, Samanin R (1976) Interactions of various drugs with amphetamine. Annals of the New York Academy of Sciences 281: 409-425.

33. Gerdeman GL, Ronesi J, Lovinger DM (2002) Postsynaptic endocannabinoid release is crtical to long-term depression in the stratum. Nature Neuroscience 5: 446-451.

34. Gerdeman GL, Partridge JG, Lupica CR, Lovinger DM (2003) It could be habit forming: drugs of abuse and striatal synaptic plasticity. Trends in Neurosciences 26: 184-192.

35. Giros B, Jaber M, Jones SR, Wightman RM, Caron MG (1996) Hyperlocomotion and indifference to cocaine and amphetamine in mice lacking the dopamine transporter. Nature 379: 606-612.

36. Giuffrida A, Parsons LH, Kerr TM, Rodriguez de Fonseca F, Navarro M, Piomelli D (1999) Dopamine activation of endogenous cannabinoid signaling in dorsal striatum. Nature Neuroscience 2: 358-363.

37. Gonzalez SC, Karniol IG, Carlini EL (1972) Effects of cannabis sativa extract on conditioned fear. Behavioral Biology 7: 83-94.

38. Hampson RE, Zhuang SY, Weiner JL, Deadwyler SA (2003) Functional significance of cannabinoid-mediated, depolarization-induced suppression of inhibition (DSI) in the hippocampus. Journal of Neurophysiology 90: 55-64.

39. Hardingham G, Chawla S, Johnson C, Bading H (1997) Distinct functions of nuclear and cytoplasmic calcium in the control of gene expression. Nature 385: 260-265.

40. Harmer CJ, Phillips GD (1999) Enhanced dopamine efflux in the amygdala by a predictive, but not a non-predictive, stimulus: facilitation by prior repeated d-amphetamine. Neuroscience 90: 119-130.

41. Hoffman AF, Lupica CR (2002) Mechanisms of cannabinoid inhibition of GABA (A) synaptic transmission in the hippocampus. J ournal of Neuroscience 20: 2470-2479.

42. Hsu EH, Schroeder JP, Packard MG (2002) The amygdala mediates memory consolidation for an amphetamine conditioned place preference. Behavioural Brain Research 129: 93-100.

43. Huang CC, Hsu KS, Gean PW (1996) Isoproterenol potentiates synaptic transmission primarily by enhancing presynaptic calcium influx via P-and/or Q-type calcium channels in the rat amygdala. Journal of Neuroscience 16: 1026-1033.

44. Huang YC, Wang SJ, Chiou LC, Gean PW (2003) Mediation of amphetamine-induced long-term depression of synaptic transmission by CB1 cannabinoid receptors in the rat amygdala. Journal of Neuroscience 23: 10311-10320.

45. Iversen L (2003) Cannabis and the brain. Brain 126: 1252-1270.

46. Jones S, Kauer JA (1999) Amphetamine depresses excitatory synaptic transmission via serotonin receptors in the ventral tegmental area. Journal of Neuroscience 19: 9780-9787.

47. Kalivas PW, Stewart J (1991) Dopamine transmission in the initiation and expression of drug- and stress-induced sensitization of motor activity. Brain Research Reviews 16: 223-244.
48. Kandel ES, Hay N (1999) The regulation and activities of the multifunctional serine/thronine kinase Akt/PKB. Experimental Cell Research 253: 210-229.

49. Kanterewicz BI, Urban NN, McMahon DBT, Norman ED, Giffen LJ, Favata MF, Scherie PA, Traskos JM, Barrionuevo G, Klann E (2000) The extracellular signal-regulated kinase cascade is required for NMDA receptor-independent LTP in area CA1 but not area CA3 of the hippocampus. Journal of Neuroscience 20: 3057-3066.

50. Katona I, Rancz EA, Acsady L, Ledent C, Mackie K, Hajos N, Freund TF (2001) Distribution of CB1 cannabinoid receptors in the amygdale and their role in the control of GABAergic transmission. Journal of Neuroscience 21: 9506-9518.

51. Khoshbouei H, Wang H, Lechleiter JD, Javitch JA, Galli A (2003) Amphetamine-induced dopamine efflux. A voltage-sensitive and intracellular Na+-dependent mechanism. Journal of Biological Chemistry 278: 12070-12077.

52. Koob GF (1996) Drug addiction: the yin and yang of hedonic homeostasis. Neuron 16: 893-896.

53. Koob GF (1992) Neural mechanism of drug reinforcement. Annals of the New York Academy of Sciences 654: 171-191.

54. Koob GF, Bloom FE (1988) Cellular and molecular mechanisms of drug dependence. Science 242: 715-723.

55. Kreitzer AC, Regehr WG (2001a) Retrograde inhibition of presynaptic calcium influx by endogenous cannabinoids at excitatory synapses onto Purkinje cells. Neuron 29: 717-727.

56. Kreitzer AC, Regehr WG (2001b) Cerebellar depolarization-induced suppression of inhibition by endogenous cannabinoids. Journal of Neuroscience 21: RC174-178.

57. Kreitzer AC, Regehr WG (2002) Retrograde signaling by endocannabinoids. Current Opinion in Neurobiology 12: 324-330.

58. LeDoux JE (1994) The amygdala: contributions to fear and stress. Seminars in Neuroscience 6: 231-237.

59. LeDoux JE (1994) Emotion, memory and the brain. Scientific American 270: 50-57.

60. LeDoux JE (2000) Emotion circuits in the brain. Annual Review of Neuroscience 23: 155-184.

61. Lin CH, Lee CC, Gean PW (2003) Involvement of a calcineurin cascade in amygdala depotentiation and quenching of fear memory. Molecular Pharmacology 63: 44-52.

62. Lin CH, Yeh HW, Lin CH, Lu KT, Leu TH, Chang WC, Gean PW (2001) A role for the PI-3 kinase signaling pathway in fear conditioning and synaptic plasticity in the amygdala. Neuron 31: 841-851.

63. Littleton JM, Little HJ (1989) In psychoactive drugs: tolerance and sensitization, A.J. Goudie and M.W. Emmett-Oglesby, eds. ( Clifton, New Jersey : Humana Press ) 461-518.

64. Llinas R, Steinberg IZ, Walton K (1981) Presynaptic calcium currents in squid giant synapse. Biophysical Journal 33: 289-322.

65. Lokiec F, Rapin JR, Jacquot C, Cohen Y (1978) A comparison of the kinetics of d- and l-amphetamine in the brain of isolated and aggregated rats. Psychopharmacology 58: 73-77.

66. Losonczy A, Biro AA, Nusser Z (2004) Persistently active cannabinoid receptors mute a subpopulation of hippocampal interneurons. Proceedings of the National Academy of Sciences of the United States of America 101: 1362-1367.

67. Lu KT, Walker DL, Davis M (2001) Mitogen-activated protein kinase cascade in the basolateral nucleus of amygdala is involved in extinction of fear-potentiated startle. Journal of Neuroscience. 21:RC162.

68. Lutz B (2002) Molecular biology of cannabinoid receptors. Prostaglandins, Leukotrienes and Essential Fatty Acids 66: 123-142.

69. Maejima T, Hashimoto K, Yoshida T, Aiba A, Kano M (2001) Presynaptic inhibition caused by retrograde signal from metabotorpic glutamate to cannabinoid receptors. Neuron 31: 463-475.

70. Maejima T, Ohno-Shosaku T, Kano M (2001) Endogenous cannabinoid as a retrograde messenger from depolarized postsynaptic neurons to presynaptic terminals. Neuroscience Research 40: 205-10.

71. Maingret F, Patel AJ, Lazdunski M, Honore E (2001) The endocannabinoid anandamide is a direct and selective blocker of the background K(+) channel TASK-1. EMBO Journal 20: 47-54.

72. Marciano-Cabral F, Ferguson T, Bradley SG, Cabral G (2001) Delta-9-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, exacerbates brain infection by Acanthamoeba. Journal of Eukaryotic Microbiology 48 Suppl: 4S-5S.

73. Marsicano G, Wotjak CT, Azad SC, Bisogno T, Rammes G, Cascio MG, Hermann H, Tang J, Hofmann C, Zieglgansberger W, Di Marzo V, Lutz B (2002) The endogenous cannabinoid system controls extinction of aversive memories. Nature 418: 530-534.

74. Matias I, Bisogno T, Melck D, Vandenbulcke F, Verger-Bocquet M, De Petrocellis L, Sergheraert C, Breton C, Di Marzo V, Salzet M (2001) Evidence for an endocannabinoid system in the central nervous system of the leech Hirudo medicinalis. Brain Research Molecular Brain Research 87: 145-159.

75. McDonald AJ, Mascagni F (2002) Localization of the CB1 type cannabinoid receptor in the rat basolateral amygdala: high concentrations in a subpopulation of cholecystokinin-containing interneurons. Neuroscience 107: 641-652.
76. McKernan MG, Shinnick-Gallagher P (1997) Fear conditioning induces a lasting potentiation of synaptic currents in vitro. Nature 390: 607-610.

77. Mechoulam R, Ben Shabat S, Hanus L, Fride E, Vogel Z, Baywitch M, Sulcova AE (1996) Endogenous cannabinoid ligands: chemical and biological studies. Journal of Lipid Mediators and Cell Signalling 14: 45-49.

78. Mechoulam R, Fride E, Marzo VD (1998) Endocannabinoids European Journal of Pharmacology 359: 1-18.

79. Melis M, Pistis M, Perra S, Muntoni AL, Pillolla G, Gessa GL (2004) Endocannabinoids mediate presynaptic inhibition of glutamatergic transmission in rat ventral tegmental area dopamine neurons through activation of CB1 receptors. Journal of Neuroscience 24: 53-62.

80. Nikulina EM, Covington HE 3rd, Ganschow L, Hammer RP Jr, Miczek KA (2004) Long-term behavioral and neuronal cross-sensitization to amphetamine induced by repeated brief social defeat stress: Fos in the ventral tegmental area and amygdala. Neuroscience 123: 857-865.

81. Ohno-Shosaku T, Maejima T, Kano M (2001) Endogenous cannabinoids mediate retrograde signals from depolarized postsynaptic neurons to presynaptic terminals. Neuron 29: 729-738.

82. Olive MF, Koenig HN, Nannini MA, Hodge CW (2001) Stimulation of endorphin neurotransmission in the nucleus accumbens by ethanol, cocaine, and amphetamine. Journal of Neuroscience. 21: RC184.

83. Ong WY, Mackie K (1999) A light and electron microscopic study of the CB1 cannabinoid receptor in primate brain. Neuroscience 92: 1177-1191.

84. Ostrander MM, Badiani A, Day HE, Norton CS, Watson SJ, Akil H, Robinson TE (2003) Environmental context and drug history modulate amphetamine-induced c-fos mRNA expression in the basal ganglia, central extended amygdala, and associated limbic forebrain. Neuroscience 120: 551-571.

85. Panikashvili D, Simeonidou C, Ben-Shabat S, Hanusce L, Breuer A, Mechoulam R, Shohami E (2001) An endogenous cannabinoid (2-AG) is neuroprotective after brain injury. Nature 413: 527-531.

86. Pavolov IP (1927) Conditioned reflex: an investigation of the physiological activity of the cerebral cortex. ( Oxford university Press, London ).

87. Paxinos G, Watson CR, Emson PC (1980) AChE-stained horizontal sections of the rat brain in stereotaxic coordinates. Journal of Neuroscience Methods 3: 129-49.

88. Piazza PV, Deminiere JM, Le Moal M, Simon H (1989) Factors that predict individual vulnerability to amphetamine self-administration. Science 245: 1511-1513.

89. Pifl C, Drobny H, Reither H, Hornykiewicz O, Singer EA (1995) Mechanism of the dopamine-releasing actions of amphetamine and cocaine: plasmalemmal dopamine transporter versus vesicular monoamine transporter. Molecular Pharmacology 47: 368-373.

90. Piomelli D, Beltramo M, Glasnapp S, Lin SY, Goutopoulos A, Xie XQ, Makriyannis A (1999) Structure determinants for recognition and translocation by the anadamide transporter. Proceedings of the National Academy of Sciences of the United States of America 96: 5802-5807.

91. Reuter H (1996) Diversity and function of presynaptic calcium channels in the brain. Current Opinion in Neurobiology 6: 331-337.

92. Robbe D, Alonso G, Chaumont S, Bockaert J, Manzoni OJ (2002) Role of P/Q-Ca2+ channels in metabotropic glutamate receptor 2/3-dependent presynaptic long-term depression at nucleus accumbens synapses. Journal of Neuroscience 22: 4346-4356.

93. Robinson TE, Berridge KC (1993) The neural basis of drug craving: an incentive-sensitization theory of addiction. Brain Research Reviews 18: 247-291.

94. Rodriguez de Fonseca F, Carrera MR, Navarro M, Koob GF, Weiss F (1997) Activation of corticotropin-releasing factor in the limbic system during cannabinoid withdrawal. Science 276: 2050-2054.

95. Rogan MT, Staubli UV, LeDoux JE (1997) Fear conditioning induces associative long-term potentiation in the amygdala. Nature 390: 604-407.

96. Rubino T, Vigano D, Massi P, Parolaro D (2001) The psychoactive ingredient of marijuana induces behavioural sensitization. European Journal of Neuroscience 14: 884-886.

97. Sah P (2002) Never fear, cannabinoids are here. Nature 418: 488-489.

98. Saunders C, Ferrer JV, Shi L, Chen J, Merrill G, Lamb ME, Leeb-Lundberg LM, Carvelli L, Javitch JA, Galli A (2000) Amphetamine-induced loss of human dopamine transporter activity: an internalization-dependent and cocaine-sensitive mechanism. Proceedings of the National Academy of Sciences of the United States of America 97: 6850-6855.

99. Schafe GE, Atkins CM, Swank MW, Bauer EP, Sweatt JD, LeDoux JE (2000) Activation of ERK/MAPK kinase in the amygdala is required for memory consolidation of Pavlovian fear conditioning. Journal of Neuroscience 20: 8177-8187.

100.Seger R, Krebs EG (1995) The MAPKs signaling cascade. The FASEB Jouranl 9: 726-735.

101.Seiden LS, Sabol KE, Ricaurte GA (1993) Amphetamine: effects on catecholamine systems and behavior. Annual Review of Pharmacology and Toxicology 33: 639-676.

102.Sim-Selley LJ (2003) Regulation of cannabinoid CB1 receptors in the central nervous system by chronic cannabinoids. Critical Reviews in Neurobiology 15: 91-119.

103.Solomon, RL (1977) In psychopathology : Experimental models, J.D. Master and M.E.P. Seligman, eds. ( San Francisco; W.H. Freeman and Company ) 124-145.

104.Spector S, Sjoerdsma A, Udenfriend S (1965) Blockade of endogenous norepinephrine synthesis by a-methyl-p-tyrosine, an inhibitor of tyrosine hydroxylase. Journal of Pharmacology and Experimental Therapeutics 147: 86-95.

105.Sulzer D, Chen TK, Lau YY, Kristensen H, Rayport S, Ewing A (1995) Amphetamine redistributes dopamine from synaptic vesicles to the cytosol and promotes reverse transport. Journal of Neuroscience 15: 4102-4108.

106.Teyler TJ, Cavus I, Coussens C (1995) Synaptic plasticity in the hippocampal slice: functional consequences. Journal of Neuroscience Methods 59: 11-17.

107.Ungerstedt U (1971) Stereotaxic mapping of monoamine pathways in the rat brain. Acta Physiologica Scandinavica 82: 1-48.

108.Varma N, Brager D, Morishita W, Lenz RA, London B, Alger B (2002) Presynaptic factors in the regulation of DSI expression in hippocampus. Neuropharmacology 43: 550-562.

109.Vincenzo DM, Dominique M, Tiziana B, Luciano DP (1998) Endocannabinoids: endogenous cannabinoid receptor ligands with neuromodulatory action. Trends in Neuroscience 21: 521-528.

110.Wachtel SR, ElSohly MA, Ross SA, Ambre J, de Wit H (2002) Comparison of the subjective effects of Delta(9)-tetrahydrocannabinol and marijuana in humans. Psychopharmacology 161: 331-339.

111.Wang SJ, Sihra TS, Gean PW (2001) Lamotrigine inhibition of glutamate release from isolated cerebrocortical nerve terminals (synaptosomes) by suppression of voltage-activated calcium channel activity. NeuroReport 12: 2255-2258.

112.Wang Z, Rebec GV (1998) Neuroethological assessment of amphetamine-induced behavioral changes and their reversal by neuroleptics: focus on the amygdala and nucleus accumbens. Progress in Neuro-Psychopharmacology and Biological Psychiatry 22: 883-905.

113.Weiner I, Gal G, Rawlins JN, Feldon J (1996) Differential involvement of the shell and core subterritories of the nucleus accumbens in latent inhibition and amphetamine-induced activity. Behavioural Brain Research 81: 123-133.

114.Wilson RI, Nicoll RA (2001) Endogenous cannabinoids mediate retrograde signaling at hippocampal synapses. Nature 410: 588-592.

115.Wilson RI, Kunos G, Nicoll RA (2001) Presynaptic specificity of endocannabinoid signaling in the hippocampus. Neuron 31: 453-462.

116.Wise RA (1998) Drug-activation of brain reward pathways. Drug and Alcohol Dependence 51: 13-22.

117.Wise RA, Bozarth MA (1987) A psychomotor stimulant theory of addiction. Psychological Review 94: 469-492.

118.Wolf ME (1998) The role of excitatory amino acids in behavioral sensitization to psychomotor stimulants. Progress in Neurobiology 54: 679-720.

119.Woods VE, Ettenberg A (2004) Increased amphetamine-induced locomotion during inactivation of the basolateral amygdala. Behavioural Brain Research 149: 33-39.

120.Wu SP, Lu KT, Chang WC, Gean PW (1999) Involvement of mitogen-activated protein kinase in hippocampal long-term potentiation. Journal of Biomedical Science 6: 409-417.
121.Yao RJ, Cooper GM (1995) Requirement for phosphatidylinositol 3-kinase in the prevention of apoptosis by nerve growth factor. Science 267: 2003-2006.

122.Yeh SH, Lin CH, Lee CF, Gean PW (2002) A requirement of nuclear factor-kappaB activation in fear-potentiated startle. Journal of Biological Chemistry 277: 46720-46729.

123.Zald DH, Pardo JV (2002) The neural correlates of aversive auditory stimulation. Neuroimage 16: 746-753.

124.Zhang XF, Cooper DC, White FJ (2002) Repeated cocaine treatment decreases whole-cell calcium current in rat nucleus accumbens neurons. Journal of Pharmacology and Experimental Therapeutics 301: 1119-1125.

125.Zimmermann S, Moelling K. (1999) Phosphorylation and regulation of Raf by Akt (protein kinase B). Science 286: 1741-1744.

126.Zucker RS (1989) Short-term synaptic plasticity. Annual Review of Neuroscience 12: 13-31.