魚缸里自由自在游動(dòng)的金魚看似無憂無慮，沒有痛苦也沒有記憶,。然而挪威和美國(guó)科學(xué)家研究發(fā)現(xiàn),，金魚不僅有痛感，還能記住痛苦的經(jīng)歷,。
知痛知熱
挪威獸醫(yī)學(xué)院和美國(guó)珀杜大學(xué)研究人員把實(shí)驗(yàn)金魚分為兩組，給一組金魚注射嗎啡止痛劑,，另一組金魚注射鹽溶液,。
他們給金魚穿上內(nèi)置微小金屬箔加熱器的“迷你上衣”。加熱器最高溫度控制在50攝氏度,，以免傷害金魚,。
加熱器溫度升至38攝氏度時(shí)，兩組金魚或蜷縮身體,，或擺動(dòng)尾巴,，想要逃離。研究人員記錄下金魚的反應(yīng)后即關(guān)閉加熱器,，把它們放回普通魚缸,。
實(shí)驗(yàn)結(jié)束2小時(shí)后兩組金魚顯現(xiàn)出明顯差異。注射鹽溶液的金魚比注射嗎啡的同伴更易表現(xiàn)出恐懼和警惕,，它們驚慌不安地來回游動(dòng),。
研究報(bào)告發(fā)表在最新一期《應(yīng)用動(dòng)物行為科學(xué)》雜志上。研究人員說,，實(shí)驗(yàn)結(jié)束后金魚出現(xiàn)害怕等表現(xiàn)意味著,，這些金魚曾在實(shí)驗(yàn)過程中承受痛苦并牢牢記住了這一經(jīng)歷。
疼痛記憶
珀杜大學(xué)參與研究的約瑟夫·加納博士說：“測(cè)試中,，嗎啡一定程度上影響金魚的行為,。更重要的是2小時(shí)后金魚的（恐懼）反應(yīng)。這種反應(yīng)很關(guān)鍵,。”
他說,，“沒注射嗎啡的金魚來回游動(dòng)，表現(xiàn)得更不活躍。這是一種充滿恐懼的防御行為”,，顯示出不斷加劇的恐懼和警惕,。這些金魚因經(jīng)歷疼痛而“草木皆兵”。
“絕對(duì)不能把2小時(shí)后的這種表現(xiàn)解釋為反射,，”加納解釋說,，“金魚行為的顯著變化有力證明它們記住了（那段經(jīng)歷）。我認(rèn)為,，這顯示金魚有痛感,。”
“嗎啡能減少金魚行為的改變。這說明疼痛刺激有一種主要體驗(yàn),，”他說,。
先前研究顯示，魚有能對(duì)疼痛刺激做出反應(yīng)的神經(jīng)細(xì)胞,，但一些科學(xué)家認(rèn)為,，這種神經(jīng)細(xì)胞不足以說明魚有痛感。
加納等人的研究則是魚有痛感的有力佐證,。英國(guó)《每日電訊報(bào)》4月25日評(píng)論說,，因?yàn)橥锤泻头瓷渥畲蟮膮^(qū)別在于，疼痛是一種有意識(shí)的情緒,，能被記憶和喚起,。
保護(hù)動(dòng)物
其實(shí)不僅魚有痛感，甲殼類動(dòng)物也能感到疼痛,。
英國(guó)研究人員今年3月發(fā)現(xiàn),，寄生蟹等甲殼類動(dòng)物也有痛感。研究人員電擊寄居蟹居住的貝殼,，遭受電擊的寄居蟹紛紛逃離“居所”,。
研究人員降低電壓再次電擊，這次寄居蟹不會(huì)立即傾巢而出,，卻一直守在“家”里伺機(jī)逃跑,。科學(xué)家說,，這說明寄居蟹能記住疼痛經(jīng)歷,。
英國(guó)貝爾法斯特女王大學(xué)教授鮑勃·埃爾伍德曾發(fā)現(xiàn)對(duì)蝦有痛感。他說：“（學(xué)術(shù)界）長(zhǎng)期以來一直對(duì)蟹,、對(duì)蝦,、龍蝦等甲殼類動(dòng)物是否有痛感存有爭(zhēng)議。寄居蟹離開貝殼不僅僅是簡(jiǎn)單反射,，而是因?yàn)樗鼈儽苊鈧Φ男枨蟪^了對(duì)貝殼的需求,。”
埃爾伍德說：“已有人提議立法保護(hù)甲殼類動(dòng)物，但這似乎只能在科學(xué)研究領(lǐng)域?qū)崿F(xiàn)。數(shù)以百萬計(jì)的甲殼類動(dòng)物被捕撈或養(yǎng)殖供人們食用,。它們得不到保護(hù),，因?yàn)槿藗兿氘?dāng)然地以為它們感覺不到痛。”（生物谷Bioon.com）
生物谷推薦原始出處：
Applied Animal Behaviour Science doi:10.1016/j.applanim.2009.03.015
Thermonociception in fish: Effects of two different doses of morphine on thermal threshold and post-test behaviour in goldfish (Carassius auratus)
Janicke Nordgreena, , , Joseph P. Garnerb, , Andrew Michael Janczakc, , Birgit Ranheima, , William M. Muirb, and Tor Einar Horsberga,
aDepartment of Pharmacology and Toxicology, The Norwegian School of Veterinary Science, Oslo, Norway
bDepartment of Animal Sciences, Purdue University, West Lafayette, IN, USA
cDepartment of Production Animal Clinical Sciences, The Norwegian School of Veterinary Science, Oslo, Norway
The question of whether fish can perceive pain is controversial, and pain is a potentially grave threat to fish welfare. To be able to study pain in a species, knowledge of its nociceptive system is necessary. There is therefore a need for standardised, repeatable and quantifiable measures of nociception and pain in fish. Sensitivity to noxious heat is readily quantifiable. We developed an apparatus to expose goldfish to controlled, localised heat stimulation, and tested the hypothesis that goldfish perceive heat as aversive. We predicted that they would respond to increasing heat with an escape response, that morphine would decrease their heat sensitivity and that the heat stimulation would affect post-test behaviour. A safety cut-off temperature of 50 °C was built into the test apparatus. All 16 fish responded to the heat with an escape response, with a mean baseline of 38 °C. However, morphine at 40 and 50 mg kg?1 could not be demonstrated to have a biologically relevant analgesic effect, but did significantly decrease the impact of heat stimulation on behaviour in the home tank. To our knowledge, this study is the first to systematically investigate thermonociception in unanaesthetised fish.
