Cross-Mellor Shelley K, Kavaliers Martin, Ossenkopp Klaus-Peter
Neuroscience Program and Department of Psychology, University of Western Ontario, Social Science Building, London, Ont, Canada N6A 5C2.
Behav Brain Res. 2004 Jan 5;148(1-2):11-9. doi: 10.1016/s0166-4328(03)00181-5.
Feeding and drinking typically involve both appetitive and consummatory behaviors. Appetitive behaviors include those behaviors produced by an animal prior to the actual consumption, such as approach movements, whereas consummatory behaviors (such as licking and chewing) are involved in the actual consumption of food. The present research compared the gustatory conditioning effects of bacterial lipopolysaccharide (LPS) and lithium chloride (LiCl) in two different paradigms, conditioned taste avoidance and conditioned taste aversion which differentially affect the appetitive and consummatory components of feeding. Male rats were implanted with intraoral cannulae and habituated to a water deprivation schedule and afterwards received two conditioning days (Days 1 and 4). Each conditioning day consisted of 1 h access to a novel sucrose solution (0.3 M) immediately followed by a systemic injection of LPS (200 microg/kg), LiCl (0.15 M, 3 meq) or NaCl vehicle. Conditioned taste aversion was assessed using the taste reactivity test on Day 7, where orofacial and somatic responses were videotaped and analyzed during 3 brief (1 min) exposures to the sucrose solution. Conditioned taste avoidance was assessed on Days 8 and 9 using a two-bottle preference test (sucrose versus water). Animals conditioned with LiCl displayed typical aversive-like responses in the taste reactivity paradigm evidenced by significant reductions in positive ingestive responses (P<0.05) and an increase in active aversive responses (P<0.05) relative to controls. Furthermore, LiCl treatment resulted in conditioned avoidance of sucrose in the two-bottle preference test characterized by a decreased sucrose preference (P<0.05). Conditioning with LPS produced a reduced sucrose preference (P<0.05) relative to controls, comparable to the avoidance seen in LiCl-treated rats. In contrast, conditioning with LPS resulted in similar positive ingestive responses to intraorally infused sucrose as seen in controls. The present results demonstrate that LPS treatment produces conditioned avoidance but not aversion and suggest that LPS can selectively condition the appetitive aspects of feeding whereas the consummatory behaviors remain unaffected.
进食和饮水通常涉及欲求行为和完成行为。欲求行为包括动物在实际进食之前产生的那些行为，如趋近动作，而完成行为（如舔舐和咀嚼）则涉及食物的实际摄取。本研究在两种不同范式（条件性味觉回避和条件性味觉厌恶）中比较了细菌脂多糖（LPS）和氯化锂（LiCl）的味觉条件作用效果，这两种范式对进食的欲求成分和完成成分有不同影响。雄性大鼠植入口腔内插管并适应禁水时间表，之后接受两天的条件作用（第1天和第4天）。每个条件作用日包括1小时接触一种新的蔗糖溶液（0.3M），随后立即进行一次全身注射LPS（200微克/千克）、LiCl（0.15M，3毫当量）或生理盐水。在第7天使用味觉反应测试评估条件性味觉厌恶，在3次短暂（1分钟）接触蔗糖溶液期间对口腔面部和躯体反应进行录像并分析。在第8天和第9天使用双瓶偏好测试（蔗糖与水）评估条件性味觉回避。用LiCl进行条件作用的动物在味觉反应范式中表现出典型的厌恶样反应，相对于对照组，积极摄取反应显著减少（P<0.05），主动厌恶反应增加（P<0.05）。此外，LiCl处理导致在双瓶偏好测试中对蔗糖的条件性回避，表现为蔗糖偏好降低（P<0.05）。与对照组相比，用LPS进行条件作用导致蔗糖偏好降低（P<0.05），与LiCl处理的大鼠中观察到的回避情况相当。相比之下，用LPS进行条件作用导致对口腔内注入蔗糖的积极摄取反应与对照组相似。本研究结果表明，LPS处理产生条件性回避但不产生厌恶，并表明LPS可以选择性地对进食的欲求方面进行条件作用，而完成行为不受影响。
