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Contributions of the Ventrolateral Orbital Cortex to Pain-related Negative Emotion in Rats

Author: NiSuZuo
Tutor: PengZuoPing；ZhangYuQiu
School: Nantong University
Course: Physiology
Keywords: Conditioned place avoidance Ventrolateral orbital cortex Formalin Pain -related aversion cAMP response element binding protein Proto-oncogene c-fos Wake Acute nociceptive behavior Rats
CLC: R402
Type: Master's thesis
Year: 2008
Downloads: 127
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Abstract

Pain is a tissue injury or potential injury unpleasant subjective sensory and emotional experience (International Pain Society, 1994). This definition gives the pain two meanings: that feeling of pain resolution (sensory discrimination) and the pain of emotional experience (affective dimension). The growing number of clinical observations suggest that chronic pain patients suffered vicious emotions, such as anxiety, fear, loneliness, even world-weary due to physical or mental harm to patients may be more serious than the pain itself. Clinically, patients with chronic intractable pain often become stress, depression, and even suicidal tendencies, this ongoing tension and events such as the fear of vicious mood is expected to occur, in turn, largely enhanced pain feelings. Therefore, to clarify the mechanisms of pain and emotional reaction is of great significance for our comprehensive, in-depth understanding of the nature of the pain as well as treatment and mitigation of adverse emotional reactions of chronic intractable pain patients. Ventrolateral orbital cortex (Ventrolateral Orbital cortex, VLO) is an important component of the prefrontal cortex, occupy most of the area of ??the prefrontal cortex, the major recipient of the fiber projection from the hypothalamic medial central nucleus (thalamus nucleus submedius, Sm), ventrolateral Ministry issued downlink fiber dense projected onto the the bilateral midbrain periaqueductal gray (periaqueductal gray, PAG), play an important role in pain modulation. The VLO and body somatosensory cortex (SI, SII), the anterior cingulate cortex (Anterior cingulate cortex, ACC), piriform cortex, insular cortex, amygdala and parabrachial nuclei more pain, learning and memory, and emotional response from the fiber link between the cortex and subcortical structures. Our recent studies have shown that the ACC and the amygdala is important in the formation of aversion related pain. Between fiber contact the VLO with the ACC and the amygdala, also suggest that may be involved in pain emotional process? CAMP response element binding protein (cAMP response element binding protein, CREB) is an important transcription factor in the nucleus, involved in hippocampal long-term memory and the formation of persistent pain induced by spinal cord dorsal horn neurons central sensitization. Immediate early genes (immediately early gene IEG) c-fos is the first to identify the CREB target gene, its protein product of Fos, as a marker of neuronal activation, has been widely used in the study of animal behavior. Our previous studies show that pain can wake aversion induced Fos expression in the ACC, insular cortex and amygdala pain and emotion-related brain areas. Well, in the process of forming pain aversion also accompanied VLO neurons CREB and c-fos activation? To answer these questions, the plantar subcutaneous injection of formalin and location of the conditioned avoidance device combination to create rat formalin-induced conditioned place avoidance (Formalin-induced conditioning place avoidance, F-CPA) model (the model has been confirmed may reflect the the adverse emotional state of animals due to noxious stimuli), the observed large rat VLO in pain aversion to the formation of emotional injury conditions and the pain of emotional arousal induced pCREB (activated state CREB) and the level of Fos expression in VLO. The results show: (1) unilateral plantar subcutaneous injection of 5% formalin combination of conditioned place avoidance the rat training can lead to avoidance of the formalin matching conditions, the electrolytic damage bilateral VLO completely cancel such avoidance behavior, F -CPA scores with the sham lesioned rats decreased significantly compared; (2) plantar electric shock (0.5 ma, 1sec) can also be induced to produce conditioned place avoidance (S-CPA), damage to the fear of such bilateral VLO the conditioned avoidance no significant effect on S-CPA scores compared with the sham-lesioned rats no significant difference; (3) bilateral the VLO damage also had no significant effect on the dual-phase formalin-induced acute pain reaction; (4) single side plantar injection of 5% formalin 50μl can cause the rats were VLO CREB persistent (gt; 24 hr) activation of Fos expression levels also will be raised; (5) of the rats again exposure to harmful two hours in the wake of the pain experienced in the match environment, pCREB and Fos expression level bilateral VLO also significantly raised. These results suggest that the VLO may be involved in specific pain aversion related process, rather than the pain of feeling and a general aversion learning process; VLO within CREB and c-fos activation may be one of the molecular basis of pain aversion and memory intracellular . In summary, the VLO structural integrity may be required pain related aversion. An important role in the formation of the VLO CREB and c-fos in the formalin-induced pain aversion and \Combined with previous reported results of this study, we hypothesized that: VLO, the ACC and the amygdala or other limbic structures together constitute the neural network may have a key pain-related aversion formation.

Contributions of the Ventrolateral Orbital Cortex to Pain-related Negative Emotion in Rats

Abstract

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