Afferent and efferent connections of the rat tail flick reflex (a model used to analyze pain control mechanisms).

摘要: Although the rat tail flick reflex (TFR) is widely used to study neural mechanisms of analgesia, its underlying anatomy has not been systematically studied. In present axonal transport horseradish peroxidase (HRP) was trace efferent and afferent connections TFR. The extensor caudae medialis (ECM), lateralis (ECL), abductor dorsalis (ACD) were identified as muscles injected with HRP. Labeled motor neurons found in lumbar segments L4–L6, sacral S1–S4, coccygeal Co1–Co2; ECL injections also labeled cells Co3. Motor concentrated at levels L5-S2 for ECM, S2-Co2 ECL, L5-Co1 ACD. To label terminals afferents, dorsolateral nerve (DLTN) ventrolateral (VLTN) which innervate skin cut exposed Application HRP either DLTN or VLTN S4, Co1, Co2, For DLTN, greatest density observed lateral half laminae I II dorsal horn. contrast, afferents from medial I–II. With longer survival times S3, ventral horn L6-S2. Bilateral rhizotomies S3-Co3 necessary sufficient abolish flick. This corroborated results anatomical studies. Although ten spinal segments, L4-Co3, caudally S3-Co3. Thus, addition segmental connections, TFR requires an ascending propriospinal connection caudal S1, S2, enlargement. intense labeling substantia gelatinosa (SG) consistent pharmacological, anatomical, physiological studies implicating SG important site inhibition by opiates brainstem stimulation.