beta-Casomorphin causes hypoalgesia in 10-day-old rats: evidence for central mediation.

摘要: Two experiments determined behavioral effectiveness of β-casomorphins(β-CM) in 10-d-old rats by evaluating changes heat escape latency from a 48°C stimulus applied to forepaw. In one study were injected systemically with β-CM4, -5, or -7 at dose range 0.1-2.5 mg/kg. Onlyβ-CM5 was effective, and the dose-response relationship graded. The second evaluated locus action β-CM5 through two experimental manipulations: first, injecting it (0.25 μg) into lateral ventricles attempting block its effects systemic injections naloxone. Second, received intracerebroventricular naloxone β-CM.β-CM effective centrally, suggesting central detection drug. Naloxone blocked administration β-CM, implying that circulating β-CM their precursors cause change mechanisms.