An analgesic to bridge the gap between Narcotics and NSAIDs: opiorphin

Pain management is an all-time challenge in dentistry. Discontent to pain management is a concern among patients and professionals. Unrelieved pain affects physical and mental well-being contributing to delayed recovery, psychological distress and anxiety. Studies have revealed that chronic pain interferes with normal daily chores of the individual like exercise, sleep, social life and lifestyle. At one end of pain management spectrum are Non-steroidal anti-inflammatory drugs (NSAIDs) while at the other end are the opioids. These drugs are not without constituent side effects. The quest is for new analgesics with potent and long term analgesia with minimal or no side effects. An analgesic that is intermediate in this spectrum is the need of the hour. Opiorphin is an endogenous peptide isolated from human saliva. Opiorphin produces analgesia, by inhibiting enkephalin (ENK) metabolizing enzymes, thus increasing the half-life of circulating ENKs. Apart from being a potent analgesic it can also be a potential biomarker for various systemic and psychosocial disorders. This review focuses on the pharmacological effects of opiorphin and its potential role as a biomarker in various disease conditions.

Pain behavior to electroacupuncture in rabbit tooth pulp

Aim: The aim of this study was to verify the pain behavior to electroacupuncture (EACP) in rabbit tooth-pulp assay. Methods: Albino rabbits weighing 1.5-2.0 kg) were pretreated with saline or morphine (5mg/kg, e.v.) 10 min before the nociceptive test (NT). In another group, EACP (rectangular pulses, f1=2 Hz, f2=0.1 s, 3 mA) was applied in acupoints and sham points, before and during the NT. After 120 min, EACP was withdrawn and the nociceptive threshold was measured every 10 min until the initial nociceptive threshold was achieved. Results: EACP, using the Yintang, ST4 and ST5 acupoints, induced an increased in the nociceptive threshold and this effect persisted for up to 2 h, even after the removal of electric stimulation. Application of EACP at sham points did not show significant analgesic activity. The present results demonstrated that males presented a higher initial level of analgesia, but a poorer maintenance of analgesic effect after the EACP procedure, while females demonstrated a long lasting analgesic effect even after discontinuation of EACP. Conclusions: EACP presented an analgesic effect in a rabbit tooth pulp assay that was probably due to the release of endogenous opioids. The duration of this analgesic effect seems to be different for males and females.

Manual acupuncture and its central mechanisms: involvement of propriosinal and descending pain inhibitory system / 全日本鍼灸学会雑誌

Manual acupuncture to ST 36 Zusanli induces both long-lasting and short-term inhibitory effects on C-evoked discharges of wide dynamic range (WDR) neurons in the lumbar cord. The possible involvement of the central nervous system in producing these two types of inhibitions was investigated in urethane-anesthetized rats. In one expriment, the existence of a descending pain inhibitory system was studied using spinal conduction blocks at the cervical level. In a separate experiment, naloxone was administered systemically to investigate the participation of endogenous opioids.<br>Long-lasting inhibition was found to be due to a descending pain inhibitory system from the upper central nervous system together with the involvement of an opioidergic link. On the other hand, short-term inhibition was attributed to a propriospinal pain inhibitory system and endogenous opioids were not implicated.