Attenuation of systemic morphine-induced analgesia by central administration of ghrelin and related peptides in mice.

Ghrelin, an acylated 28-amino peptide secreted in the gastric endocrine cells, has been demonstrated to stimulate the release of growth hormone, increase food intake, and inhibit pro-inflammatory cascade, etc. Ghrelin mainly combines with its receptor (GHS-R1α) to play the role in physiological and pathological functions. It has been reported that ghrelin plays important roles in the control of pain through interaction with the opioid system in inflammatory pain and acute pain. However, very few studies show the effect of supraspinal ghrelin system on antinociception induced by intraperitoneal (i.p.) administration of morphine. In the present study, intracerebroventricular (i.c.v.) injection of ghrelin (0.1, 1, 10 and 100 nmol/L) produced inhibition of systemic morphine (6 mg/kg, i.p.) analgesia in the tail withdrawal test. Similarly, i.c.v. injection GHRP-6 and GHRP-2 which are the agonists of GHS-R1α, also decreased analgesia effect induced by morphine injected intraperitoneally in mice. Furthermore, these anti-opioid activities of ghrelin and related peptides were not blocked by pretreatment with the GHS-R1α selective antagonist [d-Lys(3)]-GHRP-6 (100 nmol/L, i.c.v.). These results demonstrated that central ghrelin and related peptides could inhibit the analgesia effect induced by intraperitoneal (i.p.) administration of morphine. The anti-opioid effects of ghrelin and related peptides do not interact with GHS-R1a. These findings may pave the way for a new strategy on investigating the interaction between ghrelin system and opioids on pain modulation.

Protective effect of Shenfu injection on thromboangiitis obliterans model rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Thromboangiitis obliterans (TAO) or Buerger's disease is a non atherosclerotic, segmentar inflammatory vasculitis that is incurable at present. Shenfu injection (SFI), a traditional Chinese formulation, have been confirmed to produce protective influences on several organs and limb during ischemia and reperfusion (IR) injury in rats. However, the effects of SFI on TAO remain unclear. MATERIALS AND METHODS: Adult male Sprague Dawley rats were randomly divided into sham operated group, TAO model group, SFI 2.5mg/kg (low dose), 5mg/kg (medium dose) and 10mg/kg (high dose) groups (n=8). Rats were intravenously administered SFI 2.5, 5 and 10mg/kg or saline once per day for 15 days. TAO model was prepared by injecting sodium laurate into the femoral artery of rats. Then we examined the changes of pathological signs, pathologic grading of thrombus, the indexes of hematology, the contents of thromboxane B2 (TXB2), 6-keto-prostaglandin F(lα) (6-K-PGF(1α)) in plasma following SFI or saline treatment. RESULTS: More pathological signs of lesions, higher grades of pathological thrombosis, increased blood platelet counts, the increase in the TXB2 and TXB2/6-K-PGF(1α) ratio, as well as the decrease of 6-K-PGF(1α) in TAO model group were shown in present experiments; SFI treatment significantly improved the pathological signs of lesions induced by sodium laurate injection, reduced the numbers of thrombus formation, blood platelet counts, the TXB2 and TXB2/6-K-PGF(1α) ratio but increased the 6-K-PGF(1α) compared with TAO model group. However, there were no significant alterations in the counts of red blood cell, leucocyte and neutrophil among these groups. CONCLUSIONS: Our preliminary findings first indicated that SFI can produce significant therapeutic effects on experimental Buerger's disease model rats in a dose independent manner. The underlying mechanisms may be due to its modifying hematology, inhibiting platelet aggregation and enhancing anti-thrombotic function of vessel endothelia.