Peripheral and central sites of action for the non-selective cannabinoid agonist WIN 55,212-2 in a rat model of post-operative pain

Background and purpose:

Activation of cannabinoid (CB) receptors decreases nociceptive transmission in inflammatory or neuropathic pain states. However, the effects of CB receptor agonists in post-operative pain remain to be investigated. Here, we characterized the anti-allodynic effects of WIN 55,212-2 (WIN) in a rat model of post-operative pain.

Experimental approach:

WIN 55,212-2 was characterized in radioligand binding and in vitro functional assays at rat and human CB₁ and CB₂ receptors. Analgesic activity and site(s) of action of WIN were assessed in the skin incision-induced post-operative pain model in rats; receptor specificity was investigated using selective CB₁ and CB₂ receptor antagonists.

Key results:

WIN 55,212-2 exhibited non-selective affinity and agonist efficacy at human and rat CB₁ versus CB₂ receptors. Systemic administration of WIN decreased injury-induced mechanical allodynia and these effects were reversed by pretreatment with a CB₁ receptor antagonist, but not with a CB₂ receptor antagonist, given by systemic, intrathecal and supraspinal routes. In addition, peripheral administration of both CB₁ and CB₂ antagonists blocked systemic WIN-induced analgesic activity.

Conclusions and implications:

Both CB₁ and CB₂ receptors were involved in the peripheral anti-allodynic effect of systemic WIN in a pre-clinical model of post-operative pain. In contrast, the centrally mediated anti-allodynic activity of systemic WIN is mostly due to the activation of CB₁ but not CB₂ receptors at both the spinal cord and brain levels. However, the increased potency of WIN following i.c.v. administration suggests that its main site of action is at CB₁ receptors in the brain.British Journal of Pharmacology (2009) 157, 645–655; doi:10.1111/j.1476-5381.2009.00184.x; published online 3 April 2009     

Dietary management of acute diarrhea with local foods in a Guatemalan rural community

A community-based, randomized trial was conducted to evaluate a locally available diet for the management of acute diarrhea ( n = 99 episodes) in 90 Guatemalan children, 4–42 months of age. The Test Diet (TD), a combination of a semi-solid pap (maize flour, black beans, oil) and a liquid gruel, Incaparina (maize flour, cotton seed flour, sugar), in addition to breast-milk and other home foods (group TD, n = 45 episodes) was offered for 14 d and compared to usual home feeding (group HF, n = 54 episodes). Diarrhea episodes after admission were significantly shorter for group TD (median 2. 0 d) than group HF (median 4. 4 d, p = 0. 003) after adjusting for potential confounders. Weight gains did not differ significantly between groups. We conclude that community-based dietary management of acute childhood diarrhea using energy-dense, locally available foods is feasible and may shorten diarrhea duration. This may encourage mothers to follow recommendations for continued feeding during diarrhea in developing country environments.     

Age-related differences in distractibility and response to methylphenidate in monkeys

Increased susceptibility to distraction is a symptom of normal aging and several clinical syndromes, including Alzheimer's disease and attention deficit disorders. In the present study, aged and young adult macaques were well-trained to perform an automated delayed matching-to- sample (DMTS) task which assesses both attention and short-term memory. On 19% of all trials, a task-relevant distracting stimulus was presented during either the initial 1 or 3 s of delay intervals (early onset) or the final 1 or 3 s of delay intervals (late onset). In aged monkeys, both early and late onset distractors lasting 1 or 3 s impaired delayed recall on trials with the shortest delay intervals, but did not affect accuracy on trials with long delay intervals. In contrast, young adult monkeys were impaired only by the presence of an early onset distractor lasting 3 s. Impairment was selective for only those trials with the shortest delay intervals. Late onset distractors were relatively ineffective in producing distractibility in young adult animals. Methylphenidate (MPH; 0.005-1.0 mg/kg) failed to reduce distractibility in aged monkeys, producing locomotor abnormalities and hypophagia at doses ranging from 0.25 to 1.0 mg/kg. In young adult monkeys, however, distractibility was significantly attenuated by administration of the 0.125 mg/kg dose. Habituation to the distracting stimulus (under saline conditions) was assessed throughout the study and was not evident at any time point of testing. These data indicate that attention and recall after brief delays are impaired following exposure to a task-relevant distracting stimulus in both aged and young adult monkeys, but that aged monkeys are more susceptible to distraction and do not receive significant benefit from MPH administration.      

证据!久坐“危害巨大”,或增加死于14种疾病的风险

正导读:从椅子、沙发上站起来吧!即使你经常锻炼,坐得太久也可能会危及生命。近日,来自美国癌症协会的一项研究表明,与每天坐不到3小时的人相比,如果你一天坐6个小时或者更久,过早死亡的风险会增加19%。2018年6月26日,这一成果以"Prolonged Leisur-Time Spent Sitting in Relation to Cause-specific Mortality     

The ontogeny of terminal deoxynucleotidyl transferase positive cells in the human fetus

The ontogeny of cells containing the enzyme terminal deoxynucleotidyl transferase (TdT) in human fetal liver, bone marrow, and thymus has been studied using a highly specific antiserum to TdT together with monoclonal antiprecursor cell antibodies in double and triple marker immunofluorescence. TdT+ cells were first observed in fetal liver at 12 wk of gestation and accounted for 55% of the lymphoid-like cells isolated after Ficoll-Hypaque separation. TdT+ cells were first observed in the bone marrow 16 wk after gestation. Like TdT+ cells in normal infant bone marrow, the majority of TdT+ cells in fetal liver and bone marrow expressed both BA-1 and RFB-1 antigens. This suggests that fetal TdT+ cells include progenitors of the B lineage (BA-1+) and perhaps of thymocytes (RFB-1+). Nevertheless, TdT was not observed in fetal thymocytes until after 20 wk of gestation, although thymic blasts and the majority of thymocytes were strongly RFB-1+ from 12 wk of gestation. These results clearly show that fetal thymus is first populated by TdT, RFB-1+, BA-1 cells, but does not exclude the fact that a second "wave" of TdT+ prothymocytes, possibly bone marrow derived, also exists.     

Development of pluripotent hematopoietic progenitor cells in the human fetus

Pluripotent hematopoietic progenitor cells (CFU-GEMM), myeloid progenitor cells (CFU-GM), and erythroid progenitors (BFU-E) were studied in midtrimester human fetuses using the mixed colony assay. All three progenitor cell populations were detected at high levels in the fetal liver from 12 to 23 wk of gestation. Stem cells were first observed in the bone marrow at 15-16 wk of gestation, although bone marrow cultures from earlier fetuses showed heavy growths of stromal cells. Spleen cultures first showed growth of stem cells at 18-19 wk, but fetal thymus showed no hematopoietic activity. Peripheral blood from four fetuses aged 13, 18, 20, and 21 wk showed very high levels of all 3 progenitor cells. The results demonstrate that hematopoietic development in the human fetus parallels that of the mouse. The observation that stromal cell development in the bone marrow precedes the appearance of hematopoietic progenitor cells suggests that they may be closely involved in stem cell growth.     

Binding of G-CSF, GM-CSF, tumor necrosis factor-alpha, and gamma- interferon to cell surface receptors on human myeloid leukemia cells triggers rapid tyrosine and serine phosphorylation of a 75-Kd protein

Granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), gamma-interferon (gamma-IFN), or tumor necrosis factor-alpha (TNF-alpha) triggered the rapid, stable phosphorylation of a 75-Kd protein (p75) when incubated with permeabilized HL60 human myeloid leukemia cells in the presence of [gamma-32P] ATP. Among several chemical inducers of HL60 cell differentiation, dimethyl sulfoxide also triggered p75 labeling, but retinoic acid or 12-O-tetradecanoylphorbol-13-acetate did not elicit this response. Pretreatment of cells with G-CSF or GM-CSF for more than 30 seconds before permeabilization rendered the p75 labeling undetectable, suggesting that ligand-stimulated labeling was rapidly completed within this time in intact cells. Phosphorylation of p75 occurred on serine and tyrosine residues. This conclusion was confirmed by direct phosphoamino acid analysis. Immunoblot analysis of lysates of intact HL60 cells that had been incubated with G-CSF, GM-CSF, IFN, or TNF confirmed that tyrosine phosphorylation of a p75 also occurred in response to these cytokines in intact cells. Pretreatment of intact HL60 cells with one biologic agent or dimethyl sulfoxide abolished p75 labeling in response to incubation of permeabilized cells with a second agent, strongly suggesting that the same protein was phosphorylated in response to these treatments. p75 labeling was strictly dependent on expression of the appropriate ligand receptor. Data suggest that activation of a tyrosine kinase system is an early response to the binding of G-CSF, GM-CSF, TNF, or IFN to their respective cell surface receptors, or to the addition of dimethyl sulfoxide, and that the resulting phosphorylation event(s) may play a role in securing common elements in the biologic responses to these agents.