BackgroundMany men suffering from stress, including post-traumatic stress disorder (PTSD), report sexual dysfunction, which is traditionally treated via psychological counseling. Recently, we identified a gastrin-releasing peptide (GRP) system in the lumbar spinal cord that is a primary mediator for male reproductive functions.Methodology/Principal FindingsTo ask whether an acute severe stress could alter the male specific GRP system, we used a single-prolonged stress (SPS), a putative rat model for PTSD in the present study. Exposure of SPS to male rats decreases both the local content and axonal distribution of GRP in the lower lumbar spinal cord and results in an attenuation of penile reflexes in vivo. Remarkably, pharmacological stimulation of GRP receptors restores penile reflexes in SPS-exposed males, and induces spontaneous ejaculation in a dose-dependent manner. Furthermore, although the level of plasma testosterone is normal 7 days after SPS exposure, we found a significant decrease in the expression of androgen receptor protein in this spinal center.Conclusions/SignificanceWe conclude that the spinal GRP system appears to be a stress-vulnerable center for male reproductive functions, which may provide new insight into a clinical target for the treatment of erectile dysfunction triggered by stress and psychiatric disorders.

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Platelet function of immune thrombocytopenia (ITP) has been controversial because of methodological problems associated with low platelet counts. In this study, we evaluated platelet function in 21 patients with chronic ITP (cITP) using the recently developed flow cytometry (FCM)based platelet aggregation assay (FCA) along with a PAC1/CD62P assay. Since ITP platelets are larger than controls, whole platelets (whole gating method) and size-adjusted platelets (size-adjusted method) were analysed in the PAC1/CD62P via FCM. We found that: (i) aggregation was equivalent [phorbol myristate acetate (PMA) or adenosine diphosphate (ADP)-induced] or enhanced [protease-activated receptor 1-activating peptide (PAR1AP)-induced] in cITP compared with control by FCA; (ii) PAC1 or CD62P was also equivalent or enhanced in cITP in the whole gating method; and (iii) in sharp contrast, the size-adjusted method revealed that ADP-, PAR1AP-, and collagen synthetic liquid reactive peptide (SRP)-induced PAC1 and ADP-induced CD62P were impaired in cITP. These data suggested that an increase in the number of larger-sized platelets may compensate for the impaired platelet function of cITP, leading to non-inferiority of overall platelet function in cITP. Furthermore, we revealed that ADPinduced aggregation was impaired in the patients with thrombopoietin receptor agonists (TPO-RAs) or platelet-associated anti-aIIbb3 antibodies compared with the control, suggesting that the presence of anti-aIIbb3 autoantibodies and/or administration of TPO-RAs may have a negative impact on platelet function.

Acquired Glanzmann thrombasthenia (aGT) is generally caused by function‐blocking antibodies (Abs). We demonstrated a unique aGT case due to marked reduction of αIIbβ3 with anti‐αIIbβ3 Abs. The anti‐αIIbβ3 Abs of the patient did not inhibit platelet function but reduced surface αIIbβ3. Internalization of αIIbβ3 induced by the Abs binding may be responsible for the phenotype. Summary BackgroundAcquired Glanzmann thrombasthenia (aGT) is a bleeding disorder generally caused by function‐blocking anti‐αIIbβ3 autoantibodies. AimWe characterize an unusual case of aGT caused by marked reduction of surface αIIbβ3 with non‐function‐blocking anti‐αIIbβ3 antibodies (Abs). MethodsA 72‐year‐old male suffering from immune thrombocytopenia since his 50s showed exacerbation of bleeding symptom despite mild thrombocytopenia. Platelet aggregation was absent with all agonists but ristocetin. Analysis of αIIbβ3 expression and genetic analysis were performed. We also analyzed effects of anti‐αIIbβ3 Abs of the patient on platelet function and αIIbβ3 expression. ResultsSurface αIIbβ3 expression was markedly reduced to around 5% of normal, whereas his platelets contained αIIbβ3 to the amount of 40–50% of normal. A substantial amount of fibrinogen was also detected in his platelets. There were no abnormalities in ITGA2B and ITGB3 cDNA. These results indicated that reduced surface αIIbβ3 expression caused a GT phenotype, and active internalization of αIIbβ3 was suggested. Anti‐αIIbβ3 IgG Abs were detected in platelet eluate and plasma. These Abs did not inhibit PAC‐1 binding, indicating that the Abs were non‐function‐blocking. Surface αIIbβ3 expression of a megakaryocytic cell line and cultured megakaryocytes tended to be impaired by incubation with the patient's Abs. After 2 years of aGT diagnosis, his bleeding symptom improved and surface αIIbβ3 expression was recovered to 20% of normal with reduction of anti‐αIIbβ3 Abs. ConclusionWe demonstrated a unique aGT phenotype due to marked reduction of surface αIIbβ3. Internalization induced by anti‐αIIbβ3 Abs may be responsible in part for the phenotype.

Background:To date, several mutations that induce constitutive activation of integrin αIIbβ3 have been identified in congenital macrothrombocytopenia. Of these, αIIb(R995W) is the most prevalent mutation observed in Japanese patients with αIIbβ3-related congenital macrothrombocytopenia. Objective and Methods:The present study aimed to explore the effects of constitutive activation of the αIIb(R995W) mutation on platelet production, morphology, and function. We generated αIIb(R990W) knock-in (KI) mice corresponding to human αIIb(R995W).Results: Platelet counts of heterozygous (hetero) and homozygous (homo) KI mice were decreased by ~10% and ~25% relative to those of wild-type (WT) mice, respectively, with increase in platelet size. Decrease in absolute reticulated platelet numbers in steady state, delayed recovery from thrombocytopenia induced by anti-platelet antibody and impaired response to exogenous thrombopoietin administration suggested impaired platelet production in KI mice. WT and KI mice showed no significant differences in the number of megakaryocytes and ploidy of megakaryocytes, whereas proplatelet formation was significantly impaired in homo mice. We observed a slight but significant reduction in platelet lifespan in homo mice. The homo mice showed dramatic reduction in αIIbβ3 expression in platelets, which was accompanied by severe in vivo and in vitro platelet dysfunction. Conclusion:The αIIb(R990W) KI mice developed macrothrombocytopenia, which was primarily attributed to impaired proplatelet formation. In addition, homo KI mice showed marked downregulation in αIIbβ3 expression in platelets with severe impaired platelet function, similar to Glanzmann thrombasthenia. K E Y W O R D Sblood platelets, gene knock-in techniques, platelet activation, platelet glycoprotein GPIIb-IIIa complex, thrombocytopenia