No abstract

One reported mechanism for morphine activation of dopamine (DA) neurons of the ventral tegmental area (VTA) is the disinhibition model of VTA-DA neurons. Morphine inhibits GABA inhibitory neurons, which shifts the balance between inhibitory and excitatory input to VTA-DA neurons in favor of excitation and then leads to VTA-DA neuron excitation. However, it is not known whether morphine has an additional strengthening effect on excitatory input. Our results suggest that glutamatergic input to VTA-DA neurons is inhibited by GABAergic interneurons via GABAB receptors and that morphine promotes presynaptic glutamate release by removing this inhibition. We also studied the contribution of the morphine-induced disinhibitory effect on the presynaptic glutamate release to the overall excitatory effect of morphine on VTA-DA neurons and related behavior. Our results suggest that the disinhibitory action of morphine on presynaptic glutamate release might be the main mechanism for morphine-induced increase in VTA-DA neuron firing and related behaviors.DOI: http://dx.doi.org/10.7554/eLife.09275.001

Type 1 diabetes mellitus (T1DM) is associated with a series of bone complications, which are still a great challenge in the clinic. Bone marrow stromal cells (BMSCs) are crucial to bone remodeling and are attractive candidates for tissue engineering. Hence, we aimed to investigate whether impaired functions of BMSCs play a role in the pathogenesis of bone complications associated with T1DM. BMSCs were isolated from normal and streptozotocin-induced diabetic rats, and their proliferation and osteogenic differentiation ability were analyzed. Diabetic BMSCs demonstrated reduced proliferation ability, osteoblast gene expression, alkaline phosphatase activity and mineralization. Nude mice transplanted with diabetic BMSCs in a calcium phosphate cement scaffold exhibited reduced new bone formation, as detected by hematoxylin and eosin staining and immunohistochemistry. These changes may be partially related to impaired insulin and insulin-like growth factor 1 (IGF-1) signaling. Weak gene expression of insulin receptor (IR), IGF-1, insulin-like growth factor 1 receptor (IGF-1R), and insulin receptor substrate-1 (IRS-1) was observed in the diabetic BMSCs compared with normal BMSCs, together with decreased protein level of IGF-1, IGF-1R, IRS-1 and phosphorylated extracellular signal-regulated kinase. Therefore, impaired proliferation and osteogenic potential of BMSCs may be responsible for bone complications related to T1DM, mediated partially by impaired insulin and IGF-1 signaling. These findings may provide a new target with which to devise strategies for therapy.

Mental health disorders(MHD) in chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) have been widely studied. However, the underlying role of inflammatory cytokines and their associated signaling pathways have not been investigated. Here, we report the potential role of cytokines and associated signaling pathways in CP/CPPS patients with MHD and in a CP/CPPS animal model. CP/CPPS patients (n = 810) and control subjects (n = 992) were enrolled in this case-control multicenter study, and serum cytokine levels were measured. Male Sprague-Dawley rats received multiple intracutaneous injections of an immuno-agent along with a pertussis-diphtheria-tetanus triple vaccine for autoimmune CP/CPPS development. The results revealed that, in CP/CPPS patients with significant MHD, elevated IL-1α, IL-1β, IL-4, IL-13, and TNF-α serum levels were observed. The above five cytokines in CP/CPPS rats were significantly elevated in prostate tissue (p < 0.05), and IL-1β levels were elevated in serum and cerebrospinal fluid. In behavioral tests, CP/CPPS rats showed anxiety- and depression-like symptoms, and impaired spatial and associative memory performance (p < 0.05). In the CP/CPPS group, ERK1/2 phosphorylation levels were increased in the amygdala and nucleus accumbens, and decreased in the hippocampus, but not caudate nucleus. Thus, prostate-derived cytokines, especially IL-1β, cross the blood brain barrier and may lead to enhanced ERK1/2 signaling in several brain areas, possibly underlying induction of CP/CPPS-related MHD.