Postsynaptic M1 and M3 receptors are responsible for the muscarinic enhancement of retrograde endocannabinoid signalling in the hippocampus

The cholinergic system is crucial for higher brain functions including learning and memory. These functions are mediated primarily by muscarinic acetylcholine receptors (mAChRs) that consist of five subtypes (M(1)-M(5)). A recent study suggested a novel role of acetylcholine as a potent enhancer of endocannabinoid signalling that acts retrogradely from postsynaptic to presynaptic neurons. In the present study, we further investigated the mechanisms of this cholinergic effect on endocannabinoid signalling. We made paired whole-cell recordings from cultured hippocampal neurons, and monitored inhibitory postsynaptic currents (IPSCs). The postsynaptic depolarization induced a transient suppression of IPSCs (DSI), a phenomenon known to involve retrograde signalling by endocannabinoids. The cholinergic agonist carbachol (CCh) markedly enhanced DSI at 0.01-0.3 microM without changing the presynaptic cannabinoid sensitivity. The facilitating effect of CCh on DSI was mimicked by the muscarinic agonist oxotremorine-M, whereas it was eliminated by the muscarinic antagonist atropine. It was also blocked by a non-hydrolizable analogue of GDP (GDP-beta-S) that was applied intracellularly to postsynaptic neurons. The muscarinic enhancement of DSI persisted to a substantial degree in the neurons prepared from M1-knockout and M3-knockout mice, but was virtually eliminated in the neurons from M1/M3-compound-knockout mice. CCh still enhanced DSI significantly under the blockade of postsynatpic K(+) conductance, and did not significantly influence the depolarization-induced Ca(2+) transients. These results indicate that the activation of postsynaptic M1 and M3 receptors facilitates the depolarization-induced release of endocannabinoids.     

False lateralization of mesial temporal lobe epilepsy by noninvasive neurophysiological examinations

Mesial temporal lobe epilepsy (mTLE) is the most common form of symptomatic localization-related epilepsy and is surgically remediable. Lateralization of the seizure onset is particularly important to determine from a surgical perspective. A 39-year-old woman with intractable mTLE first exhibited seizure at the age of 3 years. She experienced epigastric sensation and placed her right hand on her abdomen before falling backward. Although interictal scalp electroencephalography (EEG), sphenoidal scalp ictal EEG, and magnetoencephalography showed right temporal side focus, computed tomography and magnetic resonance imaging showed atrophy of the left cerebral hemisphere. Single photon emission computed tomography with technetium-99m ethyl cysteinate dimmer and I-123 iomazenil showed obscure focus on the left side. As a discrepancy existed between the results of neurophysiological examinations and imaging, we performed subdural electrode implantation on the bilateral temporal lobe. Although a bemegride-induced seizure arose from the right side during the subdural recording, the onset of 5 habitual seizures was observed in the left hippocampus. On the basis of these results, the seizure was diagnosed as left mTLE, and left anterior temporal lobectomy and amygdalohippocampectomy were performed. The patient has been free from the seizures for more than 1.5 years of follow up. Bilateral subdural electrode measurement of habitual seizures is indispensable for clarifying the actual focus when a discrepancy exists between neuroimaging and noninvasive neurophysiological examinations.     

Quantification of corneal opacity after refractive corneal surgery using the anterior segment analyzer

PURPOSE: We quantified normal clear and postoperative hazed corneas using the Scheimpflug image of Pentacam, an anterior segment analysis system by Oculus. SUBJECTS AND METHODS: We measured 77 eyes with normal clear corneas, and analyzed 48 eyes in 2 groups before and 1, 4, and 12 weeks after undergoing LASIK (24 eyes) or Epi-LASIK (24 eyes). RESULT: Clear corneas averaged a level of 30.9 +/- 2.4(mean +/- standard deviation) and showed no correlation with gender or age. At 1 week after Epi-LASIK and LASIK, the 2 surgery groups averaged a level of 41.0 +/- 8.1 and 31.9+/- 2.5 respectively. Epi-LASIK demonstrated a statistically significantly higher level than LASIK (Student's t-test, p < 0.01), whereas no difference was observed between the 2 groups at 4 and 12 weeks after surgery. CONCLUSION: Pentacam is useful in quantifying corneal haze following excimer laser keratectomy.     

Ig SF11 regulates osteoclast differentiation through association with the scaffold protein PSD-95

Osteoclasts are multinucleated, giant cells derived from myeloid progenitors. While receptor activator of NF-κB ligand(RANKL)stimulation is the primary driver of osteoclast differentiation, additional signaling further contributes to osteoclast maturation.Here, we demonstrate that immunoglobulin superfamily member 11(Ig SF11), whose expression increases during osteoclast differentiation, regulates osteoclast differentiation through interaction with postsynaptic density protein 95(PSD-95), a scaffold protein with multiple protein interaction domains. Ig SF11 deficiency in vivo results in impaired osteoclast differentiation and bone resorption but no observed defect in bone formation. Consequently, Ig SF11-deficient mice exhibit increased bone mass.Using in vitro osteoclast culture systems, we show that Ig SF11 functions through homophilic interactions. Additionally, we demonstrate that impaired osteoclast differentiation in Ig SF11-deficient cells is rescued by full-length Ig SF11 and that the Ig SF11-PSD-95 interaction requires the 75 C-terminal amino acids of Ig SF11. Our findings reveal a critical role for Ig SF11 during osteoclast differentiation and suggest a role for Ig SF11 in a receptor-and signal transduction molecule-containing protein complex.     

Neuronal responses to face‐like stimuli in the monkey pulvinar

The pulvinar nuclei appear to function as the subcortical visual pathway that bypasses the striate cortex, rapidly processing coarse facial information. We investigated responses from monkey pulvinar neurons during a delayed non‐matching‐to‐sample task, in which monkeys were required to discriminate five categories of visual stimuli [photos of faces with different gaze directions, line drawings of faces, face‐like patterns (three dark blobs on a bright oval), eye‐like patterns and simple geometric patterns]. Of 401 neurons recorded, 165 neurons responded differentially to the visual stimuli. These visual responses were suppressed by scrambling the images. Although these neurons exhibited a broad response latency distribution, face‐like patterns elicited responses with the shortest latencies (approximately 50 ms). Multidimensional scaling analysis indicated that the pulvinar neurons could specifically encode face‐like patterns during the first 50‐ms period after stimulus onset and classify the stimuli into one of the five different categories during the next 50‐ms period. The amount of stimulus information conveyed by the pulvinar neurons and the number of stimulus‐differentiating neurons were consistently higher during the second 50‐ms period than during the first 50‐ms period. These results suggest that responsiveness to face‐like patterns during the first 50‐ms period might be attributed to ascending inputs from the superior colliculus or the retina, while responsiveness to the five different stimulus categories during the second 50‐ms period might be mediated by descending inputs from cortical regions. These findings provide neurophysiological evidence for pulvinar involvement in social cognition and, specifically, rapid coarse facial information processing.     

Mammalian Target of Rapamycin Complex 1 and Cyclooxygenase 2 Pathways Cooperatively Exacerbate Endometrial Cancer

The underlying causes of endometrial cancer (EMC) are poorly understood, and treatment options for patients with advanced stages of the disease are limited. Mutations in the phosphatase and tensin homologue gene are frequently detected in EMC. Cyclooxygenase 2 (Cox2) and mammalian target of rapamycin complex 1 (mTORC1) are known downstream targets of the phosphatase and tensin homologue protein, and their activities are up-regulated in EMC. However, it is not clear whether Cox2 and mTORC1 are crucial players in cancer progression or whether they work in parallel or cooperatively. In this study, we used a Cox2 inhibitor, celecoxib, and an mTORC1 inhibitor, rapamycin, in mouse models of EMC and in human EMC cell lines to explore the interactive roles of Cox2 and mTORC1 signaling. We found that a combined treatment with celecoxib and rapamycin markedly reduces EMC progression. We also observed that rapamycin reduces Cox2 expression, whereas celecoxib reduces mTORC1 activity. These results suggest that Cox2 and mTORC1 signaling is cross-regulated and cooperatively exacerbate EMC.Endometrial cancer (EMC) is the most common gynecological malignancy among American women.^1,2 According to National Cancer Institute estimates, about 50,000 women will be diagnosed with EMC in 2013 and approximately 8200 patients are likely to die from it. Underlying causes of EMC are not clearly understood, and treatment options for patients with advanced stages are limited.^1,2 Several genetic alterations are associated with EMC.^1,2 One of the most common mutations is in the phosphatase and tensin homologue gene (PTEN). Mutations of the TP53 gene, which encodes p53, are also found in EMC and primarily occur in poorly differentiated carcinomas.^1,2The loss of PTEN results in increased phosphoinositide 3-kinase (PI3K) activity and thymoma viral proto-oncogene 1 (Akt) activation. Increased levels of phosphorylated (activated) Akt (pAkt) stimulate cyclooxygenase 2 (Cox2) and mammalian target of rapamycin complex 1 (mTORC1) activities.^3–9 Heightened Cox2 and mTORC1 signaling are associated with EMC.^9–14 Cox2 is overexpressed in many solid tumors, and Cox2-derived prostaglandins (PGs), especially PGE₂ via its receptors EP₂/EP₄, significantly contribute to carcinogenesis.^15,16 Interestingly, analogues of rapamycin and related inhibitors of mTORC1 signaling are in phase I to II clinical trials to treat EMC, and the beneficial effects of celecoxib in cancers are also the subject of current clinical trials (http://www.clinicaltrials.gov, last accessed July 22, 2014).Animal models of spontaneously developed cancers are powerful tools for studying the mechanisms underlying cancer initiation and progression and for developing treatment strategies. We previously generated mouse models with conditional uterine deletion of Pten (Pten^d/d) or of Pten and Trp53 (Pten/Trp53^d/d) using the Cre/loxP approach.¹⁷ Female mice with floxed alleles of Pten and/or Trp53 were crossed with males expressing Cre recombinase driven under the progesterone receptor promoter (Pgr-Cre).¹⁸ Pten^d/d females spontaneously developed EMC with 100% penetrance by 30 days of age, and Pten/Trp53^d/d females developed a more aggressive form of this disease by 21 days of age. Using these mouse models, we previously showed that pAkt and Cox2 levels are elevated in the uteri of both Pten^d/d and Pten/Trp53^d/d mice.¹⁷Here, we show that a downstream component of the mTORC1 effector pathway is significantly up-regulated in the uteri of these mice. These results suggest that Cox2 and mTORC1 are associated with EMC. We then examined whether the Cox2 and mTORC1 pathways are critical in cancer progression and whether they influence EMC independently or cooperatively. We treated Pten^d/d females and their control littermates (Pten^f/f) with rapamycin (mTORC1 inhibitor) and/or celecoxib (Cox2 inhibitor) by oral gavage on every alternate day for 29 days, beginning at 30 days of age. We found that treatment with rapamycin or celecoxib monotherapy attenuated tumor growth, whereas maximal reductions in tumor growth and progression were noted in Pten^d/d females receiving both rapamycin and celecoxib. We also observed a similar reduction in tumor progression in Pten/Trp53^d/d females after combined treatment with rapamycin and celecoxib. Using a mouse EMC cell line established from Pten/Trp53^d/d uteri and three human EMC cell lines, we also found that rapamycin reduces Cox2 expression at the mRNA and protein levels and that celecoxib reduces mTORC1 activity, suggesting that Cox2 and mTORC1 activities are cross-regulated and cooperatively exacerbate EMC. Thus, a combined treatment with celecoxib and rapamycin could be an effective therapeutic strategy for combating EMC.