Endocannabinoid CB1 receptors modulate visual output from the thalamus

[Abstract] Rationale Endocannabinoids have emerged as a modulatory brain system affecting different types of synapses, broadly distributed throughout the CNS, which explain the diverse psychophysical effects observed following activation of the endocannabinoid system. Objectives and methods The present study aimed to characterize the effect of CB1-mediated activity in the visual thalamus. In vivo single-unit extracellular recordings were performed in anaesthetized adult pigmented rats, measuring visual and spontaneous activity, combined with application of CB1 receptor agonists (anandamide, 2-AG, and O2545) and one antagonist, AM251. Results CB1 receptors activation revealed two cellular populations, with excitatory effects on ∼28% of cells and inhibitory in ∼72%, actions which were blocked by the antagonist AM251. The agonist action significantly altered both spontaneous and visual activity, shifting the signal-tonoise ratio (S/N), with accompanying changes in the variability within the visual response. Increased responses by agonist application were accompanied by a decrease in S/N and an increase in variability, while those cells inhibited by the agonist showed an increase in S/N and a decrease in variability. There was no obvious correlation between the two effects and any other response property suggesting a more general role in modulating all information passing from LGN to cortex. Conclusions Our data support a role for CB1 at the level of the thalamus acting as a dynamic modulator of visual information being sent to the cortex, apparently maintaining the salience of the signal within upper and lower boundaries. This may account for some of the behavioral effects of cannabis.Ministerio de Ciencia e Innovación; BFU2009-08169Xunta de Galicia; 2007/000140-

Different Sources of Nitric Oxide Mediate Neurovascular Coupling in the Lateral Geniculate Nucleus of the Cat

Understanding the link between neuronal responses (NRs) and metabolic signals is fundamental to our knowledge of brain function and it is a milestone in our efforts to interpret data from modern non invasive optical techniques such as fMRI, which are based on the close coupling between metabolic demand of active neurons and local changes in blood flow. The challenge is to unravel the link. Here we show, using spectrophotometry to record oxyhaemoglobin and methemoglobin (surrogate markers of cerebral flow and nitric oxide levels respectively) together with extracellular neuronal recordings in vivo and applying a multiple polynomial regression model, that the markers are able to predict up about 80% of variability in NR. Furthermore, we show that the coupling between blood flow and neuronal activity is heavily influenced by nitric oxide (NO). While NRs show the typical saturating response, blood flow shows a linear behaviour during contrast-response curves, with nitric oxide from different sources acting differently for low and high intensity

New functions of Semaphorin 3E and its receptor PlexinD1 during developing and adult hippocampal formation

The development and maturation of cortical circuits relies on the coordinated actions of long and short range axonal guidance cues. In this regard, the class 3 semaphorins and their receptors have been seen to be involved in the development and maturation of the hippocampal connections. However, although the role of most of their family members have been described, very few data about the participation of Semaphorin 3E (Sema3E) and its receptor PlexinD1 during the development and maturation of the entorhino-hippocampal (EH) connection are available. In the present study, we focused on determining their roles both during development and in adulthood. We determined a relevant role for Sema3E/PlexinD1 in the layer-specific development of the EH connection. Indeed, mice lacking Sema3E/PlexinD1 signalling showed aberrant layering of entorhinal axons in the hippocampus during embryonic and perinatal stages. In addition, absence of Sema3E/PlexinD1 signalling results in further changes in postnatal and adult hippocampal formation, such as numerous misrouted ectopic mossy fibers. More relevantly, we describe how subgranular cells express PlexinD1 and how the absence of Sema3E induces a dysregulation of the proliferation of dentate gyrus progenitors leading to the presence of ectopic cells in the molecular layer. Lastly, Sema3E mutant mice displayed increased network excitability both in the dentate gyrus and the hippocampus proper

Study of breast cancer incidence in patients of lymphangioleiomyomatosis

Molecular evidence has linked the pathophysiology of lymphangioleiomyomatosis (LAM) to that of metastatic breast cancer. Following on this observation, we assessed the association between LAM and subsequent breast cancer. An epidemiological study was carried out using three LAM country cohorts, from Japan, Spain, and the United Kingdom. The number of incident breast cancer cases observed in these cohorts was compared with the number expected on the basis of the country-specific incidence rates for the period 2000–2014. Immunohistochemical studies and exome sequence analysis were performed in two and one tumors, respectively. All cohorts revealed breast cancer standardized incidence ratios (SIRs) ≥ 2.25. The combined analysis of all cases or restricted to pre-menopausal age groups revealed significantly higher incidence of breast cancer: SIR = 2.81, 95 % confidence interval (CI) = 1.32–5.57, P = 0.009; and SIR = 4.88, 95 % CI = 2.29–9.99, P = 0.0007, respectively. Immunohistochemical analyses showed positivity for known markers of lung metastatic potential. This study suggests the existence of increased breast cancer risk among LAM patients. Prospective studies may be warranted to corroborate this result, which may be particularly relevant for pre-menopausal women with LAM. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10549-016-3737-8) contains supplementary material, which is available to authorized users

Cautions, Curbs, and Corners: A poem cycle.

Exploring the danger and fame of F1 racing

Cannabis, endocannabinoid CB1 receptors, and the neuropathology of vision

[Abstract] Cannabinoid (CB) receptors are widely distributed through the central nervous system, where they play a relevant role in various cognitive processes such as learning, memory, or attention. However, despite the distortion in sensory perception caused by cannabis, it has not been until recently that the effect of CB activation on visual physiology and pathophysiology has been studied in detail. These studies reflect a critical role for CB in visual perception, modulating not only the processing of visual information by the retina, but also further processing and computation of visual signals by the thalamus and cortex. Interestingly, activation of cannabinoid receptors in therapies can result in some cases in an improvement of visual function

Gingival proliferative lesions in children and adolescents in Brazil: A 15-year-period cross-sectional study

Background: Studies assessing the prevalence of oral lesions in children and adolescents, particularly in gingiva are scarce in the literature. The aim of the study was to describe the distribution of gingival proliferative lesions based on clinical and histopathological diagnoses in children and adolescents. Materials and Methods: A review of clinical charts of children and adolescents aged between 0 and 18 years old, admitted to the Oral Medicine Outpatient Unit, of Universidade Federal do Paraná, for 15 years (1994–2009) was performed. Results: Six hundred and sixty-nine out of 5,129 patients treated during this period were aged between 0 and 18 years old, and 45 of these had gingival lesions. The largest number of lesions was observed between 11 and 16 years old. The majority of the patients were referred by Curitiba's public health system. Pyogenic granuloma was the most frequent lesion (19 = 42.2%), followed by peripheral giant cell lesion (11 = 24.4%), gingival fibromatosis (10 = 22.2%), and peripheral ossifying fibroma (5 = 11.1%). Conclusion: Gingival proliferative lesions can show similar clinical characteristics. Appropriate clinical and histopathological diagnoses are necessary to guide the healthcare professional to establish the adequate treatment and to estimate the risk of recurrence