A Discrete Dorsal Raphe to Basal Amygdala 5-HT Circuit Calibrates Aversive Memory.

Despite a wealth of clinical and preclinical data implicating the serotonin (5-HT) system in fear-related affective disorders, a precise definition of this neuromodulator's role in fear remains elusive. Using convergent anatomical and functional approaches, we interrogate the contribution to fear of basal amygdala (BA) 5-HT inputs from the dorsal raphe nucleus (DRN). We show the DRN→BA 5-HT pathway is engaged during fear memory formation and retrieval, and activity of these projections facilitates fear and impairs extinction. The DRN→BA 5-HT pathway amplifies fear-associated BA neuronal firing and theta power and phase-locking. Although fear recruits 5-HT and VGluT3 co-expressing DRN neurons, the fear-potentiating influence of the DRN→BA 5-HT pathway requires signaling at BA 5-HT1A/2A receptors. Input-output mapping illustrates how the DRN→BA 5-HT pathway is anatomically distinct and connected with other brain regions that mediate fear. These findings reveal how a discrete 5-HT circuit orchestrates a broader neural network to calibrate aversive memory.

Obstrucción intestinal secundaria a invaginación yeyunal como forma de presentación de paraganglioma gangliocítico / Bowel obstruction secondary to yeyunal intussusception due to gangliocytic paraganglioma

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Neuroendocrine markers and sustentacular cell count in benign and malignant pheochromocytomas - a comparative study.

Pheochromocytomas are rare tumours with uncertain clinical behaviour. Histological separation between benign and malignant pheochromocytomas is usually difficult. The utilization of PASS criteria (Pheochromocytoma of the Adrenal Gland Scaled Score) has not provided a solid basis for separating benign from malignant tumours. The aim of this study was to investigate immunohistochemical markers (chromogranin, synaptophysin, S-100 and Ki-67) to find out if they could provide useful diagnostic and/or prognostic data in a series of 62 pheochromocytomas (5 cases followed an aggressive clinical course). Chromogranin and synaptophysin immunoreactivity proved to be diagnostically useful, allowing, together with the absence of immunoreactivity for inhibin and melan A, an unequivocal diagnosis of pheochromocytoma. The pattern of staining did not provide, however, significant prognostic information. The mean count of sustentacular S-100 positive cells was lower in malignant than in benign pheochromocytomas but the frequent architectural variability and the haemorrhagic and cystic changes make it very difficult to achieve a precise and reproducible count in the majority of tumours. Without questioning that the occurrence of metastases and/or recurrent disease still remains the only unquestionable criterion for diagnosing a malignant pheochromocytoma, we think that the combined use of the PASS score and Ki-67 index provides useful information for diagnosing malignancy.

[Distribution and structural organization of autonomic neural apparatus of the rat pancreas (an immunohistochemical study)].

Using the immunohistochemical methods for detection of neurofilaments (NF), peripherin (PRF), synaptophysin (SF), tyrosine hydroxylase (TH) and Nissl-staining with toluidine blue, thick sections (10-20 microm) prepared through all parts of pancreas of adult Wistar rats (n=7) were studied. The topography and the density of distribution of pancreatic islets in the various parts of pancreas were defined. The greatest density of the islets was found in the body of pancreas. The dense innervation of the organ was detected which included several nervous plexuses: the big-looped one consisting of nervous bundles and small trunks of NF-positive myelinated and unmyelinated nervous fibers, the second one was formed by PRF-positive thin posganglionic bundles of axons and microganglia, and the third one, detected with SF-staining, was main terminal plexus consisting of varicose axons with en passant synapses. Interactions of synaptophysin-positive terminals (distant en passant synapses) with blood vessels, endocrine (islet) and exocrine cells, excretory ducts of the pancreatic lobules are described in details. Peculiarities of the structure of parasympathetic ganglia, their neurons, and pericellular synaptic apparatus are described; problems of the innervation and the nature of pancreatic insular endocrine cells are discussed. Attention is drawn to the fact that in no case neurons were found in the islets in the rat pancreas.