Distribution of vasoactive intestinal peptide (VIP) immunoreactivity in the rat pallial and subpallial amygdala and colocalization with γ-aminobutyric acid (GABA).

The amygdaloid complex, also known as the amygdala, is a heterogeneous group of distinct nuclear and cortical pallial and subpallial structures. The amygdala plays an important role in several complex functions including emotional behavior and learning. The expression of calcium-binding proteins and peptides in GABAergic neurons located in the pallial and subpallial amygdala is not uniform and is sometimes restricted to specific groups of cells. Vasoactive intestinal polypeptide (VIP) is present in specific subpopulations of GABAergic cells in the amygdala. VIP immunoreactivity has been observed in somatodendritic and axonal profiles of the rat basolateral and central amygdala. However, a comprehensive analysis of the distribution of VIP immunoreactivity in the various pallial and subpallial structures is currently lacking. The present study used immunohistochemical and morphometric techniques to analyze the distribution and the neuronal localization of VIP immunoreactivity in the rat pallial and subpallial amygdala. In the pallial amygdala, VIP-IR neurons are local inhibitory interneurons that presumably directly and indirectly regulate the activity of excitatory pyramidal neurons. In the subpallial amygdala, VIP immunoreactivity is expressed in several inhibitory cell types, presumably acting as projection or local interneurons. The distribution of VIP immunoreactivity is non-homogeneous throughout the different areas of the amygdaloid complex, suggesting a distinct influence of this neuropeptide on local neuronal circuits and, consequently, on the cognitive, emotional, behavioral and endocrine activities mediated by the amygdala.

Endoscopic and surgical treatment of non-neoplastic proximal duodenal ulceration in dogs, and anatomical study of proximal duodenal vascularisation.

OBJECTIVES: Proximal duodenal ulceration is often characterised by continuous bleeding, and treatment is challenging. The aims of this study were to investigate the role of vascularisation in proximal duodenal ulceration and describe clinical aspects, endoscopic features and treatment in dogs. MATERIAL AND METHODS: Polyurethane foam casts of gastroduodenal vessels were obtained from five dogs which had died from disorders unrelated to the digestive system. In addition, 12 dogs having proximal duodenal ulcers diagnosed by endoscopic examination were enrolled in a treatment trial. After the endoscopic diagnosis of a duodenal ulcer, all the dogs were treated medically and, in the absence of resolution, were subsequently treated by endoscopic electrocauterisation or by surgery. RESULTS: A submucosal vascular network was evident in all the casts, with a prominent venous plexus seen exclusively in the first half inch of the duodenum. In clinical cases, on endoscopic examination, the duodenal ulcer was located at the proximal part of the duodenum, involving the mesenteric portion of the wall. The dogs not responding to medical treatment (6/12) were treated with endoscopic electrocauterisation, surgical coagulation or resection of the proximal duodenal portion. All the dogs survived until discharge, and the median survival time following discharge was 107.5 days. CLINICAL SIGNIFICANCE: Based on the anatomical details highlighted in this study, the continuous bleeding observed in our patients may have been due to the prominent venous plexus evidenced at the level of the proximal duodenum. Surgical and endoscopic treatments in six patients resolved the ulcer bleeding with no recurrences noted during follow-up.

Connections of the sheep basolateral amygdala: A diffusion tensor imaging study.

BACKGROUND: A large amount of anatomic data published over the past decade has provided novel insight into the connections of the basolateral amygdala (BLA) in the rat, cat, and monkey. The mammalian (rat, cat, and monkey) BLA has strong connections with the cortex (especially piriform, and frontal cortices), the hippocampal region (especially perirhinal cortex, entorhinal cortex, and subiculum), the thalamus (in particular, the posterior internuclear nucleus and medial geniculate nucleus) and, to some extent, the hypothalamus. An important question remains as to how well the data obtained in rodents and primates can be extrapolated to ruminants. NEW METHOD: To address this issue the connections of the sheep BLA has been determined by Magnetic Resonance Imaging (MRI) and Diffusion Tensor Imaging (DTI, Tractography). RESULTS: Tractography showed ipsilateral connections between the BLA and several areas. COMPARISON WITH EXISTING METHOD(S): Reviews based mainly on description of the results obtained using anterograde and retrograde neuronal tracers. In the present research, we prefer to use a non-invasive technique (DTI). CONCLUSIONS: This report shows the existence of specific amygdaloid connections in the sheep.

Effect of chronic heat stress on gastrointestinal histology and expression of feed intake-regulatory hormones in broiler chickens.

Heat stress (HS) dramatically impairs the growth performance of broiler chickens, mainly as a consequence of reduced feed intake due to the loss of appetite. This study was aimed at evaluating the alterations induced by chronic HS conditions on the morphological and morphometric features of the gastrointestinal (GI) tract and on the expression of some enteroendocrine cells (EECs) involved in the regulation of feed intake in chickens. Three hundred male chickens (Ross 308) were divided into two experimental groups and raised either in thermoneutral environment for the whole fattening period (0-41 days) (TNT group) or subjected to chronic HS conditions (30 °C for 24 h/day) from 35 to 41 days (HS group). Samples of proventriculus, duodenum, jejunum and cecum were collected from 24 broilers (12/group). Haematoxylin-eosin was used for the morphometric evaluations, while immunohistochemistry was applied for the evaluation of EECs expressing ghrelin (GHR), cholecystokinin (CCK), neuropeptide Y (NPY), glucagon-like peptide-1 (GLP-1), and serotonin (5-HT). In the proventriculus, HS reduced total wall thickness and mucous layer height (P ≤ 0.01) as well as mean diameter, circumference, and area of the compound tubular glands (P ≤ 0.001) with respect to TNT. The small intestine of HS birds was characterised by decreased villous height and total thickness (duodenum, P ≤ 0.01; jejunum, P ≤ 0.001), whereas crypt depth and width were reduced only in the jejunum (P ≤ 0.01). HS had negligible effects on the morphological aspects of the cecum. In the proventriculus, an increase in GHR and NPY EECs was observed in response to HS (P ≤ 0.001). Similarly, the small intestine villi of the HS group showed greater GLP-1 (P ≤ 0.05), 5-HT (P ≤ 0.001) and CCK (P ≤ 0.01) EECs. Moreover, the expression of 5-HT EECs was higher in the duodenal (P ≤ 0.01) and jejunal (P ≤ 0.01) crypts of HS birds, whereas GLP-1 and CCK EECs increased only in jejunal crypts (P ≤ 0.05). Finally, 5-HT EEC expression was increased in the cecum of HS group (P ≤ 0.01). In conclusion, these outcomes demonstrate that chronic HS induces morphometric alterations not only in the small intestine but also in a key organ such as the proventriculus. Furthermore, HS conditions affect the presence and distribution of EECs, suggesting that some GI peptides and biogenic amine may be implicated in the regulation of appetite and voluntary feed intake in heat-stressed broiler chickens.

Localization of the 5-hydroxytryptamine 4 receptor in equine enteric neurons and extrinsic sensory fibers.

BACKGROUND: Serotonin plays a pivotal role in regulating gut motility, visceral sensitivity, and fluid secretion via specific receptors. Among these receptors, 5-HT4 exerts a prominent control on gut motor function. Although the prokinetic effect exerted by 5-HT4 agonists is well known, the cellular sites of 5-HT4 expression remain poorly understood in large mammals, e.g., horses. In this study, we evaluated the distribution of 5-HT4 in the horse intestine and in foals with enteric aganglionosis, reminiscent of human Hirschsprung's disease. METHODS: The intestine and spinal ganglia were obtained from three healthy horses and two foals with hereditary ileocolonic aganglionosis. Tissues were processed for immunohistochemistry using a specific antibody to 5-HT4 and a variety of neuronal markers. Myenteric and submucosal plexus 5-HT4 -immunoreactive (IR) neurons were quantified as relative percentage (mean±SD) to the total number of neurons counted. Furthermore, the density of 5-HT4 -IR nerve fibers was evaluated in the mucosa and tunica muscularis. KEY RESULTS: The 5-HT4 immunoreactivity was localized to large percentages of myenteric neurons ranging from 28±9% (descending colon) to 63±19% (ileum), and submucosal neurons ranging from 54±6% (ileum) to 68±14% (duodenum). The 5-HT4 -immunoreactivity was co-expressed by some substance P-IR (SP-IR) spinal ganglion neurons and extrinsic sensory fibers of aganglionic foals. CONCLUSIONS & INFERENCES: The presence of 5-HT4 in many enteric and extrinsic sensory neurons and nerve fibers provides solid morphological evidence of the cellular sites of 5-HT4 expression in horses. The evidence of SP-IR sensory neurons positive for 5-HT4 suggests its role in visceral sensitivity.

Estimating stomatal conductance with thermal imagery.

Most thermal methods for the study of drought responses in plant leaves are based on the calculation of 'stress indices'. This paper proposes and compares three main extensions of these for the direct estimation of absolute values of stomatal conductance to water vapour (gs) using infrared thermography (IRT). All methods use the measured leaf temperature and two environmental variables (air temperature and boundary layer resistance) as input. Additional variables required, depending on the method, are the temperatures of wet and dry reference surfaces, net radiation and relative humidity. The methods were compared using measured gs data from a vineyard in Southern Portugal. The errors in thermal estimates of conductance were of the same order as the measurement errors using a porometer. Observed variability was also compared with theoretical estimates of errors in estimated gs determined on the basis of the errors in the input variables (leaf temperature, boundary layer resistance, net radiation) and the partial derivatives of the energy balance equations used for the gs calculations. The full energy balance approach requires accurate estimates of net radiation absorbed, which may not be readily available in field conditions, so alternatives using reference surfaces are shown to have advantages. A new approach using a dry reference leaf is particularly robust and recommended for those studies where the specific advantages of thermal imagery, including its non-contact nature and its ability to sample large numbers of leaves, are most apparent. Although the results suggest that estimates of the absolute magnitude of gs are somewhat subjective, depending on the skill of the experimenter at selecting evenly exposed leaves, relative treatment differences in conductance are sensitively detected by different experimenters.