A co-localization study on the ovine pancreas innervation

Localisation of S100 Protein and Acetylated Tubulin in Sheep Pancreas

The pancreas plays a critical role in the control of nutritional homeostasis. It consists of two major parts, the exocrine pancreas, and the endocrine pancreas. In the present study S100 protein and acetylated α-tubulin were used to identify positive structures in both the exocrine and endocrine part of the ovine pancreas. In the exocrine part of the pancreas, a positive reaction to S100 protein was confined to centroacinar cells, intercalated, and intralobular ducts cells. In addition, the S100 protein was localized in the Schwann cells of nerve fibres. On the pancreatic islets, the S100 protein has been observed in Schwann cells of nerve axons, where they form a fine envelope that invests the islet surface. Inside the pancreatic islets, the Schwann cells positive for S100 protein envelope the endocrine cells of the islets. The difference in positivity of the S100 protein was found in relation to the endocrine cells. The relationship between endocrine cell positivity and positive exocrine duct cells was discussed. Acetylated α-tubulin (AT) was restricted to axons of the nerve fibres and was located within the connective tissue accompanying intralobular and inter-lobular ducts, and between secretory acini in close contact with secretory cells.

Immunohistochemical study on the expressions of neuropeptides in the superficial and deep gland of the third eyelid of pigs

The superficial gland of the third eyelid (SGTE) and deep gland of the third eyelid (DGTE) are classified as accessory lacrimal glands. The aim of the present study was to immunohistochemically investigate the expression of vasoactive intestinal peptide (VIP), dopamine beta-hydroxylase (DβH), substance P (SP), galanin, neuropeptide Y (NPY), pituitary adenylate cyclase-activating peptide (PACAP), somatostatin and calcitonin gene-related peptide (CGRP) in the porcine SGTE and DGTE. We demonstrated the distribution patterns of VIP, DβH, SP, NPY and galanin in the nerve fibres in the SGTE and DGTE. None of somatostatin-, PACAP- and CGRP-immunoreactive (IR) nerve fibres were found in the SGTE and DGTE. The majority of VIP- and DβH-IR nerves fibres were found near to glandular acini, tubules, secretory ducts and blood vessels in the SGTE and DGTE. VIP-IR nerve fibres were found in external connective tissue in SGTE and DGTE and only in interlobular connective tissue in the SGTE. DβH-IR nerve fibres were found in interlobular and external connective tissue in the DGTE but not in the SGTE. Single galanin-, SP- and NPY-IR nerve fibres were observed in close proximity to acini and tubules in the SGTE and DGTE. Single galanin-, SP-, NPY-IR nerve fibres were found in close proximity to the secretory ducts in the DGTE, however only SP-IR nerve fibres were found near to the secretory ducts in SGTE. In conclusion, our research aims to highlight some aspects of SGTE and DGTE innervation in pigs and may also be a source of basic knowledge for further studies.

Distinct Pattern of NPY in Gastro-Entero-Pancreatic System of Goat Kids Fed with a New Standardized Red Orange and Lemon Extract (RLE)

Simple Summary

In the last decades the European ban towards antibiotics resulted in an increase of the number of studies on the effects of natural feed additives, that can enhance the health of farm animals intended for human consumption. Polyphenols such as flavanones and anthocyanins (responsible of the red, purple or blue colors) are bioactive compounds found in fruits and vegetables. Polyphenols possess multiple pharmacological characteristics, like antioxidant, anti-inflammatory and immunostimulant properties. Although many of the biological effects of polyphenols are known, only a limited number of studies has been focused on the effects of their supplementation in ruminant diet. Therefore, we evaluated the effect of a diet supplemented with a standardized powder extract, red (blood) orange and lemon extract (RLE), rich in flavanones, anthocyanins and other polyphenols on the neuropeptide Y (NPY) distribution in the gastro–entero–pancreatic system of goat kids. In mammals, NPY occurs in both the central and peripheral nervous systems and it is involved in the control of different physiological processes, including food intake regulation. For the first time, we document that NPY is widely distributed in the abomasum, duodenum and pancreas of goat kids and that significantly increases in the abomasum and pancreas of RLE supplemented feed animals.

Abstract

The use of natural compounds as feed additive is also increasing in farm animals, thanks to the beneficial effect on both animals and consumers health. Here, we questioned whether natural extracts, such as red orange and lemon extract (RLE) rich in flavanones, anthocyanins, and other polyphenols, used as feed additives could display an effect on the neuropeptide Y (NPY) in the gastro–entero–pancreatic tract of goat kids. NPY is one of the most abundant neuropeptides in mammals, known for its orexigenic role although it is involved in many central and peripheral functions. We carried out immunohistochemical analyses on samples of abomasum, duodenum and pancreas collected from two experimental groups: one fed with standard diet and one with standard diet + RLE. For the first time we document NPY distribution in the abomasum, duodenum and pancreas of goats and observe the highest number of NPY positive cells in neuroendocrine cells of duodenum. Remarkably, upon RLE feed supplementation, NPY immunoreactive cells increased significantly in abomasal epithelium and pancreatic islets but not in duodenum, likely due to pH variation of abomasum and duodenum. Our observations represent a baseline for future studies on the interaction between neuropeptides and polyphenols, used as feed additive.

An Immunohistochemical Study of Cocaine- and Amphetamine-Regulated Transcript (Cart) Expression in the Pterygopalatine Ganglion of the Pig

Although, a great effort has been made to understand the synthesis, regulation, processing and function of cocaine- and amphetamine-regulated transcript (CART) peptide at the central level, its peripheral function(s) are still obscure. Moreover, scarce studies describing the presence of CART in peripheral autonomic ganglia are mainly limited to laboratory rodents. Thus, the aim of the present study was to immunohistochemically investigate the expression of CART in Hu C/D-positive neurons of the porcine pterygopalatine ganglion (PPG). The distribution pattern of CART-IR nerve elements in PPG has been also assessed. The co-localization of CART with substance P (SP), galanin or somatostatin was studied by means of double immunohistochemical stainings. The presence of Hu C/D-positive/CART-positive neurons was detected both in the left and right PPG (4.7±1.2% and 5.2% ± 1.4%, respectively). The CARTimmunoreactive (IR) neurons were categorized as either middle (ca. 80%) or small (ca. 20%) in size. Moderate numbers of CART-IR boutons were also detected between CART-negative ganglionic neurons. CART-IR basket-like formations around PPG neurons were regularly observed. Virtually all CART-IR neurons additionally co-stored VIP, whereas none of the CART-expressing cells showed the presence of galanin, SP or somatostatin. CART-IR basket-like formations exclusively encircled VIP-IR PPG neurons. Thus, CART-IR nerve cells seem to constitute a relatively small homologous population of the porcine PPG neurons with largely unknown functions. Further functional studies aiming at whether CART-IR neurons could serve as interneurons are necessary.

Substance P expresses in intrapancreatic ganglia of the rats

Substance P (SP) is an important neuropeptide regulating the functions of the pancreas and might play a vital role in the onset of diabetes. SP has been shown to express in nerve fibers of the pancreas, but whether SP exists in the intrapancreatic ganglia, which are components of a complex autonomous nervous system to co-ordinate the functions of the pancreas, is unsure. The aim of this study was to systematically investigate rat intrapancreatic ganglia and the expression of SP in intrapancreatic ganglia. After surgical denervation of posterior branches of bilateral T₅-L₂ dorsal root ganglia, SP expression remained >60% in the pancreas. Moreover, after high doses of capsaicin were injected to destroy sensory nerves, the remainder of SP protein levels was still >50% in the pancreas. In the intrapancreatic ganglia, for anti-SP polyclonal antibody, the immunoreactivity to SP was found in 34.0±1.2% of PGP 9.5-positive intrapancreatic neurons (47 ganglia from 13 rats); for anti-SP monoclonal antibody, the immunoreactivity to SP was found in 26.6±1.0% of PGP 9.5-positive intrapancreatic neurons (18 ganglia from 6 rats). In summary, the present molecular and immunocytochemistry studies showed that there existed intrinsic SP expression in the neurons of intrapancreatic ganglia, which constituted around half of SP origins in the pancreas suggesting that intrapancreatic ganglia might play an important role on mechanisms involving SP.

Immunodetection of cocaine- and amphetamine-regulated transcript in bovine pancreas

This study was aimed at identifying and determining the configuration of structures which contain the cocaine- and amphetamine-regulated transcript peptide (CART) in the bovine pancreas. The study material was collected from 20 animals. The distribution of CART in the bovine pancreas was investigated, by an immunohistochemical evaluation. CART peptide in the normal pancreas has been identified in intrapancreatic ganglia, nerve fibres and in endocrine cells of Langerhans islets and exocrine pancreas. CART immunoreactive nerve fibres innervate the exocrine and endocrine regions and the intrapancreatic ganglia, where they form a moderate number of networks, encircling the cell bodies. The few CART-immunoreactive endocrine cells, that appear in the bovine pancreas, are not limited to the islet cells, where they form a subpopulation of CART-containing cells, but are also individually distributed in the exocrine region. Furthermore, CART has been visualized in nerve fibres, innervating pancreatic outlet ducts and blood vessels. CART plays a physiological role in the integrated mechanisms that regulate both endocrine and exocrine pancreatic secretion. These results are consistent with the hypothesis that CART expression in nerve fibres and intrapancreatic ganglia is a common feature of the mammalian pancreas, whereas its expression in endocrine cells appears to be restricted to single cells of the bovine pancreas.

Differential expression and localization of neuropeptide Y peptide in pancreatic islet of diabetic and high fat fed rats

Neuropeptide Y (NPY) inhibits insulin secretion. Increased numbers of pancreatic islet cells expressing NPY have been observed in type 1 diabetic rats. To understand the functional significance of NPY expression in islet cells, we investigated the effects of high fat feeding and diabetic conditions on the expression and location of NPY expressing cells in normal and diabetic rats. Twenty rats were maintained on either normal chow (ND) or a high fat dietary regimen (HFD) for 4 weeks. In half of each group, type 1 or type 2 diabetes (groups T1DM and T2DM, respectively) was induced by injection of streptozotocin. At 8 weeks rats were euthanized and the pancreases were processed for immunofluorescence labeling (NPY/insulin, NPY/glucagon, NPY/somatostatin, and NPY/pancreatic polypeptide). Compared with the ND group, HFD rats had significantly fewer alpha cells, but beta cells were similar, while T1DM and T2DM rats showed significant increases in the proportions of alpha, delta, and PP cells. Robust increases in NPY-positive islet cells were found in the HFD, T1DM, and T2DM rats compared with ND controls. In ND rats, 99.7% of the NPY-positive cells were PP cells. However, high fat feeding and diabetes resulted in significant increases in NPY-positive delta cells, with concomitant decreases in NPY-positive PP cells. In summary, high-fat feeding and diabetes resulted in changes in the hormonal composition of pancreatic islet and increased number of NPY-expressing islet cells. Under diabetic conditions NPY expression switched from predominantly a characteristic of PP cells to predominantly that of delta cells. This may be a factor in reduced pancreatic hormone secretion during diabetes.

Expression of Neuronal Nitric Oxide Synthase in the Pancreas of the Sheep

In numerous mammals, nitric oxide (NO) influences the activity of the exocrine and endocrine pancreas. In this study, immunocytochemistry was utilized to investigate the expression of neuronal nitric oxide synthase (nNOS) in the pancreas of sheep. In double immunocytochemical staining, the co-localization of nNOS with vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) or substance P (SP) was studied. The presence of nNOS was confined to the intrapancreatic neurones (9.6 +/- 1.3%) as well as to nerve fibres of the endocrine pancreas and intrapancreatic ganglia. nNOS-immunoreactive (IR) neurones were round and oval in shape and predominantly (83.3 +/- 2.6%) belonged to the middle-size group (25-50 mum). Numerous, fine islets supplying nNOS-IR nerve terminals were devoid of VIP, SP or NPY. Moderately numerous, non-varicose nNOS-IR nerve fibres of intrapancreatic ganglia frequently expressed VIP or NPY, but not SP; 2.2 +/- 0.6% of nNOS-IR intrapancreatic neurones displayed lack of VIP, whereas 7.5 +/- 0.8% were VIP-IR. All nNOS-IR neurones were devoid of SP. The frequencies of nNOS-IR/NPY-IR and nNOS-IR/NPY-negative intrapancreatic neurones were 2.2 +/- 0.4% and 6.1 +/- 1.1%, respectively. Comparison with other mammals indicated that nitrergic innervation of the ovine pancreas is species-determined and may be a reflection of the ruminants' digestion specificity. The possible origin of nNOS-IR nerve fibres and functional significance of NO in the pancreas of sheep were discussed.

Cholinergic innervation of the pancreas in the sheep

Antibodies raised against vesicular acetylcholine transporter (VAChT) were applied to study the cholinergic innervation pattern of the pancreas of the sheep. To determine whether the cholinergic pancreatic neuronal elements contain tyrosine hydroxylase (TH), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) or substance P (SP) double immunocytochemistry was used. A moderate number of VAChT-immunoreactive (IR) nerve terminals were distributed between the acini, whereas only single cholinergic nerve fibres innervated the interlobular connective tissue. VAChT-positive nerve fibres supplying the endocrine pancreas were found only occasionally. The pancreatic blood vessels and ducts system were devoid of VAChT-containing nerve endings. All intrapancreatic neurons studied showed immunoreactivity to VAChT, but intrapancreatic ganglia were not innervated with cholinergic nerve fibres. The colocalization of VAChT and TH or VAChT and SP was detected in distinct populations of nerve fibres localized amongst the acini, but not within the islet nor in the connective tissue. Single VAChT-IR nerve terminals co-expressing NPY were distributed around the acini, islets as well as in the connective tissue septa. A moderate number of VAChT-IR/VIP-IR nerve endings were located in the exocrine pancreas, whereas the islets and connective tissue were innervated with VAChT/VIP-containing nerve fibres only occasionally. In the vast majority of VAChT-positive intrapancreatic perikarya the presence of TH was additionally found. A moderate number of VAChT-IR intrapancreatic perikarya co-expressed NPY, SP or VIP. The results of the present study demonstrate species-dependent cholinergic innervation pattern of the pancreas of the sheep. The co-localization of VAChT with the neuropeptides suggests the existence of functional interactions influencing the ovine pancreas (mainly exocrine) activity.