Galanin is Co-Expressed with Substance P, Calbindin and Corticotropin-Releasing Factor (CRF) in The Enteric Nervous System of the Wild Boar (Sus scrofa) Small Intestine

The neuroendocrine pathways and mechanisms for the control of the reproduction in female pigs

Within the hypothalamic-pituitary-gonad (HPG) axis, the major hierarchical component is gonadotropin-releasing hormone (GnRH) neurons, which directly or indirectly receive regulatory inputs from a wide array of regulatory signals and pathways, involving numerous circulating hormones, neuropeptides, and neurotransmitters, and which operate as a final output for the brain control of reproduction. In recent years, there has been an increasing interest in neuropeptides that have the potential to stimulate or inhibit GnRH in the hypothalamus of pigs. Among them, Kisspeptin is a key component in the precise regulation of GnRH neuron secretion activity. Besides, other neuropeptides, including neurokinin B (NKB), neuromedin B (NMB), neuromedin S (NMS), α-melanocyte-stimulating hormone (α-MSH), Phoenixin (PNX), show potential for having a stimulating effect on GnRH neurons. On the contrary, RFamide-related peptide-3 (RFRP-3), endogenous opioid peptides (EOP), neuropeptide Y (NPY), and Galanin (GAL) may play an inhibitory role in the regulation of porcine reproductive nerves and may directly or indirectly regulate GnRH neurons. By combining data from suitable model species and pigs, we aim to provide a comprehensive summary of our current understanding of the neuropeptides acting on GnRH neurons, with a particular focus on their central regulatory pathways and underlying molecular basis.

The effect of Raphanus sativus L. seeds on regulation of intestinal motility in rats consuming a high-calorie diet

PURPOSE

The purpose of this study was to explore the effects of a short-term high-calorie diet and the regulation mechanism of Raphanus sativus L. seeds (RSL seeds) on the intestinal motility of young rats.

METHODS

We fed 20 Specific Pathogen Free (SPF) 4-week-old male Sprague-Dawley (SD) rats special high-calorie diet for 3 days and then randomized them to a high-calorie diet group (HCG, 10 rats) and an RSL seeds treatment group (TG, 10 rats). Ten rats of the same age served as the control group (CG). HCG and TG rats continued to be fed high-calorie feed. All of the rats were weighed every 2 days. After 3 days of treatment, the effects of RSL seeds on the regulation of intestinal motility in rats consuming a high-calorie diet were examined.

RESULTS

After 3 days of consuming a high-calorie diet, body weight was significantly lower in the HCG group than in the control group, and body weight of the HCG group increased slowly with time. Serum substance P (SP) and ghrelin levels were significantly lower, while the nitric oxide (NO) level was significantly higher. There were no differences in hematoxylin-eosin (HE) staining of colon sections between the groups. The expression levels of Cx43 and BDNF protein and mRNA in colon tissue were significantly lower in the HCG group. There were no significant differences in body weight between the CG and TG groups. Serum SP and ghrelin indexes in TG group were higher than those in the HCG group, and the NO index was significantly decreased. The expression levels of Cx43 and BDNF proteins and mRNA in the colon tissue were also significantly greater.

CONCLUSION

Consumption of a short-term high-calorie diet may result in intestinal motility dysfunction and reduced intestinal motility. RSL seeds may improve the intestinal motility by regulating the secretion of gastrointestinal motility hormones and the expression of intestinal motility-related proteins, such as Cx43 and BDNF.

Changes in the Population Size of Calbindin D-28k-Immunoreactive Enteric Neurons in the Porcine Caecum under the Influence of Bisphenol A: A Preliminary Study

Calbindin D-28k (CB) is a calcium-binding protein widely distributed in living organisms that may act as a calcium buffer and sensory protein. CB is present in the enteric nervous system (ENS) situated in the gastrointestinal tract, which controls the majority of activities of the stomach and intestine. The influence of various doses of bisphenol A (BPA)—a chemical compound widely used in plastics production—on the number and distribution of CB-positive enteric neuronal cells in the porcine caecum was investigated with an immunofluorescence technique. The obtained results showed that low dosages of BPA resulted in an increase in the number of CB-positive neuronal cells in the myenteric (MP) and inner submucous (ISP) plexuses, whereas it did not alter the number of such neuronal cells in the outer submucous plexus (OSP). High dosages of BPA caused the increase in the amount of CB-positive perikarya in all the above-mentioned kinds of the caecal neuronal plexuses. These observations strongly suggest that CB in the ENS participates in the processes connected with the toxic activity of BPA. Most likely, the changes noted in this experiment result from the adaptive and protective properties of CB.

Aspirin Administration Affects Neurochemical Characterization of Substance P-Like Immunoreactive (SP-LI) Nodose Ganglia Neurons Supplying the Porcine Stomach

Background

Acetylsalicylic acid (ASA) is a commonly used anti-inflammatory, antipyretic, and analgesic drug, which has many side effects on the gastric mucosal layer. Despite this, knowledge concerning the influence of ASA on neuronal cells supplying the stomach is very scanty.

Methods

This investigation was performed on ten immature gilts of the Large White Polish race divided into two groups (five animals in each): a control group and animals which were treated with ASA. The retrograde neuronal tracer Fast Blue (FB) was injected into the prepyloric region of the stomach in all animals. ASA was then given orally to the experimental (ASA) group of gilts from the seventh day after FB injection to the 27th day of the experiment. After this period, all animals were euthanized. Immediately after euthanasia, nodose ganglia (NG) were collected and subjected to a standard double-labelling immunofluorescence technique using antibodies directed toward substance P (SP) and other selected neuronal factors, such as galanin (GAL), neuronal isoform of nitric oxide synthase (nNOS), vasoactive intestinal polypeptide (VIP), and calcitonin gene-related peptide (CGRP). Key Results. The obtained results show that SP-LI neurons located in NG supplying the porcine stomach were also immunoreactive to all the above-mentioned neuronal factors. Moreover, ASA administration caused an increase in the degree of colocalization of SP with other neuronal active substances, and the most visible changes concerned the number of neurons simultaneously immunoreactive to SP and CGRP. Conclusions and Inferences. These observations indicate that the population of SP-LI neurons supplying the stomach is not homogeneous and may undergo changes after ASA administration. These changes are probably connected with inflammatory processes and/or neuroprotective reactions although their exact mechanisms remain unknown.

Long-term treatment with naproxen changes the chemical coding of the porcine intramural duodenum neurons

Due to numerous therapeutic applications and high availability, non-steroidal anti-inflammatory drugs (NSAIDs) are the most widely used drugs worldwide. However, long-term use of these drugs can lead to damage to the gastrointestinal mucosa. The enteric nervous system (ENS), which is part of the autonomic nervous system, controls most aspects of gastrointestinal activity. Enteric neurons are characterized by considerable chemical plasticity and the appearance of a pathological factor results in a change in the synthesis of neurotransmitters. The purpose of this study was to determine the effects of naproxen on expression of biologically active substances by intramural neurons supplying the porcine duodenum. The study was performed on eight immature pigs of the Pietrain x Duroc race (approximately 20kg of body weight). The animals were divided into two groups - a control (C group) and an experimental group (N group). Group C (n=4) consisted of animals which received empty gelatine capsules. Group N (n=4) was composed of pigs who received naproxen orally for 28 days, approximately one hour before feeding. After this time, animals from both groups were euthanized. Frozen sections (14μm thickness) were then prepared from the collected duodenum and subjected to double immunofluorescence staining. Antibodies against the neuronal marker PGP 9.5 and against vasoactive intestinal polypeptide (VIP), substance P (SP), neuronal nitric oxide synthase (nNOS), galanin (GAL), pituitary adenylate cyclase-activating polypeptide (PACAP) and cocaine- and amphetamine- regulated transcript peptide (CART) were used as primary antibodies. The polyclonal donkey anti-rabbit, anti-mouse and anti-guinea pig IgG antibodies - Alexa Fluor 488 and 546 - were also used for staining. Analysis of the results obtained with a fluorescence microscope showed a significant increase in the number of nNOS-, VIP-, GAL-, PACAP- and CART-immunoreactive ganglionated neurons and a decrease in the number of SP-positive neurons in the myenteric and submucosal plexuses of the porcine duodenum. The obtained results indicate the participation of enteric neurotransmitters in the neuronal duodenal response to naproxen-induced inflammation.