G Protein-Coupled Estrogen Receptor (GPER) and ERs Are Modulated in the Testis-Epididymal Complex in the Normal and Cryptorchid Dog

There is growing evidence by the literature that the unbalance between androgens and estrogens is a relevant condition associated with a common canine reproductive disorder known as cryptorchidism. The role of estrogens in regulating testicular cell function and reproductive events is supposedly due to the wide expression of two nuclear estrogen receptors (ERs), ER-alpha and ER-beta and a trans-membrane G protein-coupled estrogen receptor (GPER) in the testis. In this study, immunohistochemistry, Western blotting and qRT-PCR were used to assess the distribution and expression of GPER in the testis-epididymal complex in the normal and cryptorchid dog. ER-alpha and ER-beta were also evaluated to better characterize the relative abundances of all three receptors. In addition, in these tissues, the expression level of two proteins as SOD1 and Nrf2 normally associated with oxidative stress was investigated to evaluate a possible relationship with ERs. Our data revealed changes in the distribution and expression of the GPER between the normal and cryptorchid dog. In particular, dogs affected by cryptorchidism showed an upregulation of GPER at level of the examined reproductive tract. Also considering the obtained result of a modulation of SOD1 and Nrf2 expression, we could hypothesize the involvement of GPER in the cryptorchid condition. Further studies are, however, necessary to characterize the role of GPER and its specific signaling mechanisms.

Does Orexin B-Binding Receptor 2 for Orexins Regulate Testicular and Epididymal Functions in Normal and Cryptorchid Dogs?

Orexins A (OXA) and B (OXB) and the receptors 1 (OX1R) and 2 (OX2R) for orexins are hypothalamic peptides found in several mammalian organs and participated to the control of a wide assortment of physiological and pathological functions. The distribution of OXA and OX1R has been extensively studied in the male gonad of mammals. Here, we examined the expression and localization of OXB and OX2R as well as their possible involvement in the regulation of testicular and epididymal functions, in healthy and cryptorchid dogs, employing some techniques such as immunohistochemistry, Western blotting, and real-time RT-PCR. In vitro tests were also carried out for evaluating the steroidogenic effect of OXB. OXB and OX2R were expressed in spermatocytes, spermatids, and Leydig cells in normal testis. Their localization was restricted to Sertoli and Leydig cells in cryptorchid conditions. OXB was found to be localized in all tracts of both normal and cryptorchid epididymis, whereas OX2R was found only in the caput. Because the small molecular weight of the peptides OXA and OXB, the expression of their precursor prepro-orexin (PPO), OX1R, and OX2R proteins and mRNAs were investigated by means of Western blot and real-time RT-PCR analyses, respectively, in all tested groups of. In particular, the mRNA level expression of all three genes was higher in cryptorchid dogs than in normal ones. In vitro tests demonstrated that OXB—by binding OX2R—is not involved in testicular steroidogenic processes. Therefore, the findings of this study might be the basis for further functional and molecular studies addressing the possible biochemical effects of OXB and OX2R in normal and pathological conditions of the male reproductive system.

Differential abundances of AQP3 and AQP5 in reproductive tissues from dogs with and without cryptorchidism

Aquaporins (AQPs) are integral transmembrane proteins facilitating transport of water and small solutes, such as glycerol and urea, between cells. In male reproductive tracts, AQPs maintain a milieu conducive for sperm formation, maturation, and storage. The aim of this study was to clarify effects of testicular and epidydimal function on male fertility by investigating localisation and abundances of AQP3 and AQP5 in testes and epididymal segments from dogs with and without unilateral cryptorchidism. Immunohistochemistry results indicated AQP3 and AQP5 have different distribution patterns in reproductive tissues of dogs with and without unilateral cryptorchidism. The AQP3, an aquaglyceroprotein, is present in different germ and Sertoli cells in testis of dogs without cryptorchidism. The AQP5 protein was not detected in germ cells but was present in Sertoli and Leydig cells and in endothelia of blood vessels. In cryptorchid dogs, AQP3 was detected in early-developing germ and Sertoli cells, and AQP5 had a distribution pattern similar to testes of dogs without cryptorchidism. In the epididymis, AQP3 and AQP5 were localised in epithelial cells of dogs with and without cryptorchidism in a cell-specific manner. The AQP3 and AQP5 protein was in larger abundance in the gonads from dogs with and without cryptorchidism. In contrast, AQP3 and AQP5 abundance increased in each segment of the cryptorchid epididymis, likely as a compensatory mechanism associated with the pathologic condition. These results indicate involvement of AQP3 and AQP5 in spermatogenesis and sperm maturation. Results from the present study indicate dogs are a useful for comparative reproductive biology studies.

Effects of Curcumin on the Renal Toxicity Induced by Ochratoxin A in Rats

Ochratoxin A (OTA) is a powerful nephrotoxin and the severity of its damage to kidneys depends on both the dose and duration of exposure. According to the scientific data currently available, the mechanism of action still is not completely clarified, but it is supposed that oxidative stress is responsible for OTA-induced nephrotoxicity. Bioactive compound use has emerged as a potential approach to reduce chronic renal failure. Therefore, curcumin (CURC), due to its therapeutic effects, has been chosen for our study to reduce the toxic renal effects induced by OTA. CURC effects are examined in Sprague Dawley rats treated with CURC (100 mg/kg), alone or in combination with OTA (0.5 mg/kg), by gavage daily for 14 days. The end result of the experiment finds rats treated with OTA show alterations in biochemical and oxidative stress parameters in the kidney, related to a decrease in the Glomerular Filtration Rate (GFR). Conversely, the administration of CURC attenuates oxidative stress and prevents glomerular hyperfiltration versus the OTA group. Furthermore, kidney histological tests show a reduction in glomerular and tubular damage, inflammation and tubulointerstitial fibrosis. This study shows that CURC can mitigate OTA-induced oxidative damage in the kidneys of rats.

Red orange and lemon extract prevents the renal toxicity induced by ochratoxin A in rats

In this work, we investigated the effects of red orange and lemon extract (RLE) on ochratoxin A (OTA)-induced nephrotoxicity. In particular, we analyzed the change in renal function and oxidative stress in Sprague-Dawley rats treated with OTA (0.5 mg/kg body weight, b.w.) and with RLE (90 mg/kg b.w.) by oral administration. After OTA treatment, we found alterations of biochemical and oxidative stress parameters in the kidney, related to a severe decrease of glomerular filtration rate. The RLE treatment normalized the activity of antioxidant enzymes and prevented the glomerular hyperfiltration. Histopathological examinations revealed glomerular damages and kidney cortex fibrosis in OTA-rats, while we observed less severe fibrosis in OTA plus RLE group. Then, we demonstrated that oxidative stress could be the cause of OTA renal injury and that RLE reduces this effect.

Urocortins in the mammalian endocrine system

Urocortins (Ucns), peptides belonging to the corticotropin-releasing hormone (CRH) family, are classified into Ucn1, Ucn2, and Ucn3. They are involved in regulating several body functions by binding to two G protein-coupled receptors: receptor type 1 (CRHR1) and type 2 (CRHR2). In this review, we provide a historical overview of research on Ucns and their receptors in the mammalian endocrine system. Although the literature on the topic is limited, we focused our attention particularly on the main role of Ucns and their receptors in regulating the hypothalamic–pituitary–adrenal and thyroid axes, reproductive organs, pancreas, gastrointestinal tract, and other tissues characterized by “diffuse” endocrine cells in mammals. The prominent function of these peptides in health conditions led us to also hypothesize an action of Ucn agonists/antagonists in stress and in various diseases with its critical consequences on behavior and physiology. The potential role of the urocortinergic system is an intriguing topic that deserves further in-depth investigations to develop novel strategies for preventing stress-related conditions and treating endocrine diseases.

Urocortinergic system in the epididymis of the normal and cryptorchid dogs

Cryptorchidism is associated with changes in the gonads and the spermatic duct system, which may cause infertility problems. Urocortin (UCN) is a corticotrophin-releasing hormone (CRH)-related peptide, which affects several functions of male genital organs. The aim of the present study was to investigate the expression of UCN and its receptors CRHR1 and CRHR2 using immunohistochemistry, western blotting and real-time reverse transcription polymerase chain reaction in tissues collected from the epididymis of normal and cryptorchid dogs. The lumen of the cryptic epididymal duct was found to be relatively smaller than that of the normal one, and interstitial tissue was abundant in the cryptic epididymis. In addition, only a few spermatids were observed in the lumen of the epididymal duct. Results showed that UCN, CRHR2 and CRHR1 were expressed in tissues collected from normal and cryptic epididymal ducts. Urocortin- and CRHR2-immunoreactivities (IRs) were detected in the principal cells of the caput, corpus and cauda of the normal and cryptic epididymides. CRHR1-IR was detected in vascular smooth muscles and fibromuscular cells surrounding epididymal tubules of the normal and cryptorchid dogs. Expression levels of UCN and CRHR2 mRNA were higher in cryptic epididymal ducts than that in normal epididymal ducts. These results suggest that UCN and its receptors might play a role in regulating the maturation and storage of spermatozoa. These findings indicated that the expression of these proteins could be modulated by the cryptorchidism condition.

Orexin A-Mediated Modulation of Reproductive Activities in Testis of Normal and Cryptorchid Dogs: Possible Model for Studying Relationships Between Energy Metabolism and Reproductive Control

Orexin A (OxA) is a neuropeptide produced in the lateral hypothalamus that performs pleiotropic functions in different tissues, including involvement in energy homeostasis and reproductive neuroendocrine functions. The role of OxA is particularly important given the well-studied relationships between physiological mechanisms controlling energy balance and reproduction. The enzyme P450 aromatase (ARO) helps convert androgens to estrogens and has roles in steroidogenesis, spermatogenesis, and energy metabolism in several organs. The goal of this study was thus to investigate the role of OxA in ARO activity and the effects of this regulation on reproductive homeostasis in male gonads from healthy and cryptorchid dogs. The cryptorchidism is a specific condition characterized by altered reproductive and metabolic activities, the latter of which emerge from impaired glycolysis. OxA helps to stimulate testosterone (T) synthesis in the dog testis. We aimed to investigate OxA-mediated modulation of 17β-estradiol (17β-E) synthesis, ARO expression and metabolic indicators in testis of normal and cryptorchid dogs. Our results indicate putative effects of OxA on estrogen biosynthesis and ARO activity based on western blotting analysis and immunohistochemistry for ARO detection and in vitro tests. OxA triggered decrease in estrogen production and ARO activity inhibition; reduced ARO activity thus prevented the conversion of T to estrogens and increasing OxA-mediated synthesis of T. Furthermore, we characterized some metabolic and oxidative modulations in normal and cryptorchid dog's testis. The steroidogenic regulation by OxA and its modulation of ARO activity led us to hypothesize that OxA is a potential therapeutic target in pathological conditions associated with steroidogenic alterations and OxA possible involvement in metabolic processes in the male gonad.

Localization of orexin B and orexin-2 receptor in the rat epididymis

The peptides orexin A (OXA) and orexin B (OXB) derived from the proteolytic cleavage of a common precursor molecule, prepro-orexin, were originally described in the rat hypothalamus. Successively, they have been found in many other brain regions as well as in peripheral organs of mammals and other less evolved animals. The widespread localization of orexins accounts for the multiple activities that they exert in the body, including the regulation of energy homeostasis, feeding, metabolism, sleep and arousal, stress, addiction, and cardiovascular and endocrine functions. Both OXA and OXB peptides bind to two G-coupled receptors, orexin-1 (OX1R) and orexin-2 (OX2R) receptor, though with different binding affinity. Altered expression/activity of orexins and their receptors has been associated with a large number of human diseases. Though at present evidence highlighted a role for orexins and cognate receptors in mammalian reproduction, their central and/or local effects on gonadal functions remain poorly known. Here, we investigated the localization of OXB and OX2R in the rat epididymis. Immunohistochemical staining of sections from caput, corpus and cauda segments of the organ showed intense signals for both OXB and OX2R in the principal cells of the lining epithelium, while no staining was detected in the other cell types. Negative results were obtained from immunohistochemical analysis of hypothalamic and testicular tissues from OX2R knock-out mice (OX2R^-/-) and OX1R/OX2R double knock-out (OX1R^-/-; OX2R^-/-) mice, thus demonstrating the specificity of the rabbit polyclonal anti-OX2R antibody used in our study. On contrary, the same antibody clearly showed the presence of OX2R in sections from hypothalamus and testis of normal mice and rats which are well known to express the receptor. Thus, our results provide the first definite evidence for the immunohistochemical localization of OXB and OX2R in the principal cells of rat epididymis.

Effects of orexins on 17β-estradiol synthesis and P450 aromatase modulation in the testis of alpaca (Vicugna pacos)

The steroidogenic enzyme P450 aromatase (ARO) has a key role in the conversion of testosterone (T) into estrogens (E), expressed as 17β-estradiol. The presence and localization of this key enzyme have not been described before in the South American camelid alpaca (Vicugna pacos). In our previous studies of the expression and biological effects of orexin A (OxA) and OxB on the alpaca testis demonstrated that OxA, via its specific receptor 1 (OX1R), stimulated T synthesis. In order to extend these findings, we presently explored the presence and localization of ARO in the alpaca male gonad, and the possible correlation between ARO and the orexinergic complex. Western blotting and immunohistochemistry demonstrated the presence of ARO in tissue homogenates and its localization in the tubular and interstitial compartments of the alpaca testis, respectively. The addition of OxA to fresh testicular slices decreased the 17β-estradiol E levels. This effect was annulled by the sequential addition of the selective OX1R antagonist, SB-408124. OxB incubation did not have any effect on the biosynthesis of E. Furthermore, the OxA-mediated down-regulation of E secretion could be ascribed to ARO inhibition by exogenous OxA, as indicated by measurement of ARO activity in tissue slices incubated with OxA. Overall, our findings suggest that locally secreted OxA interacting with OX1R could indirectly inhibit ARO activity, disabling the conversion of T to E, and consequently lowering E biosynthesis and increasing the production of T in mammalian testis.

Potential role of orexin A binding the receptor 1 for orexins in normal and cryptorchid dogs

Background

Cryptorchidism is one of the most common birth disorders of the male reproductive system identified in dogs and other mammals. This condition is characterised by the absence of one (unilateral) or both (bilateral) gonads from the scrotum. The peptides orexin A (OxA) and B (OxB) were obtained by post-transcriptional proteolytic cleavage of a precursor molecule, called prepro-orexin. These substances bind two types of G-coupled receptors called receptor 1 (OX1R) and 2 (OX2R) for orexins. OX1R is specific to OxA while OX2R binds the two peptides with equal affinity. Orexins modulate a great variety of body functions, such as the reproductive mechanism. The purpose of the present research was to study the presence of OxA and its receptor 1 and their possible involvement in the canine testis under healthy and pathological conditions.

Methods

This study was performed using adult male normal dogs and male dogs affected by unilateral cryptorchidism. Tissue samples were collected from testes and were divided into three groups: normal, contralateral and cryptic. The samples were used for immunohistochemistry, Western blot and in vitro tests for testosterone evaluation in normal and pathological conditions.

Results

OxA-immunoreactivity (IR) was described in interstitial Leydig cells of the normal gonad, and Leydig, Sertoli cells and gonocytes in the cryptic gonad. In the normal testis, OX1R-IR was described in Leydig cells, in pachytene and second spermatocytes and in immature and mature spermatids throughout the stages of the germ developing cycle of the male gonad. In the cryptic testis OX1R-IR was distributed in Leydig and Sertoli cells. The presence of prepro-orexin and OX1R was demonstrated by Western blot analysis. The incubation of fresh testis slices with OxA caused the stimulation of testosterone synthesis in the normal and cryptic gonad while the steroidogenic OxA-induced effect was cancelled by adding the selective OX1R antagonist SB-408124.

Conclusions

These results led us to hypothesise that OxA binding OX1R might be involved in the modulation of spermatogenesis and steroidogenesis in canine testis in healthy and pathological conditions.

Effect of rMnSOD on Sodium Reabsorption in Renal Proximal Tubule in Ochratoxin A-Treated Rats

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium that represent toxic real threat for human beings and animal health. In this study we evaluated the effect of a new recombinant mitochondrial manganese containing superoxide dismutase (rMnSOD) on oxidative stress and on the alterations of fluid reabsorption in renal proximal tubule (PT) as possible causes of OTA nephrotoxicity. Finally, we have measured the concentration of O₂^- in the kidney through dihydroethidium assay (DHE) and nitric oxide (NO) concentration through nitrites and nitrates assay. Male Sprague Dawley rats weighing 120-150 g were treated for 14 days by gavage, as follows: Control group, 12 rats received a corresponding amount of saline solution (including 10% DMSO); rMnSOD group, 12 rats treated with rMnSOD (10 µg/kg bw); OTA group, 12 rats treated with OTA (0.5 mg/kg bw) dissolved in 10% DMSO and then scaled to required volume with corn oil; rMnSOD + OTA, 12 rats treated with rMnSOD (10 µg/kg bw) plus OTA (0.5 mg/kg bw). Our results have shown that rMnSOD restores the alteration of reabsorption in PT in rats treated with OTA plus rMnSOD, probably through the response to pressure natriuresis, where nitric oxide plays a key role. Moreover, rMnSOD prevents the nephrotoxicity induced by OTA probably restoring the balance between superoxide and NO that is most probably the cause of hypertension and renal functional alterations through the inhibition of NO synthase. In conclusion these data provide important information for understanding of mechanism of toxic action of OTA. J. Cell. Biochem. 119: 424-430, 2018. © 2017 Wiley Periodicals, Inc.

Expression of orexin B and its receptor 2 in rat testis

The peptides orexin A (OxA) and orexin B (OxB) deriving from a common precursor molecule, prepro-orexin, by proteolytic cleavage, bind the two G-coupled OX₁ and OX₂ receptors. While OX₁ selectively binds OxA, OX₂ shows similar affinity for both orexins. Firstly discovered in the hypothalamus, orexins and their receptors have been found in other brain regions as well as in peripheral tissues of mammals, thus resulting involved in the regulation of a broad variety of physiological functions. While the functional localization of OxA and OX₁ in the mammalian genital tract has been already described, the expression of OxB and OX₂ and their potential role in the reproductive functions remain to be explored. Here, we investigated the presence of OxB and OX₂ in the rat testis by immunohistochemical and biochemical analyses. The results definitely demonstrated the localization of OxB and OX₂ in pachytene and second spermatocytes as well as in spermatids at all stages of the cycle of the seminiferous epithelium. The expression of both OX₂ mRNA and protein in the rat testis was also established by RT-PCR and Western blotting, respectively. The analysis of the molecular mechanism of action of OxB in the rat testis showed that OxB, in contrast with OxA, is unable to promote steroidogenesis. These results translate into the regulation of diverse biological actions by OxA and OxB in the male gonad.

Aquaporins in Health and Disease: An Overview Focusing on the Gut of Different Species

Aquaporins (AQPs) play a pivotal role in gut homeostasis since their distribution and function is modulated both in physiological and in pathophysiological conditions. The transport of water and solutes through gut epithelia is essential for osmoregulation and digestive and absorptive functions. This passage is regulated by different AQP isoforms and characterized by their peculiar distribution in the gastrointestinal tract. To date, AQP localization has been identified in the gut and associated organs of several mammalian species by different techniques (immunohistochemical, western blotting, and RT-PCR). The present review describes the modulation of AQP expression, distribution, and function in gut pathophysiology. At the same time, the comparative description of AQP in animal species sheds light on the full range of AQP functions and the screening of their activity as transport modulators, diagnostic biomarkers, and drug targets. Moreover, the phenotype of knockout mice for several AQPs and their compensatory role and the use of specific AQP inhibitors have been also reviewed. The reported data could be useful to design future research in both basic and clinical fields.

Effect of colostrum and milk on small intestine expression of AQP4 and AQP5 in newborn buffalo calves

Functional studies indicate differences in newborn gastrointestinal morphology and physiology after a meal. Both water and solutes transfer across the intestinal epithelial membrane appear to occur via aquaporins (AQPs). Given that the physiological roles of AQP4 and AQP5 in the developing intestine have not been fully established, the objective of this investigation was to determine their distribution, expression and respective mRNA in the small intestine of colostrums-suckling buffalo calves by using immunohistochemistry, Western blot, and reverse transcriptase-PCR analysis. Results showed different tissue distribution between AQP4 and AQP5 with the presence of the former along the enteric neurons and the latter in the endocrine cells. Moreover, their expression levels were high in the ileum of colostrum-suckling buffalo calves. The data present a link between feeding, intestinal development and water homeostasis, suggesting the involvement of these channel proteins in intestinal permeability and fluid secretion/absorption during this stage of development after birth.

Expression and Localization of Aquaporin 4 and Aquaporin 5 along the Large Intestine of Colostrum-Suckling Buffalo Calves

Aquaporins (AQPs) are membrane channel proteins that play a role in regulating water permeability in many tissues. To date, seven isoforms of AQPs have been reported in the gastrointestinal tract in different mammalian species. In contrast, both tissue distribution and expression of AQPs are unknown in the buffalo. The purpose of this study was to investigate the expression of both AQP4 and AQP5 mRNAs and their relative proteins in the large intestinal tracts of buffalo calves after colostrum suckling using reverse transcriptase polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. Our results revealed a diversified tissue AQP4 and AQP5 immunolocalization accompanied by their highest expression in the tissues of colostrum-suckling buffalo calves confirmed by Western blotting. In particular, AQP4 was distributed along the endothelium and enterocytes while AQP5 in the endocrine cells. These findings provide direct evidence for AQP4 and AQP5 expression in the large intestine, suggesting that different AQPs collaborate functionally and distinctively in water handling during intestinal development, especially during the first period after delivery.

Expression and potential role of the peptide orexin-A in prostate cancer

The peptides orexin-A and orexin-B and their G protein-coupled OX1 and OX2 receptors are involved in multiple physiological processes in the central nervous system and peripheral organs. Altered expression or signaling dysregulation of orexins and their receptors have been associated with a wide range of human diseases including narcolepsy, obesity, drug addiction, and cancer. Although orexin-A, its precursor molecule prepro-orexin and OX1 receptor have been detected in the human normal and hyperplastic prostate tissues, their expression and function in the prostate cancer (PCa) remains to be addressed. Here, we demonstrate for the first time the immunohistochemical localization of orexin-A in human PCa specimens, and the expression of prepro-orexin and OX1 receptor at both protein and mRNA levels in these tissues. Orexin-A administration to the human androgen-dependent prostate carcinoma cells LNCaP up-regulates OX1 receptor expression resulting in a decrease of cell survival. Noteworthy, nanomolar concentrations of the peptide counteract the testosterone-induced nuclear translocation of the androgen receptor in the cells: the orexin-A action is prevented by the addition of the OX1 receptor antagonist SB-408124 to the test system. These findings indicate that orexin-A/OX1 receptor interaction interferes with the activity of the androgen receptor which regulates PCa onset and progression, thus suggesting that orexin-A and its receptor might represent novel therapeutic targets to challenge this aggressive cancer.

Expression and Localization of Aquaporin-1 Along the Intestine of Colostrum Suckling Buffalo Calves

Aquaporin-1 (AQP1), a six-transmembrane domain protein, belongs to a highly conserved group of proteins called aquaporins known to regulate permeability across cell membranes. Although the role of AQP1 has been extensively studied, its specific activity along the gastrointestinal tract in animals during early postnatal development is poorly known. This study investigates the expression of AQP1 mRNA and protein in the small and large intestine of water buffalo calves after colostrum ingestion using reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and cellular localization of AQP1 by immunohistochemistry. Our results revealed AQP1 immunoreactivity and the presence of the corresponding mRNA in all the examined tracts of the intestine but with a different cellular localization. Western blotting confirmed the presence of AQP1, with a more intense band in colostrum-suckling animals. These findings offer insights into AQP1 expression in the small and large intestine, suggesting its involvement in osmoregulation in gastrointestinal physiology particularly during the first week after birth in relation to specific maturation of intestinal structures.

Increased leptin mRNA expression in the blood of dogs naturally infected by Leishmania infantum

Canine leishmaniosis (CL) is a severe and potentially fatal zoonosis caused by the protozoan Leishmania infantum. Severe forms of CL are commonly associated with a non-protective, humoral immune-response and high parasitic loads. Leptin, a 16 kD hormone mainly secreted by adipocytes, regulates both the innate and adaptive immunity. The goal of this study was to evaluate leptin mRNA expression levels in blood samples from privately owned dogs with CL (n = 11) and healthy controls (n = 10) using quantitative, real-time polymerase chain reaction. Blood samples from dogs with CL expressed significantly higher leptin mRNA levels (two-fold) compared to healthy controls (P = 0.018). The results suggest a possible involvement of leptin in the pathophysiology of Leishmania infection in dogs and the possible use of leptin as a biomarker for CL. Future studies investigating the immunological role of leptin in dogs with CL are warranted.

Presence and distribution of urocortin and corticotrophin-releasing hormone receptors in the bovine thyroid gland

Urocortin (UCN), a 40 amino acid peptide, is a corticotrophin-releasing hormone (CRH)-related peptide. The biological actions of CRH family peptides are mediated via two types of G-protein-coupled receptors, CRH type 1 (CRHR1) and CRH type 2 (CRHR2). The aim of this study was to investigate the expression of UCN, CRHR1 and CRHR2 by immunoprecipitation, Western blot, immunohistochemistry and RT-PCR in the bovine thyroid gland. Immunoprecipitation and Western blot analysis showed that tissue extracts reacted with the anti-UCN, anti-CRHR1 and anti-CRHR2 antibodies. RT-PCR experiments demonstrated that mRNAs of UCN, CRHR1 and CRHR2 were expressed. UCN immunoreactivity (IR) and CRHR2-IR were found in the thyroid follicular and parafollicular cells and CRHR1-IR in the smooth muscle of the blood vessels. These results suggest that a regulatory system exists in the bovine thyroid gland based on UCN, CRHR1 and CRHR2 and that UCN plays a role in the regulation of thyroid physiological functions through an autocrine/paracrine mechanism.

Presence, distribution and steroidogenic effect of the peptides orexin A and receptor 1 for orexins in the testis of the South American camelid alpaca (Vicugna pacos)

The orexins A (oxA) and B are peptides discovered in the rat hypothalamus and successively found in some peripheral organs of the mammalian body. They binds two protein G-coupled receptors defined receptor 1 (ox1r) and 2 for orexins, the first of which is highly specific for oxA while the second binds both the peptides with equal affinity. This work aimed to detect the presence of oxA and ox1r in the testis of the South American camelid alpaca (Vicugna pacos) and investigate the role played by them on Leydig cell steroidogenesis. The species alpaca acquired, in the last years, increasing zootechnical interest for the quality of the wool produced and its breeding spread from the country of origin to USA, Australia and Europe. Immunohistochemistry allowed us to detect oxA in Leydig and Sertoli cells, spermatogonia, resting spermatocytes, round and oval spermatids. Ox1r-immunoreactivity was found in Leydig cells and round, oval and elongated spermatids. The expression of the two peptides in tissue extracts was established by using Western blotting technique. Such results demonstrated that in the alpaca testis exists in a cellular complex able to produce and/or internalize oxA. Finally, the effect of oxA on steroidogenesis was investigated by means of in vitro cultured thin testis slices which were added with oxA or/and Müllerian Inhibiting Substance (MIS), a steroidolitic agent basally produced by the Sertoli cell. OxA evoked increase of testosterone production while MIS a decrease. The consecutive addition of oxA and MIS, or vice versa, highlighted an antagonistic interplay between the two substances which has been thought to be the main molecular event at the basis of the oxA-stimulated steroidogenesis mechanism.

Effects of castration on the expression of the NGF and TrkA in the vas deferens and accessory male genital glands of the rat

Nerve Growth Factor (NGF) is a member of the neurotrophin family. Neurotrophins exert their effects by binding to corresponding receptors, which are formed by the tyrosine protein kinases TrkA, TrkB, and TrkC, and the low affinity p75NTR receptor. The role of neurotrophins in the biology of male genital organs is far from clear. In particular, little is known about the influence of sex hormones on the expression of neurotrophins and their receptors. In the present study, using immunohistochemistry and real time RT-PCR, we investigated the expression of NGF and TrkA in the vas deferens and accessory male genital glands in normal and castrated rats.In normal rats, both NGF- and TrkA-immunoreactivities (IR) were localized in the epithelial layer of the vas deferens. NGF-IR was also found in the stroma and epithelium of the vesicular gland and prostate. TrkA-IR was distributed in the epithelial cells of vesicular and prostate glands. The nerves were weakly immunoreactive in all the examined organs. After castration the immunoreactivities increased. Real-time RT-PCR experiments indicated that NGF and TrkA mRNA levels increased significantly after castration. These results suggest that NGF and TrkA are expressed in the internal male genital organs of the rat and that their expression is downregulated by androgen hormones. We hypothesize NGF and TrkA play a role in the processes that regulate the involution of these organs under conditions of androgen deprivation.

Expression of urocortin and corticotropin-releasing hormone receptors in the bovine adrenal gland

Urocortin (UCN), a 40 amino acid peptide, is a corticotrophin-releasing hormone (CRH)-related peptide. The biological actions of CRH family peptides are mediated via two types of G protein-coupled receptors, CRH type 1 receptor (CRHR1) and CRH type 2 receptor (CRHR2). The aim of the present study was to investigate the expression of UCN, CRHR1 and CRHR2 by immunohistochemistry, western blot and real-time RT-PCR in the bovine adrenal gland to clarify the mechanisms of the intra-adrenal CRH-based regulatory system. The results showed that UCN, CRHR1 and CRHR2 were expressed in both the cortex and medulla. Specifically, UCN-immunoreactivity (IR) was distributed in the outer part of the zona fasciculata and in the zona reticularis of the cortex and in the medulla. UCN and CRHR2 mRNA expression levels were higher in the cortex than in the medulla, while CRHR1 mRNA levels were undetectable in the cortex. These results suggest that UCN, CRHR1 and CRHR2 are expressed in the bovine adrenal gland and that UCN might play a role in the intra-adrenal CRH-based regulatory system through an autocrine mechanism.

Urocortin-like immunoreactivity in the primary lymphoid organs of the duck (Anas platyrhynchos)

Urocortin (UCN) is a 40 aminoacid peptide which belongs to corticotropin-releasing factor (CRF) family. This family of peptides stimulates the secretion of proopiomelanocortin (POMC)-derived peptides, adrenocorticotropic hormone (ACTH), β-endorphin and melanocyte-stimulating hormone (MSH) in the pituitary gland. In the present study, using Western blotting and immunohistochemistry, the distribution of UCN in the primary lymphoid organs of the duck was investigated at different ages. In the cloacal burse and thymus, Western blot demonstrated the presence of a peptide having a molecular weight compatible with that of the mammalian UCN. In the cloacal burse, immunoreactivity was located in the medullary epithelial cells and in the follicular associated and corticomedullary epithelium. In the thymus, immunoreactivity was located in single epithelial cells. Double labelling immunofluorescence studies showed that UCN immunoreactivity completely colocalised with cytokeratin immunoreactivity in both the thymus and cloacal burse. Statistically significant differences in the percentage of UCN immunoreactivity were observed between different age periods in the cloacal burse. The results suggest that, in birds, urocortin has an important role in regulating the function of the immune system.

Urocortin-like immunoreactivity in the primary lymphoid organs of the duck (Anas platyrhynchos)

Urocortin (UCN) is a 40 aminoacid peptide which belongs to corticotropin-releasing factor (CRF) family. This family of peptides stimulates the secretion of proopiomelanocortin (POMC)-derived peptides, adrenocorticotropic hormone (ACTH), beta-endorphin and melanocyte-stimulating hormone (MSH) in the pituitary gland. In the present study, using Western blotting and immunohistochemistry, the distribution of UCN in the primary lymphoid organs of the duck was investigated at different ages. In the cloacal burse and thymus, Western blot demonstrated the presence of a peptide having a molecular weight compatible with that of the mammalian UCN. In the cloacal burse, immunoreactivity was located in the medullary epithelial cells and in the follicular associated and cortico-medullary epithelium. In the thymus, immunoreactivity was located in single epithelial cells. Double labelling immunofluorescence studies showed that UCN immunoreactivity completely colocalised with cytokeratin immunoreactivity in both the thymus and cloacal burse. Statistically significant differences in the percentage of UCN immunoreactivity were observed between different age periods in the cloacal burse. The results suggest that, in birds, urocortin has an important role in regulating the function of the immune system.

Gammaglutamyltransferase activity in buffalo mammary tissue during lactation

In the present study, the rôle of gammaglutamyltransferase (GGT) during lactation has been investigated in the water buffalo. GGT activity has been evaluated in the mammary tissue at 4 and 6 months after calving and during the non-lactating period. The highest GGT activity levels were found at day 120 (32·57±7·41 U per g) of lactation and were statistically higher than those at 180 (10·76±3·6 U per g) or during the non-lactating period (9·86±7·94 U per g). Histochemistry confirmed these findings and revealed that GGT reactivity was distributed throughout the cytoplasm of alveolar epithelial cells. Such results showed that the GGT production is high during lactation thus supporting the hypothesis that this enzyme plays a rôle in determining milk production in water buffalo by supporting milk protein synthesis.

Expression of pituitary adenylate cyclase-activating polypeptide in the primary lymphoid organs of the duck Anas platyrhynchos

The expression of pituitary adenylate cyclase-activating polypeptide (PACAP) was studied in the thymus and bursa of Fabricius of the duck Anas platyrhynchos, at different ages, using immunohistochemistry, Western blotting, RT-PCR and sequencing. In the thymus, PACAP immunoreactivity (-ir) was found in lymphoid cells. CD68/ and PGP 9.5/PACAP38 double labelling showed that PACAP was not expressed either in macrophages or in epithelial cells, suggesting that the PACAP-positive cells observed were lymphoid cells. Immunoreactive lymphocytes were observed in the interlobular septa. They increased in number with ageing. In the bursa, PACAP-ir was found in nerve fibres and in a few lymphoid cells. RT-PCR revealed PACAP mRNA expression in the thymus but not in the bursa. These results suggest that PACAP plays a role in the functions of the immune system in birds.

Effects of castration on the expression of brain-derived neurotrophic factor (BDNF) in the vas deferens and male accessory genital glands of the rat

Brain-derived neurotrophic factor (BDNF) is a growth factor belonging to the family of neurotrophins. Although neurotrophins in the male genital organs have been well documented, their role in the biology of these organs is far from clear. In particular, little is known about the influence of sex hormones on neurotrophin expression. In the present study, using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), we investigated the distribution and tissue concentration of BDNF in the vas deferens and accessory male genital glands in normal and castrated rats. The expression of BDNF mRNA was also investigated. In normal rats, BDNF immunoreactivity was localized in the musculature of the vas deferens and vesicular gland and in the fibromuscular stromal cells of the prostate. In the ventral prostatic lobes, BDNF immunoreactivity was localized in basal, secretory and neuroendocrine epithelial cells. Innervating ganglia and nerves were immunoreactive in all the examined tracts. After castration, BDNF immunoreactivity increased in the musculature of the vesicular gland and in the fibromuscular stromal cells of both dorsal and ventral prostatic lobes. BDNF immunoreactivity also increased in the nerves. ELISA and reverse transcription/real-time polymerase chain reaction confirmed the findings of the immunohistochemical study. In the accessory glands, castration induced an increase of both BDNF tissue concentration and mRNA expression. These results suggest that BDNF is expressed in the internal male genital organs of the rat and that its expression is downregulated by androgen hormones. We hypothesize that the observed BDNF increases are related to the castration-induced regression of the sympathetic nerves.

Expression of agouti-related protein (AgRP) in the hypothalamus and adrenal gland of the duck ( Anas platyrhynchos)

The presence and distribution of agouti-related protein (AgRP) immunoreactivity were investigated in the hypothalamus and adrenal gland of the duck using immunohistochemistry and Western blot analysis. Expression of AgRP mRNA was also studied using reverse transcriptase polymerase chain reaction (RT-PCR). A partial coding sequence (cds) of the duck AgRP gene was identified. Western blot analysis showed the presence of an AgRP-like peptide having a molecular weight consistent with the number of predicted amino acids of the avian AgRP. In the hypothalamus, AgRP immunoreactivity was found in neurons of the nucleus infundibularis and in fibers projecting to the median eminence. In the adrenals, AgRP immunoreactivity was observed in medullary cells. These findings suggest that in the duck, AgRP may play a role in regulating energy homeostasis and adrenal endocrine functions.

Topography and neurochemistry of the enteric ganglia in the proventriculus of the duck (Anas platyrhynchos)

The topographical distribution of the enteric ganglia has been investigated in the proventriculus of the duck using protein gene product 9.5 (PGP 9.5) immunohistochemistry. Myenteric ganglia were usually located between the outer longitudinal and the inner circular muscle layer. Submucous ganglia were sparsely distributed and seemed to be substituted by ganglia located in the tunica mucosa. The neurochemical profile of proventricular ganglion cells was also investigated using nicotinamide adenine dinucleotide phosphate reduced-diaphorase (NADPH-d)-histochemistry and pituitary adenylate cyclase activating peptide (PACAP)/galanin (Gal) double-labelling immunohistochemistry. The majority of mucosal ganglion cells were shown to contain the NADPH-d enzyme and both the investigated peptides. These findings provide evidence for the presence of a mucosal ganglionated plexus in the glandular stomach of birds. Moreover, the neurochemical characteristics of this plexus suggest that it plays an important role in regulating several mucosal functions and, in particular, the production and the composition of the gastric juice.

Innervation of vas deferens and accessory male genital glands in the water buffalo (Bubalus bubalis). Neurochemical characteristics and relationships to the reproductive activity

Autonomic nerves supplying mammalian male internal genital organs have an important role in the regulation of reproductive function. To find out the relationships between the neurochemical content of these nerves and the reproductive activity, we performed a histochemical and immunohistochemical study in a species, the water buffalo, exhibiting a seasonal sexual behaviour. The distribution of noradrenergic and nitric oxide synthase (NOS)- and peptide-containing nerves was evaluated during the mating and non-mating periods. Fresh segments of vas deferens and accessory genital glands were collected immediately after slaughter and immersed in 4% paraformaldehyde. Frozen sections were obtained and processed according to single and double labelling immunofluorescent procedures or NADPH-diaphorase histochemistry. During the mating period, a dense noradrenergic innervation was observed to supply the vas deferens as well as the accessory genital glands. NOS- and peptide-containing nerves were also observed but with a lower density. During the non-mating period noradrenergic nerves dramatically reduced. In addition, neuropeptide Y (NPY)- and vasoactive intestinal peptide (VIP)-containing nerves were also reduced. These findings suggest the presence of complex interactions between androgen hormones and the autonomic nerve supply in the regulation of male water buffalo reproductive functions.

Pituitary adenylate cyclase activating peptide (PACAP) immunoreactivity and mRNA expression in the duck gastrointestinal tract

The presence and distribution of pituitary adenylate cyclase activating peptide (PACAP) immunoreactivity were studied in the duck gastrointestinal tract using immunohistochemistry and radioimmunoassays. Expression and distribution of PACAP mRNA were also studied using reverse transcriptase polymerase chain reaction (RT-PCR) and hybridization techniques. In addition, a partial coding sequence (cds) of the duck growth hormone-releasing hormone (GRF)/PACAP gene was identified. The presence of both PACAP-38 and PACAP-27 was demonstrated, the former being the predominant form. PACAP immunoreactivity was found in neurons and fibers of the enteric nervous system (ENS), in endocrine cells and in the gut associated lymphoid tissue (GALT). Double immunostaining showed that PACAP is almost completely colocalized with vasoactive intestinal peptide (VIP) in the ENS. Moreover, PACAP was also found in nitric oxide synthase (NOS)-containing neurons and nerve fibers. Radioimmunoassay (RIA) performed on denervated gut showed that more than one-half of the duodenal PACAP is extrinsic in origin. RT-PCR, Northern blot analysis and in situ hybridization confirmed the immunohistochemical data. The findings of the present study suggest that, in birds, PACAP may have multiple roles in regulating gastrointestinal functions.

Morphostructural changes of the kidney microvasculature during the prenatal period in Bubalus bubalis

The microcirculation of the foetal kidney was studied in the buffalo using light (LM) and scanning electron microscopy (SEM). The primordial glomerules originated from the peripheral zone of the metanephros at the stage of 8 cm CRT. The glomerular capillaries started to differentiate at the stage of 10-15 cm CRT. They were sparse and showed a few primordial pores. In addition, they began to make contacts with primordial podocytes. At the stage of 40-60 cm CRT, the renal microcirculation showed a complex and almost completely organized morphology.