Double labelling immunohistochemical characterization of autonomic sympathetic neurons innervating the sow retractor clitoridis muscle

Retrograde neuronal tracing and immunohistochemical methods were used to define the neurochemical content of sympathetic neurons projecting to the sow retractor clitoridis muscle (RCM). Differently from the other smooth muscles of genital organs, the RCM is an isolated muscle that is tonically contracted in the rest phase and relaxed in the active phase. This peculiarity makes it an interesting experimental model. The fluorescent tracer fast blue was injected into the RCM of three 50 kg subjects. After a one-week survival period, the ipsilateral paravertebral ganglion S1, that in a preliminary study showed the greatest number of cells projecting to the muscle, was collected from each animal. The co-existence of tyrosine hydroxylase with choline acetyltransferase, neuronal nitric oxide synthase, calcitonin gene-related peptide, leuenkephalin, neuropeptide Y, substance P and vasoactive intestinal polypeptide was studied under a fluorescent microscope on cryostat sections. Tyrosine hydroxylase was present in about 58% of the neurons projecting to the muscle and was found to be co-localized with each of the other tested substances.Within fast blue-labelled cells negative to the adrenergic marker, small populations of neurons singularly containing each of the other enzymatic markers or peptides were also observed. The present study documents the complexity of the neurochemical interactions that regulate the activity of the smooth myocytes of the RCM and their vascular components

Alfaxalone and Dexmedetomidine as an alternative to gas anesthesia for micro-CT lung imaging in a bleomycin-induced pulmonary fibrosis murine model

Micro-CT imaging could be considered a powerful non-invasive tool for accessing pulmonary fibrosis in mice. However, the choice of the anesthesia protocol plays a fundamental role to obtain robust and reproducible data, avoiding misinterpretations of the results. Inhaled anesthesia is commonly used for micro-CT lung imaging, but sometimes the standardization of the protocol may be challenging for routine activities in drug discovery. In this study we used micro-CT to evaluate the effects of two anesthetic protocols, consisting in Alfaxalone and Dexmedetomidine mixture, as injectable agents, and gaseous isoflurane, on vehicle and bleomycin-treated mice. No significant differences were highlighted between the protocols either for lung aeration degrees by micro-CT or histologic analyses in both the controls and bleomycin-treated groups. Our results support Alfaxalone and Dexmedetomidine mixture as a suitable and safe alternative compared to isoflurane for lung imaging. We also concluded that this injectable mixture may be applied for several imaging technologies and on different mice models

Double labelling immunohistochemistry on the sympathetic trunk ganglia neurons projecting to the extrinsic penile smooth musculature of the pig: an experimental study on the retractor penis muscle

Retrograde neuronal tracing and double labelling immunofluorescence methods were used to define the neurochemical content of sympathetic trunk ganglia neurons projecting to the pig retractor penis muscle, which was taken as an experimental model of the male genital smooth musculature. After the injection of Fast Blue into the bulbo-penile portion of the retractor penis muscle, the eventual co-existence of the catecholaminergic marker tyrosine hydroxylase with calcitonine gene related peptide, leu-enkephalin, neuropeptide Y, neuronal nitric oxide synthase, substance P, vasoactive intestinal polypeptide or vesicular acetylcholine transporter was studied in the ipsilateral S1 sympathetic trunk ganglia, which resulted to contain the greatest number of autonomic retractor penis muscle projecting cells. The observation of Fast Blue positive neurons under the fluorescent microscope allowed the identification of different subpopulations of catecholaminergic and non-catecholaminergic retractor penis muscle-projecting neurons. The majority of catecholaminergic cells contained tyrosine hydroxylase alone, while the remaining part showed co-localization of tyrosine hydroxylase with all the other tested markers. These last neurons were immunoreactive, in decreasing percentages, for neuropeptide Y, leu-enkephalin, neuronal nitric oxide synthase, substance P, calcitonine gene related peptide, vasoactive intestinal polypeptide and vesicular acetylcholine transporter. The majority of non-catecholaminergic neurons were immunonegative for all the tested markers. The remaining non-catecholaminergic cells contained, in decreasing percentages, neuropeptide Y, neuronal nitric oxide synthase, leu-enkephalin, vasoactive intestinal polypeptide, vesicular acetylcholine transporter, substance P and calcitonine gene related peptide. Our findings documented the complexity of the neurochemical interactions that regulate both the motor functions of RPM and the blood flow through the muscle

Immunohistochemical characteristics of the nerve fibres of sow retractor clitoridis muscle

The occurrence of several biologically active neuropeptides (calcitonine gene-related peptide, leu-enkephaline, neuropeptide Y, substance P, and vasoactive intestinal peptide) or nitric oxide-synthesizing enzymes (neuronal nitric oxide synthase), tyrosine hydroxylase, vesicular acetylcholine transporter, and their co-localization with tyrosine hydroxylase were investigated by immunohistochemistry in the retractor clitoridis muscle of slaughtered sows. Single immunolabelling revealed that tyrosine hydroxylase and neuropeptide Y immunoreactive nerve fibres were the most numerous, followed by the neuronal nitric oxide synthase and calcitonine gene-related peptide immunoreactive ones, the vasoactive intestinal peptide, substance P and leu-enkephaline immunoreactive nerve fibres were few and vesicular acetylcholine transporter immunoreactivity were observed only in single fibres. Double immunolabelling revealed the only co-localization of tyrosyne hydroxylase with neuropeptide Y. The most reliable labelling of nerve fibres of the retractor clitoridis muscle was observed around blood vessels, followed by non-vascular smooth muscles. The present data indicate that the sow retractor clitoridis muscle receives nerve fibres that exhibit different chemical codes and, likely, differences in their chemical coding depend on the target-structure

Influence of genetic selection on the myofibre type composition of porcine biceps femoris muscle: a comparative study of a purebred (Nero di Parma) and commercial hybrid pigs (Large White × Landrace × Duroc)

This study is aimed to evaluate histological features related to the different quality of meat cuts obtained from different pig breeds. We compared animals genetically selected to restore the original local purebred “Nero di Parma” pig, and highly selected fast-growing commercial hybrids. As weight is the main factor determining the time of slaughter, we compared equally weighing animals, sampled from slaughter for edible use, regardless of their age and sex, and immunohistochemically demonstrated the myofibre type composition of their biceps femoris muscle. In both groups we observed type I myofibres, situated as central islets, encircled by type IIA, IIX and IIB myofibres ordered in concentric rings according to the dynamic of their differentiation/maturation. However, the purebred pig muscles contained a smaller quantity of myofibres expressing the MyHC-IIb isoform, related to rapid postmortem glycolytic rate, meat toughness and poorer quality, in comparison to commercial hybrids. This proves that the latter are subjected to a more rapid transition in the expression of the different MyHC, probably as a consequence of genetic selection and breeding conditions, such as different feeding and housing reducing the possibility of continuous physical exercise. Further studies on the postnatal transitions timing of myosin heavy chain isoforms in functionally different muscles of various breeds are necessary to verify if they might be “artificially modulated”, with the aim to design breeding programs allowing a good balance between growth performance, muscularity and meat quality

On the autonomic and sensitive nervous components of digital, metacarpal and metatarsal pads of the coypu (<i>Myocastor coypus</i>)

The innervation of the coypu foot pads (digital, metacarpal and metatarsal) is represented by an autonomic and a sensitive components. The former is constituted by isolated or grouped ganglion cells located along the course of nerve bundles, while the latter is composed by free and encapsulated nerve endings morphologically classified as Pacini, Pacini-like and Golgi-Mazzoni corpuscles. The above named corpuscles show the typical structure and can be found isolated or grouped to organize simple and complex flower-sprays, opposite-polar corpuscles and poikilomorphous fibres. The AA. notice the morphological variability of the encapsulated receptors found in this and previous similar investigations but point out also that they are functionally mechanoreceptors and so compatible with the role of the considered anatomical district

Quantification of Lung Fibrosis in IPF-Like Mouse Model and Pharmacological Response to Treatment by Micro-Computed Tomography

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive degenerative lung disease leading to respiratory failure and death. Although anti-fibrotic drugs are now available for treating IPF, their clinical efficacy is limited and lung transplantation remains the only modality to prolong survival of IPF patients. Despite its limitations, the bleomycin (BLM) animal model remains the best characterized experimental tool for studying disease pathogenesis and assessing efficacy of novel potential drugs. In the present study, the effects of oropharyngeal (OA) and intratracheal (IT) administration of BLM were compared in C57BL/6 mice. The development of lung fibrosis was followed in vivo for 28 days after BLM administration by micro-computed tomography and ex vivo by histological analyses (bronchoalveolar lavage, histology in the left lung to stage fibrosis severity and hydroxyproline determination in the right lung). In a separate study, the antifibrotic effect of Nintedanib was investigated after oral administration (60 mg/kg for two weeks) in the OA BLM model. Lung fibrosis severity and duration after BLM OA and IT administration was comparable. However, a more homogeneous distribution of fibrotic lesions among lung lobes was apparent after OA administration. Quantification of fibrosis by micro-CT based on % of poorly aerated tissue revealed that this readout correlated significantly with the standard histological methods in the OA model. These findings were further confirmed in a second study in the OA model, evaluating Nintedanib anti-fibrotic effects. Indeed, compared to the BLM group, Nintedanib inhibited significantly the increase in % of poorly aerated areas (26%) and reduced ex vivo histological lesions and hydroxyproline levels by 49 and 41%, respectively. This study indicated that micro-computed tomography is a valuable in vivo technology for lung fibrosis quantification, which will be very helpful in the future to better evaluate new anti-fibrotic drug candidates

Experimental study on the location of neurons associated with the first sacral sympathetic trunk ganglion of the pig.

The neurons associated with the left first sacral sympathetic trunk ganglion (STG S1), an autonomic ganglion particularly concerned in the innervation of the smooth and striated musculature associated with pelvic organs, were identified in the pig, using the non-trans-synaptic fluorescent retrograde neuronal tracer Fast Blue. The labelled neurons were located mostly ipsilaterally, in the intermediolateral nucleus of the spinal cord segments T10-L5, in the sympathetic trunk ganglia L3-Co1, in the caudal mesenteric ganglia, in the pelvic ganglia, and in the spinal ganglia T13-S4. Our results could indicate the existence of visceral neuronal circuits concerning the ganglia of the sympathetic trunk and the caudal mesenteric, pelvic and spinal ganglia with or without the intervention of the central nervous system, whose identification and preservation during surgical treatments could be helpful in reducing the risk of subsequent urinary and sexual disfunctions