Search

The acceptance of the tumor as a non-isolated structure within the organism has opened a space for the study of a wide spectrum of potential direct and indirect interactions, not only between the tumor tissue and its vicinity, but also between the tumor and its macroenvironment, including the nervous system. Although several lines of evidence have implicated the nervous system in tumor growth and progression, for many years, researchers believed that tumors lacked innervation and the notion of indirect neuro-neoplastic interactions via other systems (e.g., immune, or endocrine) predominated. The original idea that tumors are supplied not only by blood and lymphatic vessels, but also autonomic and sensory nerves that may influence cancer progression, is not a recent phenomenon. Although in the past, mainly due to the insufficiently sensitive methodological approaches, opinions regarding the presence of nerves in tumors were inconsistent. However, data from the last decade have shown that tumors are able to stimulate the formation of their own innervation by processes called neo-neurogenesis and neo-axonogenesis. It has also been shown that tumor infiltrating nerves are not a passive, but active components of the tumor microenvironment and their presence in the tumor tissue is associated with an aggressive tumor phenotype and correlates with poor prognosis. The aim of the present review was to 1) summarize the available knowledge regarding the course of tumor innervation, 2) present the potential mechanisms and pathways for the possible induction of new nerve fibers into the tumor microenvironment, and 3) highlight the functional significance/consequences of the nerves infiltrating the tumors.

Innervation of cancerous tissue represents an important pathway enabling the nervous system to influence the processes associated with the initiation, progression, and metastasis of a neoplastic process. In the context of prostate cancer, several papers report the presence of innervation and its modulating effect on the cancer prognosis. However, most of the data are experimental, with limited information on human prostate cancer innervation. Morphometric analysis of archival prostate specimen immunohistochemistry with neural markers PGP9.5 and S100 showed a significant decrease of nerve density in the prostate cancer (n=44) compared to the normal prostate tissue (n=18) and benign prostatic hyperplasia (n=28). Sympathetic nerves were detected with TH, parasympathetic with VAChT, and sensory nerves with SP and CGRP protein detection. Dual immunofluorescence revealed numerous sympathetic nerves in normal prostate and benign prostatic hyperplasia, especially in the peripheral parts. Only a few parasympathetic nerves were found between the glands and in the peripheral parts of the prostate and benign hyperplasia. Sporadic positivity for sensory innervation was present only in approximately 1/10 of nerve fibers, especially in the larger nerves. The pattern of innervation in prostate cancer was analogous to that in normal prostate gland and benign prostatic hyperplasia but there was a significantly lower amount of all nerve types, especially in high-grade carcinoma cases. Although not significant, there was a tendency of decreasing innervation density with increasing Gleason score. Regarding the low density of nerves in prostate carcinoma, the significantly lower PCNA counts in nerves of the cancer specimens cannot be ascribed to lower proliferation activity. Our data confirmed the lower nerve density in the prostate cancer compared to the benign prostate tissue. We could not approve an increased nerve proliferation activity in prostate cancer. All nerve types, most the sympathetic, less the parasympathetic, and the sensory nerves, are present in prostate cancer. The highest nerve density at the periphery of the cancer tissue implies this to be the result of an expansive tumor growth. It is evident that the results of experimental prostate cancer models can be applied to human pathology only to a certain extent. The relation between the range of innervation and the biology of prostate cancer is very complex and will require more detailed information to be applied in therapeutic solutions. [ABSTRACT FROM AUTHOR]

The consistency of the diet may affect the development and maintenance of the muscular and bony parts of the masticatory apparatus. Therefore, we investigated the effect of chronic intake of liquid nutrition (Fresubin) on the growth and maintenance of the weight and size of the skull, mandible, and teeth in Wistar rats fed with liquid nutrition during different developmental periods: (i) from weaning to adulthood, (ii) only in the juvenile period, or (iii) only in adulthood. We found that in all groups of rats fed with liquid nutrition, the skull and the mandible were significantly lighter in weight than those of control rats fed exclusively with pelleted chow from weaning to adulthood. In addition, in rats fed with liquid nutrition, the length of the mandible was significantly increased, whereas the height of the mandible and the length of the upper incisors were reduced. Our data indicate that food consistency may profoundly affect the growth pattern and the maintenance of the mass and size of skull bones and teeth during different periods of life. The extent of the effect was found to depend on the period during which liquid nutrition is provided and on the duration of its intake. In conclusion, the findings indicate that prolonged intake of liquid nutrition can significantly affect the development of the bone part of the masticatory apparatus. [ABSTRACT FROM AUTHOR]