Brain-derived neurotrophic factor (BDNF) and polysialylated-neural cell adhesion molecule (PSA-NCAM) in the human brainstem precerebellar nuclei from prenatal to adult age.

Occurrence and distribution of the neurotrophin brain-derived neurotrophic factor (BDNF) and polysialylated-neural cell adhesion molecule (PSA-NCAM), a neuroplasticity marker known to modulate BDNF signalling, were examined by immunohistochemistry in the human brainstem precerebellar nuclei at prenatal, perinatal and adult age. Western blot analysis performed in human brainstem showed for both molecules a single protein band compatible with the molecular weight of the dimeric form of mature BDNF and with that of PSA-NCAM. Detectability of both molecules up to 72 h post-mortem was also assessed in rat brain. In neuronal perikarya, BDNF-like immunoreactivity (LI) appeared as intracytoplasmic granules, whereas PSA-NCAM-LI appeared mostly as peripheral staining, indicative of membrane labelling; immunoreactivity to both substances also labelled nerve fibres and terminals. BDNF- and PSA-NCAM-LI occurred in the external cuneate nucleus, perihypoglossal nuclei, inferior olive complex, arcuate nucleus, lateral reticular formation, vestibular nuclei, pontine reticulotegmental and paramedian reticular nuclei, and pontine basilar nuclei. With few exceptions, for both substances the distribution pattern detected at prenatal age persisted later on, though the immunoreactivity appeared often higher in preand full-term newborns than in adult specimens. The results obtained suggest that BDNF operates in the development, maturation, maintenance and plasticity of human brainstem precerebellar neuronal systems. They also imply a multiple origin for the BDNF-LI of the human cerebellum. The codistribution of BDNF- and PSA-NCAM-LI in analyzed regions suggests that PSA-NCAM may modulate the functional interaction between BDNF and its high and low affinity receptors, an issue worth further analysis, particularly in view of the possible clinical significance of neuronal trophism in cerebellar neurodegenerative disorders.

Morphological changes induced by neuropeptide in vitro stimulation of the rat parotid gland

The effect of in vitro stimulation of rat parotid gland with the neuropeptides substance P, calcitonin gene-related peptide and galanin has been studied by microfilament fluorescence staining and in semithin sections, and compared to control incubations and in vitro stimulation with b­adrenergic and muscarinic agonists. Clear-cut aspects of massive granule exocytosis and cytoplasm vacuolation, indicative of protein and fluid secretion respectively, were obvious only after substance P stimulation, whereas treatment with galanin and calcitonin gene-related peptide produced little to no morphological changes. The results being in agreement with the outcome of other methodological approaches, these procedures appear reliable, may be effectively applied to the study of the functional regulation of secretory mechanisms, and may be particularly useful in human tissue analyses

The rat dorsal column nuclei contain a region homologous to the human Locus K

Locus K is a newly identified region within the territory of the human nucleus cuneatus that shares neurochemical and histological features with protopathic second order sensory nuclei (Del Fiacco et al., 2013; Serra et al., 2013; SIAI 2014). This work is aimed at examining the rat dorsal column nuclei in order to ascertain whether a structure homologous to the human Locus K occurs in the rat brain. Rat brainstem sections were observed by means of ABC and fluorescence immunohistochemistry for neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP), Kluver-Barrera and Nissl staining. Results of the peptide immunoreactive structures in the rat dorsal column nuclei are in general good agreement with findings in previous studies (Hoeflinger et al., 1993). However, at caudalmost levels of the complex, in the territory of the cuneate fascicle and dorsal to the caudal pole of the cuneate nucleus, a small column of gray matter area can be identified that contains a dense plexus of varicose labelled nerve fibres. The observed discrete region has never distinctly described beforehand. Both its position and aspect at neuropeptide-immunoreactivity resemble those of the Locus K we detected in the human dorsal column nuclei, allowing the possibility that it represents the its homologous nucleus in the rat brain. Work funded by Fondazione Banco di Sardegna

The human nucleus cuneatus contains discrete territories that share neurochemical features with the relay nuclei for nociceptive information

Traditionally, the spinal dorsal column and the gracile (GN) and cuneate (CN) nuclei are believed to be involved in somatic tactile and proprioceptive perceptions. However, more recent clinical and experimental studies show that this system is also involved in the neurotransmission of visceral nociceptive stimuli (Willis et al., Proc. Natl. Acad. Sci. USA 96, 7675, 1999; Pale?ek J., Physiol. Res. 53, S125, 2004). Early studies in our laboratory (Del Fiacco et al., Brain Res. 264, 142, 1983; Neuroscience, 12, 591, 1984) showed that, at variance with that of laboratory animals, the human CN contains discrete subregions that are strongly immunoreactive to substance P, a neuropeptide classically involved in pain transmission. Here we provide further information on the chemical neuroanatomy of the human dorsal column nuclei and show that the substance P-immunoreactive subregions of the CN retain the neurochemical features of the protopathic relay nuclei. Tissue distribution of a number of neuropeptides, trophic factors and neuroplasticity-associated proteins was analyzed by immunohistochemistry in postmortem specimens of medulla oblongata from subjects aged 21 gestation weeks to 78 years, with no signs of neuropathology. Immunoreactivity to neuropeptides calcitonin gene-related peptide, leucine- and methionine-enkephalin, somatostatin, galanin, and peptide histidine-isoleucine, to trophins of the Neurotrophin and glial-derived neurotrophic factor families and related receptors, and to the neuroplasticity-associated proteins growth-associated protein-43 and polysialylated-neural cell adhesion molecule labels neuronal elements in restricted areas of the cuneate nucleus, located along its dorsal edge or embedded in the white matter of the cuneate fasciculus. Multiple immunolabelling shows that, with respect to one another, the examined substances are distributed in these regions as in the superficial layers of the spinal dorsal horn and trigeminal subnucleus caudalis. By contrast, the immunoreactivity in the GN is usually sparse and not gathered in definite subregions. The results show that, at variance with that of laboratory mammals, including primates, the human CN contains clear-cut subregions with neurochemical features reminiscent of those present in the relay nuclei for protopathic and pain perception. Moreover, the peculiar localization of the examined substances suggests that the superficial layers of those regions may constitute a “gelatinous subnucleus”. The origin as well as the functional involvement of such innervation remains to be elucidated

Transient receptor potential vanilloid type 1 (TRPV1) and neuropeptides in the dorsal root ganglia and spinal cord in a rat model of Bortezomib-induced neuropathy

Bortezomib (BTZ) is an effective antineoplastic drug that acts by inhibiting the ubiquitin-proteasome cellular pathways. In clinical practice, its chronic administration triggers a significant neurotoxicity, which has been associated with impairment of Aβ, Aδ, and C type primary afferent fibers, though the mechanism underlying its harmful effects remains still to be fully clarified. In order to mimic the clinical use of the drug, we have recently designed an experimental model based on the use of 0,20 mg/kg drug concentration for 8 weeks followed by a follow-up period of 4 weeks. We have previously shown that, in these conditions, a hallmark of neurotoxicity is represented by a small fiber neuropathy, whereas dorsal root ganglia (DRG) neurons did not show any morphological alterations. In order to provide data regarding the mechanism underlying BTZ harmful effects, here we characterize the spinal primary sensory neurons on the basis of their expression of the transient receptor potential vanilloid type-1 (TRPV1) and sensory neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP). In fact, TRPV1 is expressed by sensory neurons where it functions as a molecular integrator for nociception. Its activation causes depolarisation leading to burning pain and release of CGRP and SP which, in turn, activate their effector cell receptors and enhance the sensitization of nociceptors. With this aim, lumbar DRG and spinal cord of BTZ-treated model rats were processed for avidine-biotin-peroxidase complex or fluorescence immunohistochemistry. In the DRG, the immunolabelling for TRPV1 revealed a subpopulation of predominantly small- to medium-sized neurons which appeared more extensive in BTZ-treated rats. Centrally, TRPV1-LI labelled fiber tracts and terminal-like elements distributed in laminae I and II of the dorsal horn where they appeared widely codistributed with both CGRP-LI and SP-LI. With the exception of a slight more intense TRPV1 staining in lamina I of the dorsal horn of BTZ-treated vs control rats, no clear-cut differences in the distribution and amount of immunoreactivity for the three markers could be observed

Dietary essential oil components in the prevention of hypoperfusion/reperfusion-induced tissue damage in the rat cerebral cortex

To extend our previous observations on the beneficial effect of dietary Pistacia lentiscus L. essential oil during cerebral bilateral common carotid artery occlusioninduced injury, we evaluated the activity of one of its major components, beta-caryophyllene (BCP), already known to possess peculiar biological activities, in Wistar rat cerebral cortex. Cerebral hypoperfusion was produced by a 30 min bilateral common carotid artery occlusion followed by 60 min reperfusion (BCCAO/R). Animals were starved for 12 hours before surgery and, 6 hours prior to hypoperfusion, BCP (40 mg/kg/0, 45 ml of sunflower oil as vehicle) was administered via gavage. Biological samples of brain tissue, plasma and cerebrospinal fluid (CSF) were examined by HPLC, western blot, gel zymography and immunohistochemistry and analyzed for fatty acids, expression of the enzyme ciclooxygenase-2 (COX-2), CB receptors for endocannabinoids (eCBs), and peroxisome proliferator-activated receptor (PPAR)-alpha and enzymatic activity of matrix-metalloprotease-9 (MMP9). Data obtained indicate that BCP appears to influence the outcome of BCCAO/R cerebral injury by modulating changes in levels of polyunsaturated fatty acids, biosynthesis of eCBs and eCB congeners, expression of CB1 and CB2 receptors, COX-2 protein levels and enzymatic activity of MMP9. Brain tissue response to the hypoperfusion/reperfusion-induced cerebral insult is modulated by dietary administration of BCP, suggesting the possible use of this molecule as nutritional treatment in neuroprevention. Work funded by Fondazione Banco di Sardegna

Effect of acute administration of dietary Pistacia lentiscus L. essential oil on the ischemia-reperfusion-induced changes in rat frontal cortex and plasma

In this study Pistacia lentiscus L. essential oil (E.O.), a mixture of terpenes and sesquiterpenes, was tested for its protective effects in cerebral ischemia/reperfusion-induced injury in Wistar rat frontal cortex and plasma. Cerebral ischemia was produced by a 20 min bilateral common carotid artery occlusion followed by 30 min reperfusion. Pistacia lentiscus L. essential oil (E.O.) (200 mg/0, 45 ml of sunflower oil as vehicle) was administered via gavage 6 hours prior to ischemia. Rats were randomly assigned to four groups, ischemic/reperfused (I/R) and sham-operated rats treated with the vehicle or with E.O.. Different brain areas were analysed for fatty acid changes and expression of the enzyme cyclooxygenase-2 (COX-2). Ischemia/reperfusion triggered in frontal cortex a decrease of docosahexaenoic acid (DHA), the membrane highly polyunsaturated fatty acid (HPUFA) most susceptible to oxidation. Pre-treatment with E.O. prevented this change and led further to decreased levels of COX-2, as assessed by Western Blot. In plasma of ischemic/reperfused rats, E.O. administration increased both the DHA-to-eicosapentaenoic acid (EPA) ratio and levels of the endocannabinoid congeners palmytoylethanolamide (PEA) and oleoylethanolamide (OEA). The results obtained suggest that ischemia/reperfusion triggers a cerebral insult sufficient to cause a a region specific lipid peroxidation as evidenced by the detectable, significant decrease in the tissue level of DHA, the most abundant essential fatty acid of neuronal membrane phospholipids. Acute dietary pre-treatment with E.O. triggers modifications both in the frontal cortex, where COX-2 expression decreases and the decrease of DHA is apparently prevented, and in plasma, where PEA and OEA levels increase. We suggest that the activity of PEA and OEA, as endogenous ligands of the peroxisome proliferator-activated receptor (PPAR)-alpha, by inducing the peroxisomal beta oxidation, may explain the observed increase in the DHA/EPA ratio. The latter, in fact, might account for an increased metabolism of n-3 aimed at restoring DHA within damaged brain tissue. The possibility that changes in fatty acid metabolism and plasmatic availability of PEA and OEA are correlated events represents an issue worth future investigations

Polysialylated-neural cell adhesion molecule (PSA-NCAM) in the human trigeminal ganglion and brainstem at prenatal and adult ages

<p>Abstract</p> <p>Background</p> <p>The polysialylated neuronal cell adhesion molecule (PSA-NCAM) is considered a marker of developing and migrating neurons and of synaptogenesis in the immature vertebrate nervous system. However, it persists in the mature normal brain in some regions which retain a capability for morphofunctional reorganization throughout life. With the aim of providing information relevant to the potential for dynamic changes of specific neuronal populations in man, this study analyses the immunohistochemical occurrence of PSA-NCAM in the human trigeminal ganglion (TG) and brainstem neuronal populations at prenatal and adult age.</p> <p>Results</p> <p>Western blot analysis in human and rat hippocampus supports the specificity of the anti-PSA-NCAM antibody and the immunodetectability of the molecule in postmortem tissue. Immunohistochemical staining for PSA-NCAM occurs in TG and several brainstem regions during prenatal life and in adulthood. As a general rule, it appears as a surface staining suggestive of membrane labelling on neuronal perikarya and proximal processes, and as filamentous and dot-like elements in the neuropil. In the TG, PSA-NCAM is localized to neuronal perikarya, nerve fibres, pericellular networks, and satellite and Schwann cells; further, cytoplasmic perikaryal staining and positive pericellular fibre networks are detectable with higher frequency in adult than in newborn tissue. In the adult tissue, positive neurons are mostly small- and medium-sized, and amount to about 6% of the total ganglionic population. In the brainstem, PSA-NCAM is mainly distributed at the level of the medulla oblongata and pons and appears scarce in the mesencephalon. Immunoreactivity also occurs in discretely localized glial structures. At all ages examined, PSA-NCAM occurs in the spinal trigeminal nucleus, solitary nuclear complex, vestibular and cochlear nuclei, reticular formation nuclei, and most of the precerebellar nuclei. In specimens of different age, the distribution pattern remains fairly steady, whereas the density of immunoreactive structures and the staining intensity may change and are usually higher in newborn than in adult specimens.</p> <p>Conclusion</p> <p>The results obtained show that, in man, the expression of PSA-NCAM in selective populations of central and peripheral neurons occurs not only during prenatal life, but also in adulthood. They support the concept of an involvement of this molecule in the structural and functional neural plasticity throughout life. In particular, the localization of PSA-NCAM in TG primary sensory neurons likely to be involved in the transmission of protopathic stimuli suggests the possible participation of this molecule in the processing of the relevant sensory neurotransmission.</p

A tale of two stories: astrocyte regulation of synaptic depression and facilitation

Short-term presynaptic plasticity designates variations of the amplitude of synaptic information transfer whereby the amount of neurotransmitter released upon presynaptic stimulation changes over seconds as a function of the neuronal firing activity. While a consensus has emerged that changes of the synapse strength are crucial to neuronal computations, their modes of expression in vivo remain unclear. Recent experimental studies have reported that glial cells, particularly astrocytes in the hippocampus, are able to modulate short-term plasticity but the underlying mechanism is poorly understood. Here, we investigate the characteristics of short-term plasticity modulation by astrocytes using a biophysically realistic computational model. Mean-field analysis of the model unravels that astrocytes may mediate counterintuitive effects. Depending on the expressed presynaptic signaling pathways, astrocytes may globally inhibit or potentiate the synapse: the amount of released neurotransmitter in the presence of the astrocyte is transiently smaller or larger than in its absence. But this global effect usually coexists with the opposite local effect on paired pulses: with release-decreasing astrocytes most paired pulses become facilitated, while paired-pulse depression becomes prominent under release-increasing astrocytes. Moreover, we show that the frequency of astrocytic intracellular Ca2+ oscillations controls the effects of the astrocyte on short-term synaptic plasticity. Our model explains several experimental observations yet unsolved, and uncovers astrocytic gliotransmission as a possible transient switch between short-term paired-pulse depression and facilitation. This possibility has deep implications on the processing of neuronal spikes and resulting information transfer at synapses.Comment: 93 pages, manuscript+supplementary text, 10 main figures, 11 supplementary figures, 1 tabl