Beyond weakness: Characterization of pain, sensory profile and conditioned pain modulation in patients with motor neuron disease: A controlled study

BACKGROUND

Motor neuron diseases (MND) represent a group of disorders that evolve with inexorable muscle weakness and medical management is based on symptom control. However, deeper characterization of non-motor symptoms in these patients have been rarely reported.

METHODS

This cross-sectional study aimed to describe non-motor symptoms in MND and their impact on quality of life and functional status, with a focus on pain and sensory changes. Eighty patients (31 females, 55.7 ± 12.9 years old) with MND underwent a neurological examination, pain, mood, catastrophizing and psychophysics assessments [quantitative sensory testing (QST) and conditioned pain modulation (CPM)], and were compared to sex- and age-matched healthy controls (HC).

RESULTS

Chronic pain was present in 46% of patients (VAS =5.18 ± 2.0). Pain of musculoskeletal origin occurred in 40.5% and was mainly located in the head/neck (51%) and lower back (35%). Neuropathic pain was not present in this sample. Compared to HC, MND patients had a lower cold detection threshold (p < 0.002), and significantly lower CPM scores (4.9 ± 0.2% vs. 22.1 ± 0.2%, p = 0.012). QST/CPM results did not differ between MND patients with and without pain. Pain intensity was statistically correlated with anxiety, depression and catastrophism, and spasticity scores were inversely correlated with CPM (ρ = -0.30, p = 0.026).

CONCLUSIONS

Pain is frequently reported by patients with MNDs. Somatosensory and CPM changes exist in MNDs and may be related to the neurodegenerative nature of the disease. Further studies should investigate the most appropriate treatment strategies for these patients.

SIGNIFICANCE

We report a comprehensive evaluation of pain and sensory abnormalities in motor neuron disease (MND) patients. We assessed the different pain syndromes present in MND with validated tools, and described the QST and conditioned pain modulation profiles in a controlled design.

Transient and Widespread Astroglial Activation in the Brain after a Striatal 6-Ohda-Induced Partial Lesion of the Nigrostriatal System

The authors have previously described astroglial activation in the ipsilateral nigrostriatal system and ventral tegmental area following small doses of 6-hydroxydopamine (6-OHDA) injected unilaterally in the striatum. This article further evaluated astroglial reactivity in several brain regions after striatal 6-OHDA-induced punctate lesion in the nigrostriatal pathway. Adult male Wistar rats received a unilateral stereotaxical injection of the 6-OHDA (8 microg/4 microl) in the neostriatum and sacrificed 1 or 3 weeks later. Control animals received only solvent. Immunohistochemistry was employed for visualization of the tyrosine hydroxylase (TH), marker for dopamine cells, and glial fibrillary acidic protein (GFAP), marker for astrocytes. TH immunoreactive terminals disappeared in the striatum close to the injection site and a disappearance of a small number of a defined population of dopamine cell bodies was observed in the ipsilateral pars compacta of the substantia nigra (SNc). No dopamine lesion was detected in the contralateral nigrostriatal pathway. Astroglial reaction was seen close to the lesion in the neostriatum and in the ipsilateral SNc of the 1 week 6-OHDA lesioned rats. Specific stereological tools employing point intercepts and rotator, revealed an increased presence of reactive astrocytes in many forebrain regions like frontal, parietal and piriform cortex, septum, neostriatum and SNc, bilaterally, and also corpus callosum after 1 week of 6-OHDA injection. The astroglial activation was characterized by increases in the size of the cell body and/or processes. Astrocytic reaction was found only in the ipsilateral nigrostriatal pathway by 3 weeks of 6-OHDA, a slight activation also remaining in the ipsilateral septum and piriform cortex. Astrocytic reaction was seen in the solvent-injected rats only in the neostriatum close to the needle track. The transient widespread astroglial reaction observed in many brain regions following a striatal injection of 6-OHDA may represent a global paracrine trophic response in the brain.

ASTROGLIAL AND MICROGLIAL ACTIVATION IN THE WISTAR RAT VENTRAL TEGMENTAL AREA AFTER A SINGLE STRIATAL INJECTION OF 6-HYDROXYDOPAMINE

Astroglial and microglial activation were analyzed in the ventral tegmental area (VTA) in adult male Wistar rats, after an unilateral striatal 6-hydroxydopamine (6-OHDA) injection. Different doses (8, 4, and 1 microg) of 6-OHDA were injected in the left side of the neostriatum; animals were sacrificed 22 days later. Control animals received an injection of the same volume of the solvent. The tyrosine hydroxylase (TH) positive dopamine cells, the glial fibrillary acidic protein (GFAP) immuno -labeled astrocytes, and the OX42 immunoreactive microglia were visualized by means of immunohistochemistry and quantified by stereologic methods employing the optical dissector and the point intercepts. The number and the density of TH immunoreactive cell bodies were decreased by 45% and 46%, respectively, in the sampled field of the ipsilateral VTA of 8 microg 6-OHDA injected rats. The GFAP immunohistochemistry revealed in the ipsilateral VTA increases the number and density of astroglial cells (154% and 166% of control, respectively) in the rats with a higher dose of the 6-OHDA, and also in the volume fraction of the astroglial processes after 8 microg (41% of control) and 4 microg (24% of control) of 6-OHDA. Increased number (76% of control) and density (77% of control) of OX42 microglial labeled profiles and microglial processes (51% of control) were found in the ipsilateral VTA of the 8 microg 6-OHDA injected animals. These results suggest that the retrograde degeneration of the mesostriatal dopamine pathways, induced by a striatal injection of 6-OHDA, leads to astroglial and microglial reactions in the VTA. The interaction between activated glial cells may be involved in the wounding and repair events in the partial lesioned system, and also in the trophic paracrine responses in the surviving VTA dopamine neurons.

Contuse lesion of the rat spinal cord of moderate intensity leads to a higher time-dependent secondary neurodegeneration than severe one. An open-window for experimental neuroprotective interventions

Secondary neurodegeneration takes place in the surrounding tissue of spinal cord trauma and modifies substantially the prognosis, considering the small diameter of its transversal axis. We analyzed neuronal and glial responses in rat spinal cord after different degree of contusion promoted by the NYU Impactor. Rats were submitted to vertebrae laminectomy and received moderate or severe contusions. Control animals were sham operated. After 7 and 30 days post surgery, stereological analysis of Nissl staining cellular profiles showed a time progression of the lesion volume after moderate injury, but not after severe injury. The number of neurons was not altered cranial to injury. However, same degree of diminution was seen in the caudal cord 30 days after both severe and moderate injuries. Microdensitometric image analysis demonstrated a microglial reaction in the white matter 30 days after a moderate contusion and showed a widespread astroglial reaction in the white and gray matters 7 days after both severities. Astroglial activation lasted close to lesion and in areas related to Wallerian degeneration. Data showed a more protracted secondary degeneration in rat spinal cord after mild contusion, which offered an opportunity for neuroprotective approaches. Temporal and regional glial responses corroborated to diverse glial cell function in lesioned spinal cord.

FGF-2 and S100? immunoreactivities increase in reactive astrocytes, but not in microglia, in ascending dopamine pathways following a striatal 6-OHDA-induced partial lesion of the nigrostriatal system

Partial lesions were induced in rat midbrain dopamine ascending pathways by intrastriatal injection of 6-hydroxydopamine (6-OHDA), and after two weeks changes were observed in the immunoreactivities of S100beta, a calcium-binding protein, and basic fibroblast growth factor (FGF-2), which is neurotrophic. Semiquantitative microdensitometric image analysis revealed increased intensities of FGF-2 and S100beta immunostaining in putative glial profiles of the ipsilateral neostriatum, pars compacta (SNc) and reticulata (SNr) of the substantia nigra and ventral tegmental area (VTA). Double immunofluorescence and immunoperoxidase procedures, using antibodies against glial fibrillary acidic protein and OX-42, showed that these increased immunoreactivities were restricted to reactive astrocytes; they were not observed in reactive microglia. These results indicate that reactive astrocytes may exert paracrine trophic actions through S100beta and FGF-2 in the midbrain dopamine ascending pathways after striatal 6-OHDA treatment. Interactions between S100beta and FGF-2 may be relevant to neuronal maintenance and repair following dopamine injury.

Decreases in the expression of CGRP and galanin mRNA in central and peripheral neurons related to the control of blood pressure following experimental hypertension in rats

Calcitonin gene-related peptide (alpha CGRP) and galanin (GAL) are peptides known to participate in central mechanisms of blood pressure control. Nonetheless, variations in the synthesis of the peptides in response to a hypertensive challenge are not well described, specially using a model, which allows acute and chronic analyses. In this study, we have employed in situ hybridization to analyse changes in mRNA expression of alpha CGRP and GAL in the nucleus tractus solitarii (NTS), hypothalamic paraventricular nucleus (PVN) as well as petrosal and nodose ganglia after aortic coarctation-induced hypertension in rats. Acute (2h) and chronic (3 and 7 days) analyses were performed in order to evaluate the involvement of both peptides in different periods of hypertension. The analysis of relative mRNA levels showed significant differences between sham-operated and aortic coarcted hypertensive rats. alpha CGRP mRNA expression was decreased 2h (40%) and 3 days (42%) in nodose and petrosal ganglia, respectively, after coarctation. No changes in CGRP mRNA signal were seen in the NTS and PVN in the analysed periods. GAL mRNA expression was decreased in the NTS (19%) and PVN (55%), 3 and 7 days, respectively, after coarctation-induced hypertension. No changes in GAL mRNA expression were observed in petrosal and nodose ganglia following aortic coarctation. Data suggest that alpha CGRP and GAL may participate in the mechanisms involved in the establishment/maintenance of hypertension induced by aortic coarctation. Acute changes might be involved with the adaptation to the hypertensive state, while changes at the chronic phase might be related to counteraction of hypertension.

Experimental models of partial lesion of rat spinal cord to investigate neurodegeneration, glial activation, and behavior impairments

The article demonstrates two experimental models of spinal cord partial injury in rats: a contuse model promoted by the NYU impactor system and a partial hemitransection model achieved by a stereotaxic-positioned adjustable wire knife. By means of a defined impact weight (10 g) and a digital optical potentiometer linked to a computer, the impactor transferred and registered a moderate or a severe contusion to the rat spinal cord at a low thoracic level after dropping the weight from distances of 25 mm and 50 mm, respectively, to the dorsal surface of the exposed dura spinal cord. Impact curve was calculated and the parameters of the trauma, like impact velocity, cord compression distance and cord compression rates were obtained in order to demonstrate trauma severity. To promote partial hemitransection, rats were positioned in a spinal cord unit of a stereotaxic apparatus and lesion was made with the adjustable wire knife spatially oriented. By means of a computerized infrared motion sensor-home cage activity monitor and a noncomputerized evaluation of motor behavior using the inclined plane and the motor score of Tarlov tests, behavior was analyzed in an acute period postlesion. Rats were sacrificed and spinal cords were processed for routine staining to show neurons and for GFAP and OX42 immunohistochemistry to demonstrate glial cells. The tissue labelings were quantified using computer assisted stereology by means of an optical disector and microdensitometric image analysis by means of quantification of gray values of discriminated profiles. While partial hemitransection model favored a more accurate control of the lesion location, the contuse model allowed us to perform different degrees of lesion severity. A close correlation between behavioral impairment and severity of trauma was seen in the rats submitted to spinal cord contusion. The stereologic lesion index showed a correlation between severity of trauma and tissue damage by 7 days and demonstrated a time-dependent secondary degeneration after moderate but not after severe spinal cord contusion from 7 to 30 days after injury. Long-lasting activations of astrocytes and microglia seen by persisted increases in the specific mean gray values of immunoreactivities were also found in all levels of the white and gray matters of the partial hemitransected spinal cord until 3 months postinjury which can be related to wound/repair events and paracrine trophic support to spinal cord remaining neurons. The results showed that controlled partial lesions may provide an important toll to study trophism and plasticity in the spinal cord.

Distant microglial and astroglial activation secondary to experimental spinal cord lesion

This paper analysed whether glial responses following a spinal cord lesion is restricted to a scar formation close to the wound or they might be also related to widespread paracrine trophic events in the entire cord. Spinal cord hemitransection was performed in adult rats at the thoracic level. Seven days and three months later the spinal cords were removed and submitted to immunohistochemistry of glial fibrillary acidic protein (GFAP) and OX42, markers for astrocytes and microglia, as well as of basic fibroblast growth factor (bFGF), an astroglial neurotrophic factor. Computer assisted image analysis was employed in the quantification of the immunoreactivity changes. At the lesion site an increased number of GFAP positive astrocytes and OX42 positive phagocytic cells characterized a dense scar formation by seven days, which was further augmented after three months. Morphometric analysis of the area and microdensitometric analysis of the intensity of the GFAP and OX42 immunoreactivities showed reactive astrocytes and microglia in the entire spinal cord white and gray matters 7 days and 3 months after surgery. Double immunofluorescence demonstrated increased bFGF immunostaining in reactive astrocytes. The results indicated that glial reaction close to an injury site of the spinal cord is related to wounding and repair events. Although gliosis constitutes a barrier to axonal regeneration, glial activation far from the lesion may contribute to neuronal trophism and plasticity in the lesioned spinal cord favoring neuronal maintenance and fiber outgrowth.

Astroglial and microglial reaction after a partial nigrostriatal degeneration induced by the striatal injection of different doses of 6-hydroxydopamine

Astroglial and microglial activation was analyzed in adult male Wistar rats after a unilateral striatal injection of different doses (8, 4 and 1 micrograms) of 6-hydroxydopamine (6-OHDA). Control animals received the injection of the same volume of the solvent. The rotational behavior was registered by a rotometer 24 and 72 hours, 7, 10, 14 and 22 days after lesion. Following, animals were sacrificed and the tyrosine hydroxylase (TH) positive dopamine cells, the glial fibrillary acidic protein (GFAP) immunolabeled astrocytes and the OX42 immunoreactive microglia were visualized by mean of immunohistochemistry and quantified by stereologic method employing the optical disector and the point intercepts. The apomorphine (0.5 mg/kg)-induced circling behavior was seen only after 8 micrograms of 6-OHDA from 72 hours postlesion until sacrifice. Decreases of the TH immunoreactive terminals and cell bodies were found in the sampled fields of the striatum and pars compacta of the substantia nigra (SNc), respectively, after 8 and 4 micrograms of 6-OHDA. The GFAP immunohistochemistry revealed increases in the number/density of astroglial cells in the ipsilateral neostriatum (137% of control) and ipsilateral SNc (83% of control) and also in the volumeal fraction of the astroglial processes in the ipsilateral neostriatum (30% of control) and ipsilateral SNc (38% of control) in the rats with higher dose of the neurotoxin. Increases in the number of OX42 microglial labeled profiles and in the volumeal fraction of microglial processes were found in the ipsilateral neostriatum (67% and 27%, respectively, of control) and ipsilateral SNc (100% and 50%, respectively, of control) in the 8 micrograms 6-OHDA injected rats. These results suggest that the retrograde degeneration induced by a intrastriatal injection of a small dose of the 6-OHDA leads to an astroglial and microglial reaction in the nigrostriatal dopamine pathway. The interaction between activated glial cells may be involved in the wounding and repair events in the partial lesioned nigrostriatal system as well as in the paracrine responses to surviving dopamine neurons.

S100 immunoreactivity is increased in reactive astrocytes of the visual pathways following a mechanical lesion of the rat occipital cortex

After demonstration of the paracrine action of glial neurotrophic factors, gliosis has also been considered to be related to neuronal trophism and plasticity rather than solely a repair event following brain injury. S100 is a Ca2+ binding protein, present mainly in astrocytes, that exerts paracrine trophic effects on several neuronal populations. This study analyses the presence of S100 protein by means of immunohistochemistry combined with stereology in the reactive glial cells of the rat visual pathways following a lesion of the visual cortex. Adult male Wistar rats were submitted to a unilateral aspiration of the occipital cortex or to a sham operation. One week later the rats were killed and their brain processed for immunochemistry. Single antibody immunohistochemistry was performed for the visualization of glial fibrillary acidic protein (GFAP, a marker for astrocytes), OX-42 (a marker for microglia) and S100 protein. Double immunofluorescence procedures were applied for co-localization of the S100/GFAP and S100/OX-42. An optical dissector, point interceptors and rotators were used to quantify the degree of glial activation and the changes in the S100 immunoreactivity. We observed an intense microglial and astroglial reaction in addition to an increased S100 immunoreactivity in the occipital cerebral cortex, geniculate nucleus and hippocampus ipsilateral to the lesion. In the ipsilateral superior colliculus, an intense astroglial activation was accompanied by an up-regulation of S100 immunoreactivity. Double-immunofluoresence revealed an increased S100 immunoreactivity in reactive astrocytes, but not in the reactive microglia. Evidence has therefore been obtained that after mechanical trauma, the astroglial S100 protein participates in the trophism and plasticity of the injured visual pathways.

The trophic factors S-100beta and basic fibroblast growth factor are increased in the forebrain reactive astrocytes of adult callosotomized rat

S-100 is a calcium-binding protein that is predominantly found in astrocytes of the central nervous system. In the present study, we investigated the temporal and spatial changes of S-100beta immunoreactivity after a stereotaxic mechanical lesion of the adult rat corpus callosum performed with an adjustable wire knife. Rats were killed 7, 14 and 28 days after surgery. S-100beta immunoreactivity was found within the cytoplasm and processes of quiescent putative astrocytes that were observed throughout the gray and white matters of the forebrain of sham-operated rats. Following callosotomy, the S-100beta immunoreactive profiles showed increased size and thick processes, as well as increased amount of S-100beta immunoreactivity. Unbiased stereologic analysis revealed a sustained and widespread increase of the Areal Fraction of S-100beta immunoreactive profiles in the medial and lateral regions of the white matter of callosotomized rats at the studied time-intervals. In the cerebral cortex of callosotomized rats, the estimated total number of S-100beta immunoreactive profiles was also increased 7 and 14 days after the lesion. Since the cellular and temporal changes in S-100beta immunoreactivity were closely similar to those described for basic fibroblast growth factor (bFGF) following brain lesions, we co-localized the S-100beta and bFGF immunoreactivities after callosotomy. bFGF immunoreactivity was found in the nuclei of S-100beta immunoreactive glial profiles throughout the forebrain regions of the sham-operated rats. bFGF immunoreactivity was increased in the nuclei of reactive S-100beta immunoreactive putative astrocytes in the forebrain white matter and in the cerebral cortex of callosotomized rats. These results indicate that after transection of the corpus callosum of adult rats, the reactive astrocytes may exert paracrine trophic actions through S-100beta and bFGF. Interactions between S-100beta and bFGF may be relevant to the events related to neuronal maintenance and repair following brain injury.

Analysis of trophic responses in lesioned brain: focus on basic fibroblast growth factor mechanisms

The actions of fibroblast growth factors (FGFs), particularly the basic form (bFGF), have been described on a large number of cells and include mitogenicity, angiogenicity and wound repair. The present review discusses the presence of the bFGF protein and messenger RNA as well as the presence of the FGF receptor messenger RNA in the rodent brain by means of semiquantitative radioactive in situ hybridization in combination with immunohistochemistry. Chemical and mechanical injuries to the brain trigger a reduction in neurotransmitter synthesis and neuronal death which are accompanied by astroglial reaction. The altered synthesis of bFGF following brain lesions or stimulation was analyzed. Lesions of the central nervous system trigger bFGF gene expression by neurons and/or activated astrocytes, depending on the type of lesion and time post-manipulation. The changes in bFGF messenger RNA are frequently accompanied by a subsequent increase of bFGF immunoreactivity in astrocytes in the lesioned pathway. The reactive astrocytes and injured neurons synthesize increased amount of bFGF, which may act as a paracrine/autocrine factor, protecting neurons from death and also stimulating neuronal plasticity and tissue repair.

Neurochemical changes in the hippocampus of the brown Norway rat during aging

Microdensitometrical and stereological techniques were applied to study the effects of aging on the hippocampus of 3-, 6-, 12-, 18-, 24-, 30-, and 36-month-old male Brown Norway rats. Stereological analysis of basic fibroblast growth factor (bFGF) immunoreactive glial cells in the CA1 area showed an age-dependent decrease in the number of cells, starting at 18 months of age. Specific mean gray values of the immunoreactivity for bFGF were reduced in the CA3 area, in the dentate gyrus, and in fields of the CA1 area, starting at 24 months of age. There were no differences between the age groups in the number of glial fibrillary acidic protein or glucocorticoid receptor (GR) immunoreactive cells of the CA1-CA2 areas. However, the intensity of the GR immunoreactivity was decreased in the 18-month-old and older rats. No changes in the immunoreactivity for the mineralocorticoid receptor were observed in the CA1-CA2 areas of any of the age groups. Spontaneous alternation test and reactivity in an open field did not reveal marked differences between the age groups. These findings give evidence that there is a loss of neural GR immunoreactivity, but no loss of GR immunoreactive neurons, in the CA1-CA2 areas of the aged Brown Norway rat. Aging may also be characterized by substantial deficits of glially derived growth factors, such as bFGF in the hippocampus. The changes in immunoreactivities were not correlated to alterations in selected behaviors dependent on normal hippocampal function.

Computer-assisted mapping of basic fibroblast growth factor immunoreactive nerve cell populations in the rat brain

We have performed a mapping of basic fibroblast growth factor (bFGF) immunoreactive (ir) glial and nerve cell populations in the male rat brain using a rabbit antibody raised against a synthetic peptide of bovine bFGF. Regional morphometric and microdensitometric analysis of the bFGF ir neuronal profiles in coronal brain sections was carried out by means of an automatic image analyser. The density and intensity of the bFGF ir glial profiles were subjectively evaluated. The bFGF immunoreactivity (IR) was detected within the cytoplasm of neurons, except within the pyramidal neurons of hippocampal CA2 region, the fasciola cinerea and the indusium griseum, where bFGF IR was present in the nucleus. In contrast, in glial cells bFGF IR was always found in the nucleus. Neuronal and glial IR was no longer observed after absorption of the bFGF antiserum with recombinant bFGF. Basic FGF IR was found in neuronal and glial cell populations throughout the brain as well as in the choroid plexus and in the ependymal cells lining the ventricles. Basic FGF ir nerve cells were found in all layers of both the neocortex and allocortex. Within the caudate putamen and the nucleus accumbens a low density of weak bFGF ir neuronal profiles was detected. The majority of the thalamic nuclei showed medium to high densities of moderate to strong bFGF ir neuronal profiles. All the hypothalamic nuclei, with the exception of the anterior and lateral hypothalamic area and of the ventral hypothalamic nucleus, contained a high density of bFGF ir profiles. The pons and the medulla oblongata were characterized by the presence of a large number of nuclei containing moderate to high densities of strong bFGF ir profiles. The Purkinje cell layer of the cerebellar cortex contained a high density of moderately bFGF ir profiles. A moderate density of strong bFGF ir nerve cell profiles was observed within all the laminae of the spinal cord, except within the II and III laminae where a high density of strongly ir profiles was found. Histogram analysis of total immunoreactivity showed that the distribution of bFGF ir profiles within the telencephalon and mesencephalon tend to be similar with regard to the central tendency and spread. Using Kendall's tau, a significant correlation between intensity and density values was obtained only in the diencephalon. The cytoplasmic bFGF IR found in distinct nerve cell populations all over the rat brain and spinal cord may represent forms of bFGF which can be released from the nerve cells via non-exocytotic mechanisms in view of the absence of an intracellular signal peptide in bFGF. The presence of nuclear bFGF IR within the glial cells all over the central nervous system (CNS) suggests an intracellular function of bFGF, such as the promotion of mitogenesis and/or participation in the transcriptional regulation of various genes.

Cholecystokinin octapeptide and the D2 antagonist raclopride induce Fos-like immunoreactivity in the shell part of the rat nucleus accumbens via different mechanisms

Induction of neuronal Fos-like immunoreactivity (IR) in the rat brain by cholecystokinin octapeptide (CCK-8) and the dopamine (DA) D2 receptor antagonist raclopride was demonstrated. In vivo treatment with the CCK-8 (0.01, 0.1 and 1 nmol/rat, i.c.v.) or the D2 antagonist raclopride (0.1, 0.5 and 1 mg/kg, i.p.) alone increased in a dose-dependent way the Fos-like ir profiles in the shell part of the rat nucleus accumbens (AcbSh). Combined treatment with CCK-8 (0.1 nmol/rat) and raclopride (0.5 mg/kg) caused significant additive increases in the Fos-like ir profiles in the AcbSh. In the central caudate-putamen, the medial olfactory tubercle, and the frontal cerebral cortex where either compound alone was weakly active or inactive, the combined treatment with both compounds led to a significant induction of neuronal Fos-like ir profiles. These results suggest that the blockade of D2 and activation of CCK transduction lines can induce Fos-like IR via different mechanisms. They may produce additive effects in AcbSh and synergistic effects in the caudate-putamen and the olfactory tubercle on the induction of neuronal Fos-like IR and thus on long-term regulation of gene expression in the striatum.

Glial and neuronal glucocorticoid receptor immunoreactive cell populations in developing, adult, and aging brain

A detailed mapping of glucocorticoid receptor (GR) immunoreactivity (IR) in rat CNS was performed employing a mouse monoclonal antibody against rat liver GR. Subjective comparisons were made between the present results and the available data in the literature. A semiquantitation of GR immunostaining was found necessary and was obtained by microdensitometric and morphometric techniques, which enabled the distinction of neuronal and glial cell populations containing GR IR in various CNS regions. GR IR in the CNS was mainly found in the nuclear compartment. The GR was present in neuronal populations with classical neurotransmitters, especially monoamines and glutamate and with various neuropeptides. The degree of colocalization varied according to the function of the brain area. Functional implications were made in relation to stress sensitivity, mood and nociception/antinociception. The global control of networks by glucocorticoids may allow an optimal integration of different types of circuits. The GR is found already in the fetal rat and the development of GR mRNA and receptor protein was followed during the pre- and postnatal periods. The GR appears to be a major factor in brain maturation and in modulation of stress responses. In aged Brown Norway rat brain GR IR but not mineralocorticoid receptor (MR) IR is reduced in the hippocampal nerve cells. The intensity of GR IR but not the number of nerve cells is altered, indicating a reduced activation of the GR in aging in this rat strain. Overall GR participates in neuronal plasticity from fetal and postnatal life to adult life and aging.

Temporal and spatial increase of astroglial basic fibroblast growth factor synthesis after 6-hydroxydopamine-induced degeneration of the nigrostriatal dopamine neurons

The present study investigates the temporal and spatial changes of the cellular expression of basic fibroblast growth factor messenger RNA and immunoreactivity after a 6-hydroxydopamine-induced lesion in the nigrostriatal dopamine system. In situ hybridization revealed a sustained (from 4 h to two weeks) and strong (300-400% of control, at the peak intervals) increase of basic fibroblast growth factor messenger RNA in the pars compacta of the substantia nigra and the ventral tegmental area ipsilateral to the lesion. A short-lasting increase of basic fibroblast growth factor messenger RNA was observed in he ipsilateral pars reticulata of the substantia nigra (from 4-24 h, 300% of control) and neostriatum (24 h, 180% of control) as well as in the ipsilateral and contralateral hippocampus and neocortex (by 4 h, 200% of control). Brightfield microscopy showed an increased number of putative glial cells expressing the basic fibroblast growth factor messenger RNA signal. Basic fibroblast growth factor immunohistochemistry revealed on control brains the protein in the nuclei of glial cells throughout the forebrain and the midbrain and in the nuclei of neurons of the layer II of the retrosplenial granular cortex, the CA2 region of the hippocampus and the fasciola cinereum as well as in the nuclei of ependymal cells. The injection of 6-hydroxydopamine increased basic fibroblast growth factor immunoreactivity in the nuclei of astrocytes only within the ipsilateral substantia nigra and ventral tegmental area. By 2 h after the drug injection, the density of glial basic fibroblast growth factor-immunoreactive profiles was increased in the pars compacta of the substantia nigra and the ventral tegmental area. The density, size and intensity of the astroglial basic fibroblast growth factor immunoreactive nuclei were increased in the entire substantia nigra and the ventral tegmental area at 72 h, and peaked one week after the 6-hydroxydopamine injection. The saline injection promoted a time-dependent increase in the density of the glial basic fibroblast growth factor immunoreactivity but only in the ipsilateral pars compacta of the substantia nigra. In conclusion, the dopamine cell degeneration may give rise to extracellular signals activating the surrounding astroglia, leading to a sustained increased synthesis of astroglial basic fibroblast growth factor, which may exert neuroprotective action and increase repair on the nigrostriatal dopamine system.

Basic fibroblast growth factor and steroid receptors in the aging hippocampus of the brown Norway rat: immunocytochemical analysis in combination with stereology

The effect of aging on the hippocampal formation of the male Brown Norway rat was studied by immunohistochemistry and measurements of the immunoreactive hippocampal cells using stereological techniques. The total estimated number of glucocorticoid receptor (GR) immunoreactive neurons of the CA1-CA2 area did not differ in the 3- and the 36-month-old rat. However, the intensity of the GR immunoreactivity was decreased in the aged animals. A gradual decrease of the immunoreactivity for the mineralocorticoid receptor was also observed in the CA1-CA2 area. In the stratum oriens and the stratum radiatum of the CA1-CA2 area the immunoreactivity for basic fibroblast growth factor (bFGF) present in the glia was found to be reduced [20,000 +/- 2100 (n = 6)] in the 36-month-old rat vs the 3-month-old rat [28,500 +/- 4500 (n = 4) (*P = 0.05)]. However, there was no difference in the number of glial fibrillary acidic protein immunoreactive cells of this area in these two age groups. The present findings give evidence that in the Brown Norway rat there is no loss of the neuronal population containing glucocorticoid receptors of the CA1-CA2 area during aging but suggest that aging is characterized by deficits of glially derived growth factors, such as bFGF.

Adrenalectomy increases the number of substance P and somatostatin immunoreactive nerve cells in the rat lumbar dorsal root ganglia

Using an immunocytochemical technique we have analyzed changes in substance P, somatostatin, calcitonin gene-related peptide, and galanin immunoreactivity pattern in the rat dorsal root ganglia. After 7 days of adrenalectomy, sham operated rats were compared with adrenalectomized animals either receiving a daily intraperitoneal injection of 10 mg/kg b.wt. corticosterone or vehicle. Three lumbar ganglia from each animal were blocked, serially cut, and immunostained for each neuropeptide by means of the biotin-avidin-peroxidase technique. A systematic sampling of immunoreactive ganglion cells was performed and the sample number of immunoreactive ganglion cells was calculated. After adrenalectomy, the number of substance P and somatostatin immunoreactive ganglion cells markedly increased ((means +/- S.E.M.): 245 +/- 68 versus 123 +/- 12 for sham operated animals, P < 0.01 (substance P) and 42 +/- 8 as compared to 22 +/- 9 for sham operated animals, P < 0.01 (somatostatin)). No significant changes were found in the number of calcitonin gene-related peptide and galanin immunoreactive cells after adrenalectomy. These results suggest that adrenal steroid hormones may reduce the synthesis of both substance P and somatostatin in the dorsal root ganglion cells. Daily treatment with a high dose of corticosterone, mimicking its serum levels after stress, failed to prevent the increase of peptide contents after adrenalectomy. These observations also indicate that a tonic action of corticosterone on mineralocorticoid receptors may be crucial for peptide regulation in the spinal ganglia. These results may be of relevance to adrenalectomy induced changes in sensory mechanisms, neurogenic inflammation and pain transmission and to a role of substance P and somatostatin in these processes.

Evidence for a regional distribution of hyaluronic acid in the rat brain using a highly specific hyaluronic acid recognizing protein

By means of a highly specific hyaluronic acid-recognizing protein the localization and regional distribution of hyaluronic acid was demonstrated in the tel- and diencephalon and in the midbrain of the adult rat nervous system. Histochemistry revealed labeling associated with the plasma membrane in highly discrete nerve cell bodies of the frontoparietal cortex, the red nucleus, the zona reticulata of the substantia nigra, the oculomotor nucleus and the reticular thalamic nucleus. A strong labeling without association with perikarya was demonstrated in the subgranular zone of the dentate gyrus of the hippocampal formation. The present results open up the possibility that the hyaluronic acid found in high concentrations associated with some perikarya may have a special role in plasticity responses in these discrete nerve cell populations.

Increase of basic fibroblast growth factor (bFGF, FGF-2) messenger RNA and protein following implantation of a microdialysis probe into rat hippocampus

In vivo microdialysis is an established tool for sampling extracellular fluid compartments. However, microdialysis faces the problem that the implantation of the probe damages the microenvironment from which measurements are derived. In this study, we examined the expression of basic fibroblast growth factor mRNA and protein at the cellular level after implantation of a microdialysis probe into the dorsal hippocampus and found that 8 h after inserting the probe bFGF mRNA was markedly increased in a relatively large area centered around the probe, involving both the dorsal hippocampus and the overlying cerebral cortex, as revealed by radioactive in situ hybridization. Using nonradioactive in situ hybridization with digoxigenin-labelled riboprobes, combined with immunohistochemistry for glial fibrillary acidic protein we demonstrated that bFGF mRNA was exclusively increased in astrocytes at the probe insertion site. Using immunohistochemistry we also found that bFGF-like immunoreactivity was increased after implantation of the probe close to the lesion site, as shown by an increased number of bFGF immunoreactive nuclear glial profiles. These results provide evidence that the implantation of a microdialysis probe into the brain induces activation of bFGF gene expression in astrocytes associated with nuclear bFGF-like immunoreactivity. We conclude that lesion-induced effects have to be considered when evaluating microdialysis data, and that mechanical trauma to the brain will activate astroglial trophism, as seen from the increased density of astroglial profiles demonstrating bFGF mRNA and protein levels.

Subpopulations of primary sensory neurons show coexistence of neuropeptides and glucocorticoid receptors in the rat spinal and trigeminal ganglia

The coexistence of the neuropeptides substance P, calcitonin gene-related peptide, galanin, somatostatin and neuropeptide Y with glucocorticoid receptors was studied in neurons of the rat lumbar dorsal root and trigeminal ganglia by means of the double immunofluorescence technique. Based on analysis of microphotographs, about one-third of the populations of nerve cells (small and large) containing substance P or calcitonin gene-related peptide immunoreactivity (IR) showed nuclear glucocorticoid receptor IR. A similar pattern was observed within the dorsal root and trigeminal ganglia. Furthermore, within the lumbar dorsal root ganglia 50% of the small neurons, containing galanin IR, possessed nuclear glucocorticoid receptor IR of moderate intensity. Glucocorticoid receptor IR was not observed in the galanin immunoreactive neurons of the trigeminal ganglion neither in the somatostatin and NPY immunoreactive neurons of both the dorsal root and the trigeminal ganglia. The results provide a chemical anatomical basis for a direct regulation by glucocorticoids of distinct populations of substance P and calcitonin gene-related peptide immunoreactive nerve cells in the lumbar spinal and trigeminal ganglia and of galanin immunoreactive nerve cells of the spinal but not of the trigeminal ganglia.

On the regional distribution of heparan sulfate proteoglycan immunoreactivity in the rat brain

By means of two monoclonal antibodies specific for heparan sulfate (HS)-related epitopes, one (10E4) against native HS chains and one (3G10) against desaturated uronates, a highly regional and differential distribution of these two epitopes have been observed in the adult rat brain. The 10E4 epitope immunoreactivity (IR) is mainly found in the substantia nigra, the red nucleus and the subgranular zone of the dentate gyrus, while the 3G10 epitope IR is mainly found in the CA2 area of the hippocampal formation and the pyramdial cells in the layer V of the frontoparietal cortex. The codistribution of both types of IRs with basic fibroblast growth factor (bFGF, FGF-2) in neurons and astroglia supports the notion that heparan sulfate proteoglycans (HSPG) in the extracellular matrix may serve as a site for storage of bFGF and assist in the bFGF-induced activation of the high-affinity FGF receptors linked to astroglia and neurons in these discrete areas.

Myenteric neurons of the mouse small intestine. Morphometry and acetylcholinesterase activity

1. The myenteric plexus of the small intestine of five C57BL/6J male 5-month-old mice was investigated in whole-mount preparations of the muscularis externa by Giemsa staining and by the acetylcholinesterase (AChE) histochemical technique. 2. The neuronal density was 20212 +/- 3038/cm2 (mean +/- SEM) in the duodenum, 21948 +/- 1488/cm2 in the jejunum, and 25048 +/- 2356/cm2 in the ileum. The difference in neuronal density between duodenum and ileum was statistically significant (P < 0.05). The total serosal surface area of the small intestine was about 30.80 +/- 2.90 cm2, and the total number of neurons was estimated at about 690,000. 3. The neuronal cell and nucleus profile areas ranged, respectively, from 23 to 325 microns 2 and from 6 to 95 microns 2 in the small intestine of the mice studied. There were no significant differences in any of the 3 regions in terms of average neuronal cell or nucleus profile areas. 4. For the histochemical demonstration of AChE, the "direct coloring" copper ferrocyanide method was used. AChE-positive nerve fibers were distributed in the myenteric plexus which was formed by a primary meshwork of relatively large nerve bundles and a secondary meshwork of finer nerve bundles. Most of the neurons of the plexus displayed AChE activity in the cytoplasm though the neurons presented different reaction intensities.(ABSTRACT TRUNCATED AT 250 WORDS)

Fast and widespread increase of basic fibroblast growth factor messenger RNA and protein in the forebrain after kainate-induced seizures

Basic fibroblast growth factor promotes the survival and outgrowth of neurons and protects neurons from glutamate mediated excitotoxicity. The present study investigates the effects of kainate-induced epileptic seizures on the cellular expression of basic fibroblast growth factor messenger RNA and protein. Seizures were induced by injection of 12 mg/kg kainic acid. Rats were killed 3 h, 6 h, and 24 h after injection of the drug and analysed by radioactive and non-radioactive in situ hybridization as well as immunohistochemistry for glial fibrillary acidic protein and basic fibroblast growth factor. Radioactive in situ hybridization revealed a fast (6 h), strong (300-400% of control) and widespread increase of basic fibroblast growth factor messenger RNA after kainate-induced seizures. Non-radioactive in situ hybridization using digoxigenin-labeled riboprobes combined with glial fibrillary acidic protein immunohistochemistry showed that basic fibroblast growth factor messenger RNA was markedly increased in astroglial cells throughout the brain. Immunohistochemistry for basic fibroblast growth factor revealed labeling of nuclei in astrocytes in many forebrain areas and in neurons in area CA2 and fasciola cinereum. Kainate markedly increased basic fibroblast growth factor-like immunoreactivity in nuclei of astrocytes in several forebrain areas. This effect peaked 24 h after injection. It is concluded that basic fibroblast growth factor may play a neuroprotective role in kainate mediated excitotoxicity as seen from a massive and widespread astroglial increase in basic fibroblast growth factor messenger RNA and -like immunoreactivity. These effects may, to a large degree, be mediated through the excessive release of endogenous glutamate, induced by the epileptic seizures, leading to activation of glutamate receptors on astroglial cells through volume transmission, i.e. via diffusion of electrochemical signals in the extracellular fluid pathways.

Protective actions of human recombinant basic fibroblast growth factor on MPTP-lesioned nigrostriatal dopamine neurons after intraventricular infusion

Basic fibroblast growth factor (bFGF, FGF-2) is a trophic factor for neurons and astrocytes and has recently been demonstrated in the vast majority of dopamine (DA) neurons of the ventral midbrain of the rat. Potential neuroprotective actions of FGF-2 in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model have also been reported. The actions of the FGF-2 have now been further analyzed in a combined morphological and behavioural analysis in the MPTP model of the adult black mouse, using a continuous human recombinant FGF-2 (hrFGF-2) intraventricular (i.v.t.) administration in a heparin-containing (10 IU heparin/ml) mock cerebrospinal fluid (CSF) solution. Tyrosine hydroxylase (TH) immunocytochemistry in combination with computer assisted microdensitometry demonstrated a counteraction of the MPTP-induced disappearance of neostriatal TH-immunoreactive (ir) nerve terminals following the FGF-2 treatment. Unbiased estimates of the total number of nigral TH ir neurons, using stereological methods involving the optical disector (Olympus), showed that the MPTP-induced reduction in the number of nigral TH ir nerve cell bodies counterstained with cresyl violet (CV; by 56%) was partially counteracted by the FGF-2 treatment (by 26%). The behavioral analysis demonstrated an almost full recovery of the MPTP-induced reduction of the locomotor activity after FGF-2 treatment. This action was maintained also 1 week after cessation of treatment. The hrFGF-2 produced an astroglial reaction as determined in the lateral neostriatum and in the substantia nigra (SN) far from the site of the infusion, indicating that the growth factor may have reached these regions by diffusion to activate the astroglia. Immunocytochemistry revealed FGF-2 immunoreactivity (IR) in the nuclei of the astroglia cell population in the dorsomedial striatum and the microdensitometric and morphometric evaluation demonstrated an increase in the number, but not in the intensity, of these profiles on the cannulated side, suggesting the possibility that hrFGF-2 stimulates FGF-2 synthesis in astroglial cells with low endogenous FGF-2 IR. These results indicate that hrFGF-2, directly and/or indirectly via astroglia, upon i.v.t. infusion exerts trophic effects on the nigrostriatal DA system and may increase survival of nigrostriatal DA nerve cells exposed to the MPTP neurotoxin

Basic fibroblast growth factor (bFGF, FGF-2) immunoreactivity exists in the noradrenaline, adrenaline and 5-HT nerve cells of the rat brain

By means of two colour immunofluorescence procedures it has been possible to demonstrate in the rat brain the coexistence of TH and bFGF immunoreactivities (IRs) in the perikarya of large numbers of noradrenaline (NA) nerve cells of the locus coeruleus and of the NA cell groups A1, A5 and A7 and in many perikarya of the adrenaline (A) cell groups C1, C2 and C3. The coexistence of 5-hydroxytryptamine (5-HT) and bFGF IRs was demonstrated in the perikarya of large numbers of 5-HT nerve cells of practically all raphe nuclei. These results open up the possibility that bFGF may have a trophic role in the NA, A and 5-HT cell groups of the rat brain.

Corticosterone increases FGF-2 (bFGF) immunoreactivity in the substantia nigra of the rat

The effects of acute and subchronic (7 days) administrations of the adrenocortical hormone corticosterone on basic fibroblast growth factor (bFGF, FGF-2) immunoreactivity were studied in the substantia nigra of the rat by semiquantitative immunocytochemistry coupled with image analysis. Corticosterone was able to increase FGF-2 immunoreactivity in different nigral subregions and cell types (astrocytes and neurones) depending on the duration of the treatment. These results open up the possibility that stress hormones can modulate the trophic state of the substantia nigra through an action on FGF-2.

[Number and thickness of myelinic fibres of the phrenic nerve of young and aged rats]

The phrenic nerve of albino rats was studied for age changes in number of fibres, myelin sheath thickness and axon calibre. There is no significant morphological differences between nerves from young and aged rats and no difference with age was found in the number of fibres, myelin sheath thickness and axon calibre.