1,720,981 research outputs found
Fos-related protein expression in the midline paraventricular nucleus of the rat thalamus: basal oscillation and relationship with limbic efferents
No full textThe expression of Fos-related protein, encoded by the proto-oncogene c-fos, was investigated by means of immunohistochemistry in the paraventricular nucleus of the thalamic midline (PV) during nighttime and daytime in rats entrained to a 12-h light/12-h dark cycle. In the first step of this study the animal's physiological state preceding perfusion was monitored with electro-encephalographic recording. It was thus detected that the PV contained a considerable number of Fos-like-immunostained neurons during the hours of darkness, when the rats had been awake, and that the number of Fos-like-immunoreactive neurons was significantly lower during the hours of light, after a period of sleep. In the second step of this study Fos immunohistochemistry was combined with the retrograde transport of a gold-labeled tracer injected either in the amygdala or in the nucleus accumbens. This strategy enabled us to determine that in the rats perfused during nighttime Fos-related protein was spontaneously induced in PV cell s projecting to these targets, with a significant prevalence of neurons projecting to the amygdala in the anterior portion of the PV and of neurons projecting to the nucleus accumbens in the posterior part of the nucleus. In addition, a significant reduction of Fos-like-immunoreactive cells was detected in the PV ipsilaterally to the injection, indicating that tracer administration and axonal transport may interfere with c-fos expression in neurons. Altogether the present data indicate that Fos-related protein expression undergoes a marked oscillation in the PV during 24 h in basal conditions, and that c-fos is induced in the PV relay neuronal subsets when the animal is awake.(ABSTRACT TRUNCATED AT 250 WORDS
A sensitive double immunostaining protocol for Fos-immunoreactive neurons
No full textImmunostaining of Fos, the nuclear protein encoded by the immediate early gene c-fos, is widely used to reveal the functional activation of neurons. The chemical identity of cells that express c-fos can be investigated with double immunohistochemistry. We report the usefulness of a sequential two-color avidin-biotin-immunoperoxidase method that provides a highly sensitive double immunostaining and allows long-term storage of the sections. In this protocol, metal intensification of diaminobenzidine (int-DAB) resulted in dark brown/black Fos immunostaining of the neuronal nucleus. The use of alpha-naphthol/pyronin reaction product yielded pink immunostaining of a second antigen in the cytoplasm. This combination produced higher contrast than that produced by int-DAB Fos immunostaining combined with conventional DAB light brown cytoplasmic staining. The sensitivity of the use of int-DAB and alpha-naphthol/pyronin was verified in different experimental paradigms, combining the immunocytochemical detection of Fos with that of the p75 nerve growth factor receptor, or parvalbumin, or calbindin D28k
Neuronal IFN-gamma in tuberomammillary neurones
No full textNeuronal interferon-gamma (N-IFN-gamma), recently isolated from the nervous system, has a molecular weight distinct from that of lymphocyte-derived IFN-gamma, but crossreacts immunologically and shares certain bioactivities with this cytokine. In the rat brain N-IFN-gamma-immunoreactive perikarya were concentrated in the hypothalamic tuberomammillary nuclei; some immunostained neurones were also detected in the dorsal pontine tegmentum. Immunopositive nerve fibres were profusely distributed through the periventricular hypothalamus and midline thalamus. Scattered fibres occurred diffusely through the brain, ramified in the subpial layer and also surrounded intrathecal vessels. A dense concentration of puncta was detected in the suprachiasmatic nuclei and in the molecular layer of the hippocampal dentate gyrus. A role of N-IFN-gamma in immunological reactions and in modulation of selective brain functions is suggested
Nitric oxide synthase induction in injured motoneurons: a neurotoxic or neuroprotective
No full textNitric oxide synthase induction in injured motoneurons: a neurotoxic or neuroprotective role
Dysregulation of photic induction of Fos-related protein in the biological clock during experimental trypanosomiasis
No full textThe mammalian suprachiasmatic nuclei of the hypothalamus (SCN) serve as pacemaker for circadian rhythms and the immediate-early gene c-fos is known to be induced by photic stimulation in the SCN of rodents. We studied the induction of Fos-related protein following a light pulse in rats infected with Trypanosoma brucei. This parasite causes in humans African sleeping sickness, a neuropsychiatric syndrome that involves changes of endogenous biological rhythms. Fos-like immunoreactivity after photic stimulation was dramatically reduced in the SCN of trypanosome- infected rats during the subjective night. These findings indicate that the photic entrainment of the biological clock may be altered during the infection
Co-induction of neuronal interferon-gamma and nitric oxide synthase in rat motor neurons after axotomy: a role in nerve repair or death?
No full textInduction of an interferon-gamma-like molecule, previously isolated from neurons (N-IFN-gamma), and of the neuronal isoform I of the synthetic enzyme of the free radical nitric oxide, nitric oxide synthase I, as well as of NADPH-diaphorase, were examined in axotomized dorsal motor vagal and hypoglossal neurons. Unilateral transection of the vagal and hypoglossal nerves was performed in the same rat and an induction of N-IFN-gamma and nitric oxide synthase I immunostaining as well as NADPH-diaphorase histochemical positivity was observed in the ipsilateral motoneurons after 2-4 days. The immuno- and enzyme-histochemical positivities were much stronger in the dorsal motor vagal neurons than in hypoglossal neurons. Two and 4 weeks after axotomy N-IFN-gamma immunoreactivity and NADPH-diaphorase positivity persisted in the former, but started to decrease in the latter neurons. Previous data have shown that 23 weeks after nerve transection the majority of the dorsal motor vagal neurons are lost, while the major ity of the hypoglossal neurons survive. The high and persistent expression of N-IFN-gamma and nitric oxide synthase I after axotomy in the dorsal motor vagal neurons, that are largely destined to die, indicates that the co-induction of these two molecules may be implicated in the pathogenesis of neuronal degeneration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Fos induction by nerve growth factor in the adult rat brain
No full textThe distribution of Fos, the protein product of the immediate early gene c-fos, was studied with immunocytochemistry in the adult male rat brain after nerve growth factor (NGF) administration. NGF was injected in the lateral cerebral ventricle through a previously implanted cannula. The total number of Fos-immunoreactive (ir) neurons in the brain was 2-3 times higher after NGF administration than in control animals (untreated or injected with cytochrome c). With respect to control rats, in the NGF-treated cases Fos-ir cells were more numerous in the anterior olfactory nucleus, in the medial prefrontal and anterior cingulate cortices, in the basal forebrain, in the preoptic and ventromedial nuclei of the hypothalamus, as well as anterior hypothalamic area, in the thalamic midline nuclei, and in some brainstem structures, such as the parabrachial nucleus. The relative quantitative increase of Fos-ir neurons varied in the different structures. In addition, Fos-ir neurons were evident after NGF administration in areas devoid of immunopositive cells in control animals. These included: frontoparietal and occipital cortical fields, the hypothalamic arcuate nucleus, and many brainstem structures, such as the dorsal nucleus of the lateral lemniscus, posterodorsal tegmental, medial and lateral vestibular, ventral cochlear, and prepositus hypoglossal nuclei. These findings demonstrate that the intracerebroventricular administration of NGF can induce c-fos expression in neurons in vivo. The distribution of Fos-ir neurons indicates that NGF can induce activation of functionally and chemically heterogeneous neuronal subsets in the brain
Sleep and timekeeping changes, and dysregulation of the biological clock in experimental trypanosomiasis
No full textThe rest-activity and body temperature 24 hours cycles, as well as the pattern of spontaneous sleep, were investigated in rats after infection with Trypanosoma brucei brucei. In the infected rats, which were entrained to a 12 hours/12 hours photoperiod, a considerable hypokinesia was detected during the hours of darkness. In most of the infected animals, the body temperature cycle displayed a lower amplitude and an advance of about 3 hours in respect to control rats; in addition, the body temperature rhythm was not significant in some infected rats. The relative proportion of slow wave synchronized sleep, as well as the rapid-eye movement (REM) latency, were significantly reduced in the infected animals, in which sleep was considerably fragmented. The induction of Fos (the protein encoded by the immediate early gene c-fos), in response to light stimulation during the early subjective night, was severely impaired in the hypothalamic suprachiasmatic nuclei in trypanosome-infected rats. Altogether these data point out a disruption of locomotor activity and body temperature 24 hours cycle and a major disorganization of sleep during experimental trypanosomiasis. In addition, our findings indicate that the molecular and functional correlates of the synchronizing action of the suprachiasmatic nuclei, which play a major role of biological clock of endogenous biological rhythms, could be altered during trypanosome infection
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