Effect of gamma-hexachlorocyclohexane and its isomers on proto-oncogene c-fos expression in brain.

By means of in situ hybridization, the induction of proto-oncogene c-fos in rat brain after administration of several convulsants has been studied. The organochlorine insecticide gamma-hexachlorocyclohexane (lindane) has been shown to induce c-fos expression in a dose dependent manner. 30 mg/kg of lindane increased c-fos expression in cortical and hippocampal areas. The two non convulsant isomers of lindane, alpha- and delta-HCH, were not able to induce the expression of the proto-oncogene, but blocked that elicited by lindane. Pentylenetetrazole (PTZ) and picrotoxin (PTX), a known GABAA-receptor antagonist, have also been considered. Both of them were able to induce c-fos, although the pattern of expression was not the same in each case. alpha- and delta-HCH, were administered prior to the mentioned toxicants, affecting the proto-oncogene expression in different ways. We propose here that the distribution of c-fos mRNA after different treatments can be used as a marker of neurotoxic action.     

Electrically stimulated rapid gene expression in the brain: ornithine decarboxylase and c-fos

A single electroconvulsive shock (ECS) resulted in a major induction of cerebral ornithine decarboxylase (ODC) mRNA and a rapid and transient elevation of ODC enzyme activity. The proto-oncogene c-fos was also transiently induced under the same conditions. Following a rapid rise in mRNA levels, the messages for these proteins take different courses. The c-fos mRNA fell to below control levels by 1 h, while the ODC mRNA remained elevated beyond 24 h. The ECS-induced elevation of ODC enzyme activity was not abolished by adrenalectomy but was attenuated significantly by the anti-convulsant MK-801. These results imply that the induction of cerebral ODC may be neuronal activity dependent, and suggest that the ODC/polyamine system may be linked to the proposed third messenger cascade, involving c-fos, which couples cell stimulation to gene expression, resulting in long-term adaptive responses.     

Effect of different convulsants on calmodulin levels and proto-oncogene c-fos expression in the central nervous system.

In the present study, a relationship between convulsant activity and two cellular events, changes in calmodulin (CaM) concentration and proto-oncogene c-fos expression has been considered. c-fos has been found activated after the administration of the organochlorine insecticide lindane, the Ca2+ channel agonist Bay K, and N-methyl-D-aspartate (NMDA). The administration of the voltage-dependent Ca2+ channel antagonist nifedipine was able to block the expression elicited by lindane. The effect of lindane on c-fos expression could not be blocked by prior administration of MK-801, a non-competitive antagonist of the NMDA receptor. These results suggest a possible role for the voltage-dependent Ca2+ channels in the mechanism of action of lindane. By means of in situ hybridization, the different patterns of c-fos expression after the administration of the mentioned compounds have been described. A possible modification of the levels of CaM has also been investigated. Among all the subcellular fractions considered, only levels of nuclear CaM appeared to be affected after the different treatments. The changes observed seemed to follow a similar pattern to that described for c-fos induction. Calcium entry through these voltage-dependent calcium channels would be the link between membrane depolarizing events and expression of c-fos and/or increase in nuclear CaM.     

Induction of c-fos mRNA in cerebral cortex by excitotoxin stimulation of cortical inputs: involvement of N-methyl-D-aspartate receptors.

In this study we have characterized the induction of c-fos mRNA in cerebral cortex in response to unilateral kainate injection into the nucleus basalis. This treatment is associated with an intense stimulation of the ascending pathway and the subsequent induction of ornithine decarboxylase (ODC) enzyme activity and ODC mRNA in ipsilateral cerebral cortex which is sensitive to treatment with MK-801 and dihydropyridine antagonists. Unilateral injection of kainate into nucleus basalis caused a marked induction of c-fos mRNA in ipsilateral cortex which was detectable at 1 h, reached a maximal value at 8 h where c-fos mRNA levels were 16 times those in unoperated animals and then returned to control values by 24 h. However, the early induction of c-fos mRNA at 1 h was not related to a specific effect of kainate since at this time point, sham-operated animals also showed a significant increase in the level of c-fos mRNA in ipsilateral cerebral cortex. No significant induction of c-fos mRNA was detected in ipsilateral cortex in sham-operated animals at 4 and 8 h after injection of vehicle. Treatment with the N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 (3 mg/kg) significantly attenuated the response obtained at 4 h and 8 h after kainate injection by 73% and 55% respectively, but did not influence the level of c-fos mRNA induced at 1 h. Delaying administration of MK-801 by 30 min reduced the effectiveness of this treatment on the response obtained at 4 h.(ABSTRACT TRUNCATED AT 250 WORDS)     

柴胡疏肝汤对戊四氮致痫大鼠海马及额叶皮质c-fos表达的影响

目的 观察柴胡疏肝汤对戊四氮致痫大鼠海马及额叶皮质c-fos表达的影响.方法 选取经戊四氮诱导制作的癫痫模型大鼠48只,按随机数字表法分成6组:癫痫模型组、德巴金组、定痫丸组、柴胡疏肝汤低剂量组、柴胡疏肝汤中剂量组和柴胡疏肝汤高剂量组,每组各8只;另设正常对照组8只.正常对照组和癫痫模型组常规饲养,其他各组给予药物德巴金,定痫丸,低、中、高剂量柴胡疏肝汤处理,均连续灌胃治疗5周.免疫组化染色检测各组大鼠海马及额叶皮质c-fos的表达情况.结果 戊四氮致痫后大鼠海马及额叶皮质c-fos表达明显增强,而应用中、高剂量的柴胡疏肝汤,德巴金和定痫丸治疗后,大鼠海马及额叶皮质c-fos表达均明显减弱,与癫痫模型组比较差异均有统计学意义(P<0.05),而柴胡疏肝汤低剂量组大鼠海马及额叶皮质c-fos表达无明显减弱.结论 柴胡疏肝汤的抗癫痫作用机制可能与其含有柴胡皂甙及其他多种有效的抗癫痫成份多靶点干预海马及额叶皮质c-fos表达水平有关.

Abstract：

Objective To observe the effect of chaihushugantang on the expression of c-fos in the hippocampus and frontal lobe cortex of pentylenetetrazole (PTZ)-induced epileptic rats. Methods Forty-eight PTZ-induced epileptic rats were randomly divided into 6 groups: epileptic model group,Valproate treatment group, Dingxianwan treatment group, and lower-dose, medium-dose and high-dose chaihushugantang treatment groups (n=8). Normal control group was also employed (n=8). The epileptic rats in the normal control group and epileptic model group were fed normally. Rats of the treatment groups were performed intragastric administration of medicines (Valproate, Dingxianwan and chaihushugantang) for 5 weeks in succession respectively. The expression of c-fos in the hippocampus and frontal lobe cortex of all the rats was observed. Results The expression of c-fos in the hippocampus and frontal lobe cortex of rats in the epileptic model group was significantly increased, while the c-fos expression in the hippocampus and the frontal lobe cortex of rats in the medium-dose and high-dose chaihushugantang treatment groups and Valproate treatment group and Dingxianwan treatment group was significantly decreased as compared with that in epileptic model group (P<0.05). But the c-fos expression in the hippocampus and the frontal lobe cortex of rats in the low-dose chaihushugantang treatment group showed no obvious decrease. Conclusion Chaihushugantang has good antiepileptic effect, might through affecting the c-fos expression in the epileptic rats. The antiepileptic mechanism of chaihushugantang can be related to saikosaponins and other antiepileptic constituents in it.     

Induction of c-fos mRNA in rat brain by conditioned and unconditioned stressors.

Intense depolarizing stimuli induce the expression of the proto-oncogene c-fos which may be useful as a marker of neuronal activity. To determine if mild physical and behavioral stressors may also induce c-fos expression, we subjected rats to an unconditioned stressor (footshock) or a conditioned stressor (a tone previously paired with footshock) and measured c-fos mRNA levels in various brain regions using in situ hybridization. Removing rats from their home cage and exposing them to a tone was sufficient to cause increases in c-fos mRNA in several forebrain areas while further increases in c-fos occurred in the septum, cingulate cortex, and endopiriform nucleus in response to acute footshock stress. Both unconditioned and conditioned stressors increased c-fos mRNA levels in the locus ceruleus which correlated with stress-induced plasma corticosterone concentrations. Unconditioned footshock stress also increased c-fos mRNA in the hypothalamic paraventricular nucleus (PVN). However, neither conditioned nor unconditioned stressors induced c-fos in the PVN in rats which had been previously exposed to footshock. C-fos appears to be a sensitive marker for stress-responsive brain areas and may be important in mediating long-term neurochemical changes that result from stress.     

帕罗西汀对束缚应激与额叶皮质相关性的影响研究

目的：观察束缚应激对大鼠额叶皮质的影响,探讨帕罗西汀在防治束缚应激引起焦虑的作用机制。方法：复制大鼠束缚应激模型,分为束缚应激组、治疗组和保护组,另设对照组（不束缚应激）,每组均n=10。观察大鼠行为学改变、额叶皮质c-fos基因表达、5-羟色胺（5-HT）和血浆皮质酮含量的变化,观察帕罗西汀干预的影响。结果：与对照组比较,束缚应激组大鼠额叶皮质的c-fos表达显著增加,5-HT表达明显减少,血浆皮质酮含量明显升高;与束缚应激组比较,治疗组和保护组血浆皮质酮含量和额叶皮质c-fos表达明显减少,5-HT表达明显增加。结论：额叶皮质参与了束缚应激反应;帕罗西汀抑制额叶皮质的c-fos基因表达、减少血浆皮质酮含量和增加额叶皮质5-HT含量可能是其抗焦虑作用机制之一。     

Regional expression of c-fos and heat shock protein-70 mRNA following hypoxia-ischemia in immature rat brain.

Cerebral ischemia induces the expression of a number of proteins that may have an important influence on cellular injury. The purpose of this study was to compare the regional effects of hypoxia-ischemia on the expression of the proto-oncogene, c-fos, and the heat shock protein-70 (HSP-70) gene in developing brain. Unilateral hypoxia-ischemia was produced in the brain of immature rats (7, 15, and 23 days after birth) using a combination of carotid artery ligation and systemic hypoxia (8% O2). After recovery for 2 and 24 h, the regional expression of c-fos and HSP-70 mRNA was determined using in situ hybridization. Littermates were permitted to recover for 1 week for assessment of histologic injury. Hypoxia-ischemia increased the expression of both c-fos and HSP-70 mRNA, but the topography of expression varied with the age of the animal as well as the mRNA species. In the 7-day-old group, expression of c-fos at 2 h increased in multiple regions of the ipsilateral hemisphere in nearly one-half of the animals, while HSP-70 mRNA was not expressed until 24 h and, then, predominantly in the hippocampus. In 15- and 23-day-old rats, expression of c-fos was increased at 2 h in the entorhinal cortex and in the dendritic field of the upper blade of the hippocampal dentate gyrus, while HSP-70 mRNA was prominently expressed in neocortex and the cell layers of the hippocampus. Interestingly, the strong expression of HSP-70 mRNA in dentate granule cells did not occur in the innermost layer of cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

大鼠海马快速点燃模型的建立及机制研究

目的：建立大鼠海马快速点燃模型并对其机制进行初步探讨。方法：制备大鼠海马快速点燃模型;观察经典抗杏仁核点燃药物对该模型的影响;观察大鼠海马快速点燃模型和大鼠杏仁核点燃模型海马CA_3区和皮层区c-fos蛋白的表达情况及蛋白抑制剂对其表达的影响。结果：大鼠海马快速点燃模型点燃成功率与刺激参数有关;苯巴比妥20,50mg·kg~1 及地西泮2,5mg·kg~(-1)对大鼠海马快速点燃ADD和Racine＇s分级有抑制作用(P＜0．05);与正常组比较,海马快速点燃大鼠和杏仁核点燃大鼠海马CA_3区、大脑皮层c-fos免疫阳性细胞增多(P＜0．05),在蛋白抑制剂作用下,海马c-fos免疫阳性细胞减少,但仍比正常组高(P＜0．05)。结论：大鼠海马快速点燃成功率与刺激参数具有相关性;传统抗点燃药物具有抗海马快速点燃作用;大鼠海马快速点燃模型c-fos蛋白在不同脑区和核团的免疫阳性表达细胞增加。     

Localization and induction of c-fos protein-like immunoreactive material in the nuclei of adult mammalian neurons

The distribution of the proto-oncogene product, c-fos protein, has been studied in tissue from adult rat brain using immunocytochemical techniques. Sections of rat brain were incubated with a polyclonal antibody to a synthetic fragment of the c-fos protein (M-peptide) and visualized for immunoreactivity using the avidin-biotin technique. Low levels of c-fos protein-like immunoreactivity were concentrated in the nucleus. Dark nuclear staining of cells was observed in the cerebral cortex, in hippocampal pyramidal neurons, in granule cells of the dentate gyrus and other regions. Neurons in the cat visual cortex also showed low levels of c-fos protein-like immunoreactivity. Pre-absorbing the antibody with the M-peptide abolished the immunostaining. Generalized seizures evoked by injection of pentylenetetrazol produced a massive induction of fos protein(s) in the piriform and cingulate cortices as well as the dentate gyrus of rats. These results demonstrate that c-fos protein-like immunoreactive materials is found within the nuclei of fully differentiated adult mammalian neurons at low basal levels and that activation of nerve cells leads to an induction of c-fos proteins.     

Effect of cold, restraint, reserpine, and splanchnicotomy on the ornithine decarboxylase activity of rat adrenal medulla and cortex

The activity of ornithine decarboxylase (EC 4.1.1.17, ODC) of the adrenal medulla and cortex was studied after subjecting rats to three different forms of stress: administration of reserpine, exposure to short periods of cold, or bodily restraint. Reserpine, cold exposure, and immobilization significantly increased ODC activity in both adrenal tissues. For medullary ODC this effect was prevented by denervation of the adrenal gland. In the cortex, splanchnicotomy reduced or prevented the stimulation of ODC activity caused by reserpine and cold exposure. When animals pretreated with reserpine were subjected to restraint, a potentiation was observed for the medullary enzyme; this effect was prevented by denervation. The cortical enzymic activity attained levels of activity similar to those observed with the individual stimuli. Exposure of rats treated with reserpine to cold led to a reduction of adrenal ODC activity, a reduction that was statistically significant only for the cortical enzyme. Denervation had no effect. Cortical ODC responses appear to be strongly influenced by hypothalamopituitary factors which, in turn, are known to be modified by stress, whereas medullary ODC activity seems to be more susceptible to changes in sympathetic activity associated with stress.     

Induction of the c-fos proto-oncogene during opiate withdrawal in the locus coeruleus and other regions of rat brain.

Opiate regulation of the nuclear proto-oncogene c-fos was studied in the locus coeruleus (LC) and other regions of rat brain by immunoblotting, northern blotting, and in situ hybridization procedures. Precipitation of opiate withdrawal in rats, which is known to increase LC firing rates 4-fold, led to a two- to three-fold increase in levels of mRNA and protein for c-fos in the LC 1-2 h after initiation of withdrawal. In contrast, levels of c-fos expression were decreased in LC from rats treated acutely or chronically with morphine but not experiencing withdrawal, conditions under which LC firing rates are depressed. Similar regulation of c-fos expression during opiate withdrawal was found in the amygdala, ventral tegmentum, nucleus accumbens, neostriatum, and cerebral cortex, but not in a number of other brain regions studied, which included the hippocampus, dorsal raphe, periaqueductal gray, and paragigantocellularis. In the LC and some other brain regions, induction of c-fos during opiate withdrawal was associated with a parallel induction of c-jun, another nuclear proto-oncogene, which, like c-fos, is expressed rapidly in brain in response to certain extracellular stimuli. The results demonstrate a novel use of c-fos in neuropharmacology, namely to map neuronal pathways and neuronal cell types activated in response to acute and chronic opiate administration and during opiate withdrawal, as well as in response to other psychotropic drug treatments.     

Ornithine decarboxylase in developing brain of normal and hydrocephalic rats Biochemical and immunohistochemical studies

Polyamines have various roles in cortical development. We examined the ontogenic changes in ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, in cerebral cortices of normal and hydrocephalic rats. Both biochemical and immunohistochemical examinations revealed increased ODC protein and enzyme activity during the perinatal period. Apical dendrites of developing neuroblasts migrating from the superficial layer of cortical plate showed intense ODC immunoreactivity. Once they had settled at their final destination, ODC immunoreactivity weakened. Both ODC immunoreactivity and enzyme activity reached very low levels after completion of layer formation of cortex. The enzyme activity of ODC in hydrocephalic cortices exceeded that in normal cortex during the perinatal periods. ODC was rather overexpressed, but no characteristic distribution was observed in the hydrocephalic cortex. These findings indicate the participation of polyamines in the cortical development, especially in the layer formation. The overexpression of ODC in hydrocephalus appears to promote development despite increased hydrostatic pressure.     

Effects of unilateral cortex lesions on gene expression of rat cortical cholecystokinin neurons.

In rat neocortex, the gene encoding preprocholecystokinin is expressed in interneurons which also synthetize gamma-aminobutyric acid. An injury to the meninges and the underlying cortex increased the concentration of mRNA coding for preprocholecystokinin in all ipsilateral cortical areas. Simultaneous treatment of the rats with the anti-inflammatory agent diclofenac did not affect the injury-induced change in gene expression indicating that inflammatory processes were not involved. The injury also enhanced the expression of the immediate early gene c-fos in the ipsilateral cortex in a time-dependent manner. There was an increase in c-fos mRNA 1 h after the operation, which was no longer observed 3 h later. Twenty-four hours after the operation, cells containing c-fos mRNA were found in cortical layers II, III, V and VI. The neurons which showed an increased expression of preprocholecystokinin were also in these layers. The N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 prevented the injury-induced increases in both preprocholecystokinin and c-fos gene expression, indicating that stimulation of this glutamate receptor subtype may initiate the changes in expression of both genes. It is hypothetized that the immediate early gene c-fos is activated first and this then leads to the increase in preprocholecystokinin mRNA.     

Depressive-like behavioral alterations and c-fos expression in the dopaminergic brain regions in WAG/Rij rats with genetic absence epilepsy

Wistar derived inbred line, the WAG/Rij rats, genetically absence epilepsy prone and their normal counterparts, outbred Wistar rats, were compared in respect to differences in behavior, in acute and chronic antidepressant imipramine treatment and in the immediate early gene c-fos expression in the brain regions induced by forced swimming test procedure. The WAG/Rij rats as compared with Wistar rats were found to exhibit decreased activity in the open field test, increased immobility in the forced swimming test and decreased sucrose intake (anhedonia). Interline differences indicating increased anxiety in the WAG/Rij rats were not revealed in the light-dark choice, social interaction and elevated plus-maze tests. The WAG/Rij rats in contrast to Wistar rats responded only to chronic antidepressant imipramine treatment with a reduction in their enhanced immobility in the forced swimming test. "Behavioral despair" induced by forced swimming led to c-fos expression in frontal cortex, nucleus accumbens and striatum, terminal regions of three dopaminergic brain systems (mesocortical, mesolimbic, nigrostriatal). The c-fos expression in the brain of WAG/Rij rats was substantially higher than that of Wistar rats. Moreover, the strains differed in the distribution of c-fos expression between brain regions. Results suggest that WAG/Rij rats are prone to adopt passive strategies of behavior in stressful situations, and so in this certain aspect this strain might be regarded as new experimental (genetic) model of depressive-like (passive) behavior accompanying absence epilepsy. Further testing this hypothesis is proceeding. This putative model could be used for the investigation of neurobiological basis and mechanisms of such "double pathology" and for the examination of new concepts of its therapy.     

Pentylenetetrazole (PTZ)-induced c-fos expression in the hippocampus of kindled rats is suppressed by concomitant treatment with naloxone

Rats were kindled by repeated injections of pentylenetetrazole (PTZ; 37.5 mg/kg; i.p.) in the presence or absence of the opioid receptor antagonist naloxone. Naloxone (10 mg/kg; i.p.) applied 30 min before each PTZ application had no major effect on the seizure development, although a slight decrease in the seizure expression of fully kindled animals could be observed. In the kindled animals, a pronounced but transient increase in c-fos mRNA level was observed in several brain areas after the injection of PTZ. The magnitude of c-fos induction was related to the seizure stage reached. Detectable c-fos mRNA levels in the cortex were observed in rats showing stage four seizures, whereas the expression of c-fos in the hippocampus required stage five kindled seizures. The induction of c-fos expression in the hippocampus of stage five kindled rats but not in other brain areas was prevented by treatment of naloxone prior to each PTZ application. In contrast, a single injection of naloxone to kindled rats was not sufficient to prevent c-fos mRNA expression in the hippocampus. In addition, a single PTZ application (at the higher dose of 45 mg/kg) to rats that were not kindled also caused c-fos expression in several brain regions, but this was not influenced by naloxone. Assuming that c-fos expression reflects neuronal activity our findings suggest a functional role of endogenous opioid peptides in the development of kindling-induced neuronal excitation in the hippocampus. In addition, the excitation of the hippocampus does not appear to be involved in the seizure activity but may be responsible for the impairment of learning in PTZ-kindled rats which can be prevented by pretreatment with naloxone [A. Becker, G. Grecksch, M. Brosz, Naloxone ameliorates the learning deficit induced by pentylenetetrazole kindling in rats, Eur. J. Neurosci. 6 (1994) 1512–1515].     

A study of neurotoxic biomarkers, c-fos and GFAP after acute exposure to GSM radiation at 900 MHz in the picrotoxin model of rat brains

The acute effects of microwave exposure from the Global System for Mobile Communication (GSM) were studied in rats, using 900MHz radiation at an intensity similar to mobile phone emissions. Acute subconvulsive doses of picrotoxin were then administered to the rats and an experimental model of seizure-proneness was created from the data. Seventy-two adult male Sprague-Dawley rats underwent immunochemical testing of relevant anatomical areas to measure induction of the c-fos neuronal marker after 90min and 24h, and of the glial fibrillary acidic protein (GFAP) 72h after acute exposure to a 900MHz electromagnetic field (EMF). The experimental set-up facilitated measurement of absorbed power, from which the average specific absorption rate was calculated using the finite-difference time-domain (FDTD) 2h after exposure to EMF radiation at 1.45W/kg in picrotoxin-treated rats and 1.38W/kg in untreated rats. Ninety minutes after radiation high levels of c-fos expression were recorded in the neocortex and paleocortex along with low hippocampus activation in picrotoxin treated animals. Most brain areas, except the limbic cortical region, showed important increases in neuronal activation 24h after picrotoxin and radiation. Three days after picrotoxin treatment, radiation effects were still apparent in the neocortex, dentate gyrus and CA3, but a significant decrease in activity was noted in the piriform and entorhinal cortex. During this time, glial reactivity increased with every seizure in irradiated, picrotoxin-treated brain regions. Our results reveal that c-fos and glial markers were triggered by the combined stress of non-thermal irradiation and the toxic effect of picrotoxin on cerebral tissues.     

Immunohistochemical studies of noradrenergic-induced expression of c-fos in the rat CNS.

Previous studies have shown that stimulation of adrenergic receptors in the rat brain causes increased levels of mRNA of the immediate early gene, c-fos. The present studies were undertaken to determine if this stimulation also induces increased levels of c-fos immunoreactivity in the central nervous system (CNS). Rats were treated with the alpha-2 adrenoceptor blockers, yohimbine or atipamezole, or with restraint stress to activate central noradrenergic activity and were perfused 2 h later for immunohistochemical analysis of the cerebral cortex. Yohimbine, atipamezole and restraint stress each was found to cause increases in c-fos-like immunoreactivity (c-fos-li). Western blot analysis revealed increased c-fos protein in the cortex after yohimbine treatment. The c-fos-li response to yohimbine was blocked by prior administration of the beta receptor antagonist, dl-propranolol, and to a lesser degree by the alpha-1 antagonist, prazosin. It is concluded that adrenergic receptor stimulation in the cortex causes increased production of c-fos or fos related antigens and that this (these) immediate early gene product(s) may play a role in noradrenergic function in the CNS.