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In the present study, we investigated the antiproliferative activity of Naja ashei full venom (NAV) on human colorectal cancer cells. The NAV-induced antiproliferative effect was associated with cell cycle arrest in S phase and increased number of cells with sub G0/G1 DNA content, which is considered a marker of apoptosis. Apoptosis has also been confirmed with annexin V/PI staining. Furthermore, flow cytometric analysis revealed loss of mitochondrial membrane potential with concomitant increase in cytochrome c and Smac/DIABLO protein content. These effects were associated with the activation of caspase-9 and caspase-3, as well as with PARP cleavage. Moreover, phosphorylation of antiapoptotic Bcl-2 protein in NAV-treated HCT116 was observed. In conclusion, our study for the first time documented antiproliferative/pro-apoptotic effect of NAV in colorectal cancer cells. Our results strongly suggest the involvement of mitochondria in NAV induced apoptosis of cancer cells. Future studies are needed to further examine the potential of NAV in the treatment of colon cancer.

OBJECTIVES Activity of neuropeptide Y (NPY), tyrosine hydroxylase (TH), corticoliberine (CRH), and oxytocin (OXY) producing cells was investigated in the ovariectomized (OVX) female C57BL/6 mice kept on the high fat diet for 16 weeks and their response to colchicine stress in selected brain areas, including the hypothalamic paraventricular (PVN), dorsomedial (DMN) and arcuate (ARC) nuclei, A1/C1 (in the ventrolateral medulla), and A2/C2 (in the nucleus of the solitarii tract, NTS) catecholaminergic cell groups. METHODS The OVX female C57BL/6 mice kept on high fat diet were sacrificed by transcardial perfusion with fixative 48 h after intracerebroventricular injection of colchicine (18 µg mice). Dual Fos/neuropeptide immunohistochemistry was employed to investigate Fos/neuropeptide colocalizations. RESULTS In the OVX saline-treated mice (sham control) with standard diet (St diet), no immunopositive CRH and NPY neurons were identified in the PVN and weak Fos immunostainig was visible in TH neurons in the DMN and ARC nuclei. Colchicine treatment in the OVX mice with St diet increased the number of CRH and OXY immunopositive neurons in the PVN as well as the number of NPY and TH neurons in DMN and ARC nuclei and NPY neurons in the middle NTS (mNTS) and A1/C1 cell group. Prolonged HF diet in OVX sham control mice moderately increased the number of Fos/TH neurons in the mNTS and commissural NTS (cNTS) in comparison with St diet mice. However, prolonged HF diet in OVX colchicines-treated mice reduced the number of Fos/NPY neurons in the anterior NTS (aNTS) and A1/C1 cell group in comparison with colchicines-treated animals with St diet as well as Fos-TH neurons in the mNTS and cNTS in comparison with saline-treated animals with HF diet. CONCLUSION The data of this pilot study indicate that prolonged high fat diet might: 1) represent itself a light/moderate stimulus for activation of TH neurons in the NTS and A1/C1 cell group as well as NPY neurons in the A1/C1 cell group and 2) interfere with colchicines-induced and time-delayed Fos activation in the NPY and TH neurons in both the above mentioned brain nuclei.

The liver is a vital organ, with a wide range of functions. This organ plays an important role in the metabolism, including the glycogen storage, decomposition of red blood cells, plasma protein synthesis, hormone production, and detoxification. The liver is innervated by sympathetic and parasympathetic nerves which are involved in the regulation of the hepatic metabolism. Tissue injury connected with ischemia and reperfusion has been implicated in several clinical settings, including myocardial infarction, brain ischemia, and organ transplantation. Consequences of the liver ischemia reperfusion injury (LIRI) induce first of all an organ failure and afterwards multiorgan system damages that may eventually lead to a death. Many models with an attempt to reduce harmful consequences of the LIRI, directing to develop a variety of prophylactic strategies, has been introduced including models of warm, cold or normothermic ischemia, ischemic pre- and post-conditionings, pharmacological interventions, etc. In spite of the improvements in the medical care and accumulation of a large amount of experimental data concerning the prevention of ischemia and reperfusion related injuries, many destructive processes explanation still remains problematic.

Objective Little is known about the response of tyrosine hydroxylase (TH) containing hypothalamic neurons to stress in corticoliberine deficient (CRH-KO) mice. This study was aimed to extend this issue and reveal the data leading to a better understanding of physiological/anatomical plasticity of hypothalamic TH cells in response to acute immobilization stress (IMO) as well as of possible of CRH body deficiency contribution in the regulation of TH cells during stress. We examined the topographic distribution of TH protein immunolabeled perikarya in selected hypothalamic structures including the paraventricular (PVN), supraoptic (SON), periventricular (PeVN), arcuate (ArcN), dorsomedial (DMN), and ventromedial (VMN) nuclei and extrahypothalamic zona incerta (ZI) in CRH-KO and wild type (WT) mice. Methods The animals were perfused with fixative 120 min after a single IMO stress. The brains were removed, cryo-sectioned throughout the hypothalamus and Fos-TH co-localizations were processed immunohistochemically. Fos protein was visualized by diaminobenzidine (DAB) intensified with nickel ammonium sulphate, while TH cells were labeled only with DAB chromogen. The evaluation of Fos-TH co-labeled perikarya was performed with the use of computerized Leica light microscope and expressed as the percentage of total amount of TH labeled cells. Results From the qualitative point of view, the present data indicate similar anatomical distribution of TH immunoreactive perikarya in all brain structures investigated in both WT and CRH-KO mice, while from the quantitative point of view only TH cells in the DMN of CRH-KO mice showed a trend for increased activation by IMO. Conclusions In several hypothalamic structures the basic population of TH neurons was not affected by the absence of endogenous CRH. Based on the data of this study it can also be assumed that despite of the presence of direct reciprocal connections between PVN and DMN neurons, PVN CRH neurons possibly are not participating in the regulation of TH neurons in the DMN during IMO stress. Keywords Hypothalamic nuclei - Fos-immunohistochemistry - Tyrosine hydroxylase - Immobilization stress - CRH knockout mice.

The hypothalamus plays an important role in food consumption, receiving information about energy balance via hormonal, metabolic, and neural inputs. Its neurons produce neuropeptides influencing energy balance. Especially important to regulation of food consumption are certain hypothalamic structures, including the arcuate (ARC) and ventromedial (VMN) nuclei and the lateral hypothalamic area (LHA). We determined the impact of cholecystokinin (CCK) and cocaine and amphetamine regulated transcript (CART) peptide, on activity of ARC and VMN neurons and hypocretin (Hcrt) synthesizing neurons in LHA. ARC is an integrative nucleus regulating food consumption, VMN is considered to be a satiety centre, and LHA a hunger sensing centre. After overnight fasting, male C57Bl/6 mice received intraperitoneal injection of (i.p.) saline (SAL) or CCK (4microg/kg) or intracerebroventricular injection of (i.c.v.) CART peptide (0.1microg/mice) or CCK (i.p.) followed by CART peptide (i.c.v.) 5min later. Sixty minutes later, the presence of Fos or Fos/Hcrt immunostaining indicated activity of ARC and VMN neurons, as well as of Hcrt cells in LHA. CCK alone did not influence neuronal activity in any of the nuclei studied. CART peptide stimulated neurons in ARC and VMN (p

Liver ischemia-reperfusion injury (LIRI) influences different body cells. Little is known about the effect of LIRI on the activity of neurons. Response of neurons to: (1) single ligation of hepatic artery (LIRIa) for 30 min and (2) combined ligation of portal triade (common hepatic artery, portal vein, common bile duct, LIRIb) for 15 min was investigated in Wistar rats. Ninety minutes, 5 h, and 24 h after liver reperfusion, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), interleukin 1alpha (IL-1alpha), and tumor necrosis factor alpha (TNFalpha) serum levels were analyzed and Fos-immunolabeled cells counted in subfornical organ (SFO), suprachiasmatic (SCH), paraventricular (PVN), supraoptic (SON), arcuate (ARC), and ventromedial (VMN) hypothalamic nuclei, locus coeruleus (LC), nucleus of the solitary tract (NTS), and A1/C1 catecholaminergic cell groups. LIRIb increased ALT serum level after 90 min and 24 h while AST activity only after 24 h in all experimental groups. IL-1alpha serum level was increased only after 90 min of LIRIb while TNFalpha level did not change. Ninety minutes after surgeries more Fos-immunostained cells occurred in both LIRIs than sham-operated animals in all structures studied. More distinct Fos expression occurred after LIRIb than LIRIa in SON, PVN, VMN, and NTS. Five hours after both LIRIs, Fos increased in the parabrachial nucleus (PBN) and NTS. Twenty-four hours after both LIRIs Fos incidence decreased in all groups. Although the present data indicate that increased neuronal activity after both LIRIs is mainly a consequence of the liver damage itself partial impact of non-specific factors can not be excluded. However, the anatomical distribution of Fos occurrence detected after LIRIs gives great opportunity to perform a targeted phenotypic identification of the activated neurons by LIRIs in the subsequent experiments.

Vasopressin (AVP) deficient homozygous Brattleboro rats exhibit severe osmotic challenges due to waterless chronic hypernatremia and hyperosmolality. We investigated the effect of xylazine, an alpha2-adrenoceptor agonist, on the activity of oxytocinergic (OXY) neurons in the supraoptic nucleus (SON) of homozygous (di/di), heterozygous (di/+), and control (+/+) rats. Ninety minutes after saline (0.1 mL/100 g b.w., i.p.) or xylazine injection (10 mg/kg, i.p.) rats were anaesthetized with pentobarbital (50 mg/kg i.p.) and sacrificed by transcardial perfusion with fixative. Activity of OXY neurons was evidenced by nuclear Fos protein immunoreactivity. Fos/OXY colabelings were analyzed on 40-mum thick coronal sections using computerized light microscope. As expected, plasma osmolality and water intake revealed high heterogenity within the di/di group of rats. Fos expression in SON of di/di rats was correlated with osmolality of each rat. In saline-treated rats, maximum activation of Fos reached around 4% in +/+, 20% in di/+ rats, and as much as 60% in di/di rats. Xylazine activated in SON about 70% of OXY-ergic neurons in +/+, 60% in di/+ rats, and more than 80% in di/di rats. The present findings indicate that in spite of the high spontaneous activity of SON OXY-ergic neurons due to the AVP deficiency in di/di rats, many of the silent OXY-ergic neurons in the SON remained acceptable for alpha2-adrenoceptor stimulation.

Functional activation of oxytocinergic (OXY) cells in the hypothalamic paraventricular (PVN), supraoptic (SON), and accessory (ACC) nuclei was investigated in response to acute treatment with Zolpidem (a GABA(A) receptor agonist with selectivity for alpha(1) subunits) utilizing dual Fos/OXY immunohistochemistry. Zolpidem was administered intraperitoneally in dose 10 mg/kg of BW and 60 min later the animals were sacrificed by transcardial perfusion with fixative. The Fos/OXY co-labelings were analyzed on 40 microm thick serial coronal sections using computerized light microscopy. Zolpidem elicited a concordant Fos/OXY staining in all four PVN sub-areas investigated, including the anterior (15.71+/-2.35%), middle (14.52+/-2.53%), dorsal (13.34+/-2.61%), and periventricular (18.21+/-4.75%) ones, however, had no significant stimulatory effect on OXY cells in the SON. In response to Zolpidem, statistically significant activations were also seen in certain groups of accessory structures including the circular nucleus (13.99+/-3.43%), small clusters of accessory neurons (10.55+/-1.94%), and the lateral hypothalamic perivascular nucleus (9.42+/-2.74%). Between the naive and vehicle controls, the dual Fos/OXY labelings did not elicit any significant differences. Our data provide insight into the topographic patterns of brain activity within the clusters of magnocellular OXY cells in the hypothalamus associated with stimulation of GABA(A) benzodiazepine receptors and for the first time illustrate the triggering contemporaneousness within the cells of the principal and accessory magnocellular nuclei in response to Zolpidem treatment. The present study provides a comparative background that may help in the further understanding of a possible extend of Zolpidem effect on the brain.

The quantity and topography of activated vasopressin (AVP), oxytocin (OXY), and tyrosine hydroxylase (TH) neurons were studied immunohistochemically in the anterior, middle, and posterior portions of the PVN and SON in mice 60 min after a single injection of hypertonic saline (HS, 400 microl 1.5M, i.p.). Fos-neuropeptide double-stainings revealed: (1) Fos expression in each portion of the PVN and SON; (2) maximal number of Fos-AVP (79 cells) and Fos-OXY (50 cells) double-labelings in the middle portion of the PVN; (3) low number of Fos-TH perikarya in the PVN and their lack in the SON; (4) similar incidence (around 50%) of Fos-AVP and Fos-OXY perikarya in the SON; and (5) presence of activated AVP, OXY, and TH neurons in the periventricular, subependymal, and sub-PVN zones of the PVN. Topographic analysis revealed that the majority of AVP neurons expressing Fos occupied the dorsolateral and central part of the middle portion of the PVN. In the same PVN portion, Fos-OXY neurons occurred in similar frequency, however, they were primarily distributed along the lateral and medial margins of the PVN. In the SON, Fos-OXY cells occupied mainly its dorsal, while Fos-AVP cells predominated in its ventral part. The data clearly indicate that HS is not a selective stimulus neither for PVN nor SON itself and provide evidence that both PVN and SON AVP and OXY cells play important role in the mediation of signals induced by HS. In addition, the limited number of AVP, OXY, and TH neurons activated by HS may account for their differential functional specializations selective for stress/osmotic circuits activated by HS.

It is known that the development and plasticity of the neuroendocrine system can be affected by many factors, and that adverse events during the prenatal period can result in long-lasting changes in adulthood. This study was aimed at evaluating the possible consequences for offspring from chronic inflammation during pregnancy. Chronic inflammation was simulated by treatment with increasing doses of lipopolysaccharide (LPS) to dams on days 15 through 19 of pregnancy. Attempts were made to prevent possible negative alterations by keeping animals in an enriched environment (EE). Maternal exposure to LPS resulted in a significant reduction of body weight of male offspring during the weaning period. This difference remained until the age of 63 days in controls (C), but not in animals reared in EE. The content of dopamine in the nucleus accumbens was found to be lower in prenatally stressed (PS) adult males. Furthermore, prenatal exposure to maternal immune challenge was associated with lower locomotor activity in elevated plus maze and increased number of skips in the beam-walking test, as observed in female offspring. No differences in ACTH and corticosterone concentrations with regard to prenatal treatment were found; however, both groups kept in EE showed increased levels of corticosterone as well as enlarged adrenal glands. Thus, immune activation during pregnancy may induce long-term changes in brain catecholamines and behavior, but it is not harmful to basal hormone secretion in the offspring.

The present study was conducted to demonstrate Fos expression at four levels (anterior, prefastigial, postfastigial, posterior) of the cerebellar–vestibular nuclear complex in rats exposed to 1, 6, 24, and 48 h of colchicine treatment using a light microscopic avidin biotin peroxidase (ABC) immunohistochemistry. Intracerebroventricular administration of colchicine (60 μg per 10 μl saline) elicited a continuous increase in the number of Fos-positive cells in the main cerebellar (fastigial, interpositus, dentatus) and vestibular (superior, medial, lateral, spinal, Y) nuclei. One and six hours after colchicine treatment, intensive Fos labeling was observed only in the pyriform cortex and the hypothalamic paraventricular nucleus, respectively, and there was no Fos immunolabeling in any of the cerebellar or vestibular structures investigated. On the other hand, moderate number of Fos-positive cells was visible in each of the cerebellar and vestibular nuclei 24 h after colchicine treatment. Exposure of the animals to 48 h of colchicine treatment induced an additional, more than 50%, rise in the accumulation of Fos-positive profiles in almost all the cerebellar and vestibular nuclei. In addition, at this time-point, a characteristic pattern of Fos distribution appeared almost in all of the cerebellar and vestibular nuclei, however, the numerical incidence of Fos-positive profiles in paired structures along the neuroaxis was bilaterally symmetric. The present data demonstrate for the first time that the central administration of colchicine causes a persistent and, in comparison with other brain areas, time-delayed activation of certain population of neurons in both cerebellar and vestibular nuclei. We assume that the delayed Fos activation in these structures indicate that the cerebellar and vestibular nuclei are not the primary targets of the central effect of colchicine and their activation seems to be rather a result of a postponed functional consequences of the central action of colchicine probably related to the coordination of motor performance.

1. The intent of the present study was to find out whether dexamethasone pretreatment may affect the induction of Fos protein in cell nuclei of the cerebellar vestibular neuronal complex (CVNC) elicited by central administration of colchicine. Specifically, the rate of the dexamethasone-sensitive cell population was analyzed and compared at different levels of the CVNC using a light microscopic avidin-biotin peroxidase immunohistochemistry. 2. Male Wistar rats were pretreated with dexamethasone 3 days prior (2.5 mg/kg/day, s.c.) and 24 h after an intracerebroventricular delivery of colchicine (60 microg/10 microL). Animals were sacrificed 48 h after colchicine treatment by a transcardial perfusion with fixative. 3. Dexamethasone in itself had no effect on the activity of cells of the CVNC. However, in colchicine treated animals, which exhibited a large number of Fos-positive cells over the entire CVNC, the dexamethasone elicited a substantial reduction in the number of the Fos-immunoreactive cells over the CVNC. Distinct dexamethasone dependent reduction (50-90%) of Fos-immunoreactivity was observed in each of the deep cerebellar nuclei. On the other hand, less number of dexamethasone-sensitive cells were recognized in the vestibular structures. From these, maximal Fos-inhibition by dexamethasone was recognized in the medial vestibular nucleus, however, even in this case the number of suppressed cells did not exceed 50%. 4. The results provide for the first time evidence about the dexamethasone dependent reduction of Fos-immunoreactivity in the cells of the CVNC in response to stimulation elicited by colchicine. The data also indicate that the glucocorticoids might be involved in the regulation of some functions of the CVNC under stress conditions.

Acute administration of antipsychotics elicits regionally distinct patterns of Fos expression in the rat brain. Stimulation of oxytocin (OXY) and vasopressin (AVP) release in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei indicates that antipsychotics may play a role in autonomic, neuroendocrine, and behavioral processes. This study was focused to reveal the responsiveness of hypothalamic OXY- and AVP- producing magnocellular neurons, in terms of quantitative and topographical distinctions, to antipsychotics displaying different pharmacological profiles. Naive male Wistar rats were injected intraperitoneally with haloperidol (1 mg/kg), clozapine (30 mg/kg), olanzapine (30 mg/kg), risperidone (2mg/kg), and vehicle (5% chremophor) and were sacrificed 60 min later by a fixative. Fos, Fos/OXY, and Fos/AVP labelings were visualized by immunohistochemistry in the SON, 5 accessory (ACS) cell groups, and 4 distinct PVN subdivisions using a computerized light microscope. Most apparent activation of single Fos, Fos/OXY, and Fos/AVP cells was induced by clozapine and olanzapine; effects of risperidone and haloperidol were substantially lower; no colocalizations were revealed in naive or vehicle treated control rats. The data indicate the existence of a substantial diversity in the stimulatory effect of the selected antipsychotics on quantity of Fos, Fos/OXY, and Fos/AVP immunostainings with the preferential action of the atypicals clozapine over olanzapine and little effects of risperidone and haloperidol. Variabilities in Fos distribution in the PVN, SON, and ACS induced by antipsychotics may be helpful to understand more precisely the extent of their extra-forebrain actions with possible presumption of their functional impact and side effect consequences. © 2009 Wiley-Liss, Inc.

It is generally known that hypocretin (Hcrt) neurons in lateral hypothalamus (LH) are involved in feeding behaviour. The aim of this study was to reveal the activity response of Hcrt neurons, as measured by Fos protein incidence, to prolonged high fat (HF) diet in the LH of both genders of C57B1/6 mice.Standard (St) and high fat (HF) diets were available to mice for 16 weeks and thereafter the animals were perfused transcardially with fixative. Then the brains were removed, soaked with 15 % sucrose in 0.1 M phosphate buffer (PB), and cryo-sectioned throughout the hypothalamus into 35 microm thick coronal sections. Fos/Hcrt co-localizations were processed by employing avidin-biotin-peroxidase (ABC) complex and diaminobenzidine chromogen for Hcrt labeling. Fos immunoproduct was intensified by nickel chloride as a black color inducer. Evaluation of the incidence of Fos/Hcrt co-labeled perikarya was performed using a computerized Leica light microscopy.The effect of of mice gender, applied diet, and gender plus applied diet on the activation of Hcrt neurons was found. Turkey s test revealed significant (p0.05) rise in Fos labeled Hcrt neurons in male vs. female mice after consumption of both types of diets: St (44.64 +/- 2.28 % vs. 1.47 +/- 0.195 %, resp.) and HF (44.15 +/- 3.77 % vs. 24.32 +/- 0.7 %, resp.). This showed that HF diet significantly elevated the number of activated Hcrt neurons only in female mice (24.32 +/- 0.7 % in HF fed vs. 1.47 +/- 0.195 % in St fed, p0.05). The body weight and accumulation of body fat in animals (body fat weight expressed as % of body weight) were influenced by gender and applied diet, although the body fat weight was influenced by HF diet (more noticeably in females).The data indicated a positive correlation between body weight, fat gain, and Hcrt activities in females but not in males, thus accentuating the importance of the gender impact.

We have previously demonstrated that alpha2-adrenoceptors regulate hypothalamic magnocellular oxytocinergic (OXY) neurons in Sprague Dawley rats. Here we investigated whether activation/inhibition of alpha2-adrenoceptors may similarly trigger/downregulate the activity of OXY neurons in control Long Evans (+/+) and permanently osmotically stressed Brattleboro (di/di) rats. The effect of alpha2-adrenoceptor agonist, xylazine (XYL) and alpha2-adrenoceptor antagonists, atipamezole (ATIP), and idazoxan (IDX) were evaluated in the supraoptic (SON) and paraventricular (PVN) hypothalamic nuclei. Saline (SAL, 0.1 ml/100 g), XYL (10 mg/kg), ATIP, (1 mg/kg), and IDX (10 mg/kg) and IDX or ATIP followed by XYL were applied intraperitoneally. Rats were sacrificed 90 min later and Fos/OXY co-labelings analyzed in microscope. In control +/+ rats no or few Fos/OXY co-labelings occurred in SON and PVN. XYL significantly increased Fos incidence in OXY neurons in both nuclei. ATIP significantly suppressed the effect of XYL in both nuclei and IDX only in SON. In di/di controls 81% of OXY neurons in SON and 44% in PVN revealed Fos presence and XYL did not further elevate Fos number in SON OXY neurons and slightly increased Fos number in PVN. ATIP or IDX only partially reduced Fos in SAL or XYL treated di/di rats. Our data indicate that: (1) XYL stimulation is not effective in di/di rats because of sustained upregulation of OXY neurons activity and (2) neither ATIP nor IDX reduced significantly the OXY activity in control di/di rats. These findings suggest that alpha2-adrenoceptors have only a limited impact in maintaining OXY cells activity upregulation in PVN and SON of di/di rats.

The intention of this review is to emphasize the current knowledge about the extent and importance of the substances co-localized with magnocellular arginine vasopressin (AVP) and oxytocin (OXY) as potential candidates for the gradual clarification of their actual role in the regulation of hydromineral homeostasis. Maintenance of the body hydromineral balance depends on the coordinated action of principal biologically active compounds, AVP and OXY, synthesized in the hypothalamic supraoptic and paraventricular nuclei. However, on the regulation of water-salt balance, other substances, co-localized with the principal neuropetides, participate. These can be classified as (1) peptides co-localized with AVP or OXY with unambiguous osmotic function, including angiotensin II, apelin, corticotropin releasing hormone, and galanin and (2) peptides co-localized with AVP or OXY with an unknown role in osmotic regulation, including cholecystokinin, chromogranin/secretogranin, dynorphin, endothelin-1, enkephalin, ferritin protein, interleukin 6, kininogen, neurokinin B, neuropeptide Y, vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, TAFA5 protein, thyrotropin releasing hormone, tyrosine hydroxylase, and urocortin. In this brief review, also the responses of these substances to different hyperosmotic and hypoosmotic challenges are pointed out. Based on the literature data published recently, the functional implication of the majority of co-localized substances is still better understood in non-osmotic than osmotic functional circuits. Brattleboro strain of rats that does not express functional vasopressin was also included in this review. These animals suffer from chronic hypernatremia and hyperosmolality, accompanied by sustained increase in OXY mRNA in PVN and SON and OXY levels in plasma. They represent an important model of animals with constantly sustained osmolality, which in the future, will be utilizable for revealing the physiological importance of biologically active substances co-expressed with AVP and OXY, involved in the regulation of plasma osmolality.

Treatment of newborn mice with monosodium glutamate (MSG) is neurotoxic for hypothalamic arcuate nucleus (ARC) and causes obesity. In the MSG-treated 16-week-old NMRI mice, we detected specific ablation of ARC neuronal cells, 8 times higher fat to body mass ratio but unchanged body mass compared to controls, advanced hyperglycemia and hyperinsulinemia--both more pronounced in males, and hyperleptinemia--more severe in females. After fasting, the MSG-treated mice showed attenuated food intake compared to controls. Cholecystokinin octapeptide, which decreased food intake in a dose-dependent manner in 24 h fasted controls, did not significantly affect food intake in the MSG-treated animals. We propose that the obesity-related changes in the feeding behavior of the MSG-treated obese mice were the result of missing leptin and insulin receptors in ARC and consequent altered neuropeptide signaling. This makes the MSG model suitable for clarifying generally the central control of food intake.

Role of central alpha2-adrenoceptors in the regulation of hypothalamic magnocellular cells was studied under hyperosmotic challenge elicited by hypertonic saline (HS). Rats pretreated with receptor agonist, xylazine (XYL), were injected intraperitoneally with different (low: 0.375, moderate: 0.75, high: 1.5 M) HS 30 min later. The activity of the paraventricular (PVN) and supraoptic (SON) vasopressin and oxytocin perikarya was established by Fos-dual-immunohistochemistry 60 min after HS administration. Results showed that 1/XYL is a potent stimulus for oxytocin but not vasopressin magnocellular cells under basal and weak hyperosmotic conditions 2/highHS completely overlaps the effect of XYL. In addition, XYL partially suppressed Fos expression in the parvocellular PVN cells activated by highHS. The data suggest that alpha2-adrenoceptors may play an important role in the regulation of oxytocinergic PVN and SON neurons under basal and weak hyperosmotic conditions and that alpha2-adrenoceptors may also participate in the control of PVN parvocellular cells under intense osmotic challenge.

Fos expression in the hypothalamus and its quantification in vasopressinergic (AVP), oxytocinergic (OXY) and tyrosine hydroxylase (TH) immunoreactive cells in the hypothalamic paraventricular (PVN), supraoptic (SON), suprachiasmatic (SCh), and arcuate (Arc) nuclei was performed in response to physiologically two different, i.e. osmotic (i.p. hypertonic saline, HS) and immobilization (IMO), stimuli in mouse using a dual Fos-neuropeptide immunohistochemistry. Both 60 min of HS and 120 min of IMO evoked Fos induction in many hypothalamic structures, whereas, HS evoked more extensive Fos labeling than IMO in the SON, ventromedial (VMN) and dorsomedial (NDM) hypothalamic nuclei and the retrochiasmatic area (RCh). Other hypothalamic structures including the anterior hypothalamic area (AHA), the latero-anterior hypothalamic nucleus (LA), the Arc, the perifornical nucleus (PeF), and the lateral hypothalamic area (LH) showed similar Fos incidence after both HS and IMO. However, after both stimuli explicitly most extensive Fos expression was observed in the PVN. In addition, in the PVN substantially more Fos-AVP (62-67% versus 10-15%) and Fos-OXY (38-45% versus 4-8%) perikarya were observed after HS than IMO, respectively. Incidence of TH-immunoreactive Fos labeled cells in the PVN was also more frequent after HS. In the SON, HS activated more than 50% of AVP and OXY neurons while IMO less than 4%. The number of TH activated neurons in Arc was also higher after HS (11%) than IMO (4%). Lowest number of colocalizations was revealed in the SCh where both HS and IMO activated around 2% of AVP neurons. The present data demonstrate that both HS and IMO are powerful stimuli for the majority of hypothalamic structures displaying considerable topographic similarity in Fos expression suggesting their multifunctional involvement. The quantity and phenotypic differences of activated hypothalamic neurons may speak out for functional dissimilarities in response to HS and IMO.

The aim of the present study was to reveal stress-type dependent differences in hindbrain catecholaminergic (CA) cells and parabrachial nuclei (PBN) in the wild-type mouse. Neuronal activities were evaluated based on the incidence of Fos-labeling analyzed 60 min after injection of hypertonic saline (HS; 400 microL, 1.5 M, i.p.) or 120 min of immobilization (IMO) stress. The phenotypic nature of neurons was identified by costaining of Fos with either tyrosine hydroxylase (TH) or the neuropeptide Y (NPY) antibody. Generally, HS elicited broader Fos-staining than IMO. In comparison with IMO, HS induced more extensive Fos activation in the nucleus tractus solitarii-area postrema complex, and in TH- and NPY-positive cells in the A1 and C1 areas. Locus coeruleus (LC) cells displayed similar Fos activation after HS and IMO, and both stimuli also evoked evident TH-Fos colocalizations. Both stimuli also induced TH-Fos costainings in the A5 area. In contrast, IMO failed to activate PBN cells. The data indicate that the activity of TH and NPY hindbrain neurons responds differently to HS and IMO stress, supporting the notion that different stressors have different effects on the activity of autonomic centers.

1. The intent of the present study was to find out whether dexamethasone pretreatment may affect the induction of Fos protein in cell nuclei of the cerebellar vestibular neuronal complex (CVNC) elicited by central administration of colchicine. Specifically, the rate of the dexamethasone-sensitive cell population was analyzed and compared at different levels of the CVNC using a light microscopic avidin-biotin peroxidase immunohistochemistry. 2. Male Wistar rats were pretreated with dexamethasone 3 days prior (2.5 mg/kg/day, s.c.) and 24 h after an intracerebroventricular delivery of colchicine (60 microg/10 microL). Animals were sacrificed 48 h after colchicine treatment by a transcardial perfusion with fixative. 3. Dexamethasone in itself had no effect on the activity of cells of the CVNC. However, in colchicine treated animals, which exhibited a large number of Fos-positive cells over the entire CVNC, the dexamethasone elicited a substantial reduction in the number of the Fos-immunoreactive cells over the CVNC. Distinct dexamethasone dependent reduction (50-90%) of Fos-immunoreactivity was observed in each of the deep cerebellar nuclei. On the other hand, less number of dexamethasone-sensitive cells were recognized in the vestibular structures. From these, maximal Fos-inhibition by dexamethasone was recognized in the medial vestibular nucleus, however, even in this case the number of suppressed cells did not exceed 50%. 4. The results provide for the first time evidence about the dexamethasone dependent reduction of Fos-immunoreactivity in the cells of the CVNC in response to stimulation elicited by colchicine. The data also indicate that the glucocorticoids might be involved in the regulation of some functions of the CVNC under stress conditions.

The aim of the present experiments was to elucidate: 1. the stability and usefulness of a 3,3 -diaminobenzidine tetrahydrochloride (DAB) chromogen intensified with nickel and cobalt (DAB-Ni-Co) in the dual immunocytochemical and in situ hybridization procedure using Fos-protein antibody and oxytocin mRNA (OXY mRNA) radiolabeled probe; 2. the susceptibility of the free floating and mounted cryostat sections, freshly prepared or stored for 24 month at -20 degrees C.The dual staining procedure was tested on neurons of the hypothalamic paraventricular nucleus (PVN) activated by an intraperitoneal injection of hypertonic saline (HS, 1.5 M, 5 ml, 60 min). Two dual labeling procedures were compared: 1/ Fos-immunostaining with DAB alone and combined with OXY mRNA in situ hybridization and 2/ Fos-immunostaining with DAB-Ni-Co and combined with OXY mRNA in situ hybridization. In both experiments free floating and mounted cryostat sections, freshly prepared or stored for 24 month at -20 degrees C, were tested.HS strongly stimulated both the parvicellular and magnocellular population of PVN neurons followed by an extensive Fos-immunolabeling in many cell nuclei. The first staining sequence with Fos-DAB labeling resulted in a good staining quality on both the fresh and for 24 month stored mounted sections. Although the free floating sections during the in situ procedure showed the same staining properties as the mounted ones, with respect to their increased fragility on the end of the hybridization procedure, they were difficult to mount and stretch on poly-L-lysine coated slides. On the other hand, Fos-immunolabeling with DAB-Ni-Co exhibited improved staining density of the single DAB chromogen in the first staining sequence of the dual staining procedure. However, DAB-Ni-Co mixture showed up as an unstable chromogen complex, which after completing the in situ hybridization process completely disappeared from each type of section.The results of the present dual immunocytochemical-in situ hybridization staining utilizing Fos-antibody and OXY mRNA oligoprobe indicate that this procedure is applicable on free floating as well as mounted cryostat sections, freshly prepared or stored for 24 month at -20 degrees C. However, the dual procedure is only successful when the immunoproduct in the first sequence is visualized with an unintensified DAB and not with combined DAB-Ni-Co chromogen and when the histological sections in the second sequence are not processed as free floating but are attached to a poly-L-lysine coated microscopic glasses.

Background CART (cocaine- and amphetamine-regulated transcript) peptide and cholecystokinin (CCK) are neuromodulators involved in feeding behavior. This study is based on previously found synergistic effect of leptin and CCK on food intake and our hypothesis on a co-operation of the CART peptide and CCK in food intake regulation and Fos activation in their common targets, the nucleus tractus solitarii of the brainstem (NTS), the paraventricular nucleus (PVN), and the dorsomedial nucleus (DMH) of the hypothalamus. Results In fasted C57BL/6 mice, the anorexigenic effect of CART(61-102) in the doses of 0.1 or 0.5 μg/mouse was significantly enhanced by low doses of CCK-8 of 0.4 or 4 μg/kg, while 1 mg/kg dose of CCK-A receptor antagonist devazepide blocked the effect of CART(61-102) on food intake. After simultaneous administration of 0.1 μg/mouse CART(61-102) and of 4 μg/kg of CCK-8, the number of Fos-positive neurons in NTS, PVN, and DMH was significantly higher than after administration of each particular peptide. Besides, CART(61-102) and CCK-8 showed an additive effect on inhibition of the locomotor activity of mice in an open field test. Conclusion The synergistic and long-lasting effect of the CART peptide and CCK on food intake and their additive effect on Fos immunoreactivity in their common targets suggest a co-operative action of CART peptide and CCK which could be related to synergistic effect of leptin on CCK satiety.