The reductions in circulating levels of leptin, insulin, and glucose with fasting serve as important homeostasis signals to neurons of the hypothalamic arcuate nucleus that synthesize neuropeptide Y ...(NPY)/agouti-related protein (AGRP) and α-MSH/cocaine and amphetamine-regulated transcript. Because the central administration of leptin is capable of preventing the inhibitory effects of fasting on TRH mRNA in hypophysiotropic neurons primarily through effects on the arcuate nucleus, we determined whether the continuous administration of 30 mU/d insulin or 648 μg/d glucose into the cerebrospinal fluid by osmotic minipump might also have similar effects on the hypothalamic-pituitary-thyroid axis. As anticipated, the intracerebroventricular infusion of leptin reduced fasting-induced elevations in NPY and AGRP mRNA and increased proopiomelanocortin and cocaine and amphetamine-regulated transcript mRNA in the arcuate nucleus. In addition, leptin prevented fasting-induced reduction in pro-TRH mRNA levels in the paraventricular nucleus and in circulating thyroid hormone levels. In contrast, whereas insulin increased proopiomelanocortin mRNA and both insulin and glucose reduced NPY mRNA in arcuate nucleus neurons, neither prevented the fasting-induced suppression in hypophysiotropic TRH mRNA or circulating thyroid hormone levels. We conclude that insulin and glucose only partially replicate the central effects of leptin and may not be essential components of the hypothalamic-pituitary-thyroid regulatory system during fasting.
TRH and CRH are secreted into the hypophysial portal circulation by hypophysiotropic neurons located in parvicellular subdivisions of the hypothalamic paraventricular nucleus (PVH). Recently these ...anatomical compartments of the PVH have been shown to contain large numbers of glutamatergic neurons expressing type 2 vesicular glutamate transporter (VGLUT2). In this report we presented dual-label in situ hybridization evidence that the majority (>90%) of TRH and CRH neurons in the PVH of the adult male rat express the mRNA encoding VGLUT2. Dual-label immunofluorescent studies followed by confocal laser microscopic analysis of the median eminence also demonstrated the occurrence of VGLUT2 immunoreactivity within TRH and CRH axon varicosities, suggesting terminal glutamate release from these neuroendocrine systems. These data together indicate that the hypophysiotropic TRH and CRH neurons possess glutamatergic characteristics. Future studies will need to address the physiological significance of the endogenous glutamate content in these neurosecretory systems in the neuroendocrine regulation of thyroid and adrenal functions.
To determine whether endotoxin-induced activation of type 2 iodothyronine deiodinase (D2) in the mediobasal hypothalamus is dependent on circulating levels of corticosterone, the effect of bacterial ...lipopolysaccharide (LPS) on D2 gene expression was studied in adrenalectomized, corticosterone-clamped adult, male, Sprague Dawley rats. In sham-adrenalectomized animals, LPS (250 μg/100 g body weight) increased circulating levels of corticosterone and IL-6, as well as tanycyte D2 mRNA in the mediobasal hypothalamus. Adrenalectomized, corticosterone-clamped animals showed no significant rise in corticosterone after LPS, compared with saline-treated controls but increased IL-6 levels and tanycyte D2 mRNA similar to LPS-treated sham controls. To further clarify the potential role of corticosterone in the regulation of D2 gene expression by LPS, animals were administered high doses of corticosterone to attain levels similar to that observed in the LPS-treated group. No significant increase in D2 mRNA was observed in the mediobasal hypothalamus with the exception of a small subpopulation of cells in the lateral walls of the third ventricle. These data indicate that the LPS-induced increase in D2 mRNA in the mediobasal hypothalamus is largely independent of circulating corticosterone and indicate that mechanisms other than adrenal activation are involved in the regulation of most tanycyte D2-expressing cells by endotoxin.
Because α-MSH has a potent stimulatory action on hypophysiotropic TRH synthesizing neurons in the hypothalamic paraventricular nucleus (PVN), preventing the effects of fasting on the gene expression ...of the TRH prohormone (proTRH), we hypothesized that agouti-related protein (AGRP), a melanocortin receptor antagonist, may exert a central inhibitory action on these neurons. To test the hypothesis, the effects of intracerebroventricularly administered AGRP on circulating thyroid hormone levels and proTRH mRNA in the hypothalamic paraventricular nucleus (PVN) were compared with the effects of the recently described central inhibitor of the HPT axis, neuropeptide Y (NPY). AGRP administration increased food consumption and weight gain, suppressed circulating levels of thyroid hormones (T3 and T4), and resulted in an inappropriately normal TSH. These alterations were associated with a significant suppression of proTRH mRNA in the PVN, indicating that AGRP infusion resulted in a state of central hypothyroidism. While similar observations were made in the NPY-infused animals, AGRP-treated animals had higher feeding efficiency, higher T4 levels, and lower type 2 iodothyronine deiodinase levels in brown adipose tissue than NPY-infused animals. These data demonstrate that AGRP and NPY have a similarly potent inhibitory action on the proTRH gene expression of hypophysiotropic neurons, indicating that both AGRP and NPY may play a major role in the inhibition of the HPT axis during fasting.
Although certain rare actinomycetes have been recognized as prolific sources of bioactive natural products, their potential for producing biologically active metabolites still remains unexplored. ...With the aim of gaining global insights into the genetic background and the metabolic capability of Saccharomonospora azurea SZMC 14600, whole-genome sequencing was performed.
Hypophysiotropic TRH-synthesizing neurons of the hypothalamic paraventricular nucleus (PVN) have a critical role in the regulation of the energy homeostasis through control of the ...hypothalamic-pituitary-thyroid axis. Recently, endocannabinoids have been shown to exert inhibitory effects on TRH neurons via the type 1 cannabinoid receptor (CB1). To understand the anatomical basis for this regulatory mechanism, we determined whether CB1 is contained in axons innervating hypophysiotropic TRH neurons using a recently developed antiserum against the C-terminal portion of mouse CB1. CB1-immunoreactive axons densely innervated the parvicellular subdivisions of the PVN where the hypophysiotropic TRH neurons are located. By double-labeling immunocytochemistry, CB1-immunoreactive varicosities were observed in juxtaposition to the vast majority of TRH neurons in the PVN. At the ultrastructural level, CB1-immunoreactivity was observed in the preterminal portion of axons establishing both symmetric and asymmetric synaptic specializations with the perikarya and dendrites of TRH neurons in the PVN. These data demonstrate that CB1 is abundantly present in axons that are in synaptic association with hypophysiotropic TRH neurons, indicating an important role for endocannabinoids in the regulation of the hypothalamic-pituitary-thyroid axis. The presence of both symmetric and asymmetric type CB1 synapses on TRH neurons in the PVN suggests that endocannabinoids may influence both excitatory and inhibitory inputs of these neurons.
Type 1 cannabinoid receptor-containing axons establish both symmetric- and asymmetric-type synapses with hypophysiotropic TSH-releasing hormone neurons, suggesting that the endocannabinoid system is involved in the regulation of the hypothalamic–pituitary–thyroid axis.
Microbiological characterization of stable resuspended dust Kováts, Nora; Horváth, Eszter; Jancsek-Turóczi, Beatrix ...
International Journal of Occupational Medicine and Environmental Health,
01/2016, Letnik:
29, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Air quality in the stables is characterized by elevated level of dust and aeroallergens which are supposed to directly cause or exacerbate several respiratory disorders. The most often recognized ...problem is recurrent airway obstruction (RAO), previously known as chronic obstructive pulmonary disease (COPD). There is some indication that aeroallergens (among them endotoxins) may also cause inflammation in human airways and may exceed safe levels in stables. Monitoring studies have covered mainly the determination of the concentration of respirable particles and of culturable fungi and their toxins. However, these particles do not only directly affect the respiratory system, but might act as a carrier conveying toxic contaminants and biological agents such as bacteria. In a typical, 20-horse Hungarian stable, microbial community of respirable fraction of resuspended dust has been characterized to reveal if these particles convey hazardous pathogenic bacteria, posing risk to either horses or staff.
Resuspended dust was sampled using a mobile instrument. The instrument contains a PARTISOL-FRM model 2000 sampler that was operated at a flow rate of 16.7 l/min and a cyclone separator which collected the particulate matter with an aerodynamic size between 1 μm and 10 μm (PM1-10) fraction. Microbial taxa were identified by culture-independent next generation sequencing (NGS) of variable 16S ribosomal ribonucleic acid (rRNA) gene regions.
In total, 1491 different taxa were identified, of them 384 were identified to species level, 961 to genus level. The sample was dominated by common ubiquitous soil and organic material-dwelling taxa.
Pathogens occurred at low abundance, and were represented by mostly facultative human pathogens, with the prevalence of Staphylococcus species.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The origin of neuropeptide Y (NPY) afferents to GnRH neurons was investigated in male mice. Neonatal lesioning of the hypothalamic arcuate nuclei (ARC) with monosodium glutamate markedly reduced the ...number of NPY fibers in the preoptic area as well as the frequency of their contacts with perikarya and proximal dendrites of GnRH neurons. Dual-label immunofluorescence studies to determine the precise contribution of the ARC to the innervation of GnRH neurons by NPY axons were carried out on transgenic mice in which enhanced green fluorescent protein was expressed under the control of the GnRH promoter (GnRH-enhanced green fluorescent protein mice). The combined application of red Cy3 and blue AMCA fluorochromogenes established that 49.1 ± 7.3% of NPY axons apposed to green GnRH neurons also contained agouti-related protein (AGRP), a selective marker for NPY axons arising from the ARC. Immunoelectronmicroscopic analysis detected symmetric synapses between AGRP fibers and GnRH-immunoreactive perikarya. Additional triple-fluorescence experiments revealed the presence of dopamine-β-hydroxylase immunoreactivity within 25.4 ± 3.3% of NPY afferents to GnRH neurons. This enzyme marker enabled the selective labeling of NPY pathways ascending from noradrenergic/adrenergic cell populations of the brain stem, thus defining a second important source for NPY-containing fibers regulating GnRH cells. The absence of both topographic markers (AGRP and dopamine-β-hydroxylase) within 26% of NPY contacts suggests that additional sources of NPY fibers to GnRH neurons exist. Future studies will address distinct functions of the two identified NPY systems in the afferent neuronal regulation of the GnRH system.
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