Forms of selenium in vitamin-mineral mixes differentially affect the expression of genes responsible for prolactin, ACTH, and α-MSH synthesis and mitochondrial dysfunction in pituitaries of steers grazing endophyte-infected tall fescue.

The goal of this study was to test the hypothesis that sodium selenite (inorganic Se, ISe), SEL-PLEX (organic forms of Se, OSe), vs. a 1:1 blend (MIX) of ISe and OSe in a basal vitamin-mineral (VM) mix would differentially alter pituitary transcriptome profiles in growing beef steers grazing an endophyte-infected tall fescue (E+) pasture. Predominately Angus steers (BW = 183 ± 34 kg) were randomly selected from fall-calving cows grazing E+ pasture and consuming VM mixes that contained 35 ppm Se as ISe, OSe, or MIX forms. Steers were weaned, depleted of Se for 98 d, and subjected to summer-long common grazing of a 10.1 ha E+ pasture containing 0.51 ppm ergot alkaloids. Steers were assigned (n = 8 per treatment) to the same Se-form treatments on which they were raised. Selenium treatments were administered by daily top-dressing 85 g of VM mix onto 0.23 kg soyhulls, using in-pasture Calan gates. As previously reported, serum prolactin was greater for MIX (52%) and OSe (59%) steers vs. ISe. Pituitaries were collected at slaughter and changes in global and selected mRNA expression patterns determined by microarray and real-time reverse transcription PCR analyses, respectively. The effects of Se treatment on relative gene expression were subjected to one-way ANOVA. The form of Se affected the expression of 542 annotated genes (P < 0.005). Integrated pathway analysis found a canonical pathway network between prolactin and pro-opiomelanocortin (POMC)/ACTH/α-melanocyte-stimulating hormone (α-MSH) synthesis-related proteins and that mitochondrial dysfunction was a top-affected canonical pathway. Targeted reverse transcription-PCR analysis found that the relative abundance of mRNA encoding prolactin and POMC/ACTH/α-MSH synthesis-related proteins was affected (P < 0.05) by the form of Se, as were (P ≤ 0.05) mitochondrial dysfunction-related proteins (CYB5A, FURIN, GPX4, and PSENEN). OSe steers appeared to have a greater prolactin synthesis capacity (more PRL mRNA) vs. ISe steers through decreased dopamine type two receptor signaling (more DRD2 mRNA), whereas MIX steers had a greater prolactin synthesis capacity (more PRL mRNA) and release potential by increasing thyrotropin-releasing hormone concentrations (less TRH receptor mRNA) than ISe steers. OSe steers also had a greater ACTH and α-MSH synthesis potential (more POMC, PCSK2, CPE, and PAM mRNA) than ISe steers. We conclude that form of Se in VM mixes altered expression of genes responsible for prolactin and POMC/ACTH/α-MSH synthesis, and mitochondrial function, in pituitaries of growing beef steers subjected to summer-long grazing an E+ pasture.

LXR activation increases the expression of GnRH AND αMSH in the rat hypothalamus in vivo.

Liver X receptors (LXR) are important transcription factors involved in the regulation of carbohydrate and lipid metabolism. Recently, we described LXR receptors expression in the hypothalamus but their function in this brain area remains unknown. Here, we evaluated the function of LXR on the expression of factors produced in the hypothalamus in vitro and in vivo by Western blotting and immunocytochemistry. More precisely we studied the expression of GnRH and GHRH, αMSH and NPY in male Sprague-Dawley rats. The effects of two synthetic LXR agonists, T0901317 and GW3965, were first tested in vitro. Hypothalamic explants were treated with either T0901317 or GW3965 (10µM) for 2, 4, 6 and 8h. As a positive control the cholesterol ABCA1 and glucose GLUT2 transporters were used. No changes were observed in the expression of the factors evaluated in vitro. The effects of the LXR agonists were then tested in vivo. Rats were injected ICV into the third ventricle with either T0901317 or GW3965 (2.5µg/5µL ICV) and after 3.5h or 24h the hypothalami were dissected out and rapidly frozen for analysis. αMSH and GnRH expression was significantly increased after 3.5h of T0901317 treatment. Anterior/posterior hypothalamic ratio increases for αMSH expression and decreases for GnRH expression after 24h of LXR activation. Altogether these results show that LXR activation affects the expression of GnRH and αMSH, suggesting that LXR in the hypothalamus is capable of modulating hypothalamic responses related to appetite, sexual behavior and reproductive functions.

Photoprotective and antioxidant effects of Rhubarb: inhibitory action on tyrosinase and tyrosine kinase activities and TNF-α, IL-1α and α-MSH production in human melanocytes.

BACKGROUND: Exposure to ultraviolet (UV) radiation causes various forms of acute and chronic skin damage, including immunosuppression, inflammation, premature aging and photodamage. Furthermore, it induces the generation of reactive oxygen species, produces proinflammatory cytokines and melanocyte-stimulating hormone (MSH) and increases tyrosinase activity. The aim of this study was to evaluate the potential photoprotective effects of Rheum rhaponticum L. rhizome extract on human UV-stimulated melanocytes. METHODS: The effects of Rheum rhaponticum rhizome extract on tyrosine kinase activity, and on interleukin-1α (IL-1α), tumour necrosis factor α (TNF-α), and α-MSH production in human epidermal melanocytes were evaluated under UV-stimulated and non-stimulated conditions. Antioxidant activity was evaluated by lipid peroxidation and 1,1-dyphenyl-2-picryl-hydrazyl (DPPH) assays, while anti-tyrosinase activity was evaluated by the mushroom tyrosinase method. RESULTS: Rheum rhaponticum L. rhizome extract showed in vitro antioxidant properties against lipid peroxidation, free radical scavenging and anti-tyrosinase activities, and inhibited the production of IL-1α, TNF-α, α-MSH, and tyrosine kinase activity in melanocytes subjected to UV radiation. CONCLUSIONS: These results support the inclusion of Rheum rhaponticum L. rhizome extract into cosmetic, sunscreen and skin care products for the prevention or reduction of photodamage.

Evidence for possible period 2 gene mediation of the effects of alcohol exposure during the postnatal period on genes associated with maintaining metabolic signaling in the mouse hypothalamus.

BACKGROUND: Animals exposed to alcohol during the developmental period develop circadian disturbances and metabolic problems that often persist during their adult period. In order to study whether alcohol and the circadian clock interact to alter metabolic signaling in the hypothalamus, we determined whether postnatal alcohol feeding in mice permanently alters metabolic sensing in the hypothalamus. Furthermore, we evaluated whether the effect of circadian disruption via Period 2 (Per2) gene mutation prevents alcohol's effects on metabolic signaling in the hypothalamus. METHODS: Per2 mutant and wild-type male and female mice of the same genetic background were given a milk formula containing ethanol (EtOH; 11.34% vol/vol) from postnatal day (PD) 2 to 7 and used for gene expression and peptide level determinations in the hypothalamus at PD7 and PD90. RESULTS: We report here that postnatal alcohol feeding reduces the expression of proopiomelanocortin (Pomc) gene and production of ß-endorphin and α-melanocyte stimulating hormone (α-MSH) in the hypothalamus that persists into adulthood. In addition, expressions of metabolic sensing genes in the hypothalamus were also reduced as a consequence of postnatal alcohol exposure. These effects were not sex-specific and were observed in both males and females. Mice carrying a mutation of the Per2 gene did not show any reductions in hypothalamic levels of Pomc and metabolic genes and ß-endorphin and α-MSH peptides following alcohol exposure. CONCLUSIONS: These data suggest that early-life exposure to alcohol alters metabolic sensing to the hypothalamus possibly via regulating Per2 gene and/or the cellular circadian clock mechanism.

Autophagy in hypothalamic AgRP neurons regulates food intake and energy balance.

Macroautophagy is a lysosomal degradative pathway that maintains cellular homeostasis by turning over cellular components. Here we demonstrate a role for autophagy in hypothalamic agouti-related peptide (AgRP) neurons in the regulation of food intake and energy balance. We show that starvation-induced hypothalamic autophagy mobilizes neuron-intrinsic lipids to generate endogenous free fatty acids, which in turn regulate AgRP levels. The functional consequences of inhibiting autophagy are the failure to upregulate AgRP in response to starvation, and constitutive increases in hypothalamic levels of pro-opiomelanocortin and its cleavage product α-melanocyte-stimulating hormone that typically contribute to a lean phenotype. We propose a conceptual framework for considering how autophagy-regulated lipid metabolism within hypothalamic neurons may modulate neuropeptide levels to have immediate effects on food intake, as well as long-term effects on energy homeostasis. Regulation of hypothalamic autophagy could become an effective intervention in conditions such as obesity and the metabolic syndrome.

Electroacupuncture in the treatment of obesity.

Obesity is becoming one of the most common health problems in the world. Many other disorders, such as hypertension and diabetes are considered as the consequences of obesity. Since effective remedies are rare (only two drugs, Orlistat and Sibutramine, were officially approved by the US Food and Drug Administration for long-term obesity treatment so far), researchers are trying to discover new therapies for obesity, and acupuncture is among the most popular alternative approaches. To facilitate weight reduction, one can use manual acupuncture, electroacupuncture (EA) or transcutaneous electrical acupoint stimulation (TEAS). As the parameters of the EA or TEAS can be precisely characterized and the results are more or less reproducible, this review will focus on EA as a treatment modality for obesity. Results obtained in this laboratory in recent five years will be summarized in some detail.

Effects of fluoxetine administration on hypothalamic melanocortin system in obese Zucker rats.

The aim of the present work was to study the potential involvement of melanocortin system in the anorectic mechanism of fluoxetine, a selective serotonin reuptake inhibitors, in obese Zucker rats. Male obese Zucker (fa/fa) rats were administered fluoxetine (10 mg/kg; i.p.) daily for two weeks. The control group was given 0.9% NaCl solution. RT-PCR for pro-opiomelanocortin (POMC), Agouti gene related peptide (AgRP) and melanocortin receptor 4 (MC4-R) in the hypothalamus, as well as regional immunostaining for alpha-melanocyte stimulating hormone (alpha-MSH) and MC4-R were carried out. Fluoxetine administration increased POMC expression and reduced MC4-R expression in the hypothalamus, without changes in AgRP mRNA levels. Moreover, an increase in the numbers of alpha-MSH positively immunostained neural cells in the hypothalamic arcuate nucleus (ARC), as well as a significant decrease in the numbers of neural cells positively immunostained for MC4-R in the paraventricular nucleus (PVN), without changes in lateral hypothalamic area (LHA), were observed. These results suggest the involvement of alpha-MSH in central fluoxetine anorectic action.

Conserved neurochemical pathways involved in hypothalamic control of energy homeostasis.

The melanocortin system, which includes alpha-melanocyte-stimulating hormone (alpha-MSH) and its endogenous antagonist, agouti-related protein (AgRP), is fundamental for the central control of energy homeostasis in mammals. Recent studies have demonstrated that many neuropeptides involved in the control of ingestive behavior and energy expenditure, including melanocortins, are also expressed and functional in teleost fishes. To test the hypothesis that the underlying neural pathways involved in energy homeostasis are conserved throughout vertebrate evolution, the neuroanatomical distribution of alpha-MSH in relation to AgRP was mapped in a teleost (zebrafish, Danio rerio) by double-label immunocytochemistry. Zebrafish alpha-MSH- and AgRP-immunoreactive (ir) cells are found in discrete populations in the ventral periventricular hypothalamus, the proposed arcuate homologue in teleosts. Major ascending projections are similar for both peptides, and dense ir-fibers innervate preoptic and ventral telencephalic nuclei homologous to paraventricular, lateral septal, and amygdala nuclei in mammals. Furthermore, alpha-MSH and AgRP-ir somata and fibers are pronounced at 5 days post fertilization when yolk reserves are depleted and larvae begin to feed actively, which supports the functional significance of these peptides for feeding behavior. The conservation of melanocortin peptide function and projection pathways further support zebrafish as an excellent genetic model system to investigate basic mechanisms involved in the central regulation of energy homeostasis.

Effect of centrally administered neuropeptide Y on hypothalamic and hypophyseal proopiomelanocortin-derived peptides in the rat.

In a previous study, we have shown that neuropeptide Y inhibits the release of alpha-melanocyte-stimulating hormone from the rat hypothalamus in vitro. The aim of the present study was to investigate the possible effect of neuropeptide Y on the regulation of proopiomelanocortin-derived peptides in vivo. Rats received acute or chronic administration of neuropeptide Y in the lateral ventricle and the amount of alpha-melanocyte-stimulating hormone was measured in the hypothalamus and in the neurointermediate lobe of the pituitary. In the same experiments, the amounts of corticotropin-releasing factor and corticotropin were quantified in the hypothalamus and anterior pituitary, respectively. Acute treatment with synthetic neuropeptide Y (0.1 to 10 micrograms/rat) did not modify the amount of alpha-melanocyte-stimulating hormone in the hypothalamus. In contrast, chronic infusion of neuropeptide Y (1.25 micrograms/h) over a seven day period significantly decreased the hypothalamic content of alpha-melanocyte-stimulating hormone, suggesting that neuropeptide Y regulates the synthesis and/or the processing of proopiomelanocortin. Concurrently, we found that both acute and chronic infusion of neuropeptide Y induced a significant reduction in corticotropin-releasing factor in the hypothalamus as well as a significant decrease in alpha-melanocyte-stimulating hormone and corticotropin in the neurointermediate and anterior lobes, respectively. Quantitative in situ hybridization histochemistry showed that chronic administration of neuropeptide Y also caused a reduction of proopiomelanocortin messenger RNA levels both in the intermediate and anterior lobes of the pituitary. Administration of neuropeptide Y (10(-6) M) on perifused rat hypothalamic slices caused a significant increase in corticotropin-releasing factor release.(ABSTRACT TRUNCATED AT 250 WORDS)