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1.
Parasit Vectors ; 17(1): 211, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38730429

RESUMO

BACKGROUND: The health and productivity of dairy goats continue to be impacted by gastrointestinal nematodes (GIN) and lungworms (LW). Eprinomectin (EPN) is frequently selected for treatment because it is generally effective and does not require a milk withdrawal period. However, some factors, such as lactation, can have an impact on EPN pharmacokinetics and potentially its efficacy. To evaluate whether this can alter the efficacy of Eprecis® 2%, an eprinomectin injectable solution, a study was performed in lactating goats using the dose currently registered in cattle, sheep and goats (0.2 mg/kg). METHODS: This study was a blinded, randomized, controlled trial performed according to the VICH guidelines. Eighteen (18) worm-free lactating goats were included and experimentally challenged on day 28 with a mixed culture of infective gastrointestinal and lung nematode larvae (Haemonchus contortus, Trichostrongylus colubriformis, Teladorsagia circumcincta, Dictyocaulus filaria). At D-1, fecal samples were collected to confirm patent infection in all animals. On D0, the goats were randomly allocated into two groups of nine goats; group 1 was treated with Eprecis® 2% at 0.2 mg/kg BW by subcutaneous injection, while group 2 remained untreated. Fecal samples for egg counts were collected from all animals on days 3, 5, 7, 9, 11 and 14. On D14, all goats were killed, and the abomasum, small intestine and lungs were removed, processed and subsampled to record the number and species of worms. RESULTS: The treatment was well tolerated. After treatment, the arithmetic mean FEC decreased in the treated group and remained < 5 EPG until the end of the study, while the arithmetic mean FEC in the control group remained > 849.0 EPG. At D14, goats in the treated group had very limited or zero total worm counts, whereas all animals from the control group had a high worm burden. The measured efficacy was 100.0% against H. contortus and T. colubriformis, 99.9% against T. circumcincta and 98.0% against D. filaria. CONCLUSIONS: Eprinomectin (Eprecis®, 20 mg/ml), administered at the label dose (0.2 mg/kg), is highly effective against gastrointestinal nematodes and lungworms in lactating goats.


Assuntos
Fezes , Doenças das Cabras , Cabras , Ivermectina , Lactação , Infecções por Nematoides , Animais , Ivermectina/análogos & derivados , Ivermectina/administração & dosagem , Ivermectina/farmacocinética , Ivermectina/uso terapêutico , Doenças das Cabras/tratamento farmacológico , Doenças das Cabras/parasitologia , Feminino , Infecções por Nematoides/veterinária , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Fezes/parasitologia , Lactação/efeitos dos fármacos , Contagem de Ovos de Parasitas/veterinária , Injeções Subcutâneas/veterinária , Anti-Helmínticos/administração & dosagem , Anti-Helmínticos/uso terapêutico , Anti-Helmínticos/farmacocinética , Nematoides/efeitos dos fármacos , Gastroenteropatias/veterinária , Gastroenteropatias/parasitologia , Gastroenteropatias/tratamento farmacológico , Pulmão/parasitologia
2.
FASEB J ; 37(10): e23189, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37713040

RESUMO

A protein altering variant in the gene encoding zinc finger homeobox-3 (ZFHX3) has recently been associated with lower BMI in a human genome-wide association study. We investigated metabolic parameters in mice harboring a missense mutation in Zfhx3 (Zfhx3Sci/+ ) and looked for altered in situ expression of transcripts that are associated with energy balance in the hypothalamus to understand how ZFHX3 may influence growth and metabolic effects. One-year-old male and female Zfhx3Sci/+ mice weighed less, had shorter body length, lower fat mass, smaller mesenteric fat depots, and lower circulating insulin, leptin, and insulin-like growth factor-1 (IGF1) concentrations than Zfhx3+/+ littermates. In a second cohort of 9-20-week-old males and females, Zfhx3Sci/+ mice ate less than wildtype controls, in proportion to body weight. In a third cohort of female-only Zfhx3Sci/+ and Zfhx3+/+ mice that underwent metabolic phenotyping from 6 to 14 weeks old, Zfhx3Sci/+ mice weighed less and had lower lean mass and energy expenditure, but fat mass did not differ. We detected increased expression of somatostatin and decreased expression of growth hormone-releasing hormone and growth hormone-receptor mRNAs in the arcuate nucleus (ARC). Similarly, ARC expression of orexigenic neuropeptide Y was decreased and ventricular ependymal expression of orphan G protein-coupled receptor Gpr50 was decreased. We demonstrate for the first time an energy balance effect of the Zfhx3Sci mutation, likely by altering expression of key ARC neuropeptides to alter growth, food intake, and energy expenditure.


Assuntos
Genes Homeobox , Proteínas de Homeodomínio , Hipotálamo , Mutação de Sentido Incorreto , Animais , Feminino , Masculino , Camundongos , Expressão Gênica , Estudo de Associação Genômica Ampla , Proteínas de Homeodomínio/genética , Hipotálamo/metabolismo , Dedos de Zinco
3.
Artigo em Inglês | MEDLINE | ID: mdl-34682626

RESUMO

Health inequities are systemic, avoidable, and unjust differences in health between populations. These differences are often determined by social and structural factors, such as income and social status, employment and working conditions, or race/racism, which are referred to as the social determinants of health (SDOH). According to public opinion, health is considered to be largely determined by the choices and behaviours of individuals. However, evidence suggests that social and structural factors are the key determinants of health. There is likely a lack of public understanding of the role that social and structural factors play in determining health and producing health inequities. Public opinion and priorities can drive governmental action, so the aim of this work was to determine the most impactful way to increase knowledge and awareness about the social determinants of health (SDOH) and health inequities in the province of Ontario, Canada. A study to test the effectiveness of four different messaging styles about health inequities and the SDOH was conducted with a sample of 805 adult residents of Ontario. Findings show that messages highlighting the challenges faced by those experiencing the negative effects of the SDOH, while still acknowledging individual responsibility for health, were the most effective for eliciting an empathetic response from Ontarians. These findings can be used to inform public awareness campaigns focused on changing the current public narrative about the SDOH toward a more empathetic response, with the goal of increasing political will to enact policies to address health inequities in Ontario.


Assuntos
Racismo , Determinantes Sociais da Saúde , Adulto , Disparidades nos Níveis de Saúde , Humanos , Renda , Ontário , Opinião Pública
4.
Mol Psychiatry ; 26(6): 2263-2276, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-32203157

RESUMO

Excessive alcohol intake is associated with 5.9% of global deaths. However, this figure is especially acute in men such that 7.6% of deaths can be attributed to alcohol intake. Previous studies identified a significant interaction between genotypes of the galanin (GAL) gene with anxiety and alcohol abuse in different male populations but were unable to define a mechanism. To address these issues the current study analysed the human UK Biobank cohort and identified a significant interaction (n = 115,865; p = 0.0007) between allelic variation (GG or CA genotypes) in the highly conserved human GAL5.1 enhancer, alcohol intake (AUDIT questionnaire scores) and anxiety in men. Critically, disruption of GAL5.1 in mice using CRISPR genome editing significantly reduced GAL expression in the amygdala and hypothalamus whilst producing a corresponding reduction in ethanol intake in KO mice. Intriguingly, we also found the evidence of reduced anxiety-like behaviour in male GAL5.1KO animals mirroring that seen in humans from our UK Biobank studies. Using bioinformatic analysis and co-transfection studies we further identified the EGR1 transcription factor, that is co-expressed with GAL in amygdala and hypothalamus, as being important in the protein kinase C (PKC) supported activity of the GG genotype of GAL5.1 but less so in the CA genotype. Our unique study uses a novel combination of human association analysis, CRISPR genome editing in mice, animal behavioural analysis and cell culture studies to identify a highly conserved regulatory mechanism linking anxiety and alcohol intake that might contribute to increased susceptibility to anxiety and alcohol abuse in men.


Assuntos
Bancos de Espécimes Biológicos , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Consumo de Bebidas Alcoólicas/genética , Animais , Ansiedade/genética , Etanol , Masculino , Camundongos , Reino Unido
5.
Soc Work Public Health ; 35(7): 617-632, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32970544

RESUMO

The COVID-19 pandemic has been particularly overwhelming for communities of color in the United States. In addition to the higher levels of underlying health conditions, circumstances related to a history of oppression and unequal access to opportunities and services are apparent. Social service programs will need to be re-developed to accommodate a new reality, both in terms of how people connect with services and how social work professionals provide them. Professional social work organizations' codes of ethics are analyzed, along with the theoretical framework of structural competency. It is an ethical imperative that social welfare policy and practice advance as culturally competent, racial equity, and empowerment-based programs. Child welfare is portrayed as an example where the pandemic could provide an opportunity to learn from the past to construct a more compassionate, competent, and ethical future.


Assuntos
Infecções por Coronavirus/epidemiologia , Pneumonia Viral/epidemiologia , Política Pública , Racismo/ética , Seguridade Social/ética , Serviço Social/ética , Betacoronavirus , COVID-19 , Competência Cultural , Humanos , Pandemias , SARS-CoV-2 , Estados Unidos/epidemiologia
6.
Psychoneuroendocrinology ; 109: 104407, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31445429

RESUMO

The cannabinoid-1 receptor (CB1) plays a critical role in a number of biological processes including nutrient intake, addiction and anxiety-related behaviour. Numerous studies have shown that expression of the gene encoding CB1 (CNR1) is highly dynamic with changes in the tissue specific expression of CNR1 associated with brain homeostasis and disease progression. However, little is known of the mechanisms regulating this dynamic expression. To gain a better understanding of the genomic mechanisms modulating the expression of CNR1 in health and disease we characterised the role of a highly conserved regulatory sequence (ECR1) in CNR1 intron 2 that contained a polymorphism in linkage disequilibrium with disease associated SNPs. We used CRISPR/CAS9 technology to disrupt ECR1 within the mouse genome. Disruption of ECR1 significantly reduced CNR1 expression in the hippocampus but not in the hypothalamus. These mice also displayed an altered sex-specific anxiety-related behavioural profile (open field test), reduced ethanol intake and a reduced hypothermic response following CB1 agonism. However, no significant changes in feeding patterns were detected. These data suggest that, whilst not all of the expression of CNR1 is modulated by ECR1, this highly conserved enhancer is required for appropriate physiological responses to a number of stimuli. The combination of comparative genomics and CRISPR/CAS9 disruption used in our study to determine the functional effects of genetic and epigenetic changes on the activity of tissue-specific regulatory elements at the CNR1 locus represent an important first step in gaining a mechanistic understanding of cannabinoid regulatory pharmacogenetics.


Assuntos
Consumo de Bebidas Alcoólicas/genética , Comportamento Aditivo/genética , Receptor CB1 de Canabinoide/genética , Animais , Ansiedade/genética , Transtornos de Ansiedade/genética , Encéfalo/metabolismo , Canabinoides/genética , Feminino , Predisposição Genética para Doença/genética , Genótipo , Hipocampo/metabolismo , Hipotálamo/metabolismo , Íntrons/genética , Desequilíbrio de Ligação/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Polimorfismo de Nucleotídeo Único/genética , Receptor CB1 de Canabinoide/metabolismo
7.
Physiol Behav ; 207: 41-47, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31034840

RESUMO

This study aimed to determine the relative efficacy of the macronutrients, protein, fat and carbohydrate to induce satiation and satiety in rats in relation to macronutrient activation of neurons in the nucleus of the solitary tract (NTS). Male Sprague Dawley rats were schedule-fed twice a day for 2 h, receiving 100% of daily ad-libitum energy intake. On test day 1, 30 min before the first scheduled meal of the day, rats were gavaged with an 8 kcal isocaloric, isovolumetric solution of a glucose, lipid or peptone macronutrient solution or a non-caloric saline solution. To assess satiation, thirty minutes later rats were given access to food for 2 h and food intake determined. A second 2 h food access period 3 h later was used for assessment of satiety. On the second test day, rats were gavaged as before and killed 90 min after food presentation. Blood was collected for measurement of circulating metabolic markers. Brains were removed for analysis of c-Fos expression by in situ hybridization in the NTS. Rats which received saline consumed a similar amount of food compared to pre-gavage intakes. However, rats gavaged with a caloric macronutrient solution all reduced food intake by 18-20 kcal. Interestingly, the reduction in caloric intake was greater than the caloric value of the macronutrient solution gavaged and was sustained following the second scheduled meal. Quantification by in situ hybridization of c-Fos mRNA expression in the NTS 90 min post-gavage, showed a significant increase with each macronutrient, but was 24-29% higher with a lipid or peptone gavage compared to a glucose gavage. In conclusion, when delivered directly to the stomach, all macronutrients can be equally effective in inducing satiation with significant neuronal activation in the NTS of the hindbrain.


Assuntos
Carboidratos da Dieta/farmacologia , Gorduras na Dieta/farmacologia , Proteínas Alimentares/farmacologia , Saciação/efeitos dos fármacos , Resposta de Saciedade/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Química Encefálica/efeitos dos fármacos , Química Encefálica/genética , Carboidratos da Dieta/administração & dosagem , Gorduras na Dieta/administração & dosagem , Proteínas Alimentares/administração & dosagem , Ingestão de Alimentos , Regulação da Expressão Gênica , Masculino , Refeições , Proteínas Proto-Oncogênicas c-fos/biossíntese , Ratos , Ratos Sprague-Dawley , Núcleo Solitário/citologia , Núcleo Solitário/efeitos dos fármacos , Núcleo Solitário/fisiologia
8.
Appetite ; 117: 234-246, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28687371

RESUMO

Food structure contributes to the induction of satiation and the maintenance of satiety following intake of a meal. There is evidence from human studies that protein-crosslinking of a milk-protein based meal may enhance satiety, but the mechanism underpinning this effect is unknown. We investigated whether a rat model would respond in a similar manner and might provide mechanistic insight into enhanced satiety by structural modification of a food source. Rats were schedule fed a modified AIN-93M based diet in a liquid form or protein-crosslinked to produce a soft-solid form. This was compared to a modified AIN-93M solid diet. Average daily caloric intake was in the order solid > liquid > crosslinked. Body composition was unaltered in the solid group, but there was a loss of fat in the liquid group and a loss of lean and fat tissue in the crosslinked group. Compared to rats fed a solid diet, acute responses in circulating GLP-1, leptin and insulin were eliminated or attenuated in rats fed a liquid or crosslinked diet. Quantification of homeostatic neuropeptide expression in the hypothalamus showed elevated levels of Npy and Agrp in rats fed the liquid diet. Measurement of food intake after a scheduled meal indicated that reduced energy intake of liquid and crosslinked diets is not due to enhancement of satiety. When continuously available ad-libitum, rats fed a liquid diet showed reduced weight gain despite greater 24 h caloric intake. During the dark phase, caloric intake was reduced, but compensated for during the light phase. We conclude that structural modification from a liquid to a solidified state is beneficial for satiation, with less of a detrimental effect on metabolic parameters and homeostatic neuropeptides.


Assuntos
Dieta Redutora , Ingestão de Energia , Hipotálamo/metabolismo , Proteínas do Leite/administração & dosagem , Neurônios/metabolismo , Resposta de Saciedade , Transglutaminases/metabolismo , Proteína Relacionada com Agouti/genética , Proteína Relacionada com Agouti/metabolismo , Animais , Manipulação de Alimentos , Regulação da Expressão Gênica , Peptídeo 1 Semelhante ao Glucagon/sangue , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Insulina/sangue , Insulina/metabolismo , Secreção de Insulina , Leptina/sangue , Leptina/metabolismo , Masculino , Proteínas do Leite/efeitos adversos , Proteínas do Leite/química , Proteínas do Leite/metabolismo , Neuropeptídeo Y/genética , Neuropeptídeo Y/metabolismo , Sobrepeso/sangue , Sobrepeso/dietoterapia , Sobrepeso/metabolismo , Sobrepeso/prevenção & controle , Ratos Sprague-Dawley , Aumento de Peso , Redução de Peso
9.
J Comp Physiol B ; 187(5-6): 857-868, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28365894

RESUMO

Thyroid hormones play an important role in regulating seasonal adaptations of mammals. Several studies suggested that reduced availability of 3,3',5-triiodothyronine (T3) in the hypothalamus is required for the physiological adaptation to winter in Djungarian hamsters. We have previously shown that T3 is involved in the regulation of daily torpor, but it remains unclear, whether T3 affects torpor by central or peripheral mechanisms. To determine the effect of T3 concentrations within the hypothalamus in regulating daily torpor, we tested the hypothesis that low hypothalamic T3 metabolism would favour torpor and high T3 concentrations would not. In experiment 1 gene expression in torpid hamsters was assessed for transporters carrying thyroid hormones between cerebrospinal fluid and hypothalamic cells and for deiodinases enzymes, activating or inactivating T3 within hypothalamic cells. Gene expression analysis suggests reduced T3 in hypothalamic cells during torpor. In experiment 2, hypothalamic T3 concentrations were altered via microdialysis and torpor behaviour was continuously monitored by implanted body temperature transmitters. Increased T3 concentrations in the hypothalamus reduced expression of torpor as well as torpor bout duration and depth. Subsequent analysis of gene expression in the ependymal layer of the third ventricle showed clear up-regulation of T3 inactivating deiodinase 3 but no changes in several other genes related to photoperiodic adaptations in hamsters. Finally, serum analysis revealed that increased total T3 serum concentrations were not necessary to inhibit torpor expression. Taken together, our results are consistent with the hypothesis that T3 availability within the hypothalamus significantly contributes to the regulation of daily torpor via a central pathway.


Assuntos
Hipotálamo/fisiologia , Phodopus/genética , Phodopus/fisiologia , Torpor/fisiologia , Tri-Iodotironina/fisiologia , Animais , Regulação da Expressão Gênica , Masculino , Microdiálise , Tiroxina/sangue , Tiroxina/fisiologia , Tri-Iodotironina/sangue
10.
Sci Rep ; 6: 29689, 2016 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-27406810

RESUMO

In nature Siberian hamsters utilize the decrement in day length following the summer solstice to implement physiological adaptations in anticipation of the forthcoming winter, but also exploit an intrinsic interval timer to initiate physiological recrudescence following the winter solstice. However, information is lacking on the temporal dynamics in natural photoperiod of photoperiodically regulated genes and their relationship to physiological adaptations. To address this, male Siberian hamsters born and maintained outdoors were sampled every month over the course of one year. As key elements of the response to photoperiod, thyroid hormone signalling components were assessed in the hypothalamus. From maximum around the summer solstice (late-June), Dio2 expression rapidly declined in advance of physiological adaptations. This was followed by a rapid increase in Mct8 expression (T3/T4 transport), peaking early-September before gradually declining to minimum expression by the following June. Dio3 showed a transient peak of expression beginning late-August. A recrudescence of testes and body mass occurred from mid-February, but Dio2 expression remained low until late-April of the following year, converging with the time of year when responsiveness to short-day length is re-established. Other photoperiodically regulated genes show temporal regulation, but of note is a transient peak in Gpr50 around late-July.


Assuntos
Regulação da Expressão Gênica/fisiologia , Hipotálamo/metabolismo , Fotoperíodo , Estações do Ano , Hormônios Tireóideos/biossíntese , Animais , Cricetinae , Feminino , Masculino , Phodopus , Hormônios Tireóideos/genética
11.
J Mol Endocrinol ; 56(2): 123-34, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26643910

RESUMO

The Siberian hamster (Phodopus sungorus) survives winter by decreasing food intake and catabolizing abdominal fat reserves, resulting in a sustained, profound loss of body weight. Hypothalamic tanycytes are pivotal for this process. In these cells, short-winter photoperiods upregulate deiodinase 3, an enzyme that regulates thyroid hormone availability, and downregulate genes encoding components of retinoic acid (RA) uptake and signaling. The aim of the current studies was to identify mechanisms by which seasonal changes in thyroid hormone and RA signaling from tanycytes might ultimately regulate appetite and energy expenditure. proVGF is one of the most abundant peptides in the mammalian brain, and studies have suggested a role for VGF-derived peptides in the photoperiodic regulation of body weight in the Siberian hamster. In silico studies identified possible thyroid and vitamin D response elements in the VGF promoter. Using the human neuroblastoma SH-SY5Y cell line, we demonstrate that RA increases endogenous VGF expression (P<0.05) and VGF promoter activity (P<0.0001). Similarly, treatment with 1,25-dihydroxyvitamin D3 increased endogenous VGF mRNA expression (P<0.05) and VGF promoter activity (P<0.0001), whereas triiodothyronine (T3) decreased both (P<0.01 and P<0.0001). Finally, intra-hypothalamic administration of T3 blocked the short day-induced increase in VGF expression in the dorsomedial posterior arcuate nucleus of Siberian hamsters. Thus, we conclude that VGF expression is a likely target of photoperiod-induced changes in tanycyte-derived signals and is potentially a regulator of seasonal changes in appetite and energy expenditure.


Assuntos
Calcitriol/farmacologia , Fatores de Crescimento Neural/metabolismo , Ativação Transcricional , Tri-Iodotironina/fisiologia , Animais , Diferenciação Celular , Linhagem Celular Tumoral , Proliferação de Células , Cricetinae , Expressão Gênica , Humanos , Masculino , Fatores de Crescimento Neural/genética , Phodopus , Regiões Promotoras Genéticas , Tri-Iodotironina/farmacologia
12.
Curr Biol ; 25(22): 2997-3003, 2015 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-26549257

RESUMO

Hypothalamic tanycytes are considered to function as sensors of peripheral metabolism. To facilitate this role, they express a wide range of receptors, including fibroblast growth factor receptor 1 (FGFR1). Using a monoclonal antibody (IMC-H7) that selectively antagonizes the FGFR1c isoform, we investigated possible actions of FGFR1c in a natural animal model of adiposity, the Siberian hamster. Infusion of IMC-H7 into the third ventricle suppressed appetite and increased energy expenditure. Likewise, peripheral treatment with IMC-H7 decreased appetite and body weight and increased energy expenditure and fat oxidation. A greater reduction in body weight and caloric intake was observed in response to IMC-H7 during the long-day fat state as compared to the short-day lean state. This enhanced response to IMC-H7 was also observed in calorically restricted hamsters maintained in long days, suggesting that it is the central photoperiodic state rather than the peripheral adiposity that determines the response to FGFR1c antagonism. Hypothalamic thyroid hormone availability is controlled by deiodinase enzymes (DIO2 and DIO3) expressed in tanycytes and is the key regulator of seasonal cycles of energy balance. Therefore, we determined the effect of IMC-H7 on hypothalamic expression of these deiodinase enzymes. The reductions in food intake and body weight were always associated with decreased expression of DIO2 in the hypothalamic ependymal cell layer containing tanycytes. These data provide further support for the notion the tanycytes are an important component of the mechanism by which the hypothalamus integrates central and peripheral signals to regulate energy intake and expenditure.


Assuntos
Anticorpos Monoclonais/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/antagonistas & inibidores , Adiposidade/fisiologia , Animais , Anticorpos Monoclonais/imunologia , Ritmo Circadiano/fisiologia , Cricetinae , Hipotálamo/metabolismo , Masculino , Modelos Animais , Phodopus , Fotoperíodo , Isoformas de Proteínas/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/imunologia , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/metabolismo , Magreza/metabolismo , Hormônios Tireóideos/metabolismo , Redução de Peso/efeitos dos fármacos
13.
PLoS One ; 8(4): e62003, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23637944

RESUMO

Exposure to short days (SD) induces profound changes in the physiology and behaviour of Siberian hamsters, including gonadal regression and up to 30% loss in body weight. In a continuous SD environment after approximately 20 weeks, Siberian hamsters spontaneously revert to a long day (LD) phenotype, a phenomenon referred to as the photorefractory response. Previously we have identified a number of genes that are regulated by short photoperiod in the neuropil and ventricular ependymal (VE) cells of the hypothalamus, although their importance and contribution to photoperiod induced physiology is unclear. In this refractory model we hypothesised that the return to LD physiology involves reversal of SD expression levels of key hypothalamic genes to their LD values and thereby implicate genes required for LD physiology. Male Siberian hamsters were kept in either LD or SD for up to 39 weeks during which time SD hamster body weight decreased before increasing, after more than 20 weeks, back to LD values. Brain tissue was collected between 14 and 39 weeks for in situ hybridization to determine hypothalamic gene expression. In VE cells lining the third ventricle, expression of nestin, vimentin, Crbp1 and Gpr50 were down-regulated at 18 weeks in SD photoperiod, but expression was not restored to the LD level in photorefractory hamsters. Dio2, Mct8 and Tsh-r expression were altered by SD photoperiod and were fully restored, or even exceeded values found in LD hamsters in the refractory state. In hypothalamic nuclei, expression of Srif and Mc3r mRNAs was altered at 18 weeks in SD, but were similar to LD expression values in photorefractory hamsters. We conclude that in refractory hamsters not all VE cell functions are required to establish LD physiology. However, thyroid hormone signalling from ependymal cells and reversal of neuronal gene expression appear to be essential for the SD refractory response.


Assuntos
Epêndima/metabolismo , Hormônios Hipotalâmicos/biossíntese , Hipotálamo/metabolismo , Iodeto Peroxidase/metabolismo , Fotoperíodo , Estações do Ano , Adaptação Fisiológica , Animais , Peso Corporal/fisiologia , Cricetinae , Iodeto Peroxidase/biossíntese , Masculino , Transportadores de Ácidos Monocarboxílicos/biossíntese , Nestina/biossíntese , Phodopus , Receptor Tipo 3 de Melanocortina/biossíntese , Receptores Acoplados a Proteínas G/biossíntese , Proteínas Celulares de Ligação ao Retinol/biossíntese , Somatostatina/biossíntese , Transcriptoma , Vimentina/biossíntese , Iodotironina Desiodinase Tipo II
14.
Am J Physiol Regul Integr Comp Physiol ; 296(5): R1307-15, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19297543

RESUMO

In the Siberian hamster, seasonal weight loss occurs gradually over many weeks during autumn and winter. This is driven by a regulatory mechanism that is able to integrate duration of exposure to short days (SDs) with the size of body energy reserves. After food restriction in SDs, followed by ad libitum refeeding, body weight of the hamster does not return to its former level; rather, it increases to a level defined by the length of time spent in SDs. In this report, we show that components of the thyroid hormone system that are involved in seasonal weight loss change expression in response to 48 h of starvation. Eight weeks in an SD photoperiod induced weight loss in the Siberian hamster. In the hypothalamus of these hamsters, type II deiodinase expression was decreased and type III deiodinase expression was induced, but there was no change in hypothalamic neuropeptide Y or thyrotropin-releasing hormone gene expression. For the first time, we show that the thyroid hormone transporter monocarboxylate transporter 8 is expressed in tanycytes and is increased in response to an SD photoperiod. Food restriction (48 h of starvation) reversed the direction of gene expression change for type II and III deiodinase and monocarboxylate transporter 8 induced by SD photoperiods. Furthermore, fasting increased neuropeptide Y expression and decreased thyrotropin-releasing hormone expression. VGF, a gene upregulated in SDs in the dorsal region of the medial posterior area of the arcuate nucleus, was not changed by starvation. These data point to a mechanism whereby energy deprivation can interact with an SD photoperiod on hypothalamic tanycytes to regulate components of the thyroid hormone system involved in photoperiodic regulation of seasonal physiology.


Assuntos
Metabolismo Energético/fisiologia , Hipotálamo/metabolismo , Phodopus/fisiologia , Fotoperíodo , Tiroxina/metabolismo , Tri-Iodotironina/metabolismo , Animais , Peso Corporal/fisiologia , Ritmo Circadiano/fisiologia , Cricetinae , Ingestão de Alimentos/fisiologia , Hipotálamo/citologia , Iodeto Peroxidase/metabolismo , Masculino , Modelos Animais , Neuropeptídeo Y/metabolismo , Estações do Ano , Hormônio Liberador de Tireotropina/metabolismo
15.
Brain Res ; 1193: 76-83, 2008 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-18187126

RESUMO

In a previous study performed in mouse models of energetic challenge, there was evidence to suggest that the orphan G protein-coupled receptor GPCR101 may have a role in the regulation of energy balance. To further investigate this possibility, we utilised in situ hybridisation to determine the effect of energetic challenges experienced by pregnant and lactating rats on GPCR101 mRNA expression. In the rat hypothalamus, GPCR101 mRNA expression was detected in a number of hypothalamic nuclei. During pregnancy and lactation, GPCR101 mRNA level remained unchanged in most nuclei, but had increased in the supraoptic nucleus by the end of pregnancy and remained elevated during lactation. GPCR101 mRNA expression showed a similar pattern of expression in the rostral ventromedial parvocellular subdivision of the paraventricular nucleus. A common feature of these two nuclei is the production of the peptide oxytocin. Dual in situ hybridisation revealed GPCR101 and oxytocin mRNA co-expression in neurons of these two nuclei. In the supraoptic nucleus, in situ hybridisation revealed that the temporal regulation of oxytocin and GPCR101 mRNA expression were similar. In the paraventricular nucleus, although temporal changes in oxytocin mRNA expression were similar to GPCR101, the spatial expression of the two mRNA species was different; in contrast to GPCR101, oxytocin mRNA expression changed in both parvo- and magnocellular neurons during lactation. In conclusion, increased GPCR101 mRNA expression in supraoptic and paraventricular nuclei from late pregnancy to late lactation may reflect the functional importance of this receptor in the regulation of neurons of these nuclei during this period.


Assuntos
Regulação da Expressão Gênica/fisiologia , Lactação/metabolismo , Proteínas do Tecido Nervoso/genética , Núcleo Hipotalâmico Paraventricular/fisiologia , Gravidez/metabolismo , RNA Mensageiro/metabolismo , Receptores Acoplados a Proteínas G/genética , Núcleo Supraóptico/fisiologia , Animais , Feminino , Proteínas do Tecido Nervoso/metabolismo , Ocitocina/genética , Ocitocina/metabolismo , Ratos , Receptores Acoplados a Proteínas G/metabolismo , Fatores de Tempo
16.
Endocrinology ; 148(8): 3608-17, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17478556

RESUMO

Seasonal adaptations in physiology exhibited by many animals involve an interface between biological timing and specific neuroendocrine systems, but the molecular basis of this interface is unknown. In this study of Siberian hamsters, we show that the availability of thyroid hormone within the hypothalamus is a key determinant of seasonal transitions. The expression of the gene encoding type III deiodinase (Dio3) and Dio3 activity in vivo (catabolism of T(4) and T(3)) is dynamically and temporally regulated by photoperiod, consistent with the loss of hypothalamic T(3) concentrations under short photoperiods. Chronic replacement of T(3) in the hypothalamus of male hamsters exposed to short photoperiods, thus bypassing synthetic or catabolic deiodinase enzymes located in cells of the ependyma of the third ventricle, prevented the onset of short-day physiology: hamsters maintained a long-day body weight phenotype and failed to undergo testicular and epididymal regression. However, pelage moult to a winter coat was not affected. Type II deiodinase gene expression was not regulated by photoperiod in these hamsters. Collectively, these data point to a pivotal role for hypothalamic DIO3 and T(3) catabolism in seasonal cycles of body weight and reproduction in mammals.


Assuntos
Peso Corporal/fisiologia , Hipotálamo/fisiologia , Reprodução/fisiologia , Estações do Ano , Tiroxina/metabolismo , Tri-Iodotironina/metabolismo , Adaptação Fisiológica/fisiologia , Animais , Ritmo Circadiano/fisiologia , Cricetinae , Ingestão de Alimentos/fisiologia , Metabolismo Energético/fisiologia , Expressão Gênica/fisiologia , Cabelo/fisiologia , Hipotálamo/enzimologia , Iodeto Peroxidase/genética , Iodeto Peroxidase/metabolismo , Masculino , Metabolismo , Fenótipo , Phodopus , Fotoperíodo , Iodotironina Desiodinase Tipo II
17.
J Endocrinol ; 191(3): 687-98, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17170225

RESUMO

Tanycytes in the ependymal layer of the third ventricle act both as a barrier and a communication gateway between the cerebrospinal fluid, brain and portal blood supply to the pituitary gland. However, the range, importance and mechanisms involved in the function of tanycytes remain to be explored. In this study, we have utilized a photoperiodic animal to examine the expression of three unrelated gene sequences in relation to photoperiod-induced changes in seasonal physiology and behaviour. We demonstrate that cellular retinol binding protein [corrected] (CRBP1), a retinoic acid transport protein, GPR50, an orphan G-protein-coupled receptor and nestin, an intermediate filament protein, are down-regulated in short-day photoperiods. The distribution of the three sequences is very similar, with expression located in cells with tanycyte morphology in the region of the ependymal layer where tanycytes are located. Furthermore, CRBP1 expression in the ependymal layer is shown to be independent of a circadian clock and altered testosterone levels associated with testicular regression in short photo-period. Pinealectomy of Siberian hamsters demonstrates CRBP1 expression is likely to be dependent on melatonin output from the pineal gland. This provides evidence that tanycytes are seasonally responsive cells and are likely to be an important part of the mechanism to facilitate seasonal physiology and behaviour in the Siberian hamster.


Assuntos
Epêndima/metabolismo , Proteínas de Filamentos Intermediários/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Phodopus/fisiologia , Fotoperíodo , Receptores Acoplados a Proteínas G/metabolismo , Receptores do Ácido Retinoico/metabolismo , Animais , Biomarcadores/análise , Barreira Hematoencefálica , Cricetinae , Epêndima/citologia , Regulação da Expressão Gênica , Hibridização In Situ/métodos , Masculino , Camundongos , Camundongos Knockout , Nestina , Phodopus/anatomia & histologia , Glândula Pineal/fisiologia , Glândula Pineal/cirurgia , Receptores Acoplados a Proteínas G/análise , Células-Tronco/citologia , Terceiro Ventrículo
18.
Can J Public Health ; 97(3): 202-6, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16827406

RESUMO

BACKGROUND: Gambling is a risky behaviour that involves uncertain financial outcomes, can be addictive, and has been associated with strongly adverse social and public health outcomes. We wanted to assess whether socio-economic and gambling-related-opportunity environments of neighbourhoods affected the uptake of video lottery terminal (VLT) gambling among Montréal youth. METHODS: Spatial and statistical analyses were conducted to examine geographical patterns of neighbourhood socio-economic conditions, VLT sites (n=407), and high school locations (n=305) within the Montréal Census Metropolitan Area (CMA). VLT concentration within high school neighbourhoods was measured to examine how the number of VLT opportunities varies according to socio-economic status of the school neighbourhood. A student survey was analyzed using logistic regression analysis to explore the role of individual (student) characteristics and environmental (neighbourhood) characteristics in predicting the VLT gambling behaviours reported among a sample (n=1206) of high school students. RESULTS: Video lottery gambling opportunities are more prevalent near schools located in socio-economically deprived neighbourhoods compared with schools located in more affluent neighbourhoods. The principal individual risk factors for VLT gambling were shown to be male sex, peer VLT-use, substance use, as well as the after-school routines of youth. INTERPRETATION: The spatial distribution of VLTs reflects local geographies of socio-economic disadvantage and may have a pronounced impact on students attending schools in lower income neighbourhoods, especially those with individual risk factors. Efforts to reduce gambling-related public health costs may want to take into account the socio-spatial distribution of gambling opportunities, particularly in the local environments that youth frequent.


Assuntos
Comportamento Aditivo/epidemiologia , Terminais de Computador/provisão & distribuição , Jogo de Azar , Assunção de Riscos , Instituições Acadêmicas , Estudantes/estatística & dados numéricos , Jogos de Vídeo/provisão & distribuição , Adolescente , Comportamento do Adolescente , Criança , Feminino , Geografia , Humanos , Masculino , Áreas de Pobreza , Quebeque , Características de Residência/classificação , Meio Social , Fatores Socioeconômicos , Estudantes/psicologia , População Urbana
19.
Am J Audiol ; 13(1): 39-53, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15248803

RESUMO

The present study used an independent-group design to compare the benefits provided by binaural, single-channel, linear, full-shell in-the-ear hearing aids and binaural, 2-channel, wide-dynamic-range-compression in-the-canal hearing aids in groups of older hearing aid wearers. Hearing aid outcome measures were obtained at both 1-month (n = 53) and 6-month (n = 34) postfit intervals with each device. Outcome measures included multiple measures of speech-recognition performance and self-report measures of hearing aid benefit, satisfaction, and usage. Aided sound-quality measurements were also obtained. Although both devices provided significant benefits to the wearers, there were no significant differences in the benefits provided by either device at the 1-month or 6-month postfit intervals.


Assuntos
Auxiliares de Audição , Perda Auditiva Neurossensorial/terapia , Idoso , Idoso de 80 Anos ou mais , Desenho de Equipamento , Feminino , Humanos , Modelos Lineares , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Dinâmica não Linear , Seleção de Pacientes , Projetos de Pesquisa , Resultado do Tratamento
20.
Int J Audiol ; 42(7): 432-41, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14582640

RESUMO

This study examined group differences on a variety of measures for three groups of elderly hearing aid candidates matched for gender, age and hearing loss. These three groups were: (1) 26 candidates who declined amplification (non-adherents); (2) 24 individuals who purchased hearing aids, but subsequently returned them (rejected HA); and (3) 26 who purchased hearing aids and continued to use their hearing aids for at least the first 6 months following delivery (accepted HA). Following demonstration of adequate reliability for these measures, using the non-adherents as the test retest study sample, group differences were examined for each pre-fit measure. The group of non-adherents who declined amplification differed from the two groups who purchased hearing aids on their scores for the Hearing Handicap Inventory for the Elderly (HHIE) and for several scales of the Communication Profile for the Hearing Impaired (CPHI) that assessed the individual's personal adjustment to hearing impairment. These findings were generally confirmed for the individual data, with the use of discriminant analysis. For the two groups who tried hearing aids, there were no group differences between those who retained them and those who did not. Discriminant analysis, however, indicated that those in the group who retained their (linear) hearing aids tended to have better finger dexterity and higher loudness discomfort levels than those who did not.


Assuntos
Auxiliares de Audição , Perda Auditiva Neurossensorial/reabilitação , Satisfação do Paciente , Adaptação Fisiológica , Adaptação Psicológica , Idoso , Idoso de 80 Anos ou mais , Audiometria de Tons Puros , Percepção Auditiva , Estudos de Casos e Controles , Comunicação , Análise Discriminante , Feminino , Dedos/fisiologia , Humanos , Leitura Labial , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Satisfação Pessoal , Ajuste de Prótese , Reprodutibilidade dos Testes
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