Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 30
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Mol Metab ; 84: 101950, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38697291

RESUMO

OBJECTIVE: The number of individuals affected by metabolic dysfunction associated fatty liver disease [1] is on the rise, yet hormonal contributors to the condition remain incompletely described and only a single FDA-approved treatment is available. Some studies suggest that the hormones ghrelin and LEAP2, which act as agonist and antagonist/inverse agonist, respectively, for the G protein coupled receptor GHSR, may influence the development of MAFLD. For instance, ghrelin increases hepatic fat whereas synthetic GHSR antagonists do the opposite. Also, hepatic steatosis is less prominent in standard chow-fed ghrelin-KO mice but more prominent in 42% high-fat diet-fed female LEAP2-KO mice. METHODS: Here, we sought to determine the therapeutic potential of a long-acting LEAP2 analog (LA-LEAP2) to treat MAFLD in mice. LEAP2-KO and wild-type littermate mice were fed a Gubra-Amylin-NASH (GAN) diet for 10 or 40 wks, with some randomized to an additional 28 or 10 days of GAN diet, respectively, while treated with LA-LEAP2 vs Vehicle. Various metabolic parameters were followed and biochemical and histological assessments of MAFLD were made. RESULTS: Among the most notable metabolic effects, daily LA-LEAP2 administration to both LEAP2-KO and wild-type littermates during the final 4 wks of a 14 wk-long GAN diet challenge markedly reduced liver weight, hepatic triglycerides, plasma ALT, hepatic microvesicular steatosis, hepatic lobular inflammation, NASH activity scores, and prevalence of higher-grade fibrosis. These changes were accompanied by prominent reductions in body weight, without effects on food intake, and reduced plasma total cholesterol. Daily LA-LEAP2 administration during the final 10 d of a 41.5 wk-long GAN diet challenge also reduced body weight, plasma ALT, and plasma total cholesterol in LEAP2-KO and wild-type littermates and prevalence of higher grade fibrosis in LEAP2-KO mice. CONCLUSIONS: Administration of LA-LEAP2 to mice fed a MAFLD-prone diet markedly improves several facets of MAFLD, including hepatic steatosis, hepatic lobular inflammation, higher-grade hepatic fibrosis, and transaminitis. These changes are accompanied by prominent reductions in body weight and lowered plasma total cholesterol. Taken together, these data suggest that LEAP2 analogs such as LA-LEAP2 hold promise for the treatment of MAFLD and obesity.

3.
Endocrinology ; 165(6)2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38626085

RESUMO

Reducing ghrelin by ghrelin gene knockout (GKO), ghrelin-cell ablation, or high-fat diet feeding increases islet size and ß-cell mass in male mice. Here we determined if reducing ghrelin also enlarges islets in females and if pregnancy-associated changes in islet size are related to reduced ghrelin. Islet size and ß-cell mass were larger (P = .057 for ß-cell mass) in female GKO mice. Pregnancy was associated with reduced ghrelin and increased liver-expressed antimicrobial peptide-2 (LEAP2; a ghrelin receptor antagonist) in wild-type mice. Ghrelin deletion and pregnancy each increased islet size (by ∼19.9-30.2% and ∼34.9-46.4%, respectively), percentage of large islets (>25 µm2×103, by ∼21.8-42% and ∼21.2-41.2%, respectively), and ß-cell mass (by ∼15.7-23.8% and ∼65.2-76.8%, respectively). Neither islet cross-sectional area, ß-cell cross-sectional area, nor ß-cell mass correlated with plasma ghrelin, although all positively correlated with LEAP2 (P = .081 for islet cross-sectional area). In ad lib-fed mice, there was an effect of pregnancy, but not ghrelin deletion, to change (raise) plasma insulin without impacting blood glucose. Similarly, there was an effect of pregnancy, but not ghrelin deletion, to change (lower) blood glucose area under the curve during a glucose tolerance test. Thus, genetic deletion of ghrelin increases islet size and ß-cell cross-sectional area in female mice, similar to males. Yet, despite pregnancy-associated reductions in ghrelin, other factors appear to govern islet enlargement and changes to insulin sensitivity and glucose tolerance in the setting of pregnancy. In the case of islet size and ß-cell mass, one of those factors may be the pregnancy-associated increase in LEAP2.


Assuntos
Grelina , Células Secretoras de Insulina , Ilhotas Pancreáticas , Camundongos Knockout , Animais , Grelina/metabolismo , Feminino , Gravidez , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Camundongos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Tamanho do Órgão/efeitos dos fármacos , Peptídeos Catiônicos Antimicrobianos , Insulina/metabolismo , Insulina/sangue , Glicemia/metabolismo
4.
Nat Rev Endocrinol ; 20(4): 228-238, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38123819

RESUMO

Despite the growing popular interest in sleep and diet, many gaps exist in our scientific understanding of the interaction between circadian rhythms and metabolism. In this Review, we explore a promising, bidirectional role for ghrelin in mediating this interaction. Ghrelin both influences and is influenced by central and peripheral circadian systems. Specifically, we focus on how ghrelin impacts outputs of circadian rhythm, including neuronal activity, circulating growth hormone levels, locomotor activity and eating behaviour. We also consider the effects of circadian rhythms on ghrelin expression and the consequences of disrupted circadian patterns, such as shift work and jet lag, on ghrelin secretion. Our Review is aimed at both the casual reader interested in gaining more insight into the scientific context surrounding the trending topics of sleep and metabolism, as well as experienced scientists in the fields of ghrelin and circadian biology seeking inspiration and a comprehensive overview of how these fields are related.


Assuntos
Relógios Circadianos , Grelina , Humanos , Grelina/metabolismo , Grelina/farmacologia , Ritmo Circadiano/fisiologia , Comportamento Alimentar/fisiologia , Dieta , Síndrome do Jet Lag
5.
J Clin Invest ; 133(24)2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-38099492

RESUMO

Ghrelin exerts key effects on islet hormone secretion to regulate blood glucose levels. Here, we sought to determine whether ghrelin's effects on islets extend to the alteration of islet size and ß cell mass. We demonstrate that reducing ghrelin - by ghrelin gene knockout (GKO), conditional ghrelin cell ablation, or high-fat diet (HFD) feeding - was associated with increased mean islet size (up to 62%), percentage of large islets (up to 854%), and ß cell cross-sectional area (up to 51%). In GKO mice, these effects were more apparent in 10- to 12-week-old mice than in 4-week-old mice. Higher ß cell numbers from decreased ß cell apoptosis drove the increase in ß cell cross-sectional area. Conditional ghrelin cell ablation in adult mice increased the ß cell number per islet by 40% within 4 weeks. A negative correlation between islet size and plasma ghrelin in HFD-fed plus chow-fed WT mice, together with even larger islet sizes in HFD-fed GKO mice than in HFD-fed WT mice, suggests that reduced ghrelin was not solely responsible for diet-induced obesity-associated islet enlargement. Single-cell transcriptomics revealed changes in gene expression in several GKO islet cell types, including upregulation of Manf, Dnajc3, and Gnas expression in ß cells, which supports decreased ß cell apoptosis and/or increased ß cell proliferation. These effects of ghrelin reduction on islet morphology might prove useful when designing new therapies for diabetes.


Assuntos
Células Secretoras de Insulina , Ilhotas Pancreáticas , Camundongos , Animais , Glicemia/metabolismo , Grelina/genética , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Células Secretoras de Insulina/metabolismo , Camundongos Knockout , Dieta Hiperlipídica/efeitos adversos , Camundongos Endogâmicos C57BL
6.
JCI Insight ; 8(24)2023 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-37962950

RESUMO

Previous studies have implicated the orexigenic hormone ghrelin as a mediator of exercise endurance and the feeding response postexercise. Specifically, plasma ghrelin levels nearly double in mice when they are subjected to an hour-long bout of high-intensity interval exercise (HIIE) using treadmills. Also, growth hormone secretagogue receptor-null (GHSR-null) mice exhibit decreased food intake following HIIE and diminished running distance (time until exhaustion) during a longer, stepwise exercise endurance protocol. To investigate whether ghrelin-responsive mediobasal hypothalamus (MBH) neurons mediate these effects, we stereotaxically delivered the inhibitory designer receptor exclusively activated by designer drugs virus AAV2-hSyn-DIO-hM4(Gi)-mCherry to the MBH of Ghsr-IRES-Cre mice, which express Cre recombinase directed by the Ghsr promoter. We found that chemogenetic inhibition of GHSR-expressing MBH neurons (upon delivery of clozapine-N-oxide) 1) suppressed food intake following HIIE, 2) reduced maximum running distance and raised blood glucose and blood lactate levels during an exercise endurance protocol, 3) reduced food intake following ghrelin administration, and 4) did not affect glucose tolerance. Further, HIIE increased MBH Ghsr expression. These results indicate that activation of ghrelin-responsive MBH neurons is required for the normal feeding response to HIIE and the usual amount of running exhibited during an exercise endurance protocol.


Assuntos
Ingestão de Alimentos , Grelina , Camundongos , Animais , Hipotálamo/metabolismo , Neurônios/metabolismo , Camundongos Knockout
8.
Obesity (Silver Spring) ; 31(6): 1644-1654, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37161883

RESUMO

OBJECTIVE: Prader-Willi syndrome (PWS) is a multisystem genetic disorder. Unfortunately, none of several mouse models carrying PWS mutations emulates the entirety of the human PWS phenotype, including hyperphagia plus obesity. METHODS: To determine whether housing at thermoneutrality (TN, 30 °C) permits the development of hyperphagia and obesity in the Snord116del PWS mouse model, the effects of housing three different ages of Snord116del and wild-type (WT) littermates at TN versus room temperature (RT, 22-24 °C) for 8 weeks were compared. RESULTS: Snord116del mice born and maintained at TN exhibited lower body weight curves, lower percentage fat mass, and lower food intake than WT mice at RT. In 4- to 6-month-old high-fat diet-fed female mice, TN raised the Snord116del body weight curve closer to that of RT-housed WT mice although the TN-housed Snord116del mice did not gain more adiposity or exhibit greater food intake. In 6- to 8-month-old high-fat diet-fed male mice, body weight, adiposity, and food intake of TN-housed Snord116del mice remained far below levels in RT-housed WT mice. TN elicited hypotonia in Snord116del adults and exacerbated mortality of Snord116del newborns. CONCLUSIONS: In none of three tested TN protocols were greater food intake, body weight, or adiposity induced in Snord116del mice compared with RT-housed WT mice.


Assuntos
Síndrome de Prader-Willi , Recém-Nascido , Humanos , Adulto , Masculino , Feminino , Animais , Camundongos , Lactente , Síndrome de Prader-Willi/genética , Hiperfagia , Peso Corporal , Obesidade/genética , Adiposidade , Ingestão de Alimentos , Composição Corporal
10.
Endocrinology ; 164(3)2023 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-36423209

RESUMO

In contrast to mammals, birds have a higher basal metabolic rate and undertake wide range of energy-demanding activities. As a consequence, food deprivation for birds, even for a short period, poses major energy challenge. The energy-regulating hypothalamic homeostatic mechanisms, although extensively studied in mammals, are far from clear in the case of birds. We focus on the interplay between neuropeptide Y (NPY) and thyrotropin-releasing hormone (TRH), 2 of the most important hypothalamic signaling agents, in modulating the energy balance in a bird model, the zebra finch, Taeniopygia guttata. TRH neurons were confined to a few nuclei in the preoptic area and hypothalamus, and fibers widely distributed. The majority of TRH neurons in the hypothalamic paraventricular nucleus (PVN) whose axons terminate in median eminence were contacted by NPY-containing axons. Compared to fed animals, fasting significantly reduced body weight, PVN pro-TRH messenger RNA (mRNA) and TRH immunoreactivity, but increased NPY mRNA and NPY immunoreactivity in the infundibular nucleus (IN, avian homologue of mammalian arcuate nucleus) and PVN. Refeeding for a short duration restored PVN pro-TRH and IN NPY mRNA, and PVN NPY innervation to fed levels. Compared to control tissues, treatment of the hypothalamic superfused slices with NPY or an NPY-Y1 receptor agonist significantly reduced TRH immunoreactivity, a response blocked by treatment with a Y1-receptor antagonist. We describe a detailed neuroanatomical map of TRH-equipped elements, identify new TRH-producing neuronal groups in the avian brain, and demonstrate rapid restoration of the fasting-induced suppression of PVN TRH following refeeding. We further show that NPY via Y1 receptors may regulate PVN TRH neurons to control energy balance in T. guttata.


Assuntos
Tentilhões , Hormônio Liberador de Tireotropina , Animais , Masculino , Hormônio Liberador de Tireotropina/genética , Neuropeptídeo Y/metabolismo , Hipotálamo/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , RNA Mensageiro/metabolismo , Mamíferos/genética
11.
J Comp Neurol ; 530(14): 2562-2586, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35715989

RESUMO

Calcium-binding proteins (CBPs) regulate neuronal function in midbrain dopamine (DA)-ergic neurons in mammals by buffering and sensing the intracellular Ca2+ , and vesicular release. In birds, the equivalent set of neurons are important in song learning, directed singing, courtship, and energy balance, yet the status of CBPs in these neurons is unknown. Herein, for the first time, we probe the nature of CBPs, namely, Calbindin-, Calretinin-, Parvalbumin-, and Secretagogin-expressing DA neurons in the ventral tegmental area (VTA) and substantia nigra (SN) in the midbrain of zebra finch, Taeniopygia guttata. qRT-PCR analysis of ventral midbrain tissue fragment revealed higher Calbindin- and Calretinin-mRNA levels compared to Parvalbumin and Secretagogin. Application of immunofluorescence showed CBP-immunoreactive (-i) neurons in VTA (anterior [VTAa], mid [VTAm], caudal [VTAc]), SN (compacta [SNc], and reticulata [SNr]). Compared to VTAa, higher Calbindin- and Parvalbumin-immunoreactivity (-ir), and lower Calretinin-ir were observed in VTAm and VTAc. Secretagogin-ir was highly localized to VTAa. In SN, Calbindin- and Calretinin-ir were higher in SNc, SNr was Parvalbumin enriched, and Secretagogin-ir was not detected. Weak, moderate, and intense tyrosine hydroxylase (TH)-i VTA neurons were demarcated as subtypes 1, 2, and 3, respectively. While subtype 1 TH-i neurons were neither Calbindin- nor Calretinin-i, ∼80 and ∼65% subtype 2 and ∼30 and ∼45% subtype 3 TH-i neurons co-expressed Calbindin and Calretinin, respectively. All TH-i neuronal subtypes co-expressed Parvalbumin with reciprocal relationship with TH-ir. We suggest that the CBPs may determine VTA DA neuronal heterogeneity and differentially regulate their activity in T. guttata.


Assuntos
Tentilhões , Área Tegmentar Ventral , Animais , Calbindina 2/metabolismo , Calbindinas/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Neurônios Dopaminérgicos/metabolismo , Tentilhões/metabolismo , Mamíferos , Parvalbuminas/metabolismo , Proteína G de Ligação ao Cálcio S100/análise , Proteína G de Ligação ao Cálcio S100/metabolismo , Secretagoginas/metabolismo , Substância Negra , Tirosina 3-Mono-Oxigenase/metabolismo , Área Tegmentar Ventral/metabolismo
12.
J Comp Neurol ; 530(11): 1743-1772, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35322425

RESUMO

Secretagogin (scgn), is a novel hexa EF-hand, phylogenetically conserved calcium-binding protein. It serves as Ca2+ sensor and participates in Ca2+ -signaling and neuroendocrine regulation in mammals. However, its relevance in the brain of non-mammalian vertebrates has largely remained unexplored. To address this issue, we studied the cDNA encoding scgn, scgn mRNA expression, and distribution of scgn-equipped elements in the brain and pituitary of a teleost, Clarias batrachus (cb). The cbscgn cDNA consists of three transcripts (T) variants: T1 (2185 bp), T2 (2151 bp) and T3 (2060 bp). While 816 bp ORF in T1 and T2 encodes highly conserved six EF-hand 272 aa protein fully capable of Ca2+ -binding, 726-bp ORF in T3 encodes 242 aa protein. The T1 showed >90% and >70% identity with scgn of catfishes, and other teleosts and mammals, respectively. The T1-mRNA was widely expressed in the brain and pituitary, while the expression of T3 was restricted to the telencephalon. Application of the anti-scgn antiserum revealed a ∼32 kDa scgn-immunoreactive (scgn-i) band (known molecular weight of scgn) in the forebrain tissue, and immunohistochemically labeled neurons in the olfactory epithelium and bulb, telencephalon, preoptic area, hypothalamus, thalamus, and hindbrain. In the pituitary, scgn-i cells were seen in the pars distalis and intermedia. Insulin is reported to regulate scgn mRNA in the mammalian hippocampus, and feeding-related neuropeptides in the telencephalon of teleost. Intracranial injection of insulin significantly increased T1-mRNA expression and scgn-immunoreactivity in the telencephalon. We suggest that scgn may be an important player in the regulation of olfactory, neuroendocrine system, and energy balance functions in C. batrachus.


Assuntos
Peixes-Gato , Secretagoginas , Animais , Peixes-Gato/genética , DNA Complementar/genética , Hipocampo/metabolismo , Insulina/metabolismo , Mamíferos , Prosencéfalo/metabolismo , RNA Mensageiro/metabolismo , Secretagoginas/genética , Secretagoginas/metabolismo
13.
Brain Struct Funct ; 226(8): 2537-2559, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34392422

RESUMO

The mesolimbic dopamine (DA)-pathway regulates food-reward, feeding-related behaviour and energy balance. Evidence underscores the importance of feeding-related neuropeptides in modulating activity of these DA neurons. The neuropeptide, CART, a crucial regulator of energy balance, modulates DA-release, and influences the activity of ventral tegmental area (VTA) DAergic neurons in the mammalian brain. Whether CART- and DA-containing systems interact at the level of VTA to regulate energy balance, however, is poorly understood. We explored the interaction between CART- and DA-containing systems in midbrain of the zebra finch, Taeniopygia guttata, an interesting model to study dynamic changes in energy balance due to higher BMR/daytime body temperature, and rapid responsiveness of the feeding-related neuropeptides to changes in energy state. Further, its midbrain DA-neurons share similarities with those in mammals. In the midbrain, tyrosine hydroxylase-immunoreactive (TH-i) neurons were seen in the substantia nigra (SN) and VTA [anterior (VTAa), mid (VTAm) and caudal (VTAc)]; those in VTA were smaller. In the VTA, CART-immunoreactive (CART-i)-fibers densely innervated TH-i neurons, and both CART-immunoreactivity (CART-ir) and TH-immunoreactivity (TH-ir) responded to energy status-dependent changes. Compared to fed and fasted birds, refeeding dramatically enhanced TH-ir and the percentage of TH-i neurons co-expressing FOS in the VTA. Increased prepro-CART-mRNA, CART-ir and a transient appearance of CART-i neurons was observed in VTAa of fasted, but not fed birds. To test the functional interaction between CART- and DA-containing systems, ex-vivo superfused midbrain-slices were treated with CART-peptide and changes in TH-ir analysed. Compared to control tissues, CART-treatment increased TH-ir in VTA but not SN. We propose that CART is a potential regulator of VTA DA-neurons and energy balance in T. guttata.


Assuntos
Tentilhões , Neuropeptídeos , Animais , Dopamina , Neurônios Dopaminérgicos/metabolismo , Tentilhões/metabolismo , Proteínas do Tecido Nervoso , Neuropeptídeos/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Área Tegmentar Ventral/metabolismo
14.
Mol Metab ; 53: 101327, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34428557

RESUMO

OBJECTIVE: The hormone liver-expressed antimicrobial peptide-2 (LEAP2) is a recently identified antagonist and an inverse agonist of the growth hormone secretagogue receptor (GHSR). GHSR's other well-known endogenous ligand, acyl-ghrelin, increases food intake, body weight, and GH secretion and is lowered in obesity but elevated upon fasting. In contrast, LEAP2 reduces acyl-ghrelin-induced food intake and GH secretion and is found elevated in obesity but lowered upon fasting. Thus, the plasma LEAP2/acyl-ghrelin molar ratio could be a key determinant modulating GHSR signaling in response to changes in body mass and feeding status. In particular, LEAP2 may serve to dampen acyl-ghrelin action in the setting of obesity, which is associated with ghrelin resistance. Here, we sought to determine the metabolic effects of genetic LEAP2 deletion. METHODS: We generated the first known LEAP2-KO mouse line. Food intake, GH secretion, and cellular activation (c-fos induction) in different brain regions following s.c. acyl-ghrelin administration in LEAP2-KO mice and wild-type littermates were determined. LEAP2-KO mice and wild-type littermates were submitted to a battery of tests (such as measurements of body weight, food intake, and body composition; indirect calorimetry, determination of locomotor activity, and meal patterning while housed in metabolic cages) over the course of 16 weeks of high-fat diet and/or standard chow feeding. Fat accumulation was assessed in hematoxylin & eosin-stained and oil red O-stained liver sections from these mice. RESULTS: LEAP2-KO mice were more sensitive to s.c. ghrelin. In particular, acyl-ghrelin acutely stimulated food intake at a dose of 0.5 mg/kg BW in standard chow-fed LEAP2-KO mice while a 2× higher dose was required by wild-type littermates. Also, acyl-ghrelin stimulated food intake at a dose of 1 mg/kg BW in high-fat diet-fed LEAP2-KO mice while not even a 10× higher dose was effective in wild-type littermates. Acyl-ghrelin induced a 90.9% higher plasma GH level and 77.2-119.7% higher numbers of c-fos-immunoreactive cells in the arcuate nucleus and olfactory bulb, respectively, in LEAP2-KO mice than in wild-type littermates. LEAP2 deletion raised body weight (by 15.0%), food intake (by 18.4%), lean mass (by 6.1%), hepatic fat (by 42.1%), and body length (by 1.7%) in females on long-term high-fat diet as compared to wild-type littermates. After only 4 weeks on the high-fat diet, female LEAP2-KO mice exhibited lower O2 consumption (by 13%), heat production (by 9.5%), and locomotor activity (by 49%) than by wild-type littermates during the first part of the dark period. These genotype-dependent differences were not observed in high-fat diet-exposed males or female and male mice exposed for long term to standard chow diet. CONCLUSIONS: LEAP2 deletion sensitizes lean and obese mice to the acute effects of administered acyl-ghrelin on food intake and GH secretion. LEAP2 deletion increases body weight in females chronically fed a high-fat diet as a result of lowered energy expenditure, reduced locomotor activity, and increased food intake. Furthermore, in female mice, LEAP2 deletion increases body length and exaggerates the hepatic fat accumulation normally associated with chronic high-fat diet feeding.


Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Grelina/análogos & derivados , Secretagogos/metabolismo , Animais , Peptídeos Catiônicos Antimicrobianos/deficiência , Peptídeos Catiônicos Antimicrobianos/genética , Dieta Hiperlipídica/efeitos adversos , Feminino , Grelina/administração & dosagem , Grelina/metabolismo , Hormônio do Crescimento , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout
15.
Mol Metab ; 53: 101258, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34023483

RESUMO

OBJECTIVE: Acyl-ghrelin regulates eating, body weight, blood glucose, and GH secretion upon binding to its receptor GHSR (growth hormone secretagogue receptor; ghrelin receptor). GHSR is distributed in several brain regions and some peripheral cell-types including pituitary somatotrophs. The objective of the current study was to determine the functional significance of acyl-ghrelin's action on GHSR-expressing somatotrophs in mediating GH secretion and several of acyl-ghrelin's metabolic actions. METHODS: GH-IRES-Cre mice and loxP-flanked (floxed) GHSR mice were newly developed and then crossed to one another to generate mice that lacked GHSR selectively from somatotrophs. Following validation of mice with somatotroph-selective GHSR deletion, metabolic responses of these mice and control littermates were assessed following both acute and chronic acyl-ghrelin administration, a 24-h fast, and a prolonged 60% chronic caloric restriction protocol modeling starvation. RESULTS: In mice with somatotroph-selective GHSR deletion, a single peripheral injection of acyl-ghrelin failed to induce GH secretion or increase food intake, unlike wild-type and other littermate control groups. However, the usual acute blood glucose increase in response to the acyl-ghrelin bolus was preserved. Similarly, chronic s.c. acyl-ghrelin administration to mice with somatotroph-selective GHSR deletion failed to increase plasma GH, food intake, or body weight. Physiologically elevating plasma acyl-ghrelin via a 24-h fast also failed to raise plasma GH and resulted in a limited hyperphagic response upon food reintroduction in mice with somatotroph-selective GHSR deletion, although those mice nonetheless did not exhibit an exaggerated reduction in blood glucose. Physiologically elevating plasma acyl-ghrelin via a 15-day caloric restriction protocol which provided only 40% of usual daily calories failed to raise plasma GH in mice with somatotroph-selective GHSR deletion, although those mice did not exhibit life-threatening hypoglycemia. CONCLUSIONS: These results reveal that direct engagement of GHSR-expressing somatotrophs is required for a peripheral ghrelin bolus to acutely stimulate GH secretion and the actions of chronic acyl-ghrelin delivery and physiological plasma acyl-ghrelin elevations to increase plasma GH. These results also suggest that actions of acyl-ghrelin to increase food intake and body weight are reliant on direct activation of GHSRs expressed on somatotrophs. Furthermore, these results suggest that the glucoregulatory actions of acyl-ghrelin - in particular, its actions to raise blood glucose when acutely administered, prevent small blood glucose drops following a 24-h fast, and avert life-threatening hypoglycemia during an acute-on-chronic caloric restriction protocol - do not depend on GHSR expression by somatotrophs.


Assuntos
Grelina/metabolismo , Hormônio do Crescimento/metabolismo , Animais , Glicemia/metabolismo , Grelina/análogos & derivados , Camundongos , Receptores de Grelina/deficiência , Receptores de Grelina/genética , Receptores de Grelina/metabolismo
16.
Indian J Psychiatry ; 62(4): 363-369, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33165355

RESUMO

BACKGROUND: There is some information from different developed coutries that mental health services have been badly affected by the COVID-19 pandemic. Little information is available from India. AIM: The aim of this study was to evaluate the impact of lockdown and COVID-19 pandemic on mental health services in India's various training centers. MATERIALS AND METHODS: In an online survey, information was collected from various training centers of India through E-mail or WhatsApp. RESULTS: Responses were received from 109 institutes. The majority of the responses were received from state-funded government medical colleges and private medical colleges. Since the lockdown and COVID-19 pandemic, brain stimulation treatments have completed stopped. Other, most affected services included electroconvulsive therapy, inpatient services, outpatient services, and psychotherapy services. However, there was an expansion of teleconsultations services because of the lockdown and the COVID-19 pandemic. In three-fourth of the centers mental health services were being provided to the patients with COVID-19 infection. In most of the institutes, mental health professionals were involved at different levels in the COVID-19 responsibilities. These included providing helpline services to the general public, screening people in quarantine for mental health issues, providing clinical care to COVID-19 patients, screening health care workers (HCWs) for mental health issues, and training the HCWs. CONCLUSION: COVID-19 pandemic and lockdown have led to the collapse of regular mental health services. The present study also shows that mental health professionals are playing a significant role in addressing the prevailing psychiatric morbidity, specifically related to the COVID-19 related issues, and taking care of the HCWs.

17.
Brain Struct Funct ; 225(9): 2775-2798, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33141294

RESUMO

This study tested the hypothesis whether hypothalamic cocaine-and amphetamine-regulated transcript (CART)-containing systems were involved in photoperiod-induced responses associated with spring migration (hyperphagia and weight gain) and reproduction (gonadal maturation) in migratory songbirds. We specifically chose CART to examine neural mechanism(s) underlying photoperiod-induced responses, since it is a potent anorectic neuropeptide and involved in the regulation of changes in the body mass and reproduction in mammals. We first studied the distribution of CART-immunoreactivity in the hypothalamus of migratory redheaded buntings (Emberiza bruniceps). CART-immunoreactive neurons were found extensively distributed in the preoptic, lateral hypothalamic (LHN), anterior hypothalamic (AN), suprachiasmatic (SCN), paraventricular (PVN), dorsomedialis hypothalami (DMN), inferior hypothalamic (IH), and infundibular (IN) nuclei. Then, we correlated hypothalamic CART-immunoreactivity in buntings with photostimulated seasonal states, particularly winter non-migratory/non-breeding (NMB) state under short days, and spring premigratory/pre-breeding (PMB) and migratory/breeding (MB) states under long days. There were significantly increased CART-immunoreactive cells, and percent fluorescent area of CART-immunoreactivity was significantly increased in all mapped hypothalamic areas, except the SCN, PVN, AN, and DMN in photostimulated PMB and MB states, as compared to the non-stimulated NMB state. In particular, CART was richly expressed in the medial preoptic nucleus, LHN, IH and IN during MB state in which buntings showed reduced food intake and increased night-time activity. These results suggest that changes in the activity of the CART-containing system in different brain regions were associated with heightened energy needs of the photoperiod-induced seasonal responses during spring migration and reproduction in migratory songbirds.


Assuntos
Migração Animal , Proteínas Aviárias/fisiologia , Hipotálamo/fisiologia , Proteínas do Tecido Nervoso/fisiologia , Fotoperíodo , Pardais/fisiologia , Animais , Masculino , Fenótipo , Estações do Ano
18.
Indian J Psychiatry ; 62(5): 488-493, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33678828

RESUMO

BACKGROUND: No information is available about the impact of lockdown and COVID-19 pandemic on the mental health services in the private practice in India. AIM: The current study is aimed to assess the impact of the COVID-19 pandemic and lockdown on the state of Mental Health Services in the Private Sector in India. MATERIALS AND METHODS: An online survey was carried out using the Survey Monkey platform during the period of 1st to 15th May 2020 among the members of the Indian Psychiatric Society. RESULTS: Three hundred and ninety six responses were analysed. There was a reduction in revenue generation by about 70%. All kinds of services, including outpatient services, inpatient services, psychotherapy services, consultation-liaison, and electroconvulsive therapy (ECT) services, were severely affected. One-third of the participants were using the teleservices during the pandemic. The most common problem faced in running the services included modifying the psychological treatment to maintain social distancing, and managing the staff. Besides providing clinical care to the patients, the majority of the mental health professionals reported that they were involved in increasing awareness about the mental health consequences of pandemic and the lockdown and addressing myths related to the spread of infection. CONCLUSION: The pandemic and the lockdown have markedly impacted mental health services in the private sector. ECT services, inpatient services, psychotherapy services and outpatient services are the most affected. However, the COVID-19 pandemic and lockdown have led to the expansion of teleconsultation services.

19.
Pharmacol Biochem Behav ; 188: 172830, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756355

RESUMO

Exposure of NMDA receptor antagonists during developmental stages leads to behavioral consequences like attention deficit hyperactivity disorder (ADHD). However, the underlying molecular mechanisms have remained poorly understood. Herein, we studied the phosphorylated Akt (pAkt) and caspase-3, the key regulators of neuronal cell survival/death, as the probable downstream targets of MK-801 often used to engender ADHD-like condition. Swiss albino mice at postnatal days (PND) 7, 14 or 21 were injected with a single dose of MK-801 and evaluated for hyperactivity (open field test) and memory deficit at adolescence (PND 30) and adult stages (PND 60). PND 7 or 14 treatment groups (but not PND 21) consistently showed hyperactivity at the adolescence stage. A significant increase in working and reference memory errors in radial arm maze was noted at the adolescence age. PND 7 group continued to display the symptoms even in adulthood. All the treatment groups showed a significant decrease in the percent alterations (Y-maze) and discrimination index (novel object recognition test) at adolescence age. A significant increase in caspase-3 expression was noted in the prefrontal cortex (PFC) and hippocampus, whereas increased pAkt was noticed only in the hippocampus, following a single injection of MK-801 at PND 7. Concurrently, PND 7 treatment group showed significantly decreased neuronal nuclei (NeuN) expression (a marker for mature neurons) in the dentate gyrus, cornu ammonis-3 and PFC, but not in cornu ammonis-1, at adolescence age. We suggest that the observed symptoms of ADHD at adolescence and adulthood stages may be linked to alteration in pAkt and caspase-3 followed MK-801 treatment at PND 7.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/metabolismo , Maleato de Dizocilpina/toxicidade , Antagonistas de Aminoácidos Excitatórios/toxicidade , Líquido Intracelular/metabolismo , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/metabolismo , Fatores Etários , Animais , Transtorno do Deficit de Atenção com Hiperatividade/induzido quimicamente , Modelos Animais de Doenças , Feminino , Líquido Intracelular/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Locomoção/fisiologia , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Camundongos , Reconhecimento Psicológico/efeitos dos fármacos , Reconhecimento Psicológico/fisiologia
20.
Neuroscience ; 424: 121-132, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31706959

RESUMO

Thermosensitive transient receptor potential vanilloid (TRPV) channels are widely expressed in the brain and known to profoundly influence Ca2+-signaling, neurotransmitter release and behavior. While these channels are expressed in the cerebellum, neuronal firing and hyperactivity/reflexes seem associated with cerebellar temperature modulation. However, the distribution and functional significance of TRPV-equipped elements in the cerebellum has remained unexplored. Among TRPV sub-family, TRPV3 is regulated by temperature within physiological range and its transcript highly expressed in the brain. The study aims at exploring the relevance of TRPV3 in the cerebellum of developing and adult rat. RT-PCR analysis showed expression of N- and C-terminal fragments of TRPV3 mRNA in the adult rat cerebellum. Using double immunofluorescence, TRPV3-immunoreactivity was observed in Calbindin D28K-labeled Purkinje neurons. The sections of cerebellum from the postnatal rats (P4, P8, P16 and P42) were processed for TRPV3-immunofluorescence. Compared to P4 and P8, the percent fluorescent area of TRPV3-immunoreactivity significantly increased in the cerebellum of P16 and P42 rats. With a view to test the significance of TRPV3 in cerebellar function, TRPV3-agonist (eugenol) or -inhibitors [ruthenium red or isopentenyl pyrophosphate (IPP)] were administered stereotaxically intra-cerebellum and motor responses analyzed. Compared to controls, rats injected with TRPV3 inhibitor significantly reduced the stride length (P < 0.001), locomotor activity (P < 0.001), and rotarod retention time (P < 0.001), but increased footprints length (P < 0.01) and escape latency (P < 0001). TRPV3-agonist treatment, however, had no effect on these behaviors. We suggest that TRPV3 in Purkinje neurons may serve as novel molecular component for Ca2+-signaling and motor coordination function of the cerebellum.


Assuntos
Cerebelo/fisiologia , Locomoção/fisiologia , Destreza Motora/fisiologia , Desempenho Psicomotor/fisiologia , Canais de Cátion TRPV/fisiologia , Animais , Cerebelo/citologia , Cerebelo/efeitos dos fármacos , Eugenol/administração & dosagem , Locomoção/efeitos dos fármacos , Masculino , Destreza Motora/efeitos dos fármacos , Desempenho Psicomotor/efeitos dos fármacos , Células de Purkinje/efeitos dos fármacos , Células de Purkinje/fisiologia , Ratos , Ratos Wistar , Rutênio Vermelho/administração & dosagem , Técnicas Estereotáxicas , Canais de Cátion TRPV/agonistas , Canais de Cátion TRPV/antagonistas & inibidores
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...