Effects of β‐hydroxy‐β‐methylbutyrate (HMB) on Muscle IGF‐I and MGF mRNA Expression in Aged Female Rats during 10‐Week Resistance Training

Hypokalemic tubular disorders may lead to growth retardation which is resistant to growth hormone (GH) treatment. The mechanism of these alterations is unknown. Weaning female rats were grouped ( n = 10) in control, potassium-depleted (KD), KD treated with intraperitoneal GH at 3.3 mg·kg−1·day−1 during the last week (KDGH), and control pair-fed with KD (CPF). After 2 wk, KD rats were growth retarded compared with CPF rats, the osseous front advance (±SD) being 67.07 ± 10.44 and 81.56 ± 12.70 μm/day, respectively. GH treatment did not accelerate growth rate. The tibial growth plate of KD rats had marked morphological alterations: lower heights of growth cartilage (228.26 ± 23.58 μm), hypertrophic zone (123.68 ± 13.49 μm), and terminal chondrocytes (20.8 ± 2.39 μm) than normokalemic CPF (264.21 ± 21.77, 153.18 ± 15.80, and 24.21 ± 5.86 μm). GH administration normalized these changes except for the distal chondrocyte height. Quantitative PCR of insulin-like growth factor I (IGF-I), IGF-I receptor, and GH receptor genes in KD growth plates showed downregulation of IGF-I and upregulation of IGF-I receptor mRNAs, without changes in their distribution as analyzed by immunohistochemistry and in situ hybridization. GH did not further modify IGF-I mRNA expression. KD rats had normal hepatic IGF-I mRNA levels and low serum IGF-I values. GH increased liver IGF-I mRNA, but circulating IGF-I levels remained reduced. This study discloses the structural and molecular alterations induced by potassium depletion on the growth plate and shows that the lack of response to GH administration is associated with persistence of the disturbed process of chondrocyte hypertrophy and depressed mRNA expression of local IGF-I in the growth plate.

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Effects of refeeding of undernourished and insulin treatment of diabetic neonatal rats on IGF and IGFBP

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.271.2.e223 ◽

1996 ◽

Vol 271 (2) ◽

pp. E223-E231 ◽

Cited By ~ 6

Author(s):

L. Goya ◽

F. Rivero ◽

M. A. Martin ◽

R. Arahuetes ◽

E. R. Hernandez ◽

...

Keyword(s):

Growth Hormone ◽

Body Weight ◽

Growth Factor ◽

Mrna Expression ◽

Insulin Treatment ◽

Diabetic Rats ◽

Insulin Like Growth Factor ◽

Neonatal Rats ◽

Igf I ◽

Serum Gh

The effect of refeeding and insulin treatment of undernourished and diabetic neonatal rats, respectively, on the regulation of insulin-like growth factor (IGF) and insulin-like growth factor binding protein (IGFBP) was investigated. The changes in body weight, insulinemia, glycemia, serum IGF-I, and growth hormone (GH) as well as the increase of the 30-kDa IGFBP in undernourished and diabetic neonatal rats previously shown elsewhere were reversed by refeeding and insulin treatment, respectively. Also, changes in liver mRNA expression of IGF-I and-II and IGFBP-1 and -2 were restored in refed undernourished and IGF-I and IGFBP-1 levels recovered in insulin-treated diabetic rats. However, serum GH was still below normal after rehabilitation in both situations. Thus the present results support the idea of a GH-independent IGF/ IGFBP regulation mediated by a balance of insulin and nutrients as has already been suggested in previous neonatal studies.

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Peripheral administration of GH induces cell proliferation in the brain of adult hypophysectomized rats

Journal of Endocrinology ◽

10.1677/joe-08-0495 ◽

2009 ◽

Vol 201 (1) ◽

pp. 141-150 ◽

Cited By ~ 42

Author(s):

N David Åberg ◽

Inger Johansson ◽

Maria A I Åberg ◽

Johan Lind ◽

Ulf E Johansson ◽

...

Keyword(s):

Cell Proliferation ◽

Corpus Callosum ◽

Progenitor Cells ◽

Parietal Cortex ◽

Cellular Proliferation ◽

Piriform Cortex ◽

Adult Brain ◽

Female Rats ◽

Igf I

IGF-I treatment has been shown to enhance cell genesis in the brains of adult GH- and IGF-I-deficient rodents; however, the influence of GH therapy remains poorly understood. The present study investigated the effects of peripheral recombinant bovine GH (bGH) on cellular proliferation and survival in the neurogenic regions (subventricular zone (SVZ), and dentate gyrus of the hippocampus), as well as the corpus callosum, striatum, parietal cortex, and piriform cortex. Hypopituitarism was induced in female rats by hypophysectomy, and the rats were supplemented with thyroxine and cortisone acetate. Subsequently, the rats received daily s.c. injections of bGH for either 6 or 28 days respectively. Following 5 days of peripheral bGH administration, the number of bromodeoxyuridine (BrdU)-positive cells was increased in the hippocampus, striatum, parietal cortex, and piriform cortex after 6 and 28 days. In the SVZ, however, BrdU-positive cells increased only after 28 days of bGH treatment. No significant change was observed in the corpus callosum. In the hippocampus, after 28 days of bGH treatment, the number of BrdU/NeuN-positive cells was increased proportionally to increase the number of BrdU-positive cells. 3H-thymidine incorporation in vitro revealed that 24 h of bGH exposure was sufficient to increase cell proliferation in adult hippocampal progenitor cells. This study shows for the first time that 1) peripheral bGH treatment increased the number of newborn cells in the adult brain and 2) bGH exerted a direct proliferative effect on neuronal progenitor cells in vitro.

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Sex-specific vascular responses of the rat aorta: effects of moderate term (intermediate stage) streptozotocin-induced diabetes

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2015-0272 ◽

2016 ◽

Vol 94 (4) ◽

pp. 408-415 ◽

Cited By ~ 3

Author(s):

Xiaoyuan Han ◽

Sonali Shaligram ◽

Rui Zhang ◽

Leigh Anderson ◽

Roshanak Rahimian

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Mrna Expression ◽

Intermediate Stage ◽

Diabetic Rats ◽

Female Rats ◽

Diabetic Rat ◽

Male And Female ◽

Male And Female Rats ◽

Oxide Synthase

Hyperglycemia affects male and female vascular beds differently. We have previously shown that 1 week after the induction of diabetes with streptozotocin (STZ), male and female rats exhibit differences in aortic endothelial function. To examine this phenomenon further, aortic responses were studied in male and female rats 8 weeks after the induction of diabetes (intermediate stage). Endothelium-dependent vasodilation (EDV) to acetylcholine (ACh) was measured in phenylephrine (PE) pre-contracted rat aortic rings. Concentration response curves to PE were generated before and after L-NAME, a nitric oxide synthase (NOS) inhibitor. Furthermore, mRNA expression of endothelial nitric oxide synthase (eNOS) and NADPH oxidase subunit (Nox1) were determined. At 8 weeks, diabetes impaired EDV to a greater extent in female than male aortae. Furthermore, the responsiveness to PE was significantly enhanced only in female diabetic rats, and basal NO, as indicated by the potentiation of the response to PE after L-NAME, was reduced in female diabetic rat aortae to the same levels as in males. In addition, eNOS mRNA expression was decreased, while the Nox1 expression was significantly enhanced in diabetic female rats. These results suggest that aortic function in female diabetic rats after 8 weeks exhibits a more prominent impairment and that NO may be involved.

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Increasing Local Levels of IGF-I mRNA Expression Using Adenoviral Vectors Does Not Alter Oligodendrocyte Remyelination in the CNS of Aged Rats

Molecular and Cellular Neuroscience ◽

10.1006/mcne.2001.1062 ◽

2002 ◽

Vol 19 (1) ◽

pp. 32-42 ◽

Cited By ~ 44

Author(s):

M.T. O'Leary ◽

G.L. Hinks ◽

H.M. Charlton ◽

R.J.M. Franklin

Keyword(s):

Mrna Expression ◽

Adenoviral Vectors ◽

Aged Rats ◽

Igf I ◽

Local Levels

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Exercise and Fasting Activate Growth Hormone Dependent Myocellular STAT5b Phosphorylation and IGF-I mRNA Expression in Humans.

10.1210/endo-meetings.2010.part1.p5.p1-226 ◽

2010 ◽

pp. P1-226-P1-226

Author(s):

MH Vendelbo ◽

N Jessen ◽

JO Jorgensen ◽

N Moller

Keyword(s):

Growth Hormone ◽

Mrna Expression ◽

Igf I

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IGF-I Increases Interferon-γ and IL-6 mRNA Expression and Protein Production in Neonatal Mononuclear Cells

Pediatric Research ◽

10.1203/00006450-199912000-00019 ◽

1999 ◽

Vol 46 (6) ◽

pp. 748-748 ◽

Cited By ~ 29

Author(s):

Wenwei Tu ◽

Pik-To Cheung ◽

Yu-Lung Lau

Keyword(s):

Mrna Expression ◽

Protein Production ◽

Mononuclear Cells ◽

Interferon Γ ◽

Igf I

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Vasopressinergic Activity of the Suprachiasmatic Nucleus and mRNA Expression of Clock Genes in the Hypothalamus-Pituitary-Gonadal Axis in Female Aging

Frontiers in Endocrinology ◽

10.3389/fendo.2021.652733 ◽

2021 ◽

Vol 12 ◽

Author(s):

Angela Cristina Nicola ◽

Larissa Brazoloto Ferreira ◽

Milene Mantovani Mata ◽

Tatiane Vilhena-Franco ◽

Cristiane Mota Leite ◽

...

Keyword(s):

Mrna Expression ◽

Suprachiasmatic Nucleus ◽

Clock Genes ◽

Feedback Loops ◽

Female Rats ◽

Hpg Axis ◽

Physiological Processes ◽

Reproductive Axis ◽

Reproductive Events ◽

Vasopressinergic Neurons

The important involvement of the suprachiasmatic nucleus (SCN) and the activity of vasopressinergic neurons in maintaining the rhythmicity of the female reproductive system depends on the mRNA transcription-translation feedback loops. Therefore, circadian clock function, like most physiological processes, is involved in the events that determine reproductive aging. This study describes the change of mRNA expression of clock genes, Per2, Bmal1, and Rev-erbα, in the hypothalamus-pituitary-gonadal axis (HPG) of female rats with regular cycle (RC) and irregular cycle (IC), and the vasopressinergic neurons activity in the SCN and kisspeptin neurons in the arcuate nucleus (ARC) of these animals. Results for gonadotropins and the cFos/AVP-ir neurons in the SCN of IC were higher, but kisspeptin-ir was minor. Change in the temporal synchrony of the clock system in the HPG axis, during the period prior to the cessation of ovulatory cycles, was identified. The analysis of mRNA for Per2, Bmal1, and Rev-erbα in the reproductive axis of adult female rodents shows that the regularity of the estrous cycle is guaranteed by alternation in the amount of expression of Bmal1 and Per2, and Rev-erbα and Bmal1 between light and dark phases, which ceases to occur and contributes to determining reproductive senescence. These results showed that the desynchronization between the central and peripheral circadian clocks contributes to the irregularity of reproductive events. We suggest that the feedback loops of clock genes on the HPG axis modulate the spontaneous transition from regular to irregular cycle and to acyclicity in female rodents.

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