Whole-body metabolism varies across the estrous cycle in Sprague–Dawley rats

Parker, Graham C.; McKee, Michael; Bishop, Christopher; Coscina, Donald V.

doi:10.1016/s0031-9384(01)00599-6

Cited by 28 publications

(17 citation statements)

References 17 publications

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“…OVX rats were 15% heavier than those in the Sham group by wk 2 after surgery. Estrogen deficiency was associated with increased food intake, which has been previously reported in rats and humans (25)(26)(27). Feed intake, feed efficiency (data not shown), and body weight (Tables 2 and 3) of the rats were not affected by dietary level of Ca or CaCO 3 particle size.…”

Section: Resultssupporting

confidence: 74%

Diet Calcium Level but Not Calcium Supplement Particle Size Affects Bone Density and Mechanical Properties in Ovariectomized Rats ,

Shahnazari¹,

Martin²,

Legette³

et al. 2009

The Journal of Nutrition

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Calcium (Ca) supplements, especially Ca carbonate (CaCO3), are the main alternative sources of dietary Ca and an important part of a treatment regimen for osteoporosis, the most common metabolic bone disorder of aging and menopause. In a female ovariectomized (OVX) rat model for studying postmenopausal osteoporosis, we tested the hypothesis that a small compared with a large particle size of CaCO3 (13.0- vs. 18.5-mum geometric diameter) would result in increased Ca balance and subsequently bone mass and that this would be affected by dietary Ca level. We used 6-mo-old rats that were OVX either at 6 or 3 mo of age as models of early or stable menopausal status, respectively. The rats received semipurified diets that contained either 0.4 or 0.2% dietary Ca provided from CaCO3 of 2 particle sizes. A group of Sham-operated rats with intact ovaries served as control and were fed 0.4% dietary Ca from large particles. Estrogen deficiency as a result of ovariectomy had an adverse effect on bone density, mineral content, and bone mechanical properties (P < 0.001). Reducing dietary Ca from 0.4 to 0.2% resulted in significant adverse effects on bone density and mechanical properties (P < 0.001). The particle size of CaCO3 did not affect total Ca balance, bone dual energy X-ray absorptiometry and peripheral quantitative computed tomography indices, bone ash and Ca content, or the mechanical determinants of bone strength. We conclude that a decrease in particle size of CaCO3 to 70% of that typically found in Ca supplements does not provide a benefit to overall Ca metabolism or bone characteristics and that the amount of Ca consumed is of greater influence in enhancing Ca nutrition and skeletal strength.

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Section: Resultssupporting

confidence: 74%

Diet Calcium Level but Not Calcium Supplement Particle Size Affects Bone Density and Mechanical Properties in Ovariectomized Rats ,

Shahnazari¹,

Martin²,

Legette³

et al. 2009

The Journal of Nutrition

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“…cycle-related events associated with this particular hormonal status (14,20,30,35,44). Furthermore, PPO mRNA expression also increased in hypothalamus only during the proestrus afternoon.…”

Section: Discussionmentioning

confidence: 91%

Impact of proestrous milieu on expression of orexin receptors and prepro-orexin in rat hypothalamus and hypophysis: actions of Cetrorelix and Nembutal

Silveyra¹,

Catalano²,

Lux‐Lantos³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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Orexins and their receptors OX1 and OX2 regulate energy balance and the sleep-wake cycle. We studied the expression of prepro-orexin (PPO), OX1, and OX2 in brain and pituitary under the influence of the hormonal status in adult rats. Primarily, PPO, OX1, and OX2 expression was determined in Sprague-Dawley female cycling rats during proestrus and in males. Animals were killed at 2-h intervals. Anterior (AH) and mediobasal (MBH) hypothalamus, anterior pituitary (P), and frontoparietal cortex (CC) were homogenized in TRIzol, and mRNAs were obtained for screening of PPO, OX1, OX2 expression by semiquantitative RT-PCR. Main findings were confirmed and extended to all days of the cycle by quantitative real-time RT-PCR. Hormones and food consumption were determined. Finally, OX1, OX2, and PPO were measured by real-time RT-PCR in tissues collected at 1900 of proestrus after treatments at 1400 with ovulation-blocking agents Cetrorelix or pentobarbital. OX1 and OX2 expression increased at least threefold in AH, MBH, and P, but not in CC, between 1700 and 2300 of proestrus, without variations in estrus, diestrus, or in males. PPO in AH and MBH showed a fourfold or higher increase only during proestrus afternoon. Cetrorelix or pentobarbital prevented increases of OX1 and OX2 only in the pituitary and blunted gonadotropin surges, but left OX1, OX2, and PPO brain expression unchanged. Reproduction, energy balance, and sleep-wake cycle are integrated. Here, we demonstrate that, in the physiological neuroendocrine condition leading to ovulation, information to the orexinergic system acts in hypothalamus and pituitary by different mechanisms.

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“…Mice were then transferred daily to metabolic chambers similar in size to their home cages and for 5 days were allowed to become habituated to the night/dark onset times used during testing. Metabolic testing was performed for 3 h during the mid-light cycle and at the beginning of the dark cycle, as reported for rats (18). Briefly, O 2 consumption and CO 2 production (milliliters per kilogram per hour) were measured using an AccuScan open-circuit calorimeter (Columbus, OH).…”

mentioning

confidence: 99%

“…The O 2 and CO 2 levels were measured sequentially across chambers for the last 30 s of the 5-min sampling periods. Energy expenditure and respiratory quotient (RQ; calculated as the ratio of VCO 2 to VO 2 ) were calculated as previously described (18). Data for the 5-min sampling periods were averaged over three periods to generate the 15-min sampling bins reported here.…”

mentioning

confidence: 99%

Resistance to Diet-Induced Obesity in μ-Opioid Receptor–Deficient Mice

et al. 2005

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Using pharmacological tools, a role for opioid receptors in the regulation of food intake has been documented. However, the involvement of specific receptor subtypes remains questionable, and little information is available regarding a role for opioid receptors in energy metabolism. Using adult male mice lacking the -opioid receptor (MOR) gene (MOR ؊/؊ ), we show that the MOR is not essential for the maintenance of normal levels of ad libitum food intake but does modulate the efficiency of energy storage during high-fat diets through the regulation of energy partitioning. When fed a regular diet, MOR ؊/؊ mice displayed only subtle alterations in energy homeostasis, suggesting a relative overuse of fat as a fuel source in the fed state. When fed a high-fat diet, MOR ؊/؊ mice were resistant to obesity and impaired glucose tolerance, despite having similar energy intake to wild-type mice. This resistance to obesity was associated with a strong induction of the expression of key mitochondrial enzymes involved in fatty acid oxidation within skeletal muscle. This metabolic role of the MOR, which is consistent with the properties of a "thrifty gene," suggests that the MOR pathway is a potential target for pharmacological intervention in the treatment of obesity associated with the intake of fatty diets. Diabetes 54: 3510 -3516, 2005 T he endogenous opioid system encompasses cloned receptor populations (, ␦, and ) and ligands (␤-endorphin, the enkephalins, and the dynorphins). Extensive work indicates that the opioid system plays a role in the regulation of appetite. Opioid receptors and peptides are expressed in sites of the central nervous system that play a role in regulating feeding behavior, and pharmacological experiments using opioid receptor ligands show that agonists promote eating and antagonists decrease food intake, at least in the short term (1-3). Numerous pharmacological studies indicate that opioids also play a role in modulating the rewarding effects of food (3-5). In contrast, little information suggests that opioids have a role in energy metabolism (6 -8).The need to establish the specific role of the opioid receptors in energy homeostasis has led to studies using putative specific opioid receptor ligands or, more recently, antisense probes directed against specific exons of opioid receptor genes (3,9). Pharmacological studies suggest that the and pathways are part of an interconnected brain network and participate in the orexigenic effect of several peptides that regulate food intake (10 -13). However, the interpretation of these data is complicated by our poor knowledge of the in vivo selectivity of ligand-receptor interactions that have been established in vitro (9,14).Recent studies conducted in mutant mice null for the opioid receptors have complemented pharmacological approaches and clarified the role of each receptor in nociception, anxiety, and drug abuse (14). To further define the role of the -opioid receptor (MOR) pathway in energy homeostasis, we characterized mice lacking the MOR gene ...

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Whole-body metabolism varies across the estrous cycle in Sprague–Dawley rats

Cited by 28 publications

References 17 publications

Diet Calcium Level but Not Calcium Supplement Particle Size Affects Bone Density and Mechanical Properties in Ovariectomized Rats ,

Diet Calcium Level but Not Calcium Supplement Particle Size Affects Bone Density and Mechanical Properties in Ovariectomized Rats ,

Impact of proestrous milieu on expression of orexin receptors and prepro-orexin in rat hypothalamus and hypophysis: actions of Cetrorelix and Nembutal

Resistance to Diet-Induced Obesity in μ-Opioid Receptor–Deficient Mice

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