Plasma Ghrelin Concentrations Were Altered with Oestrous Cycle Stage and Increasing Age in Reproductively Competent Wistar Females

Johnson, Margaret; Saffrey, M. Jill; Taylor, Victoria

doi:10.1371/journal.pone.0166229

Cited by 6 publications

(10 citation statements)

References 19 publications

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“…This study has also revealed interactions between fed/fasted status and cycle stage on GLP-1 plasma concentrations with increasing age in reproductively competent rats (between 32 and 44 weeks of age), but not on co-secreted PYY. Both fed and fasted total ghrelin (appetite-enhancing) concentrations from these plasma samples [21] were likewise significantly reduced in the slightly older animals. GLP-1 and ghrelin are both involved, in opposing roles, in glucose homeostasis [39].…”

Section: Discussionmentioning

confidence: 87%

“…There was no difference in body mass with age (P=0.555).Stomach contents data were analysed against the cycle stage of the preceding day, as the rats were fasted from the beginning of the cull day (from 08.00; before lights off at 11.00), therefore analysis of remaining stomach contents provided an indication of food consumption during the previous day/cycle stage. When fasted from estrus and dissected at metestrus, rats had significantly (F(3, 39)=3.187, P=0.034) more stomach contents (0.96 g) than those fasted from proestrus and dissected at estrus (0.44 g; P=0.028)[21].…”

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confidence: 95%

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Glucagon-like peptide-1 (GLP-1) increases in plasma and colon tissue prior to estrus and circulating levels change with increasing age in reproductively competent Wistar rats

2017

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There is a well-documented association between cyclic changes to food intake and the changing ovarian hormone levels of the reproductive cycle in female mammals. Limited research on appetite-controlling gastrointestinal peptides has taken place in females, simply because regular reproductive changes in steroid hormones present additional experimental factors to account for. This study focussed directly on the roles that gastrointestinal-secreted peptides may have in these reported, naturally occurring, changes to food intake during the rodent estrous cycle and aimed to determine whether peripheral changes occurred in the anorexigenic (appetite-reducing) hormones peptide-YY (PYY) and glucagon-like peptide-1 (GLP-1) in female Wistar rats (32-44 weeks of age). Total forms of each peptide were measured in matched fed and fasted plasma and descending colon tissue samples for each animal during the dark (feeding) phase. PYY concentrations did not significantly change between defined cycle stages, in either plasma or tissue samples. GLP-1 concentrations in fed plasma and descending colon tissue were significantly increased during proestrus, just prior to a significant reduction in fasted stomach contents at estrus, suggesting increased satiety and reduced food intake at this stage of the cycle. Increased proestrus GLP-1 concentrations could contribute to the reported reduction in food intake during estrus and may also have biological importance in providing the optimal nutritional and metabolic environment for gametes at the potential point of conception. Additional analysis of the findings demonstrated significant interactions of ovarian cycle stage and fed/fasted status with age on GLP-1, but not PYY plasma concentrations. Slightly older females had reduced fed plasma GLP-1 suggesting that a relaxation of regulatory control of this incretin hormone may also take place with increasing age in reproductively competent females.

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Section: Discussionmentioning

confidence: 87%

mentioning

confidence: 95%

Glucagon-like peptide-1 (GLP-1) increases in plasma and colon tissue prior to estrus and circulating levels change with increasing age in reproductively competent Wistar rats

2017

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“…The d8L dams consumed approximately 250% more than the mean daily food intake of all of the normally cycling nulliparous females (15.5 ± 0.09 g, n=43) used in a prior study (Johnson et al, 2016). Figure 7B) and body mass exceeded that of proestrus control rats (F(7,47)=16.208, P<0.001) by d10L (P=0.038).…”

Section: Peripartum Food Intakementioning

confidence: 88%

“…Fed blood samples were taken from a tail vein, between 12:00 and 13:00 hr, under anaesthesia (isoflurane; IsoFlo, Abbott Laboratories, Maidenhead, UK) to minimise stress during collection, as optimised from an earlier study (Johnson et al, 2016).…”

Section: Blood Collection and Preparationmentioning

confidence: 99%

Gastrointestinal capacity, gut hormones and appetite change during rat pregnancy and lactation

Johnson¹,

Saffrey²,

Taylor³

2019

Reproduction

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Pregnancy and lactation increase maternal appetite and adiposity, which in humans can lead to long-term body mass retention. Previous rat reproduction studies suggest that appetite-inhibiting gut hormone, peptide-YY (PYY), is elevated, despite hyperphagia also that gastrointestinal size increases. The present study characterised changes in orexigenic (appetite-stimulating) ghrelin and anorexigenic (appetite-inhibiting) PYY and glucagon-like peptide-1 (GLP-1), and gastrointestinal architecture during pregnancy and lactation, in matched fed and fasted plasma and gut tissue samples taken during the dark phase. Enteroendocrine cells were immunolabelled, and gut masses and lengths were measured. Fasted plasma ghrelin reduced during pregnancy: it was lowest by day 18, recovered to control values at parturition, then increased by the end of lactation. Ghrelin-immunoreactive stomach cells and stomach ghrelin concentrations were highest at birth, prior to the onset of lactation-associated hyperphagia. Plasma fed GLP-1 concentrations were elevated during pregnancy, and together with higher colon concentrations of PYY and GLP-1 during early lactation, they were associated with gastrointestinal tissue expansion, not satiety. Body mass increased during lactation, whereas white adipose tissue depots depleted. Extensive gut remodelling coincided with elevated colon concentrations of PYY and GLP-1. Modifications included stomach and caecum expansion, and duodenal, ascending and descending colon circumference increases, all peaking by day 10 of lactation; increased intestinal masses and lengths peaking at lactation day 10 for small intestine and lactation day 25 for large intestine. If these physical tissue increases persist post-partum, they could accelerate future nutrient assimilation and storage in dams, and may contribute to increased obesity risk.

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“…These Wistar females were fully anaesthetised (isoflurane; IsoFlo, Abbott) and decapitated to collect trunk blood and tissue samples for other studies. 15,16 Wistar rats have a gestation period of approximately 21 days, which is slightly shorter than that of Lister-Hooded rats (23 days). Wistar rats were checked regularly close to their expected delivery date (d21 post mating), and cages were carefully checked for pups and counted, without disturbing the dams.…”

Section: Oestrous Cycle Monitoringmentioning

confidence: 96%

Improved timed-mating, non-invasive method using fewer unproven female rats with pregnancy validation via early body mass increases

2018

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For studies requiring accurate conception-timing, reliable, efficient methods of detecting oestrus reduce time and costs, whilst improving welfare. Standard methods use vaginal cytology to stage cycle, and breeders are paired-up using approximately five proven females with proven males to achieve at least one conception on a specific day. We describe an alternative, fast, consistent, non-invasive method of timed-mating using detection of lordosis behaviour in Wistar and Lister-Hooded rats that used unproven females with high success rates. Rats under reverse lighting had body masses recorded pre-mating, day (d) 3-4, d8, d10 and d18 of pregnancy. Using only the presence of the oestrus dance to time-mate females for 24 hours, 89% of Wistar and 88% of Lister-Hooded rats successfully conceived. We did not observe behavioural oestrus in Sprague-Dawleys without males being present. Significant body mass increases following mating distinguished pregnant from non-pregnant rats, as early as d4 of pregnancy (10% AE 1.0 increase cf. 3% AE 1.2). The pattern of increases throughout gestation was similar for all pregnant rats until late pregnancy, when there were smaller increases for primi-and multiparous rats (32% AE 2.5; 25% AE 2.4), whereas nulliparous rats had highest gains (38% AE 1.5). This method demonstrated a distinct refinement of the previous timed-mating common practice used, as disturbance of females was minimised. Only the number required of nulli-, primi-or multiparous rats were mated, and body mass increases validated pregnancy status. This new breeding management method is now established practice for two strains of rat and has resulted in a reduction in animal use.

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Plasma Ghrelin Concentrations Were Altered with Oestrous Cycle Stage and Increasing Age in Reproductively Competent Wistar Females

Cited by 6 publications

References 19 publications

Glucagon-like peptide-1 (GLP-1) increases in plasma and colon tissue prior to estrus and circulating levels change with increasing age in reproductively competent Wistar rats

Glucagon-like peptide-1 (GLP-1) increases in plasma and colon tissue prior to estrus and circulating levels change with increasing age in reproductively competent Wistar rats

Gastrointestinal capacity, gut hormones and appetite change during rat pregnancy and lactation

Improved timed-mating, non-invasive method using fewer unproven female rats with pregnancy validation via early body mass increases

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