Sex and season are major determinants of voluntary food intake in sheep

2001 ◽  
Vol 13 (8) ◽  
pp. 577 ◽  
Author(s):  
Iain J. Clarke
Keyword(s):  
Food Intake ◽  
Recent Work ◽  
Seasonal Changes ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Reduce Food Intake ◽  
Orexigenic Peptide ◽  
The Brain ◽  
Female Sheep ◽  
Voluntary Food Intake

Seasonal changes in voluntary food intake (VFI) are seen in various species, including sheep. This paper reviews recent work in this area, especially in relation to alterations in the expression of appetite-regulating peptides in the brain of the sheep. Work in the hamster is also reviewed because this is another species in which VFI is regulated by photoperiod. In normally grazing sheep, appetite is maximal in the late summer/early autumn and minimal in spring. This appears to be owing to increased expression of the orexigenic peptide, neuropeptide Y. Similar results are obtained in sheep that are subjected to controlled photoperiod. The same does not appear to be true for hamsters. Further work in sheep has shown that there is a seasonal pattern of responsiveness to leptin that is more pronounced in females than in males. In particular, the effect of leptin to reduce food intake is maximal in female sheep in the spring; reasons for the sex difference are discussed.

Photoperiodic entrainment of seasonal changes in appetite and growth in pony colts

1998 ◽  
Vol 1998 ◽  
pp. 133-133
Author(s):  
Z. Fuller ◽  
J.E. Cox ◽  
C. McG. Argo
Keyword(s):  
Food Intake ◽  
Seasonal Changes ◽  
Environmental Pressures ◽  
Ambient Temperatures ◽  
Forage Availability ◽  
Photoperiodic Regime ◽  
Gross Energy ◽  
Ad Libitum ◽  
Pelleted Diet ◽  
Voluntary Food Intake

During winter, voluntary food intake (VFI) and growth decreased in light horse weanlings given ad libitum access to a forage/concentrate diet (Cymbaluk et al, 1989). These changes were attributed to decreased ambient temperatures. However, photoperiodically entrained seasonal changes in VFI and growth are documented in other Northern ungulates (Moen, 1978) and may comprise an adaptation to changes in forage availability. Throughout their evolution, horses experienced similar environmental pressures and may demonstrate similar photoperiodic adaptations. This study characterised changes in VFI and growth in pony colts maintained under an artificial photoperiodic regime.Seven, 2 year-old pony colts of Welsh Mountain type (182.4 ± 5.4 kg), were obtained from pasture (53°N). Animals were individually housed in loose-boxes, within a light-proof building. Measured quantities of a complete pelleted diet (gross energy = 16.7 MJ.kgDM-1), calculated to exceed appetite by at least 1 kg, were offered daily.

Central nervous control of voluntary food intake

1989 ◽  
Vol 13 ◽  
pp. 7-26 ◽  
Author(s):  
J. M. Forbes ◽  
J. E. Blundell
Keyword(s):  
Nervous System ◽  
Food Intake ◽  
Peptide Yy ◽  
Blood Stream ◽  
Vital Role ◽  
Nervous Control ◽  
Electrolytic Lesions ◽  
The Central Nervous System ◽  
The Brain ◽  
Voluntary Food Intake

AbstractThe central nervous system is the integrator of most of the actions of the animal and as such plays a vital rôle in the control of voluntary food intake. Much of the work to understand how intake is controlled has been carried out with rats but that which has been done with pigs is included. The first experiments used electrolytic lesions in the designation of the ‘hunger centre’ and the ‘satiety centre’. Recent work has identified the paraventricular nucleus as a sensing site for experimental manipulations. Chemical stimulation of the brain has also been carried out to try to gain understanding of the rôle of neurotransmitters. Noradrenaline (NA) stimulates intake when given into many sites. Serotonin (5-HT) inhibits intake and has been claimed to play a rôle in the selection of macronutrients but 5-HT must now be interpreted in the light of the existence of several different subtypes of 5-HT receptors. Dopamine appears to moderate the hedonic response of eating. Numerous peptides are active in the brain where their rôle as neuromodulators may be quite different from their function in the periphery and at least three types of opioid receptors are implicated with kappa antagonists producing the most potent facilitatory effects. Neuropeptide Y and peptide YY produce massive orexigenic effects which readily overcome peripheral satiety factors. The brain cannot control intake in isolation. It receives inputs in the blood stream, such as glucose, as well as via the nervous system, both from the special senses and from visceral organs such as stomach, intestines and liver. Taste and olfaction are important in diet selection and a specific appetite for protein has been demonstrated in the pig.

A comparison of the seasonal hormone changes and patterns of growth, voluntary food intake and reproduction in juvenile and adult red deer (Cervus elaphus) and Père David's deer (Elaphurus davidianus) hinds

1989 ◽  
Vol 122 (3) ◽  
pp. 733-745 ◽  
Author(s):  
A. S. I. Loudon ◽  
J. A. Milne ◽  
J. D. Curlewis ◽  
A. S. McNeilly
Keyword(s):  
Food Intake ◽  
Breeding Season ◽  
Seasonal Changes ◽  
Red Deer ◽  
Species Differences ◽  
Energy Utilization ◽  
Significant Advance ◽  
Plasma Prolactin ◽  
Père David’S Deer ◽  
Voluntary Food Intake

ABSTRACT Non-domesticated seasonally breeding ungulates exhibit marked seasonal changes in metabolic rate, voluntary food intake (VFI), pelage growth and moult and hormone secretion. It is not known whether these seasonal rhythms are regulated by the same central processes which control the onset and termination of the breeding season. Here we compare two closely related deer species which have significantly different mating and calving seasons. Seasonal changes in VFI, liveweight, coat growth, plasma prolactin and tri-iodothyronine (T3), and the timing of the breeding season were examined over a 15-month period in six adult post-pubertal red and Père David's deer from January to April the following year. The timing of the seasonal changes in prolactin, T3, VFI and coat growth were all significantly advanced by 56, 23, 60 and 54 days respectively in the Père David's deer. The times of onset and termination of the breeding season of Père David's deer were also significantly advanced by 90 days, but in both species, the breeding season was of similar duration (160 ± 5 (s.e.m.) days). Changes in liveweight of adult red deer could be explained by changes in VFI rather than efficiency of utilization. This was not the case in Père David's deer and may indicate seasonal changes in the efficiency of energy utilization. In order to establish whether these species differences develop with age, we undertook a second study in which seasonal changes in VFI, growth, plasma prolactin concentrations and the timing of the onset of the breeding season were recorded for ten red deer and six Père David's deer from 6 to 18 months of age. Both species exhibited a similar decline in VFI in the first autumn of life. Subsequently, the Père David's deer exhibited an advance in the timing of the seasonal peak in VFI and prolactin (21 and 66 days respectively); puberty occurred 3 months earlier than in red deer. The earlier breeding season of the Père David's deer was associated with a significant advance in a range of seasonal endocrine and physiological parameters. These species differences may develop with age. Our data indicate that seasonal patterns of metabolism and growth may be closely linked to those mechanisms which also regulate the onset and termination of the breeding season. Journal of Endocrinology (1989) 122, 733–745

Photoperiodic entrainment of seasonal changes in appetite and growth in pony colts

1998 ◽  
Vol 1998 ◽  
pp. 133-133
Author(s):  
Z. Fuller ◽  
J.E. Cox ◽  
C. McG. Argo
Keyword(s):  
Food Intake ◽  
Seasonal Changes ◽  
Environmental Pressures ◽  
Ambient Temperatures ◽  
Forage Availability ◽  
Photoperiodic Regime ◽  
Gross Energy ◽  
Ad Libitum ◽  
Pelleted Diet ◽  
Voluntary Food Intake

During winter, voluntary food intake (VFI) and growth decreased in light horse weanlings given ad libitum access to a forage/concentrate diet (Cymbaluk et al, 1989). These changes were attributed to decreased ambient temperatures. However, photoperiodically entrained seasonal changes in VFI and growth are documented in other Northern ungulates (Moen, 1978) and may comprise an adaptation to changes in forage availability. Throughout their evolution, horses experienced similar environmental pressures and may demonstrate similar photoperiodic adaptations. This study characterised changes in VFI and growth in pony colts maintained under an artificial photoperiodic regime.Seven, 2 year-old pony colts of Welsh Mountain type (182.4 ± 5.4 kg), were obtained from pasture (53°N). Animals were individually housed in loose-boxes, within a light-proof building. Measured quantities of a complete pelleted diet (gross energy = 16.7 MJ.kgDM-1), calculated to exceed appetite by at least 1 kg, were offered daily.

scholarly journals Circulating GLP-1 and CCK-8 reduce food intake by capsaicin-insensitive, nonvagal mechanisms

2012 ◽  
Vol 302 (2) ◽  
pp. R264-R273 ◽  
Author(s):  
Jingchuan Zhang ◽  
Robert C. Ritter
Keyword(s):  
Food Intake ◽  
Plasma Concentrations ◽  
Vagal Afferents ◽  
Reduce Food Intake ◽  
Sucrose Intake ◽  
Paracrine Effects ◽  
Distal Small Intestine ◽  
Nodose Ganglia ◽  
Glucagon Like Peptide ◽  
The Brain

Previous reports suggest that glucagon-like peptide (GLP-1), a peptide secreted from the distal small intestine, is an endocrine satiation signal. Nevertheless, there are conflicting reports regarding the site where circulating GLP-1 acts to reduce food intake. To test the hypothesis that vagal afferents are necessary for reduction of food intake by circulating GLP-1, we measured intake of 15% sucrose during intravenous GLP-1 infusion in intact, vagotomized, and capsaicin-treated rats. We also measured sucrose intake during intravenous infusion of cholecystokinin, a peptide known to reduce food intake via abdominal vagal afferents. We found that reduction of intake by GLP-1 was not diminished by capsaicin treatment or vagotomy. In fact, reduction of sucrose intake by our highest GLP-1 dose was enhanced in vagotomized and capsaicin-treated rats. Intravenous GLP-1 induced comparable increases of hindbrain c-Fos immunoreactivity in intact, capsaicin-treated, and vagotomized rats. Plasma concentrations of active GLP-1 in capsaicin-treated rats did not differ from those of controls during the intravenous infusions. Finally, capsaicin treatment was not associated with altered GLP-1R mRNA in the brain, but nodose ganglia GLP-1R mRNA was significantly reduced in capsaicin-treated rats. Although reduction of food intake by intraperitoneal cholecystokinin was abolished in vagotomized and capsaicin-treated rats, reduction of intake by intravenous cholecystokinin was only partially attenuated. These results indicate that vagal or capsaicin-sensitive neurons are not necessary for reduction of food intake by circulating (endocrine) GLP-1, or cholecystokinin. Vagal participation in satiation by these peptides may be limited to paracrine effects exerted near the sites of their secretion.

Photorefractoriness and seasonal changes in the brain in response to changes in day length in American goldfinches (Carduelis tristis)

2002 ◽  
Vol 80 (12) ◽  
pp. 2100-2107 ◽  
Author(s):  
Regan H Marsh ◽  
Scott A MacDougall-Shackleton ◽  
Thomas P Hahn
Keyword(s):  
Seasonal Changes ◽  
Late Summer ◽  
Day Length ◽  
Free Living ◽  
Strong Trend ◽  
Carduelis Tristis ◽  
Song Control System ◽  
Song Control ◽  
Seasonally Breeding ◽  
The Brain

We examined neural and gonadal responses to photoperiod in a late-summer-breeding finch, the American goldfinch (Carduelis tristis). First we measured seasonal changes in the gonads of free-living goldfinches. Next we determined whether the gonads of goldfinches held on constant long days would eventually regress spontaneously. Finally, we compared the hypothalamic gonadotropin-releasing hormone (GnRH) system and song-control system of breeding and postbreeding birds. The results confirm that the gonads of wild goldfinches regress in late summer and show that the gonads of goldfinches held on constant long days regress spontaneously. Thus, according to at least one criterion, goldfinches become photorefractory, like other seasonally breeding songbirds. As well, goldfinches exhibited similar seasonal changes in the brain to spring-breeding birds. There was a decrease in GnRH immunoreactivity in autumn and a strong trend towards a reduction in the size of song-control regions (although this was statistically significant for only one area). Thus, although goldfinches breed late in summer as day length declines, some of their physiological responses to changes in photoperiod are similar to those that occur in spring-breeding songbirds.

Seasonal changes in CSF insulin levels in marmots: insulin may not be a satiety signal for fasting in winter

1991 ◽  
Vol 260 (4) ◽  
pp. R712-R716 ◽  
Author(s):  
G. L. Florant ◽  
R. D. Richardson ◽  
S. Mahan ◽  
L. Singer ◽  
S. C. Woods
Keyword(s):  
Food Intake ◽  
Seasonal Changes ◽  
The Body ◽  
Immunoreactive Insulin ◽  
Reduce Food Intake ◽  
Marmota Flaviventris ◽  
Fasting Period ◽  
Insulin Levels ◽  
Basal Plasma ◽  
The Central Nervous System

Plasma insulin (PI) reportedly crosses the blood-brain barrier in mammals and acts with the central nervous system (CNS) to reduce food intake. Animals that hibernate (hibernators) eat little or no food from early winter (November) to spring (April). This lack of food intake may be due to elevated PI concentrations acting within the CNS. In this study, we determined whether hibernators have altered insulin levels within the CNS at different times during the circannual cycle of metabolism and feeding. Plasma and cerebrospinal fluid (CSF) immunoreactive insulin concentrations were measured in marmots (Marmota flaviventris) during the feeding phase of the body weight cycle and during the fasting period (hibernation). Basal plasma and CSF samples were collected in September, November, January, and April. In addition, plasma and CSF insulin levels were monitored during a 2-h intravenous infusion of glucose (20% wt/vol) that stimulated pancreatic B-cell production of insulin. During the spring feeding period, we found that as PI levels rise, so do CSF insulin concentrations. However, in fall and winter when marmots are fasting, very little insulin entered the CSF even when PI levels were significantly elevated. Furthermore, the longer the fast, the lower was the CSF insulin under both basal and infusion conditions. These results lead us to conclude that elevated CSF insulin is not a likely cause of suppressed food intake in fasting marmots.

Seasonal changes in leaf and stem loline alkaloids in meadow fescue

2011 ◽  
Vol 62 (3) ◽  
pp. 261 ◽  
Author(s):  
Brian Patchett ◽  
Ravi Gooneratne ◽  
Lester Fletcher ◽  
Bruce Chapman
Keyword(s):  
Seasonal Changes ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Early Spring ◽  
Early Summer ◽  
Sharp Decline ◽  
Meadow Fescue ◽  
Accumulation Pattern ◽  
Loline Alkaloids

Leaf and stem loline alkaloid concentration in 10 European meadow fescue (Festuca pratensis Huds.) lines grown in a field in Canterbury, New Zealand, were determined in samples collected six times between early spring 2004 and late autumn 2005. Significant differences in loline alkaloid concentrations were noted between lines and between harvest times. Higher total loline alkaloid concentrations (up to 4990 µg g–1) were found in stems compared to leaf (up to 1770 µg g–1). However, the seasonal accumulation pattern of different loline alkaloid concentrations in leaf and stem varied. In most lines, stem loline concentration peaked sharply in late spring and declined during early summer and autumn. The seasonal pattern of leaf loline alkaloid concentration followed the stem concentration except for a sharp decline in early summer followed by an increase in late summer. In most instances, the concentration of N-formyl loline was the highest > N-acetyl loline > N-acetyl norloline > N-methyl loline. The possible role of stem and leaf loline alkaloids to deter pasture-feeding insects is briefly discussed.

scholarly journals Hypothalamic proinflammatory lipid accumulation, inflammation, and insulin resistance in rats fed a high-fat diet

2009 ◽  
Vol 296 (5) ◽  
pp. E1003-E1012 ◽  
Author(s):  
Kelly A. Posey ◽  
Deborah J. Clegg ◽  
Richard L. Printz ◽  
Jaeman Byun ◽  
Gregory J. Morton ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Food Intake ◽  
Inflammatory Responses ◽  
Neuronal Response ◽  
Caloric Intake ◽  
Reduce Food Intake ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Regulate Food Intake ◽  
The Brain

Weight gain induced by an energy-dense diet is hypothesized to arise in part from defects in the neuronal response to circulating adiposity negative feedback signals, such as insulin. Peripheral tissue insulin resistance involves cellular inflammatory responses thought to be invoked by excess lipid. Therefore, we sought to determine whether similar signaling pathways are activated in the brain of rats fed a high-fat (HF) diet. The ability of intracerebroventricular (icv) insulin to reduce food intake and activate hypothalamic signal transduction is attenuated in HF-fed compared with low-fat (LF)-fed rats. This effect was accompanied by both hypothalamic accumulation of palmitoyl- and stearoyl-CoA and activation of a marker of inflammatory signaling, inhibitor of κB kinase-β (IKKβ). Hypothalamic insulin resistance and inflammation were observed with icv palmitate infusion or HF feeding independent of excess caloric intake. Last, we observed that central IKKβ inhibition reduced food intake and was associated with increased hypothalamic insulin sensitivity in rats fed a HF but not a LF diet. These data collectively support a model of diet-induced obesity whereby dietary fat, not excess calories, induces hypothalamic insulin resistance by increasing the content of saturated acyl-CoA species and activating local inflammatory signals, which result in a failure to appropriately regulate food intake.

Anorexia induced by interleukin 1: involvement of corticotropin-releasing factor

1989 ◽  
Vol 257 (3) ◽  
pp. R613-R617 ◽  
Author(s):  
A. Uehara ◽  
C. Sekiya ◽  
Y. Takasugi ◽  
M. Namiki ◽  
A. Arimura
Keyword(s):  
Food Intake ◽  
Interleukin 1 ◽  
Corticotropin Releasing Factor ◽  
Reduce Food Intake ◽  
Research Groups ◽  
Independent Research ◽  
Bidirectional Communication ◽  
Male Wistar Rats ◽  
Activated Monocytes ◽  
The Brain

It has recently been demonstrated by three independent research groups including ours that interleukin 1 (IL-1), a polypeptide hormone produced by activated monocytes or macrophages, or both, stimulates the release of hypothalamic corticotropin-releasing factor (CRF). Since CRF acts centrally in the brain to reduce food intake, we hypothesized that IL-1 might induce anorexia through this central action of CRF. The present study was carried out to examine the hypothesis, using male Wistar rats. Based on three lines of evidence, we report here that IL-1, both endogenously released and exogenously administered, induces the suppression of food intake in rats and that endogenous CRF in the brain is involved in the IL-1-induced anorexia. First, lipopolysaccharide (LPS), a potent stimulant of the release and production of endogenous IL-1, caused anorexia in a dose-related manner, and this effect was significantly blocked by pretreatment with glucocorticoid hormones, which have been shown to inhibit the production of endogenous IL-1 by LPS. Second, intraperitoneal injection of IL-1 resulted in a dose-related suppression of food intake. Third, anorexia induced by IL-1 was diminished by the immunoneutralization of endogenous CRF in the brain. These results provide further evidence of the existence of bidirectional communication between the immune and neuroendocrine systems. Furthermore, this connection between IL-1 and CRF may represent a mechanism by which anorexia results from the activation of the immune system by such immunological challenges as acute infectious diseases.

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