Insulin-Like Growth Factor Binding Proteins in the Bovine Anterior Pituitary

Roberts, A. J.; Funston, R. N.; Moss, G. E.

doi:10.1385/endo:14:3:399

Cited by 14 publications

(13 citation statements)

References 29 publications

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“…One more hypothesis has been put forth by Downing et al (1995) which states that ovarian responses are influenced by availability of nutrients. Nutrient deficiency potentially acts on the reproductive process and affects oestrus behaviour and ovulation rate (Roberts et al, 2001). Plasma oestrogen and progesterone showed reverse trend for the effects of both individual as well as combined stress (Figs 1 and 2).…”

Section: Discussionmentioning

confidence: 94%

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Effect of thermal stress, restricted feeding and combined stresses (thermal stress and restricted feeding) on growth and plasma reproductive hormone levels of Malpura ewes under semi-arid tropical environment

Sejian

Maurya

Naqvi

2010

Journal of Animal Physiology and Animal Nutrition

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A study was conducted to assess the effect of thermal, nutritional and combined stresses (thermal and nutritional) on the growth, oestradiol and progesterone levels during oestrus cycles in Malpura ewes. Twenty-eight adult Malpura ewes were used in the present study. The ewes were randomly allocated into four groups, viz., GI (n=7; control), GII (n=7; thermal stress), GIII (n=7; restricted feeding) and GIV (n=7; combined stress). The animals were stall fed with a diet consisting of 60% roughage and 40% concentrate. GI and GII ewes were provided with ad libitum feeding while GIII and GIV ewes were provided with restricted feed (30% intake of GI and GII ewes) to induce nutritional insufficiency. GII and GIV ewes were kept in climatic chamber at 40°C and 55% RH for 6 h a day between 10:00 and 16:00 hours to induce thermal stress for a period of two oestrous cycles. Parameters studied were body weight, oestrus incidences, plasma oestradiol 17-β, plasma progesterone, conception rate, gestation period, lambing rate, and birth weight of lambs. The results indicate that combined stress significantly (p<0.05) reduced body weight, oestrus duration, birth weight of lambs, and oestradiol 17-β whereas significantly (p < 0.05) increased oestrus cycle length and progesterone. Furthermore, the results reveal that on comparative basis, ewes were able to better adapt in terms of growth and reproduction to restricted feeding than thermal stress. However, when restricted feeding was coupled with thermal stress it had significant (p<0.05) influence on body weight, average daily gain, oestradiol 17-β and progesterone concentrations. This showed that combined stress were more detrimental for these reproductive hormones in Malpura ewes under a hot semi-arid environment.

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Section: Discussionmentioning

confidence: 94%

“…(1995) which states that ovarian responses are influenced by availability of nutrients. Nutrient deficiency potentially acts on the reproductive process and affects oestrus behaviour and ovulation rate (Roberts et al., 2001).…”

Section: Effect Of Thermal Nutritional and Combined Stress On Growtmentioning

confidence: 99%

Effect of thermal stress, restricted feeding and combined stresses (thermal stress and restricted feeding) on growth and plasma reproductive hormone levels of Malpura ewes under semi-arid tropical environment

Sejian

Maurya

Naqvi

2010

Journal of Animal Physiology and Animal Nutrition

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“…Nutrient deficiency potentially acts on the reproductive process and affects estrus behavior and ovulation rate. Nutritional influences on reproduction may be linked through variations in the GH and IGF-1 system secreted from the liver or present in other reproductive tissues (Roberts et al, 2001). Studies of both short-term and long-term feed restriction in beef heifers have shown that, negative energy balance induced by dietary restriction causes decreased growth rate and maximum diameter of dominant follicles (DF), and often results in anovulation due to reduced LH pulse frequency (Bossis et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Effect of nutritional restriction on growth, adaptation physiology and estrous responses in Malpura ewes

2014

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The study was conducted to ascertain the effects of nutritional restrictions on growth, physiological adaptability and reproduction in sheep. The experiment was conducted for a period of 35 days covering two estrus cycles in 40 adult Malpura ewes. The animals were randomly divided into four groups of 10 animals each (100%; 80%; 70%; 60% of ad libitum). The ewes were fed a ration consisting of 70% roughage and 30% concentrate. At weekly intervals, physiological responses were recorded and blood samples were also collected. Nutritional restriction of different magnitude (80%; 70%; 60% of ad libitum) altered the growth, physiological adaptability and estrus responses to different extents in Malpura ewes. But the impact was most severe in 60% of ad libitum group. Nutritional restriction to the level of 60% of ad libitum feeding significantly decreased body weight, body eondition score, plasma insulin-like growth factor, pulse rate in the morning, respiration rate and pulse rate in the afternoon, plasma glucose, total protein, albumin, total cholesterol, plasma tri-iodo-thyronine and thyroxine, plasma cortisol, plasma estradiol, estrus % and estrus duration, while it significantly increased plasma concentration of growth hormone, hemoglobin, plasma concentration of progesterone and estrus cycle length. The study clearly establishes the effect of different levels of nutrition and its impact on the biological functions necessary to adapt to semi-arid environment. Although, 80%, 70% and 60% groups showed signs of nutritional stress, the effects were more pronounced in 60% ewes. Furthermore, this study clearly establishes the role of various hormones required to adapt to different levels of nutritional stress in Malpura ewes.

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“…8 wk of age). Interestingly, IGFBP-2 is expressed in relatively high amounts in the hypothalamus and pituitary (36). Hence, it is conceivable that if this binding protein transports IGF-I locally, the absence of IGBP-2 could result in impaired presentation of IGF-I, resulting in less negative feedback within the hypothalamic-pituitary axis (37).…”

Section: Discussionmentioning

confidence: 99%

Gender-Specific Changes in Bone Turnover and Skeletal Architecture in Igfbp-2-Null Mice

et al. 2008

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IGF-binding protein-2 (IGFBP-2) is a 36-kDa protein that binds to the IGFs with high affinity. To determine its role in bone turnover, we compared Igfbp2(-/-) mice with Igfbp2(+/+) colony controls. Igfbp2(-/-) males had shorter femurs and were heavier than controls but were not insulin resistant. Serum IGF-I levels in Igfbp2(-/-) mice were 10% higher than Igfbp2(+/+) controls at 8 wk of age; in males, this was accompanied by a 3-fold increase in hepatic Igfbp3 and Igfbp5 mRNA transcripts compared with Igfbp2(+/+) controls. The skeletal phenotype of the Igfbp2(-/-) mice was gender and compartment specific; Igfbp2(-/-) females had increased cortical thickness with a greater periosteal circumference compared with controls, whereas male Igfbp2(-/-) males had reduced cortical bone area and a 20% reduction in the trabecular bone volume fraction due to thinner trabeculae than Igfbp2(+/+) controls. Serum osteocalcin levels were reduced by nearly 40% in Igfbp2(-/-) males, and in vitro, both CFU-ALP(+) preosteoblasts, and tartrate-resistant acid phosphatase-positive osteoclasts were significantly less abundant than in Igfbp2(+/+) male mice. Histomorphometry confirmed fewer osteoblasts and osteoclasts per bone perimeter and reduced bone formation in the Igfbp2(-/-) males. Lysates from both osteoblasts and osteoclasts in the Igfbp2(-/-) males had phosphatase and tensin homolog (PTEN) levels that were significantly higher than Igfbp2(+/+) controls and were suppressed by addition of exogenous IGFBP-2. In summary, there are gender- and compartment-specific changes in Igfbp2(-/-) mice. IGFBP-2 may regulate bone turnover in both an IGF-I-dependent and -independent manner.

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Insulin-Like Growth Factor Binding Proteins in the Bovine Anterior Pituitary

Cited by 14 publications

References 29 publications

Effect of thermal stress, restricted feeding and combined stresses (thermal stress and restricted feeding) on growth and plasma reproductive hormone levels of Malpura ewes under semi-arid tropical environment

Effect of thermal stress, restricted feeding and combined stresses (thermal stress and restricted feeding) on growth and plasma reproductive hormone levels of Malpura ewes under semi-arid tropical environment

Effect of nutritional restriction on growth, adaptation physiology and estrous responses in Malpura ewes

Gender-Specific Changes in Bone Turnover and Skeletal Architecture in Igfbp-2-Null Mice

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