-This paper discusses the phenomenon of nutritional flushing in ewes whereby increased nutrition stimulates folliculogenesis and ovulation rate. In addition the paper reviews recent findings on the effects of increased levels of nutrition on the blood concentrations of reproductive and metabolic hormones in the ewe and some of the intraovarian changes that take place in response to nutritional stimulation. Finally, in the paper, we propose a model of the physiological mechanism for the nutritional stimulation of folliculogenesis and we review how closely the model fits recent published and unpublished evidence examining the mechanism of flushing. Nutritional stimulation alters the blood concentrations of some metabolic hormones. By using short-term models of nutritional flushing, we have shown that as the blood concentrations of insulin and leptin increase that of growth hormone decreases while that of IGF-I appears unaffected by the nutritional flushing. Nutritional flushing also alters the blood concentrations of some reproductive hormones. Again, using the same model, we have shown that there is a transient increase in FSH and a decrease in oestradiol concentrations in the blood. The changes in oestradiol are particularly evident in the follicular phase of the oestrous cycle. In the ovary, the effect of nutrition is to stimulate folliculogenesis. These changes are associated with intra-follicular alterations in the insulin-glucose, IGF and leptin metabolic systems. The stimulation of these intra-follicular systems leads to a suppression in follicular oestradiol production. The consequence of these direct actions on the follicle is a reduced negative feedback to the hypothalamic-pituitary system and increased FSH secretion that leads to a stimulation of folliculogenesis.insulin / leptin / IGF-I / glucose / FSH / oestradiol

Background: Feline acromegaly has been reported infrequently in the veterinary literature and current knowledge of this endocrinopathy is based on limited numbers of animals with relatively advanced clinical signs. Hypothesis: This study was undertaken to screen diabetic cats for the presence of acromegaly. Animals: Diabetic cats with variable control examined by general practitioners in the United Kingdom. Methods: Blood samples were screened for the possible presence of acromegaly with basal serum concentrations of insulinlike growth factor 1 (IGF‐1) and, when available, feline growth hormone (fGH). In patients with markedly increased IGF‐1 concentrations intracranial computed tomography (CT) was offered, and in selected cats additional imaging was performed. Results: IGF‐1 was determined in 184 variably controlled diabetic cats; 59 cats had markedly increased IGF‐1 concentrations (.1,000 ng/mL; reference interval, 208–443 ng/mL). Eighteen cats subsequently were examined, and acromegaly was confirmed in 17 cats. Notable findings included absence of a detectable pituitary mass lesion in some affected cats regardless of whether CT or magnetic resonance imaging (MRI) was used. Hypertension was not found to be a complication in the evaluated cats and respiratory stridor was more prevalent than previously reported. Conclusions and Clinical Importance: Measurement of IGF‐1, growth hormone (GH), or both is useful in the diagnosis of acromegaly in cats.

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Measurement of IGF-1, growth hormone (GH), or both is useful in the diagnosis of acromegaly in cats.