GH response to GHRH before and after meals at different hours of the day in obese patients

In normal subjects several factors are involved in the regulation of the GH response to GHRH, such as nutritional status, metabolic fuels and neurotransmitters. We previously have shown a paradoxical increase in the GH response to GHRH after meals in obese patients, in contrast to the blunted GH response observed after feeding in normal subjects. We have further investigated this phenomenon, studying the GH response to GHRH before and after meal at three different hours during the day in 10 obese patients, aged 18-35 yr, in comparison to that in eight normal women, aged 20-35 yr. GHRH was injected in a fasting state or 1 hr after a standard meal (800 KCal). In obese subjects, after food ingestion the peak GH response to GHRH was increased at 0900h and 1300h and was significant when the patients were tested after lunch (1300h). On the contrary, in the evening the GH response to GHRH remained unchanged, both before and after feeding. These data point to an altered sensitivity of GH secretion to metabolic signals in patients with obesity.