Elevated levels of a hormone called TRH have been found in the pancreas of newborn rats. Scientists injected newborn rats with a substance called streptozotocin to study the effects on TRH and insulin levels in the pancreas as the rats grew. They found that TRH and insulin levels dropped drastically in the first few days after birth, but while insulin levels eventually recovered, TRH levels remained low even after 35 days. This suggests that TRH is located in specific cells that are sensitive to streptozotocin, and that the process of producing TRH may be different from that of insulin.