According to research, hypercortisolemia may result in a reduction in TRH mRNA levels in the mid-caudal PVN.113 TRH expression in the PVN is lower in nonpsychiatric patients treated with corticosteroids, and the mRNA levels of TRH are lower in the PVN of depressed patients who have recurrent suicidal thoughts. This evidence concerns the gene TRH and adrenal gland hyperfunction.