Possible Interaction: Thyrotropin-Releasing Hormone and Adrenocorticotropic Hormone

“We have recently identified a 22 amino acid peptide, prepro‐thyrotropin releasing hormone (TRH) 178‐199 that inhibits basal and stimulated ACTH synthesis and secretion in vitro and stress‐induced ACTH secretion in vivo.”

“After peripheral administration of both CRF and TRH, ACTH levels were significantly higher on the tumor side in all patients.”

“The ACTH , but not Cortisol, response was greater after combined CRH plus TRH administration than after CRH alone (p < .002).”

“Moreover, a dose-response relationship between TRH concentrations and ACTH secretion was observed.”

“The TRF induced rise in plasm cortisol and ACTH concentrations in patients with Cushing's disease and Nelson's syndrome suggests the possibility of altered hypothalamic or pituitary receptors in such patients.”

“In the PPID ID group, there was a strong correlation between the ACTH concentration after the administration of thyrotropin-releasing hormone and the expression of IL-8 (r = 0.941; P = 0.0321).”

“In conclusion, TRH inhibits the GH response not only to EP51389 but also to GHRH in horses, and in addition to its known secretagogue action on prolactin and TSH it may also stimulate ACTH at the dosage used in these experiments.”

“Stimulation of neurointermediate lobe cell columns with pulses of TRH evoked dose-dependent increases in the concomitant release of ir alpha-MSH and ir ACTH.”

“In contrast, TRH increased the amount of ACTH accumulated in the medium from AtT-20/NYU-1 cells to 190 and 420% of control at 1 and 24 h, respectively.”

“ TRH induced a dose-dependent increase in ACTH release during a 30-min incubation; half-maximal stimulation occurred at approximately 0.1 nM. TRH had no effect on ACTH release in vitro from anterior pituitary cells derived from normal rats.”

“… TRH stimulates … of ACTH in some untreated patients with Cushing's disease and Nelson's syndrome as well as pathological states associated with pituitary tumors (but not in normal subjects), AtT-20/NYU-1 cells may serve as an important in vitro model for human pituitary ACTH-secreting adenomas.”

“When the pituitary is induced to secrete TSH by TRF it concomitantly secretes less ACTH in response to stress; conversely, when the secretion of ACTH is inhibited as by pretreatment with dexamethasone and Nembutal, the pituitary secretes higher quantities of TSH in response to TRF. (”