Mass spectrometric analysis of opioid and tachykinin neuropeptides in non-secreting and ACTH-secreting human pituitary adenomas.
In a study to test the hypothesis that defects in the metabolism of neuropeptides might be a contributing factor to human anterior pituitary tumor formation, the proenkephalin A, proopiomelanocortin (POMC), and tachykinin systems, which produce methionine enkephalin (ME), beta-endorphin (BE), and substance P (SP), respectively, were measured in patients who had a wide variety of pituitary tumors. Mass spectrometry was used to optimize the level of molecular specificity of the ME and BE analytical measurements, and radioimmunoassay was used to measure SP-like immunoreactivity (SP-li). Compared to data obtained from pituitaries from post-mortem controls, the non-secreting tumors contained a significantly lower amount of the POMC neuropeptide, BE. The lower ME level was not significant. However, two adrenocorticotrophic hormone (ACTH)-secreting tumors contained ME, BE, and SP-li amounts that were much higher than both the controls and nonsecreting tumors. These data suggest that a hypometabolism of the POMC precursor may be operating in non-secreting tumors, and that a hypermetabolism of the proenkephalin A, POMC, and tachykinin precursors may be operating in two ACTH-secreting tumors. These data demonstrate that mass spectrometry plays a critical role in the study of human pituitary tumors.
Desiderio
D M
DM
Department of Neurology, University of Tennessee, Memphis 38163.
Kusmierz
J J
JJ
Zhu
X
X
Dass
C
C
Hilton
D
D
Robertson
J T
JT
Sacks
H S
HS
D000236:Adenoma / Q000737:chemistry* / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000328:Adult; D000368:Aged; D002648:Child; D002851:Chromatography, High Pressure Liquid; D004723:Endorphins / Q000032:analysis* / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D009479:Neuropeptides / Q000032:analysis* / Q000276:immunology; D010911:Pituitary Neoplasms / Q000737:chemistry* / Q000378:metabolism; D011863:Radioimmunoassay; D015320:Tachykinins / Q000032:analysis* / Q000276:immunology
D004723:Endorphins; D009479:Neuropeptides; D015320:Tachykinins; D000324:Adrenocorticotropic Hormone