Discordant changes between immunoreactive ACTH and beta-endorphin in rat brain and pituitary during early development

Discordant changes in brain concentrations of immunoreactive (IR-) adrenocorticotropic hormone (ACTH) or beta-endorphin, peptides derived from pro-opiomelanocortin (POMC), have been reported during the latter part of development and with subsequent aging. These changes were believed to be due to age-related alterations in the regulation of metabolism of POMC-related peptides. However, concentrations of IR-ACTH and IR-beta-endorphin have not been simultaneously studied during early development when many changes in brain development and behavior are occurring. To determine whether concentrations of IR-ACTH and IR-beta-endorphin change during early development and whether changes are discordant, concentrations of IR-ACTH and IR-beta-endorphin were measured in several brain regions and pituitary in rats at 10, 29 and 80 days after birth. Whereas IR-ACTH in extrahypothalamic brain increased at day 29, and decreased at day 80, it did not change in hypothalamus and pituitary. Between day 10 and 29, IR-beta-endorphin rose in all brain regions, but subsequent changes in different tissues were variable at day 80. Because concentration changes can be mediated by alterations in one or more regulatory mechanisms, chromatographic profiles of...Continue Reading