We have used specific radioimmunoassay and high-performance liquid chromatography (HPLC) to determine content and molecular forms of pituitary α-N-acetylated endorphin (NacEP) in the intact and hypothalamo-pituitary-disconnected (HPD) sheep. No significant differences were seen in anterior pituitary (AP) immunoreactive (ir-) NacEP levels (control=4.34±0.45 ng/mg; HPD=4.38±0.83 ng/mg; n=4) or in HPLC profiles following pituitary disconnection. In contrast, levels of ir-NacEP in the HPD intermediate lobe (IL) (263±16.5 ng/mg; n=4) were double those in the control (110±14 ng/mg; n=4), accompanied by a marked change in the molecular profile. In the control IL, the major species were NacαEP (30%), NacγEP (30%) and NacβEP1-27 (35%); in HPD IL, NacβEP1-27 (65%) is the dominant molecular form, with NacαEP (11%) and NacγEP (9%) relatively minor components.
- high-performance liquid chromatography
- sheep pituitary