β-Lipotropin—β-Endorphin Response to Low-Dose Ovine Corticotropin Releasing Factor in Endogenous Depression

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Abstract
• Studies in depression using a maximal stimulatory dose of corticotropin releasing factor have concluded that elevated resting cortisol levels in depressed patients exert a negative feedback effect on the corticotroph, resulting in a decreased corticotropin response. In this preliminary report, we examine the effects of a submaximal dose of corticotropin releasing factor on the release of another corticotroph secretory product, β-lipotropin—β-endorphin. We observed a decreased β-lipotropin—β-endorphin response in depressed subjects, but a normal adrenal cortisol response. Although the total β-lirotropin—β-endorphin response was decreased, the initial secretory response did not differ between patients and normal controls. Rather, the patients appeared to turn off secretion faster. This rapid shutoff was seen in all patients regardless of resting cortisol levels, suggesting that resting cortisol levels alone do not explain the decreased response seen in depressed patients.