ACTH, cortisol and the stress claim
A calm morning is an appealing image. Hormone measurements turn out to be much more particular about what changed.
ACTH fell while cortisol stayed unchanged
In an intravenous DSIP experiment in men, plasma ACTH-like immunoreactivity fell significantly for at least three hours. Cortisol was unaffected and followed its normal daily decline. I distrust a summary that lets the first half swallow the second.
Both observations deserve the sentence. The study supplies a particular ACTH finding alongside an unchanged cortisol response. A broad claim that DSIP lowered stress would require something considerably larger than the result described here.
A separate experiment in normal men also reported a decrease in plasma ACTH, while basal vasopressin and its responses to osmotic and orthostatic stimuli were unchanged. Again, one measured signal responded and another did not. I regard that selectivity as a reason to get more precise about the question.
Pituitary tissue in an animal experiment
In rat anterior pituitary tissue studied outside the animal, DSIP inhibited CRF-induced ACTH release and the associated rise in cAMP, while basal ACTH and cAMP were unaffected. That is a result about a stimulated tissue preparation.
Connecting this with the human ACTH observations appeals to me. I will credit the connection only with the tissue experiment's conditions intact: rat tissue, a specific stimulus, a measured response. The result gives a biological question something to work with. It supplies no account of how a person felt.
Stress responses in different rat strains
A study of repeated emotional stress in Wistar and August rats reported time-dependent changes in substance P, beta-endorphin and corticosterone after DSIP, with different cascades in the rat strains. The authors proposed downstream peptide and hormone changes as part of a long-term anti-stress effect.
The variation between strains is useful friction. Even within the animal work, a single smooth story about switching stress off would discard details that might matter. Those differences absorb me longer than the abstract's reassuring phrasing.
These experiments leave my original image of vitality pleasantly ordinary: enough ease to meet a morning. Establishing a biochemical route to that experience would take evidence about the experience itself. The opening essay returns to the small human observation that started the question.