The PHI (PHI-27)/corticotropin-releasing factor/enkephalin immunoreactive hypothalamic neuron: possible morphological basis for integrated control of prolactin, corticotropin, and growth hormone secretion.

By using the indirect immunofluorescence technique, one and the same neuron in the parvocellular part of the paraventricular nucleus has been shown to stain with antisera against three different peptides: PHI (PHI-27), corticotropin-releasing factor (CRF), and enkephalin. This could explain the well-known parallel increase in plasma prolactin, corticotropin, and growth hormone levels--for example, under certain types of stress--as being due to a concomitant release of PHI-like, CRF-like, and enkephalin-like peptides from the same nerve endings in the median eminence. A hypothetical mechanism for the co-ordinated release of these three anterior pituitary hormones is discussed.