His work included investigations into the effect of gonadal hormones on sexual differentiation of the brain during neonatal life, and into the isolation of hypothalamic releasing factors.

In mammals, it is the major hypothalamic releasing factor for pituitary adrenocorticotropin secretion, and is a neurotransmitter or neuromodulator at other sites in the central nervous system.

Since then, hypothalamic releasing factors have been discovered for all the major pituitary hormones (thyroid stimulating hormone, luteinising hormone and adrenocorticotropin, for example) except growth hormone.

It is associated with low circulating levels of pituitary gonadotropins secondary to inadequate stimulation by hypothalamic releasing factor (LHRH), itself a direct effect of undernutrition.

The pituitary is functionally linked to the hypothalamus by the pituitary stalk, whereby hypothalamic releasing factors are released and, in turn, stimulate the release of pituitary hormones.

Citicoline has also been shown to elevate ACTH independently from CRH levels and to amplify the release of other HPA axis hormones such as LH, FSH, GH and TSH in response to hypothalamic releasing factors.