ABSTRACT
A noteworthy example which combines the classical elements of both approaches are the hormones of the neurohypophysis which perform dissimilar homeostatic functions throughout vertebrate phylogeny but yet are surmised to be derived from one ancestral template, arginine vasotocin (AVT). Vasotocin injections elevate growth hormone levels in Coho salmon as well as in rats; thus, the glucogenic and lipolytic effect of vasotocin may be mediated via growth hormone in some species. K. Tanaka and S. Nakajo observed a depletion in neurohypophyseal vasotocin-like activity coincident with egg-laying; a concomitant rise in the amphibian water-balance principle was seen in the blood. The peptide was tentatively identified as lysine vasotocin \based on its rat pressor and rat oxytocic activities; it, too, had been synthesized in the early 1960s. A diurnal rhythm of vasotocin in the rat pineal has been demonstrated by Calb and co-workers. Pineal content of AVT was high at noon and low at midnight in both normal and hypophysectomized rats.
