Data on the evolution of hormones. Investigations on imprinting evoked by oligopeptides exhibiting no hormonal activity.

According to the present state of art, imprinting can also be evoked by di-, tri-, tetra- and heptapeptides exhibiting no hormonal activity, i.e., pretreatment with some of the oligopeptides leads to an enhancement of further hormone binding. Administration of symmetric and asymmetric molecules containing alanine resulted in positive, and negative imprinting respectively. The length of the molecule had no effect on the possibility of imprinting to develop. At the same time, the extent of imprinting evoked by molecules having no hormonal activity was approximately half of the imprinting seen in previous experiments when molecules having hormonal activity were applied. This observation indicates that in the phenomenon of development into a hormone the ability to evoke imprinting (to develop receptor memory) may be important. Thus, the development into a hormone is not an accidental event.