Roots and early routes of neuroendocrinology.

Carl C. Speidel (1919) and Ernst Scharrer (1928) were privileged witnesses of the encounter between neurons and hormones, a biological phenomenon that had been occurring in nature during millions of years of evolution, as Berta Scharrer started to unfold since 1935 on. The story of neurosecretion is intimately associated to that of the hypothalamus, such a "marvellous region", as Wolfgang Bargmann (1975) called it. This story started more than two millennia ago. We have made an effort to trace the roots of the discoveries that gave rise to a medical discipline, neuroendocrinology. Our trip to the roots covers a period from the fourth century BC, when an extraordinary Medical School was founded in Alexandria, and extends into the late 1970s of the twentieth century, when neuroendocrine research had started to grow exponentially. An effort has been made to track back the origin of each piece of knowledge that was constructing, brick upon brick, the building of this new medical science, hoping that it would help neuroendocrinologists of the new era to find their own roots, to meet their ancestors. Tracking the roots of a particular phenomenon provides the opportunity to have an overview of the whole phenomenon, allowing comprehension rather than merely knowledge. An important purpose pursued throughout this article was to pay a tribute to all those who, in the early days, contributed to the brain-endocrine encounter. We have tried our best to bring back the achievements of most of them.