Bengt Falck

Research

In his 1959 thesis (Falck, B. Site of production of oestrogen in rat ovary as studied in microtransplants. Acta physiol.scand. Suppl. 163, 1959, 47: 1-101) he was able to show that the production of estrogen in the ovaries is dependent on an interplay of two different hormone producing systems. In one, a precursor – a variant of the male sex hormone – is formed, that is then transformed to estrogen in the second system. His thesis is still well known in scientific circles, which may be noted when Googling ”Falck's two-cell hypothesis of oestrogen synthesis”.

In 1960–61 Falck and Nils-Åke Hillarp developed the Falck-Hillarp fluorescence method.

This technique made it possible to study biologically active substances called monoamines – dopamine, noradrenaline, adrenaline and serotonin – on the cellular level employing fluorescence microscope. Consequently, it was then possible to demonstrate their presence in the central as well as peripheral nervous system. Thereby, it could be established that these monoamines were actually functioning as interneuronal transmitters (signal substances).

The method is based on the important and decisive discovery that these compounds are able to react with formaldehyde – in near complete absence of water – to form fluorophores, i.e. molecules that, when irradiated with light invisible to the eye, will emit visible light (Fig1). This happens in a “dry” state, without extracting the monoamines from the cells during the entire procedure, a process that starts with separation of a tissue sample and ends with a thin tissue slice that can be examined in a fluorescence microscope.

The F-H method allowed, for the first time, the examiner to watch these monoamines light up in the microscope and to precisely determine in which cells they were present, and thereby understanding their functions. The method was developed in the 1960s at the department of Histology, University of Lund, and became a tremendous national and international breakthrough, i.a. for intense neurobiological research: now, it became possible to demonstrate the presence of monoamines in nerve cells belonging to the central and the peripheral nervous system (Fig 2, below) and – for the first time – comprehend that these substances act as signal substances, i.e. transmitters.

The initial publication, written already in 1961[1], described a wide-ranging examination of nerves supplying a large number of organs in the body. This work validated the concept of Ulf von Euler, the Nobel prize winner, that noradrenaline is the signal substance in peripheral autonomic nerves. In the same year, this first publication was followed by an explanation of the chemical background of the F–H method [2]:

Very thin membranes, e.g. the rat iris or mesentery do not have to be sectioned for microscopic studies but may simply be spread on glass, dried and then exposed to gaseous formaldehyde for subsequent study with a fluorescence microscope.

The publication on the chemical background was later named among “ The 200 Most-Cited Papers of All Time”

In 2012, the Faculty of Medicine at the University of Lund arranged a symposium “From Nerve to Pills” celebrating the 50th anniversary of the initial publication of the F-H method. (1,2,4).

Accordingly, it was not Arvid Carlsson who had discovered that dopamine is a signal substance in the central nervous system, as stated by the Nobel Committee at the Karolinska Institute in a press release in 2000. They had based their opinion on reports published by Carlsson and co-workers in 1957–1958. However, Carlsson, Falck and Hillarp published a study in 1962, which was based on the Falck-Hillarp fluorescence method on the cellular location of noradrenaline and dopamine in the brain, showing that noradrenaline is located in nerve cells (neurons) and functions as a transmitter. However, they could not ultimately define the cell type that harbors dopamine and were thus not able to state with certainty that dopamine is a transmitter. Obviously, if Carlsson had discovered this in 1957–1958, it would have been referred to and extensively discussed in the Carlsson-Falck-Hillarp publication in 1962. Both Hillarp, at the Karolinska Institute in Stockholm and Falck, at the Medical Faculty, University of Lund, had several research assistants, who studied various aspects of transmitters, using the Falck-Hillarp fluorescence method and it was not long before these two groups had established that dopamine is, indeed, a transmitter.

The first publication in this field was written by Falck and Alf Torp in 1961 and published in 1962. It is still often quoted in medical and scientific journals. Important follow-up work was published in 1962 by authors Falck, Hillarp, Thieme and Torp. It came to be one of the 200 Most-Cited Papers of All Time". This was the beginning of an intense neurobiological research which went on for several decades. In April 2012 the symposium ”Från nerv till piller” took place at the University of Lund to celebrate the 50-year jubilee of the first publications on the Falck-Hillarp fluorescence method.

In the 1960s Falck embarked on research of monoamine related substances in epidermal pigment cells (melanocytes) and in malignant melanoma. This led to a new understanding of the construction of the epidermis, and also the discovery of a novel function of the epidermal Langerhans cells. During the end of the 1960s until 2004 much of Falck's epidermal research was emphasized on the Langerhans cells. In 2004 his latest publication ”Mediated exodus of L-Dopa from human epidermal Langerhans cells", was published,

Bengt Falck is the son of Hans Falck (city court judge in Malmö, Sweden) and Maria Hagander. He married Eva Torp in 1951, and together they had four children. In 1994 he married Inger Vestvik.