Glucagon—A hormone that acts during starvation

After graduating from medical school in 1968, I first entered the laboratory of endocrine and metabolism under Professor Seiichiro Tarui and started with “research on the effects of insulin on membrane transport of carbohydrates,” using rat diaphragm. From 1967–69 onwards I studied the secretion of GLUCAGON using isolated islets of Langerhans in Detroit under Professor Piero P. Foa. After returning to Japan, I observed the secretory regulation of glucagon in vivo using dogs. Below are the current author’s thoughts on what glucagon is all about.

The birth of homo sapiens is estimated to be about seven million years ago south of the Sahara Desert in Africa, however, most of their life history was starvation, and it is thought that survival was a struggle against and overcoming starvation. The primary hormone acting in the event of starvation is glucagon, and thus glucagon was the essential hormone for survival. From a holistic view, most of the time since the birth of homo sapiens to the present day has been a time of starvation, and in short, homo sapiens history has been a history of fighting against hunger. After that, if they were lucky, they would have a short period of satiation, followed by an unpredictably long period of starvation. At a time when homo sapiens had no knowledge of farming, harvesting wild plants, and capturing small animals and fish, weather was the first thing that affected the securing of food following. Drought, flood, storm, earthquake, eruption, outbreak of insects has been also a major factor in starvation, however, in modern times, those are international dispute and wars, with the most recent events Russia’s invasion Ukraine, and the earthquakes in Turkey and Syria. This hormone is essential in times of war, earthquakes and disasters.

In contrast, in normal environments where there is enough food, insulin works to store food in the body. In times of peace and sufficient food availability, type 2 diabetes has become a problem due to overeating and lack of exercise resulting from a relative deficiency of insulin. It is a matter of times of peace. I won’t go into it further in this article.

As mentioned above, glucagon is secreted and acts under various conditions that threaten the survival of the individual and this feature has been observed at early stage of embryonic stage. It has been reported that pancreatic glucagon secretory cells appear at a much earlier stage than that of insulin-secreting cells. Also reported that glucagon-producing cells appear in the fetal period pancreas at the same concentration as at birth as early as around 10 weeks of age, when insulin-producing cells do not exist in rats during the embryonic period. The appearance of insulin-producing cells is much delayed, around 20 weeks of age, just before birth.

In terms of time phases in homo sapiens history, it seems to be a reasonable view that most of the time is the glucagon phase, in which a short insulin phase is intermittently interspersed.

Biographies

Kyohei Nonaka

Honorary Member

Professor Emeritus, Kurume University

Honorary President, Shiroishi Kyouritsu Hospital

E-mail: [e-mail]

Careers in JES

2003– Honorary Member

1999– Senior Councilor

1989–1991 Auditor

1975– Councilor

1970– Member