Biology Reference
In-Depth Information
on the development of ideas and investigations related to the possible relationships
between the central nervous and immune systems.
Despite all the shortcomings of these first steps, these scientists and investigators
proposed truly pioneering ideas with lasting value. Due appreciation for their con-
tributions is possible when one looks at them not from a position based on the pres-
ent level of knowledge, but from the position that obtained a century ago; from that
standpoint, one can appreciate how novel and risky was the very posing of this prob-
lem. At the time, immunology was in its infancy and appropriate investigative equip-
ment and skills were completely absent, so this foresighted attempt to gain a broader
and deeper understanding deserves respect even if the results are not fully consistent
with what we now know.
The origin of immunophysiological research may be traced to the 1890s, when the
pioneering works of Savchenko
[1]
and London
[2]
showed that transection of the
brain or removal of some of its parts affects the course of infection. In these studies,
major parts of the brains of pigeons were removed surgically, and then anthrax devel-
opment in the birds was followed. Pigeons are normally resistant to anthrax. However,
when the cervical segments of their spines were transected, they became susceptible to
this infection. The same was observed in pigeons that had brain hemispheres removed.
(It was later shown that transection of the cervical section of the spine impairs anti-
body production
[4]
.) It should be pointed out that these studies did not address the
possible influence of the brain on immunity; however, they were the first to show some
involvement of the brain in body responses to infection.
It is generally agreed that the founder of immunophysiological research is
Metalnikov
[3]
, a follower of Pavlov, who worked at Pasteur Institute in Paris.
Metalnikov was the first to explicitly put forward the idea that the nervous system may
influence body defenses and to experimentally check this possibility. In recognition of
his contribution, in 1993 the International Society of Neuroimmunomodulation (ISNIM)
instituted the Metalnikov Medal for outstanding achievement in this scientific field.
2.3 The Second Period
During the second developmental phase of the field, many researchers were attracted
by the idea of discriminating neural influences on the immune system and elucidat-
ing their role in the development of immunological reactions. In fact, many differ-
ent versions of experiments were designed almost simultaneously to answer the most
general question: namely, whether the nervous system has an impact on immuno-
logical processes. As a rule, the experiments involved the use of drugs that excite
or inhibit CNS activity and observation of the effect on the development of immune
responses.
These investigations led to the virtually unanimous conclusion that immunologi-
cal reactions are inhibited by substances, including hypnotic and sedative drugs, that
suppress cerebral activity. It should be stressed that the general conclusion drawn
from the absolute majority of the studies was at the level of CNS activity, and the
functional state of the CNS was found to be a significant factor of the development
