The Blueprint for Stress can be found in Invertebrates
Abstract
| Introduction |
Stress vs. a perturbation response? |
Invertebrate signaling processes: opioid and
opiate |
Receptors | Functions |
Adrenocorticotropin | Discussion
|
Acknowledgements | References
George B. Stefano, (1),
Patrick Cadet, (1),
Wei Zhu, (1),
Christos M. Rialas, (1),
Kirk Mantione, (1),
Danielle Benz, (1),
Rudy Fuentes, (1),
Federico Casares (1),
Gregory L. Fricchione (2),
Zoltan Fulop (3) and
Brian Slingsby (1)
1.
Neuroscience Research Institute, State University of New York
at Old Westbury, Old Westbury, New York 11568, USA.
2. The Carter Center, 1 Copenhill, 453 Freedom Parkway, Atlanta,
GA 30307, USA.
3. Faculty of Science and Mathematics, Wagner College, Staten
Island, NY 10305, USA.
Submitted:
February 23, 2002
Accepted: February 23, 2002
Key words:
stress, invertebrates, morphine, opioid peptides, ACTH,
CRF, enkelatin
Abstract
Through
an extremely complicated equilibrium called homeostasis, all
living organisms maintain their survival in the face of both
externally and internally generated “stimuli”. This
apparent harmony is constantly challenged. Survival through
successful adaptation is maintained as close to steady state
as possible by adaptive responses, which may also be called
perturbation responses since they have a constitutively defined
dynamic capacity, i.e., an immediate limit, in a series of balancing
and feedback activities reflecting an astounding array of biological,
psychological and sociological behaviors. The broad spectrum
of stimuli capable of engaging this protective response is remarkable.
We define stress as a type of stimulation that is stronger and
lasts for a longer duration, upsetting a typical perturbation
response given its dynamic parameters. The stress response,
which evolves out of the perturbation response, involves inducible
signal molecules, i.e., cytokines. We surmise that the ability
to exist in an ever-changing environment was a requirement for
all life forms, including invertebrates and single celled organisms.
It would be expected that these organisms exhibit both perturbation
and stress responses. In this regard, we demonstrate that these
organisms have mammalian-like signal molecule systems, i.e.,
opioid, and corresponding behaviors that are similar to those
found in mammals with regard to both perturbation and stress
responses. Thus, it would appear that these responses evolved
first in simpler organisms and were then maintained and enhanced
during evolution.
Introduction
The
present review will discuss evidence to support the hypothesis
that the highly regulated vertebrate stress-response mechanism
had its origins in the invertebrate nervous system, if not earlier
in evolution. This view is based on recent evidence that, in
both animal groups, the immune and nervous systems appear to
utilize similar intercellular signal molecules. These signal
processes appear to be involved in similar activities. This
suggests that, as in mammals, the system in invertebrates has
the potential for bi-directional communication between these
other systems as well. Furthermore, we surmise that stress processes
originated in the innate and dynamic protective perturbation
processes that restore homeostasis due to immediate changes
in both the internal and external environment. And when left
on, they turn into a stress response whereby the same processes
exhibit negative outcomes, i.e., prolonged immunosuppression.
Past studies on neuronal mechanisms in insects and mollusks
have revealed remarkable structural, functional, and biochemical
parallelisms with those in vertebrates [1-4]. For example, the
first experimental demonstration of a neurohormone on record
was that of the “pupation hormone” of insects reported
by Kopec in 1917, [1]. Invertebrates are often described as
“primitive,” or “simple,” when referred
to in scientific literature. However, their life cycle, encompassing
embryonic and postembryonic development, reproductive activity,
and changing metabolic and behavioral patterns, requires sophisticated
signal mechanisms. These episodic events are programmed with
great precision and coordination by the organism’s neuroendocrine
control system. Numerous studies, in a variety of invertebrate
species, have identified neuropeptides in parts of the neuroendocrine
and nervous system apparatus, which is analogous to the hypothalamic-hypophysial
system of vertebrates [1,2,5-7]. The list includes substances
closely resembling the following vertebrate neuropeptides and
hormones: oxytocin, vasopressin, adrenocorticotropin (ACTH),
a melanocyte stimulating hormone (MSH), somatostatin, substance
P, neurotensin, hypothalamic growth hormone releasing factor,
insulin, glucagon, gastrin/cholecystokinin, vasoactive intestinal
peptide (VIP), pancreatic polypeptide (PP), secretin, luteinizing
hormone releasing factor (LHRF), and several endogenous opioids
[8-12].
Stress
vs. a perturbation response?
Through an extremely complicated equilibrium called homeostasis,
all living organisms maintain their survival in the face of
both externally and internally generated “stimuli”.
This apparent harmony is constantly challenged [13,14]. Thus,
all life forms have developed processes to overcome immediate
perturbations, i.e., protective perturbation response, since
they will always occur. An organism without this dynamic ability
could not survive. It can also be said that the ability to overcome
perturbations is essential to survival and longevity, as it
insures that the “message” is passed on. Survival
is maintained close to a steady state as possible by these responses
in a series of balancing and feedback activities reflecting
an astounding array of biological and sociological behaviors
in simple organisms.
Psychological factors also enter into this responsive process
in cognitive animals as well. These behaviors are employed to
cope with the effects of physical trauma with the hope of reestablishing
and/or maintaining ... ...
Taken
together, one may also surmise that the perturbation-response,
if allowed to continue, would evolve into a stress-response.
Hence, the perturbation response represents an evolutionarily
conserved response ... ...
It
would be enticing to further believe that the development or
chance “alteration” of genetic material leading to
cognitive processes ... ...
Invertebrate
signaling processes: opioid and opiate
... ...
Receptors
...
...
Functions
...
...
Adrenocorticotropin
...
...
Discussion
...
...
Acknowledgements
This work was supported in part by the following grants: NIMH
COR 17138, NIDA 09010, and NIH Fogarty INT 00045.
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