AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 1 125-R129, Copyright © 1985 by American Physiological Society
Fever-specific changes in central MSH and CRF concentrations
M. Holdeman, O. Khorram, W. K. Samson and J. M. Lipton
The concentration of melanocyte-stimulating hormone (melanotropin; MSH)
within the septal region of the brain increases during the fever, and
septal injections of MSH are antipyretic. Corticotropin-releasing factor
(CRF), when injected intracerebroventricularly, is also antipyretic. Using
sensitive radioimmunoassays of microdissected tissue extracts, we
established the presence of immunoreactive MSH (IRMSH) and CRF (IRCRF)
within discrete central nervous system sites of the rabbit. Leukocytic
pyrogen-induced fever and hyperthermia due to heat exposure did not alter
concentrations of IRMSH or IRCRF in tissue extracted from preoptic-anterior
hypothalamic or midbrain central gray regions. However, significantly
greater levels of IRMSH were detected in septal extracts of febrile rabbits
than in similar extracts from afebrile controls or heat-stressed animals. A
significant decrease in IRCRF was detected in paraventricular nucleus
extracts from febrile animals compared with extracts from afebrile controls
or heat-stressed rabbits. Our results support the hypothesis that these
central peptides have a role in temperature control during fever. Since no
changes were detected in extracts from hyperthermic rabbits, it appears
that changes in concentration of these neuropeptides within particular
brain regions are specific to the febrile state and are not caused by
elevation of body temperature or by nonspecific stress.
