LYMPHOCYTE TRAFFICKING FOLLOWING ACUTE STRESS AND ALTITUDE HYPOXIA IN LOW AND HIGH HEMATOCRIT SHEEP

Abstract

The object of the present study was to investigate small and large lymphocytes
trafficking in sheep with low and high hematocrit values following shearing,
exposure to moderate altitude and transport to low altitude. Twenty out of 101 Ile
de France ewes (1-7 years old) were used in the present experiment. All ewes of
the flock were artificially inseminated in May 2015 following estrus
synchronization. The animals were allocated into two groups following threefold
measurements of hematocrit in all ewes as follows: I- low hematocrit group (n=10)
and II - high hematocrit group (n=10). The ewes were transported to the Petrohan
Pass (1440 m above sea level) in June 2015 immediately after shearing, conducted
at the experimental farm of the Institute of Animal Science, Kostinbrod (500 m
above sea level). Blood samples were collected before shearing, immediately after
shearing, 3 h after shearing, at 14 d following exposure to moderate altitude,
immediately after transport to low altitude and following 7d of stay at low altitude.
All leukocyte subpopulations were counted microscopically. In the current study
we presented the percentage of lymphocytes only, including small and large
(reactive) lymphocytes. High and low hematocrit ewes had different percentage of
small lymphocytes when exposed to various acute and chronic stress stimuli. There
were significant differences in the percentage of large (reactive) lymphocytes
between low and high hematocrit ewes following blood collection and immediately
after shearing. The observed difference in small lymphocyte dynamics among the
groups in response to different stress stimuli was attributed to hematocrit related
differences in the time course and magnitude of lymphocyte distribution at early
and late phases of stress. The results were interpreted to mean that the differences
in lymphocyte trafficking between the two groups of sheep in response to stress
were related to possible difference in the share of aerobic and glycolytic pathways
for energy supply.