Abstract:
Acute stress in the course of wildlife management has been intensively investigated. Chronic stress,
on the contrary, has not been researched at all, probably due to the difficulty in measuring it as a result
of the overriding effect of the physiological response to the restraining of wild animals. It was therefore
decided to evaluate the use of immunocytochemistry, combined with computer image analysis
to try and determine the magnitude of the structural changes of various hormone-secreting cells of
the hypophysis. Since it was a pilot study to determine whether the combination of immunocytochemistry
with computer image analysis could be of value to distinguish between two normally diverse
groups, it was decided to compare the relative activity of prolactin secreting cells of lactating and nonlactating
impala ewes. After transforming the prolactin immunoreactive area data by log10 to fall inside
the parameters for kurtosis and skewness, a significant difference (P < 0,05, 5-% level, 2-tail)
with the parametric t-test could be shown between the mean prolactin immunoreactive area of lactating
(3,0751 µm2) and non-lactating (3,0467 µm2) ewes. However, the Pearson product moment (r= 0,03)
showed that this difference may not be important for all practical reasons. This may be due to either
sampling errors or limitations of computer image analysis, as it was often difficult to distinguish individual
prolactin immunoreactive areas. Furthermore, a significant increase in the total prolactin immunoreactive
areas of lactating ewes was also established. This technique, however, could distinguish
between the hypophyses of lactating and non-lactating impala ewes, and with further refinement
could be a useful tool in determining chronic stress in wildlife populations.
