Morphological Changes after Chronic Heat Exposure on Zona Fasiculata of Adrenal Gland of Albino Rats

Abstract

Objective: To compare the microscopic changes in zona fasciculata of adrenal gland of rats between control and chronic heat exposed groups.

Study Design: Experimental Study

Place and Duration of Study: This was conducted in IBMS, DUHS. Karachi from June 2010 to May 2011.

Materials and Methods: Forty eight male wistar rats were selected for the study and divided into two groups A and B, each group consisted of 24 rats. Group A served as control and subdivided into three groups. Group B was taken as chronic heat exposed and subdivided into three groups on period of exposure (B1, B2, B3). All rats were acclimatized at temperature of 22 ± 2^oC for two weeks. Group B exposed to 35 ± 2^oC for 2 hour daily for 2 weeks, 4 weeks and 6 weeks, and sacrificed on completion of respective period of heat exposure along with their respective control. After dissection the gross changes and weight of each adrenal gland was observed, gland was fixed in Bouin’s fluid and embedded into paraffin wax. After tissue blocks made, 5µm thick sections were obtained; sections were stained with Haematoxyline and Eosin stain to observe the light microscopic changes. Statistical analysis was done by using the software SPSS version 16, t-test, Mann Whitney, ANOVA and Kruskal Wallis were applied for the comparison between the group variables.

Results: The changes in the total cortical thickness in chronic groups were shown by the P-value <0.0001.Thickness of zona fasiculata and changes between all chronic and their control groups showed the P-value = <0.0001; The other significant changes were also observed on microscopic micrometry.

Conclusion: The significant increase in the total thickness of cortex and zona fasciculata of the gland  was seen, as increased seceretory vesicles were observed after chronic exposure to heat stress. After the completion of this study, it is suggested that more investigations should be carried out to see the genetic influences and the depth of the whole process.