Microwave-induced temperature, corticosterone, and thyrotropin interrelationships.

Abstract

To delineate acute endocrine responses to microwave energy absorption, 142 unanesthetized male Long-Evans rats acclimated to experimental procedures were subjected to far-field 2.45-GHz microwave exposure for 1 h at 1-70 mW/cm/sup 2/, 4 h at 0.1-40 mw/cm/sup 2/, or sham exposure. Controls were sham exposed in a sham-exposure chamber beginning at 030 h and killed at 1230, 1330, 1530, and 1930 h. Microwave-exposed rats were equilibrated in an anechoic chamber for 3 h prior to the start of exposure. Microwave exposure was initiated at 1130 h. Exposed rats were killed at 1230 and 1530 h. Colonic temperature (T/sub col/) was measured and serum obtained for thyrotropin (TSH) and corticosterone (CS) determination immediately after exposure. Inverse relations of TSH to power density (PD) or R/sub col/ were noted in the microwave-exposed rats while CS increased with PD or T/sub col/. Similar relations of TSH and CS to T/sub col/ were also noted among ''shams.'' The increase of T/sub col/ by microwave exposure was dependent on PD but independent of an exposure duration greater than 1 h. The serum CS level increasd with PD but the effect decreased with duration of exposure. ''Low intensity'' 4-h microwave exposure inhibited normal circadian elevation ofmore » adrenocortical function in rats if the exposure was coincident with diurnal CS elevation.Inhibition of TSH became more pronounced with duration of exposure. Differences in the endocrine-body temperature relationships between sham- and microwave-exposed rats were also noted. It was concluded that endocrine control was dissociated from body temperature in the microwave-exposed rats. The endocrine control in microwave-exposed rats is different from shams.« less