Influence of thyroid hormones on the thermal selection of African house snakes (Lamprophis fuliginosus)

1. Neither thyroxine (T4) nor triiodothyronine (T3) significantly influenced mean preferred body temperature (Tb) of African house snakes, Lamprophis fuliginosus. T4 tended to decrease mean preferred Tb while T3 slightly increased preferred Tb. Although these results contrast with earlier evidence indicating significant influences of thyroid hormones on Tb, they support earlier observations suggesting independent roles for T4 and T3 in the modulation of thermoregulatory behavior. 2. Male and female snakes showed a similar lack of response to thyroid hormone treatments. However, the small sample size of male and female snakes (n=4 for each) within each treatment limits the power of these analyses for sex differences. 3. Mean selected Tb's of African house snakes in response to hormone treatments also did not differ among phases of the photoperiod. 4. We found no statistically significant differences between the thermoregulatory behaviors of snakes receiving injected control (5% ethanol in reptile Ringer's solution) and non-injected control treatments. These results have important implications for studies attempting to relate experimental manipulation (via intraperitoneal injection) of study animals to natural endogenous conditions.