Drug Administration Before or After Exposure to Low Temperatures-Does It Matter for the Therapeutic Effect?

The adaptation of the body when exposed to a lower-than-usual temperature is a challenge that involves neuro-endocrine-immune mechanisms and affects the pharmacokinetics and/or pharmacodynamics of drugs taken before or after cold exposure. The experiments presented in this study clearly show differences in the analgesic effect of an exogenously introduced model substance (C-terminal fragment of calcium-binding protein, spermatid-specific 1) before and after cold exposure compared to its effect at an ambient temperature. The model substance used for the experiments is an octapeptide, TDIFELLK, which was synthesized via standard solid-phase peptide synthesis. Preliminary studies proved TDIFELLK's analgesic activity. The ANOVA analysis performed showed statistically significant differences in the pain thresholds, measured by a paw pressure test, in 109 rats distributed among 14 groups and subjected to cold exposure according to different set-ups. Cold exposure immediately after TDIFELLK administration appears to enhance its analgesic effect, while cold exposure before administration reduces the effect. In some of the set-ups, antagonists of the most significant for analgesia receptors, i.e., opioid, cannabinoid, and serotonergic, were also introduced. The results showed that cold exposure had a modulating influence on the effect of the exogenously administered substances. The modulating effect was manifested differently depending on whether the intake occurred before or after cold exposure. The results also showed that the interaction with individual mediator systems was also subjected to differences depending on intake occurring before and after cold exposure.