Characterization of the array of steroids and their metabolites in pig hippocampus
Hodges, Heather B.
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Our objectives were to characterize the array and concentrations of steroids and their metabolites present in the pig hippocampus at basal levels, and to in tum use this novel data for comparison with results from an applied stress model. In brief, we first developed a protocol for steroid extraction from a compilation ofpublished techniques, and tested the efficiency ofthis procedure via radio immunoassay (RIA). The efficiency of the extraction protocol ranged from 31 to 75%. Then, these methods were used to extract the steroids present in pig hippocampi, attempting separation via HPLC and characterization via EIA. Once characterization was completed, we attempted to define the importance ofthese compounds in modulating stress responsiveness with a previously used stress model. Behavioral data was compared with the physiological measures of specific steroid concentrations, in attempt to discover a correlation between a behavioral stress response and the physiological stress response involving steroid stress hormones. One significant finding is that the level of cortisol (the major circulating glucocorticoid in both the pig and human body) is present in the hippocampus at much lower concentrations (approximately only 2.9% of total amount detected by four specific EIAs) than other detectable steroids and their metabolites. Due to small sample size (n=3) for each stress condition, standard errors were large though, and so no conclusions, only speculations, have been drawn. Furthermore, this was a pilot study, and therefore these preliminary results remain to be confirmed by future experimentation currently under consideration. However, this future research can take advantage ofthe novel data we present on the neuroactive steroids existing within the hippocampus.