Cortisol/DHEA ratio and hippocampal volume: A pilot study in major depression and healthy controls

Structural imaging studies investigating the relationship between hippocampal volume (HCV) and peripheral measures of glucocorticoids (GCs) have produced conflicting results in both normal populations and in individuals with MDD, raising the possibility of other modulating factors. In preclinical studies, dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS; together abbreviated, DHEA(S)) have been shown to antagonize the actions of GCs on the central nervous system. Therefore, considering the relationship of HCV to both of these hormones simultaneously may be important, although it has rarely been done in human populations. Using high-resolution magnetic resonance imaging (MRI), the present pilot study examined the relationship between morning serum cortisol, DHEA(S), and HCV in nineteen normal controls and eighteen unmedicated subjects with Major Depressive Disorder (MDD). Serum cortisol and DHEA(S) were not significantly correlated with HCV across all subjects (cortisol: r = −0.165, p = 0.33; DHEA: r = 0.164, p = 0.35; DHEAS: r = 0.211, p = 0.22, respectively). However, the ratios of cortisol/DHEA(S) were significantly negatively correlated with HCV in combined group (Cortisol/DHEA: r = −0.461, p = 0.005; Cortisol/DHEAS: r = −0.363, p = 0.03). Significant or near-significant correlations were found between some hormonal measurements and HCV in the MDDs alone (DHEA: r = 0.482, p = 0.059; DHEAS: r = 0.507, p = 0.045; cort/DHEA: r = −0.589, p = 0.02; cort/DHEAS: r = −0.424 p = 0.10), but not in the controls alone (DHEA: r = 0.070, p = 0.79; DHEAS: r = 0.077, p = 0.77; cort/DHEA: r = −0.427, p = 0.09; cort/DHEAS: r = −0.331, p = 0.19). However, Group (MDDs vs controls) did not have a significant effect on the relationship between cortisol, DHEA(S), and their ratios with HCV (p > 0.475 in all analyses). Although the exact relationship between serum and central steroid concentrations as well as their effects on the human hippocampus remains not known, these preliminary results suggest that the ratio of cortisol to DHEA(S), compared to serum cortisol alone, may convey additional information about “net steroid activity” with relation to HCV

Plants of Sabkha Ecosystems of the Arabian Peninsula.

Sabkhas are unique ecosystems that are highly saline and where specially adapted plants are able to grow, flower, and fruit. In general, saline environments are poor in species – for the Arabian Peninsula about 120 taxa are recorded as halophytes which constitute about 4% of the total flora of the Arabian Peninsula. Key halophytes of Arabia are nearly always perennial; predominant life-forms are somewhat succulent, semiwoody dwarf shrubs belonging to the families Amaranthaceae, Zygophyllaceae, and Plumbaginaceae and hemicryptophytes belonging to the Poaceae, Cyperaceae, and Juncaceae; annuals are exceptions. Coastal species are either obligate halophytes or salt-tolerant genera from unspecialized families, such as Sporobolus and Aeluropus (Poaceae), or salt-secreting species such as Avicennia (Acanthaceae) and Limonium (Plumbaginaceae). The submerged coastal vegetation, e.g., seagrasses, is one of the most important vegetation types of the Gulf coast and is of great importance to marine fauna. The north-south distribution of coastal species is more distinct on the Red Sea coast, with the border lying near Jeddah, than on the Persian Gulf coast where there is a broad transitional zone between Qatar and northern Oman. The east-west distribution of coastal species is not as distinct. The eastern elements are either restricted to the coasts around the Arabian Gulf or are Irano-Turanian species extending into the Gulf region. Several vicariant species groups of halophytes are represented in the Arabian Peninsula. Halophytes have developed strategies for seed germination such as high germination levels and fast germination speed. These traits are found in the sabkha plants of the Arabian Peninsula. Some halophytes have been investigated for their potential for phytoremediation in their ability to survive weathered oil-contaminated soils. They have been found to have a set of micoorganisms around their root system that are related to the degradation of oil in contaminated soils. Sabkha ecosystems are being degraded and altered throughout the Gulf countries as they appear to be nonproductive. Over the last two decades, there has been a growing concern in protecting and restoring mangroves, and programs do to so have seen promising results. But, on the whole, coastal and inland sabkhas are neglected, and these unique ecosystems require urgent protection