In the mid 1980s, the neuroactive steroids 3α,5α-tetrahydroprogesterone or allopregnanolone (3α,5α-THP) and 3α,5α- tetrahydrodeoxycorticosterone (3α,5α-THDOC) were shown to modulate neuronal excitability via their interaction with GABA A receptors. The steroids 3α,5α-THP and 3α,5α-THDOC were able to enhance the GABA-elicited Cl − current.  In addition, these steroids might enhance the binding of muscimol and benzodiazepines to GABA A receptors.  Structure- activity studies (SAR) showed that the 3alpha-OH group is essential for the anesthetic actions of these steroids,  they also have an optimally-placed hydrogen bond accepting group on the β face of the steroid at the C-17 position. The four steroid rings form a rigid framework for positioning these hydrogen groups in three-dimensional space.  Analogues 5 and 6 (Figure 10) are weak modulators of GABA A receptor function because the flexible side chains in these analogues do not have the conformations required for high biological activity. 
The liver also plays an important role in vitamin and mineral ( iron & copper ) storage. About 80% of the body's vitamin A stores are concentrated in fat droplets within the stellate cells of the liver. In pathological conditions like hepatic fibrosis or liver cirrhosis the stellate cells lose vitamin A, transform into fibroblasts or myofibroblasts and begin producing large amounts of collagen and adhesive glycoproteins. * Normal vitamin A reserves are enough to prevent a deficiency for about 10 months. The liver also contains about a year supply of B12. Vitamin D stores equal about 3-4 months. Small amounts of Vitamins E and K and Vitamin C are stored in the liver to facilitate liver functions.