Study Of Neurosteroids Involved In The Development Of Morphine Addiction And Its Related Neurobiochemical Mechanisms

In recent years, the abuse of exogenous administration of opiates such as morphine and heroin is becoming the more serious social problem which engulfs both addicts themselves and their families. Opiate addiction includes such behavioral processes as tolerance, physical dependence, withdrawal syndromes and self-administration. Once an individual is addictive to opiates, it is difficult to abstain and the relapse rates reported are above 95% in our country.The precise mechanisms underlying opiate addiction are still incompletely understood. It is usually regarded that after repeated exposure to opiates, adaptations that elicits in individual neurons alter the functioning of those neurons which in turn alters the functioning of the neural circuits in which those neurons operate: This leads eventually to the complex behaviors (for example, dependence, tolerance, sensitization, and craving) that characterize an addicted state. Morphine addiction involves not only the opioid receptors, but also the dopamine (DA) receptor system, amino acid receptor systems, norepinephrine (NE) receptor system, 5-hydroxytryptamine (5-HT) receptor system, acetylcholine (Ach) receptor system, and corticotropin-releasing factor (CRF) receptor system.The term neurosteroids applie to those steroids that are synthesized within the central and peripheral nervous system, either de novo from cholesterol or from steroid hormone precursors. Neurosteroids including dehydroepiandresterone (DHEA), dehydroepiandresterone sulfate (DHEAS), pregnenolone (PREG), pregnenolone sulfate (PREGS), allopregnanolone (AP), deoxycorticosterone (DOC), testosterone (T) and progesterone (PROG) could act as a new typical neurotransmitter. It is demonstrated that neurosteroids can widely influence the function of neurotransmitter receptors such as GABAA,...