| Popis: |
Neurotransmitters are chemical messengers synthesized by neurons, which enable interconnection of nerve fibers within their vicinity. Neurotransmitters traditionally consist of amino acids and their derivatives, chains of amino acids, peptides or proteins. However, several studies report that steroids and hormones also exert an acute effect on the physiology of neuronal activity and the expression of behavior that can happen within minutes. Those steroids that can bind to the neurotransmitter receptors and modulate the neurotransmission signal are included together within the term neurosteroids or neuroactive steroids. The examples of neuroactive steroids include progesterone, estradiol, testosterone, DHEA, glucocorticoid, allotetrahydrodeoxycorticosterone (THDOC), androstanediol (AD), ganaloxone, androsterone, pregnenolone, allopregnanolone and their sulfate esters. Additionally, several synthetic steroids such as alphaxalone and 3ɑ-hydroxy-5β-pregnan-20-one hemisuccinate possess similar characteristics of modulating neuronal activities to the endogenous steroids. These hormonal steroids exert their neuronal excitability functions through various receptors and ion channels such as the estrogen receptor, progesterone receptor, androgen receptor, GABAA, AMPA and NMDA receptors. These neuroactive steroids are also involved in the pathology and physiology of various neurological disorders such as epilepsy, schizophrenia and traumatic brain injury. Additionally, these neuroactive steroids have agonistic or antagonistic effects toward the neurotransmission action of various other neurotransmitters some of which have undergone clinical trials for the treatment of various neurological disorders. Thus, these steroids and hormones can act as neurotransmitters, exert either agonistic or antagonistic effects on receptors and have potential benefits in the treatment of neurological disorders. |
