Selective regulation of neurosteroid biosynthesis under ketamine-induced apoptosis of cortical neurons in vitro

Neurosteroid influence on affective tone

Affective disorders such as depression and anxiety are among the most prevalent psychiatric illnesses and causes of disability worldwide. The recent FDA-approval of a novel antidepressant treatment, ZULRESSO® (Brexanolone), a synthetic neurosteroid has fueled interest into the role of neurosteroids in the pathophysiology of depression as well as the mechanisms mediating the antidepressant effects of these compounds. The majority of studies examining the impact of neurosteroids on affective states have relied on the administration of exogenous neurosteroids; however, neurosteroids can also be synthesized endogenously from cholesterol or steroid hormone precursors. Despite the well-established influence of exogenous neurosteroids on affective states, we still lack an understanding of the role of endogenous neurosteroids in modulating affective tone. This review aims to summarize the current literature supporting the influence of neurosteroids on affective states in clinical and preclinical studies, as well as recent evidence suggesting that endogenous neurosteroids may set a baseline affective tone.

Sex differences in steroid levels and steroidogenesis in the nervous system: Physiopathological role

The nervous system, in addition to be a target for steroid hormones, is the source of a variety of neuroactive steroids, which are synthesized and metabolized by neurons and glial cells. Recent evidence indicates that the expression of neurosteroidogenic proteins and enzymes and the levels of neuroactive steroids are different in the nervous system of males and females. We here summarized the state of the art of neuroactive steroids, particularly taking in consideration sex differences occurring in the synthesis and levels of these molecules. In addition, we discuss the consequences of sex differences in neurosteroidogenesis for the function of the nervous system under healthy and pathological conditions and the implications of neuroactive steroids and neurosteroidogenesis for the development of sex-specific therapeutic interventions.

Protective effects of tetrahydropalmatine against ketamine-induced learning and memory injury via antioxidative, anti-inflammatory and anti-apoptotic mechanisms in mice

Tetrahydropalmatine exerts numerous pharmacological activities, including analgesic and narcotic effects; anti-arrhythmic, blood pressure lowering and cardioprotective effects; protective effects against cerebral ischemia-reperfusion injury; inhibition of platelet aggregation; prevention of ulcerative diseases and inhibition of gastric acid secretion; antitumor effects; and beneficial effects on the withdrawal symptoms associated with drug addiction. The present study aimed to investigate the protective effects of tetrahydropalmatine against ketamine‑induced learning and memory impairment in mice. The Morris water maze test and open field test were used to analyzed learning and memory impairment in mice. ELISA kits and western blotting were used to analyze oxidative stress, inflammation factors, caspease‑3 and caspase‑9, iNOS, glial fibrillary acidic protein (GFAP), glial cell‑derived neurotrophic factor (GDNF), cytochrome c and phospholipase C (PLC)‑γ1 protein expression. The results demonstrated that tetrahydropalmatine treatment significantly decreased escape latency in the learning phase and increased the number of platform site crossings in ketamine‑induced mice. In addition, tetrahydropalmatine significantly inhibited oxidative stress, inflammation and acetylcholinesterase activity, and decreased acetylcholine levels in ketamine‑induced mice. Tetrahydropalmatine also suppressed iNOS protein expression, weakened caspase‑3 and caspase‑9 activation, inhibited nuclear factor‑κB, glial fibrillary acidic protein, cytochrome c and phospholipase C‑γ1 protein expression, and induced glial cell‑derived neurotrophic factor protein expression in ketamine‑induced mice. Taken together, these results indicated that tetrahydropalmatine may protect against ketamine‑induced learning and memory impairment in mice via antioxidative, anti‑inflammatory and anti‑apoptotic mechanisms. The present study provided an experimental basis for the clinical application of tetrahydropalmatine to reduce the severe side effects associated with ketamine therapy in future studies.