Acute Stress Literature Review

3. Review of Literature

3.1 Stress

Stress is one factor which can affect all the three components of health namely physical, mental and social. Almost every human being undergoes stress at various stages of their life. In 2012, the Australian Psychological Society classified stress into 3 types, namely acute, episodic acute and chronic stress. Acute stress is short and specific to the demands of a particular situation. Episodic acute stress is an acute stress which is experienced over and over again. This type of stress is more common among the teenagers and office goers. The chronic stress involves demands and pressures which seems to be a day to day phenomenon. Short term stress can be adaptive but chronic stress in certain cases leads

Monoamines, serotonin and glutamate levels regulate neurogenesis. The former two stimulates neurogenesis (Chaouloff, 1989 and Brezun et al, 1999) and the latter inhibits neurogenesis (Gould et al, 1994). Acetylcholine, dopamine and norepinephrine increase the proliferation of the precursor cells (Cooper-kuhn et al, 2004, Mohapel et al, 2005). GABA plays a role in the survival (Van der Borght et al, 2005) and differentiation of the proliferated neurons (Ge et al, 2006). Substance P and opioids decrease neurogenesis, where they mainly affect the proliferation and not survival of the newly differentiated neurons (Morcuende et al, 2004 and Harburg GC et al,

Studies have also revealed that there is no effect of fluoxetine on neurogenesis with advancing age. This shows that the antidepressant action in elderly may not be mediated by neurogenesis and is yet under speculation (Despres et al, 2009). Fluoxetine was also found to improve spatial cognitive deficits post stroke recovery by increasing the neurogenesis in the hippocampus, thus opening up the possible role of fluoxetine in the treatment of stroke (Wen- lei et al, 2009). There is loss of neurogenesis in transient ischemia which was reversed by treatment with fluoxetine given at a dose of 20mg/kg (Khodanovich et al, 2016). However, other regions of the brain like the amygdala, cingulate cortex and nucleus accumbens may also have a role in the anti-depressant like activity. Very few studies have also shown that adult neurogenesis in location other than hippocampus can have a role on the anti-depressor effect (Kokoeva et al, 2005,