User:Ychhean/sandbox

As aging progresses, changes or alternations in intercellular communication occur. These intercellular communications consist mostly of three types. The first type is neuronal which consists of communication that only happens between the cells of the nervous system, specifically the neurons. The second type is neuroendocrine which consists of communication that happens between the nervous system neurons and the endocrine system's hormones. Last is endocrine which consists of communication that only happens between the cells of the endocrine system. Any of these three types of communication can be affected in the process of aging. Research has shown that altered intercellular communication due to aging leads to increased inflammation, reduced neurogenesis and decline in efficient autophagy.

Previous research done by Zhang et al. in 2013 found that the inhibition of IκB kinase-β, IKK-β, and nuclear factor κB, NF-κB, in the hypothalamus caused an increase in gonadotropin-releasing hormone, GnRH, which led to adult neurogenesis. Thus, Zhang et al. were cited in “The Hallmarks of Aging” under altered intercellular communication for their findings. Later research after 2013 also agreed with Zhang et al. that IKK-β and NF-κB is an integral part of aging and longevity. In recent years, research in altered intercellular communication in regards to aging and longevity has shifted from studying the neuronal network into examining how the circadian rhythm and cycle affects the hippocampus and neurogenesis.

However, circadian rhythm and cycle was not the only aspect being studied. Research was also conducted on various receptors, proteins, and hormones that had a connection to the effects of altered intercellular communication to see if they were the cause, effect, or otherwise. In addition, these receptors, proteins, and hormones were examined and manipulated extensively to see if they were able to improve the effect of altered interceullar communication or not. In early 2017, Lacoste et al. proposed the malfunction or impairment of the circadian clock as the tenth hallmark of aging. They suggested that aging, the circadian clock and cellular oxidative stress are interrelated, because they propose decrease efficiency of the antioxidant defense system with age. However, some of their findings about the levels of lipoperoxidation, LPO, and glutathione, GSH, as a factor of measuring oxidative stress as a person ages does not agree with earlier research. The reason behind this is still hugely unknown until further research has been conducted.