Scientists across the globe are involved with various studies on persistent symptoms associated with COVID-19 infection aside from common symptoms. Number of studies have highlighted psychological symptoms as anxiety, depression etc. Many other studies have revealed asthenia, anosmia, taste disorders etc. A research published on 1st April in Nature Communication Rutkai et al. (2022) have pointed the neurological manifestation of COVID-19 infections in non-human primates. Four Rhesus macaques (13-15 years) and four wild African green monkeys (16 years) were used in study. All of them developed infection within first week of exposure. Cell death-associated neuronal changes were noted in cerebellum of infected animals. Microhemorrhages were demonstrated in cerebellum, brainstem and basal ganglia. The study illuminates the critical mechanisms of infection and CNS involvement. Other studies have shown the expression of angiotensin-converting enzyme 2 (ACE-2) in different parts of brain through both excitatory and inhibitory neurons.
COVID-19 viruses bind to ACE-2 receptors. Mutations in spike proteins of viruses are the main reason behind new variants of COVID-19. Mutations and polymorphism are also occurring in ACE2 receptors after COVID-19 as revealed by a study published in European Journal of Medical Research (Li et al., 2022). Depending upon the level and specifications of mutations and polymorphism, persistent symptoms are observed differently on distinguished physiological bodies. These symptoms in specific parts of the body are also related to levels of ACE2 expressions. Change in expression may alter directly the electrolyte homeostasis and body fluid volume regulation. Disturbed electrolytes will influence every associated system. Researches also detail about the role of expressional changes in balancing of vasodilator peptides Angiotensin (1-7). Studies are required to affirm other mechanisms involved with such persistency. According to genetic make-up of individual physiological bodies the intensity of symptoms may change or bodies may become accustomed.