Astrocytes not only support neuronal function with essential roles in synaptic neurotransmission, action potential propagation, metabolic support, or neuroplastic and developmental adaptations. They also respond to damage or dysfunction in surrounding neurons and oligodendrocytes by releasing neurotrophic factors and other molecules that increase the survival of the supported cells or contribute to mechanisms of structural and molecular restoration. The neuroprotective responsiveness of astrocytes is based on their ability to sense signals of degeneration, metabolic jeopardy, and structural damage, and on their aptitude to locally deliver specific molecules to remedy threats to the molecular and structural features of their cellular partners. To the extent that neuronal and other glial cell disturbances are known to occur in affective disorders, astrocyte responsiveness to those disturbances may help to better understand the roles astrocytes play in affective disorders. The astrocytic sensing apparatus supporting those responses involves receptors for neurotransmitters, purines, cell adhesion molecules, and growth factors. Astrocytes also share with the immune system the capacity to respond to cytokines released upon neuronal damage. In addition, in response to specific signals, astrocytes release unique factors such as clusterin or humanin that have been shown to exert potent neuroprotective effects. Astrocytes integrate the signals above to further deliver structural lipids, remove toxic metabolites, stabilize the osmotic environment, normalize neurotransmitters, provide antioxidant protection, facilitate synaptogenesis, and act as barriers to contain varied deleterious signals, some of which have been described in brain regions relevant to affective disorders and related animal models. Since various injurious signals that activate astrocytes have been implicated in different aspects of the etiopathology of affective disorders, particularly in relation to the diagnosis of depression, potentiating the corresponding astrocyte neuroprotective responses may provide additional opportunities to improve or complement available pharmacological and behavioral therapies for affective disorders.

Alzheimer’s disease (AD), which affects around twenty-seven million people globally, is an aging-related neurodegenerative condition characterized by the extracellular deposition of misfolded amyloid-β (Aβ) peptides and the intracellular production of neurofibrillary tangles (NFTs) AD results from the death of certain groups of neurons in the brain while appearing to have no impact on neighboring neurons. It is progressive and incurable. Therefore, the pathophysiology of afflicted populations and the development of intervention measures to stop neuronal cell death have been the main areas of attention for delineating therapeutic options. Proinflammatory cytokines are responsible for the stimulation of inflammatory responses and are mostly generated by activated macrophages in the brain. This review discusses how glial cells and innate and adaptive immune responses have a critical role in AD. It also provides information about microglial activation through the cluster of differentiation 40 (CD40) ligation and CD40L. CD40L ligation of microglial CD40 results in a large increase in tumor necrosis factor-α (TNF-α) production. Cultured cortical neuronal injury is caused when microglia are activated by CD40 ligation in the presence of interferon-γ (IFN-γ). This injury is significantly reduced by blocking the CD40 pathway or neutralising TNF-α. The management of AD would require integrating all available information about the innate and adaptive immune response affecting AD-related neuronal death.

Neuropathic pain (NP), which is difficult to treat, remains a heavy burden for both individuals and society. The efficacy of current treatments is insufficient. The pathophysiology of NP is still not fully elucidated, and there is a need to explore new therapeutic targets to develop more effective treatment strategies. Recent studies showed that thrombospondin 4 (TSP4) protein expression is increased in the spinal cord following nervous system injury and that blocking or inhibiting this increase improves NP. In this review, it has been aimed to present the evidence for the role of TSP4 in the mechanisms of NP development and to evaluate the therapeutic potential of TSP4 blockade in the treatment of NP.