Axons in the peripheral nervous system have the ability to repair themselves after damage, whereas axons in the central nervous system are unable to do so. A common and important characteristic of damage to the spinal cord, brain, and peripheral nerves is the disruption of axonal regrowth. Interestingly, intrinsic growth factors play a significant role in the axonal regeneration of injured nerves. Various factors such as proteomic profile, microtubule stability, ribosomal location, and signalling pathways mark a line between the central and peripheral axons’ capacity for self-renewal. Unfortunately, glial scar development, myelin-associated inhibitor molecules, lack of neurotrophic factors, and inflammatory reactions are among the factors that restrict axonal regeneration. Molecular pathways such as cAMP, MAPK, JAK/STAT, ATF3/CREB, BMP/SMAD, AKT/mTORC1/p70S6K, PI3K/AKT, GSK-3β/CLASP, BDNF/Trk, Ras/ERK, integrin/FAK, RhoA/ROCK/LIMK, and POSTN/integrin are activated after nerve injury and are considered significant players in axonal regeneration. In addition to the aforementioned pathways, growth factors, microRNAs, and astrocytes are also commendable participants in regeneration. In this review, we discuss the detailed mechanism of each pathway along with key players that can be potentially valuable targets to help achieve quick axonal healing. We also identify the prospective targets that could help close knowledge gaps in the molecular pathways underlying regeneration and shed light on the creation of more powerful strategies to encourage axonal regeneration after nervous system injury.

Neurodegenerative and neuropsychiatric diseases are characterized by the structural and functional abnormalities of neurons in certain regions of the brain. These abnormalities, which can result in progressive neuronal degeneration and functional disability, are incurable to date. Although comprehensive efforts have been made to figure out effective therapies against these diseases, partial success has been achieved and complete functional recovery is still not a reality. At present, plants and plant-derived compounds are getting more attention because of a plethora of pharmacological properties, and they are proving to be a better and safer target as therapeutic interventions. This review aims to highlight the roles of tannins, ‘the polyphenol phytochemicals’, in tackling neurodegenerative diseases including Alzheimer’s and Parkinson’s diseases as well as neuropsychiatric disorders like depression. Among the multifarious pharmacological properties of tannins, anti-oxidative, anti-inflammatory, and anti-cholinesterase activities are emphasized more in terms of neuroprotection. The current review also throws light on mechanistic pathways by which various classes of tannins execute neuroprotective effects. Despite their beneficial properties, some harmful effects of tannins have also been elaborated.

Human bodies encompass very important symbiotic and mutualistic relationships with tiny creatures known as microbiota. Trillions of these tiny creatures including protozoa, viruses, bacteria, and fungi are present in and on our bodies. They play important roles in various physiological mechanisms of our bodies. In return, our bodies provide them with the habitat and food necessary for their survival. In this review, we comprehend the gut microbial species present in various regions of the gut. We can get benefits from microbiota only if they are present in appropriate concentrations, as if their concentration is altered, it will lead to dysbiosis of microbiota which further contributes to various health ailments. The composition, diversity, and functionality of gut microbiota do not remain static throughout life as they keep on changing over time. In this review, we also reviewed the various biotic and abiotic factors influencing the quantity and quality of these microbiota. These factors serve a significant role in shaping the gut microbiota population.

Due to the continuous increase in polystyrene microplastics (PS MPs) incorporation in the environment, growing number of adverse effects on living organisms and ecosystem have become a global concern. Therefore, current study was planned to elucidate the impacts of 5 different concentrations control, 2, 20, 200, and 2000 μgL^-1 of PS MPs on testicular tissues of rats. PS MPs significantly reduced the activities of antioxidant enzymes (catalase, superoxide dismutase and peroxidase) as well as total protein contents, while elevated the level of lipid peroxidation and reactive oxygen species. Moreover, expressions of steroidogenic enzymes (3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein) as well as the levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) in plasma, intra-testicular testosterone and plasma testosterone were reduced and a significant ( P < 0.05) reduction was noticed in the sperm count, motility and viability. Furthermore, PS MPs significantly up-regulated the expressions of Bax and caspase-3, while down-regulated the Bcl-2 expression. The histomorphological assessment revealed significant damages in the testicles as well as decrease in the number of germ cells (spermatogenic, spermatocytes and spermatids). Collectively, PS MPs generated oxidative stress (OS) and caused potential damage to the testicles of rats in a dose-dependent manner.

Neurodegeneration is a progressive loss of neuronal cells in certain regions of the brain. Most of the neurodegenerative disorders (NDDs) share the communal characteristic such as damage or reduction of various cell types typically including astrocytes and microglial activity. Several compounds are being trialed to treat NDDs but they possess solitary symptomatic advantages along with copious side effects. The finding of more enthralling and captivating compounds to suspend and standstill the pathology of NDDs will be considered as a hallmark of present times. Phytochemicals possess the potential to alternate the synthetic line of therapy against NDDs. The present review explores the potential efficacy of plant-derived flavonoids against most common NDDs including Alzheimer’s disease (AD) and Parkinson’s disease (PD). Flavonoids are biologically active phytochemicals which possess potential pharmacological effects, including antiviral, anti-allergic, antiplatelet, anti-inflammatory, anti-tumor, anti-apoptotic and anti-oxidant effects and are able to attenuate the pathology of various NDDs through down-regulating the nitric oxide (NO) production, by reducing the tumor necrosis factor-α (TNF-α), by reducing the excitotoxicity of superoxide as well as acting as tyrosine kinase (TK) and monoamine oxidase (MAO) inhibiting enzyme.

Antioxidants are the defense system of the body against the damage of reactive oxygen species, which is normally produced during the various physiological processes in the body. There are various sources of these antioxidants like endogenous antioxidant present in the body and exogenous food source. In recent decades, alternate of synthetic food antioxidants by natural ones has fostered interest on vegetable sources and the screening of inexpensive raw materials particularly from the agriculture for identifying new antioxidants. Polyphenols are the significant plant compounds with antioxidant activity, though not the only ones. Some but not only restricted to biological properties such as anticarcinogenicity, antimutagenicity, antiallergenicity, and antiaging activity have been reported for natural and synthetic antioxidants. Among the sources of natural antioxidants, the most important are those coming from routinely consuming vegetables and fruits; however, antioxidant from other plant and agriculture waste should not be ignored.