Green chemistry is being developed to make environmentally acceptable nanomaterials such as AgNPs, which have a lot of attention because of their excellent qualities. Many studies, however, have discovered their potential harm on various organs (Roda et al., 2017, Brohi et al., 2017). Intraperitoneal injection was chosen above the other regularly utilised routes for AgNPs administration in this experimental study. In terms of pharmacokinetics, intraperitoneal injections are identical to oral injections. The intraperitoneal route, on the other hand, offers the advantage of delivering drugs into the bloodstream faster than the oral route (Elkhawass et al., 2015, Fathi et al., 2018).
The current study found that repeated intraperitoneal injections of AgNPs to rats result in changes in serum male sex hormone and enzymes. In comparison to the control and another treated group, the AgNPs-treated group saw a substantial reduction in serum testosterone levels. AgNPs block cholesterol transport into the inner mitochondrial membrane by lowering steroidogenic acute regulatory protein (STAR) expression, which eventually stops the conversion of cholesterol to pregnenolone levels (Baki et al., 2014b). Furthermore, decreased TGF-1 expression results in substantially insufficient male serum and intratesticular testosterone, as well as serum androstenedione. Because serum LH and serum FSH were lowered, and exogenous LH replacement with human chorionic gonadotropin (hCG) caused serum testosterone to decrease, the testosterone hormone shortage was secondary to disturbed pituitary gonadotropin release (Ingman and Robertson, 2007).
The concentration of serum prostatic acid phosphatase (Prostatic ACP) and the rise of serum acid phosphatase (ACP) produced in the liver, spleen, and prostate gland in the AgNPs group. This increase is a sign of benign prostatic hyperplasia (BPH) and the early stages of prostate cancer (Goto et al., 2009, Lee and Finn, 2012). Using of LA with AgNPs group improved the serum male sex hormones than AgNPs group. These result was correlated with Othman et al. (2012) who revealed that lipoic acid kept cholesterol and sex hormone-binding globulin (SHBG) levels the same as in control rats. These results could be attributable to LA's antioxidant activity, which improves the signal transduction pathways required for optimal hypothalamus-testicular axis function, resulting in normal testosterone release and sperm generation. Also, the treatment with GB can enhances testosterone synthesis and secretion of Leydig cells (Wu et al., 2008a). The prostatic acid phosphatase level is reduced when the general body condition and testicles improved in using GB or LA due to their antioxidant activity.
Durán et al. (2016) concluded that the toxicity of AgNPs can be explained by three mechanisms: (1) free silver ions are taken up by cells, decreasing ATP synthesis and DNA replication; (2) the creation of reactive oxygen species (ROS) is enhanced on the surface of AgNPs and Ag ions; and (3) AgNPs directly damage cell membrane. Total GSH, GSH, GR, and GPX levels were all lower in the AgNPs-treated group. GSH depletion and increased ROS formation intracellular may cause damage to cellular components, followed by an increase in lipid peroxidation, resulting in an increase in MDA (Piao et al., 2011). AgNPs reduced antioxidants like GSH and antioxidant enzymes like glutathione peroxidase and superoxide dismutase because they exhibited a strong attraction for thiol groups, which reacted with sulfur-containing proteins like GSH (El Mahdy et al., 2015). The increase in GSSG reductase activity is proportional to the amount of GSSG present. GSH concentration drops during acute oxidative stress, which is coupled with an increase in GSSG concentration, resulting in GSH/GSSG cycle turnover. (Jones, 2002).
Antioxidants are known to reduce oxidative radical-induced reaction (Lebda et al., 2018a, Sadek et al., 2016, Sadek, 2014, Sadek et al., 2019, Sadek et al., 2018, Sadek et al., 2017). Because of its stronger antioxidant qualities and restorative potential on oxidative stress-related damage, cotreatment with LA increased antioxidant indices. The ability of LA to function as a metal chelator and reduce free oxygen radicals while increasing the regeneration capacity of oxidised versions of other endogenous antioxidant agents is what gives it its antioxidant characteristics (El-Sayed et al., 2017).
It has anti-inflammatory, anti-neoplastic, and anti-proliferative properties as well. The antioxidant activity of GB was related to its components of terpenoids and flavonoids, which operate as broadspectrum free radical scavengers and lower lipid peroxidation, which may explain why cotreatment with GB improved antioxidant indices (Yeh et al., 2009, Mohamed and Abd El-Moneim, 2017). By blocking and terminating radical chain reactions and suppressing ROS and lipid peroxidation reactions, flavonoid glycosides can either eliminate free radicals to reduce the consumption of SOD and GSH-Px or promote the production of SOD and GSH-Px to scavenge free radicals such as superoxide anion and hydrogen peroxide as a result, the antioxidant testicular enzymes SOD and catalase were restored, and the concentration of testicular MDA was reduced, as described in our findings (Wu et al., 2008a, Amin et al., 2012).
When ROS generation surpasses the capacity of the antioxidant defence, which is connected to lipid peroxidation, an imbalance in oxidative stress and antioxidant capacity ensues (Quinteros et al., 2018) and induction of apoptosis. (Kim et al., 2011). Thioredoxin is found in a variety of biological systems. It prolongs life and guards against oxidative stress in various organs and cell types (Mitsui et al., 2002).
Thioredoxin-1 (Trx-1) is one of the most essential cellular antioxidant systems, lowering oxidised proteins through thiol-disulfide exchange processes and eventually redox-sensitive signal transduction (Lu and Holmgren, 2014, Lillig and Holmgren, 2007) and protects cells from apoptosis (Lu and Holmgren, 2012). To prevent stress and cytokine-induced apoptosis, the reduced/dithiol form of Trxs binds to apoptotic signal-regulating kinase 1 (ASK1) and suppresses its activity. Due to ROS, thioredoxin-1 expression was found to be lower in the silver nanoparticles treated group compared to the control and other groups, indicating that it dissociates from Ask1 and stimulates apoptosis. Trx interacting protein (TXNIP), which binds to Trx and removes Trx from ASK1, also contributes to the apoptotic process (Jun and Arne 2012).
AgNP-induced p53 activation has also been observed in mouse and human cells (Ahamed et al., 2008, Gopinath et al., 2010). P53 is activated by a variety of cell death events that can activate gene expression or permeabilize mitochondria, causing apoptosis. P53 builds up in the nucleus and regulates the production of the proapoptotic protein Bax (Wu et al., 2008b). P53 can enter mitochondria, interact with antiapoptotic Bcl-2 proteins, neutralise them, and trigger cell death (Li et al., 2015). The proapoptotic Bax and antiapoptotic Bcl-2 molecules are two key players in cell death, and the ratio of Bax/Bcl-2 is the numerator that determines whether or not cells will die. The AgNP-treated rats had higher Bax expression, as well as a strong positive immunological response and lower Bcl-2 expression, resulting in a higher Bax/Bcl-2 ratio, as seen in humans treated with AgNPs (Gopinath et al., 2010, Piao et al., 2011).
By upregulating the expression of two genes that encode the anti-apoptotic proteins Bcl-2 and Xiap via a process that appears to include NF-B, cotreatment with LA substantially prevented apoptosis of testicular cells (Antonio et al., 2011). Ginkgo biloba also, has antiapoptotic effects through the protection of mitochondrial membrane integrity, possibly by its flavonoid constituents (Takao, 2000) this agree with (Guan et al., 2014) who found that the apoptotic index was decreased with the antioxidant and anti-inflammatory effects of the Ginkgo biloba treatment on the organs.
In fact, histological and immunohistochemical examinations revealed that AgNPs have a harmful effect. Damage to testicular tissue was observed in the AgNPs-treated group, which could be attributed to silver nanoparticles crossing the blood-testis barrier (BTB) and accumulating in the testicles, as previously reported in multiple studies (Asare et al., 2012) due to particle size of it ((Amin et al., 2015). The toxicity is related to the nano-surface. silver's In the environment and biological systems, it is easily oxidised by O2 and other molecules, resulting in the release of Ag, a recognised hazardous ion. Nano-silver has been demonstrated to infiltrate and internalise cells. As a result, nano-silver is frequently used as an Ag source within cells (McShan et al., 2014). In a concentration- and time-dependent way, AgNPs are more cytotoxic, producing apoptosis, necrosis, and reduced proliferation (Asare et al., 2012). In comparison to the control group, AgNPs treated groups had lower Ki-67 antibody expression. The reduction in KI67 expression as a result of reduced cell proliferation is owing to AgNPs' inhibitory action in cell proliferation, which explains the damaged seminiferous tubules. AgNPs can bind to membrane proteins and activate signalling pathways, resulting in cell proliferation inhibition (Asharani et al., 2008). AgNPs can also enter the cell via diffusion or endocytosis, causing mitochondrial malfunction and the production of reactive oxygen species (ROS), which causes damage to proteins and nucleic acids inside the cell, as well as cell proliferation inhibition (Lim et al., 2012).
Histopathological analysis of testicular sections from the silver nanoparticles-treated group revealed degenerative alterations in the seminiferous tubules, such as smaller, disordered seminiferous tubules with uneven basement membranes, which could lead to significant testis functional impairment (Liu et al., 2013). The loss of germinal epithelium could also be attributed to a significant disruption of the Sertoli-germ cell connection. The sloughing of the germ cells from the seminiferous epithelium could have been caused by a breakdown in this physical contact (Erkanlı Şentürk et al., 2012). Hyalinization of luminal contents, exfoliation of degenerated germinal epithelial cells, and interstitial edoema in seminiferous tubules with giant cell formations were also seen. The earliest physical symptom of testicular injury is vacuolation degeneration of spermatogonia cells, also known as coagulative necrosis. It is thought that vacuolation causes spermatogenic cells to detach from Sertoli cells, which is the first step toward cell death or apoptosis (Asare et al., 2012).
The epididymal sections of the silver-nanoparticles-treated group showed vacuolation of some caput epididymal epithelium alongside sloughed germ cells in its lumina and congestion of interstitial blood vessel with perivascular inflammatory cell infiltrations, indicating that continued exposure to toxic chemicals may lead to some histologic changes. The vacuolation of some Couda epididymal epithelium, sloughed germ cells in its lumina, hyalinization of the luminal contents of some epididymal ductulus, and low sperm density in the majority of epididymal ductulus were all observed in this study, along with congestion of interstitial blood vessels and perivascular inflammatory cell infiltrations. The blood–testis barrier must remain intact in order to maintain reproductive potential. Exposure to environmental toxins can compromise this barrier, causing the production of reactive oxygen species (ROS) in the testes, resulting in oxidative DNA damage and infertility. Because LA is a fat- and water-soluble antioxidant, it is found in cellular membranes (Prahalathan et al., 2006). LA protects against nanoparticle-induced oxidative disruption of the blood–testis barrier and testicular histological alterations, according to our findings.