The effects of probiotics on living beings and their health benefits have been emphasized in several studies. This includes their effect on hypercholesterolemia, particularly their role in suppressing advanced cholesterol synthesis and preventing the absorption of excess cholesterol [
11]. Cholesterol is essential for the body because it plays a very important role in daily life. It is a crucial component of the cell membrane, as well as bile acid synthesis, fat and fat-soluble vitamin absorption, and synthesis of steroid hormones (sex hormones, mineralocorticoids, and glucocorticoids) [
12]. A high-cholesterol diet is the primary cause of hyperlipidemia, atherosclerosis, and other lipid metabolism disorders that lead to male reproductive system defects [
13]. In hypercholesterolemia, erythrocytes and endothelial cells, as well as serum, increase the amount of cholesterol present. The increase in the quantity of oxidized free radical products in these cells has been reported to cause elevated cholesterol [
14]. Hypercholesterolemia is currently a widespread and common health issue. Several studies have shown that beneficial bacterial additives can lower serum cholesterol levels in fermented milk products or milk products containing lactic acid bacteria [
10].The therapeutic value of fermented dairy products depends on the survival of these bacteria during development and storage [
15]. In the present study, a rat model of hypercholesterolemia was developed, and
L. acidophilus ATCC 4356—the lipid-lowering properties of which have been demonstrated
in vitro and
in vivo—was administered intragastrically [
10,
16]. The results are consistent with previous reports suggesting that
L. acidophilus has a cholesterol-lowering effect [
17-
19]. Walker and Gilliland [
20] posited that
L. acidophilus secretes bile salt hydrolase to deconjugate bile salts, although no connection was found between the reduction of
in vitro cholesterol and the degree of bile salt deconjugation [
21]. These conflicting findings raise the possibility of other mechanisms that may be associated with the assimilation of cholesterol by probiotic bacteria during their development [
22]. In the present study, the TC level was elevated in the HC and HCL groups (
p<0.05) relative to the control. Our analysis indicates that
L. acidophilus plays a major role in cholesterol synthesis. The administration of this probiotic may result in increased catabolism of cholesterol in the liver, contributing to a hypocholesterolemic impact. Several clinical and epidemiological studies have shown an inverse association between serum TES levels and TC [
23]. In addition, animal experiments in TES-deficient male mice have also shown dramatically elevated serum cholesterol levels [
24,
25]. Circulating TES levels are determined by the steroidogenic potential of Leydig cells and the total number of Leydig cells per testicle. Stress-induced increases in serum glucocorticoid concentration have been reported to decrease the rate of TES release by inhibiting the activity of TES biosynthetic enzymes [
26]. In another investigation of the impact of probiotics, larger testes and higher serum TES levels were observed in male mice that regularly ingested lactic acid bacteria than in age-matched control mice.
Lactobacillus reuteri was administered as a probiotic in that study, and a thorough analysis with microscopy-assisted histomorphometry showed an increase in the extent of spermatogenesis and the number of Leydig cells per testis. Furthermore, gonadal aging symptoms were claimed to decrease [
27]. Mega
Acidophilus (a mixture of
L. acidophilus,
Bifidobacterium bifidum, and
Lactobacillus helveticus) was administered to New Zealand rabbits for 1 month to determine how the probiotic would affect certain parameters. In that study, probiotic supplements were shown to improve antioxidant activity and substantially increase the level of TES [
28]. In our study, the TES level in the group given 2% cholesterol for 8 weeks decreased in the testicular tissue, and the level of TES increased in the group given the
L. acidophilus probiotic. Therefore, TES deficiency in the liver in HC does not affect de novo cholesterol synthesis. A number of human studies have shown that hypercholesterolemia and low semen quality are associated with male infertility [
29-
31]. Research on animals fed a high-cholesterol diet has uncovered more information about this link. In animals with diet-induced hypercholesterolemia, adverse effects of hypercholesterolemia on testicular function, including spermatogenesis, were noted [
5,
32-
35]. Increased oxidative stress is of considerable research interest among the many pathways suggested for hypercholesterolemia-induced testicular injury [
16]. When mice were fed a high-fat diet, decreased TES, decreased semen quality, seminiferous tubule atrophy, and degeneration were reported. The researchers stated that the addition of selenium-enriched probiotics to the high-fat diet decreased damage to testicular tissue and raised serum TES levels [
36]. In another study, researchers examined the reproductive system structure of male rats fed a high-fat diet for 2 months. They found that sperm quality and count decreased, Leydig cell disturbances increased, spermatocyte and spermatid structures decreased, and significant narrowing of the seminiferous tubule occurred [
37]. In our sample, relative to the control group, the testicles of the group given cholesterol feed (HC) showed atrophy, vacuolization, and damaged wall structure integrity in the tubule wall cells. However, in the HCL group, degenerate tubule wall cells were almost nonexistent, and the wall structure retained its integrity. According to recent research, high cholesterol levels caused by high-fat diets contribute to urological disorders (problems with penile erection, irregular spermatogenesis, benign enlargement of the prostate, cancer, etc.). They also disrupt the epithelial structure of the tissues and cause functional disability [
11]. The secretion of FSH and TES is required for the successful completion of spermatogenesis. TES, the male sex hormone, is secreted by Leydig cells under LH stimulation and plays important roles in the differentiation of peripheral tissues and the promotion of spermatogenesis [
38,
39]. ABP binds to TES and estrogens and assists their transport into the seminiferous tubule, allowing for their use for spermatozoon maturation when required [
40]. Testicular ABP synthesis has been reported to be increased by FSH and TES in rats [
41]. In another study, researchers investigated the impact of
Lactobacillus rhamnosus PB01 on sperm kinematic parameters and found that TES, LH, and FSH levels, as well as sperm motility rates, were all significantly elevated.
L. rhamnosus has also been found to act as a positive regulatory agent on weight loss and reproductive hormones [
42]. In our study, serum ABP and LH levels were lower in the HC than in the control group, and the amount of FSH in the testicular tissue was also lower. ABP and LH levels were greater in the HCL group than in the HC group (
p>0.05). In parallel to our results, when a 2% cholesterol diet was given to male Wistar rats for 21 days, non-significant changes were seen in TES, LH, and prolactin levels, while the FSH level was significantly decreased [
43]. In another study, a high-cholesterol diet induced a significant increase in the TC level and significant decreases in the FSH, LH, and TES levels in the serum of male rats [
44]. Hypercholesterolemia has also been suggested to cause reproductive and testicular damage through excessive free radical generation and increased oxidative stress, which is cytotoxic to spermatozoa [
13,
34,
45]. In hypercholesterolemia, the administration of antioxidants and lipid-lowering agents has been shown to protect the testis and reproductive functions [
13,
34,
46]. In the present study, the FAS level was significantly greater (
p<0.05) in the HC group than in the control group, while the FAS levels did not differ significantly between the HCL group and the control group (
p>0.05). The FAS level was significantly negatively correlated with LH, FSH, and TES levels, while it was significantly positively correlated with TC level.
This study revealed that probiotic treatment is beneficial for reducing the cell degeneration in testicular tissue caused by high cholesterol. Probiotic treatment increased LH, FSH, TSH, and ABP levels, while partially reversing the increase in factor-related apoptosis associated with a high-cholesterol diet. Probiotics have an important role as a supplementary treatment for degeneration and as an adjunct in the treatment of cell structure disorders, although they are not therapeutic in isolation.