The effects of oxidative stress occur as a result of peroxidative damage of the macromolecule and membranes of the cells and with the disruption of metabolic activities in the components of the cells in living organisms. Organ and tissue pathologies are known to occur when oxidative stress is excessive in the body. It is known that thiols are one of the main protective mechanisms of the body against oxidative stress. Thiols have been shown to play important roles in enzymatic reactions, apoptosis, detoxification and antioxidant protection in the body. Many studies have shown changes in thiol status and thiol/disulphide homeostasis in various diseases such as digestive system, respiratory system, reproductive system, urinary system, metabolic diseases and cancer. This also shows that the thiol state is very important in the pathogenesis of oxidative stress-mediated diseases. Therefore, it is thought that interventions that can improve thiol status may contribute to the prevention or treatment of oxidative stress-related diseases.

Studies to determine the physiological effects and functions of progesterone started in the twentieth century. Progesterone is a steroid-structured hormone with 21 carbon atoms originating from cholesterol. The corpus luteum, formed after ovulation in ruminants, secretes progesterone, which plays a role in the continuity of the pregnancy. Progestagens can be used for estrus synchronization in cows and heifers. Similarly, they are used for estrus synchronization during the breeding season or outside the breeding season by taking advantage of the negative feedback effect of progesterone in small ruminants. It is applied for the treatment of embryonic deaths due to luteal insufficiency in cows with high milk yield. In anovulatory anestrus, exogenous progesterone applications can be very useful. Progesterone treatment contributes to the resolution of the anestrus by rearranging hypothalamic functions in cattle with follicular cysts. The oxidative stress index in the luteal phase, when progesterone is high in ruminants, is higher than in the follicular phase. In the critical period of pregnancy, a high index of oxidative stress-induced progesterone causes embryonic death. Factors that cause stress in high milk-yielding cows can affect the amount of progesterone synthesis by inhibiting luteal cell function due to excessive free radical production.

Kisspeptin is a neuropeptide encoded by the kisspeptin gene (Kiss1) and located in different brain regions, primarily in the hypothalamus. Kisspeptin and its receptor G-protein-coupled receptor-54 (GPR54), are also found in behavioural brain regions such as the hippocampus and cortex. Kisspeptin, a very powerful neuropeptide that stimulates the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary, does this by increasing gonadotropin-releasing hormone (GnRH) levels. In recent studies, it has been noted that kisspeptin is effective on reproductive functions. Globally 8 to 12% of couples have infertility problems, and the majority are residents of developing countries. Approximately 70% of infertility cases are caused by fertility problems in women. The frequency of infertility in women continues to increase every year and the underlying factors require further research. Bearing this problem in mind, this review examines the possible role of kisspeptin in female infertility. In doing so, it aims to find out how future application of kisspeptin may potentially unravel the neural reproductive disorder.

The renin-angiotensin-aldosterone system is a physiological system that plays an important role in the regulation of blood pressure and body water-electrolyte balance, in which the kidney, liver and lungs play a role in its activation. This system comes into play in various diseases such as the cardiovascular, renal, pulmonary and nervous system where blood pressure and fluid-electrolyte balance may change. The purpose of this study, which is presented in line with this information, is to explain the working principle of this system, how this system is activated, how it comes into play in the mentioned diseases, and what kind of results occur.