Electronic Theses and Dissertations (Masters)

Permanent URI for this collection

https://hdl.handle.net/10539/37981

Browse

Browsing Electronic Theses and Dissertations (Masters) by Keyword "Addiction"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Investigating the toxic effects of nyaope on the brain, liver, and kidney of Sprague- Dawley rats
    (University of the Witwatersrand, Johannesburg, 2023) Mathiki, Khethani Thendo
    Background. Worldwide drug use is estimated to be 345 million, encompassing both synthetic and plant-based medications, as well as both legal and illicit opioids. The use of these drugs is on the rise and is becoming a growing concern for public health. Moreover, the emergence of heroin dominant street drugs like nyaope have gained popularity, especially in low- and middle- income countries such as South Africa. The use of nyaope exposes individuals to the risk of substance use disorders (SUDs) and the array of mental health issues, as evidenced by social and clinical studies. Nyaope, a relatively inexpensive illicit drug, is commonly found in townships and outskirts of inner cities which are predominantly saturated with African/Black ethnic communities. Its composition varies depending on the geographical area but primarily consists of ingredients like heroin, opioid derivatives, rat poison, antiretroviral drugs (ARVs), and other substances. Similar to other opioids, heroin exerts its effects on the central nervous system (CNS) by acting on opioid receptors in various brain regions, including the prefrontal cortex (PFC), nucleus accumbens, and amygdala. These regions play a critical role in regulating mood and cognitive functions. Additionally, opioids undergo processing in the liver before being excreted by the kidneys. Our work sought to evaluate the effects of acute toxicity from the unique street drug cocktail known as nyaope on the behaviour and molecular markers of the PFC, liver, and kidney in Sprague-Dawley rats, despite the abundance of material already available on opioid usage. Methods. Twenty-five Sprague-Dawley rats were sourced from the Wits Research Animal Facility following ethical clearance and habituated for a duration of ten weeks. A pilot study involving three of these rats was conducted to determine the appropriate exposure dose of nyaope. Following the pilot study, the remaining twenty-two rats were divided into two groups; nyaope-treated (n=11) and saline-treated (n=11). Nyaope-treated rats received a single dose of nyaope at 0.4 mg/kg/bw and were subsequently exposed to the Open Field Test (OFT), which assesses various behavioural indices, including locomotor activity, mood, and exploratory behaviour, using the AnyMaze video tracking system. The saline-treated rats received a single dose of physiological saline at 0.4 mg/kg/bw and underwent the same 30-minute exposure to the OFT. After this exposure, the animals were placed in their respective home cages and qualitatively observed for an additional 30 minutes. Following this observation period, the rats were anaesthetized with isoflurane and euthanized exactly one hour after exposure to nyaope or saline. Tissues from the brain, liver, and kidney were collected, and RT-PCR was conducted to assess toxicity markers, including genes that code for proteins involved in the processes of apoptosis (BAX and Bcl-2), autophagy (SQSTM1/p62), microglial repair (ANXA3), and inflammation (IL-6). In addition, plasma samples were collected and analysed using IDEXX catalyst technology to examine the plasma presence of liver toxicity markers; aspartate transferase and alanine transferase, along with the kidney toxicity marker; creatinine. Results. The qualitative findings indicated that rats treated with nyaope exhibited reduced grooming behaviour. Additionally, the nyaope-treated rats experienced a phase of heightened activity followed by extreme lethargy. In contrast, the saline-treated rats displayed consistent mobility and curious behaviour. Compared to the saline-treated rats, the nyaope-treated rats exhibited clinical signs such as tremors, a rigid tail, hypoxia, and increased diuretic behaviour. When observing the track plots of the nyaope-treated rats, they tended to favour the outer zone in a thigmotaxis pattern, with few bouts into the centre, while the saline-treated rats showed more uniform movement within the OFT apparatus. Quantitative behavioural data using the AnyMaze tracking system revealed that nyaope-treated rats had decreased locomotor activity. They covered less total distance during the test and travelled shorter distances within the centre zone compared to saline-treated rats. Nyaope-treated rats also had fewer mobility episodes and moved at slower speeds on average than the saline-treated rats. In terms of mood assessment, the nyaope-treated rats spent less time mobile overall, both in the outer and centre zones and engaged in significantly fewer grooming bouts compared to the saline-treated rats. In the assessment of exploratory behaviour, it was noted that nyaope-treated rats exhibited fewer instances of rearing, line crossing, and head entries into the centre than the saline-treated rats.Regarding the molecular assessment of the brain and kidney, there were no significant differences in the expression of molecular markers between the two groups, except for a decreased expression of Bcl-2 (p < 0.001) in the kidneys of nyaope-treated rats compared withthe saline-treated rats. Additionally, plasma expression levels of AST, ALT, and creatinine were similar between the two groups. Conclusion. These findings indicate that exposure to 0.4 mg/kg/bw of nyaope for one hour does result in behavioural changes, even though it does not immediately lead to acute molecular toxicity in the brain, liver and kidney. Conversely, nyaope exposure causes a reduction in mRNA expression of Bcl-2, suggesting that the drug induces cell and tissue damage in the kidney through apoptosis