Gentamicin nephrotoxicity–a comparison of in vitro findings with in vivo experiments in equines.

The research article examines the side effects of the antibiotic gentamicin, mainly focusing on its potential to cause kidney damage (nephrotoxicity), in horses. The study includes both lab tests (in vitro) and in-horse experiments (in vivo) to understand gentamicin’s mechanisms of toxicity and to identify sensitive markers for assessing kidney damage.

Objective of the Study and Methodology

• The overarching aim was to explore the factors ingenuities of kidney damage caused by gentamicin and identify sensitive markers that can indicate potential harm to the proximate tubule, a part of the kidney nephron where the filtrate from glomerulus enters.
• The study adopted two-dimensional methods. First, in-vitro experiments, and then validate the findings within in-vivo experiments.
• In-vitro tests were conducted on kidney-derived cell lines—LLC-PKI and MDCK. These cells were treated with gentamicin at variable concentrations.
• Cell toxicity was determined by measuring the release of gamma-glutamyl transferase (GGT), a potential marker for cellular damage, and assessing the production of reactive oxygen species (ROS), which are indicative of oxidative stress in cells.
• Cell viability was gauged by using Alamar Blue (AB) and Neutral red (NR) cytotoxicity assays. These assays provide a real-time evaluation of cell health.

Findings from the In-vitro Study

• The research discovered gentamicin induces dose-dependent toxicity on kidney-derived cell lines. The drug causes damage to the brush border membrane of kidney cells, as evident by GGT leakage, and induces the production of ROS.
• GGT emerges as a sensitive marker pinpointing gentamicin’s induced injury to renal cells. The higher the GGT leakage, the more pronounced is the cell damage.

In-vivo Experiments and Results

• In the following in-vivo experiment, ponies were given gentamicin at two different dosages for five consecutive days. Researchers tracked the urinary excretion and plasma levels of GGT and creatinine, and the ratio of GGT and creatinine was calculated.
• The researchers observed increased GGT levels in the urine post gentamicin therapy, indicating membrane damage in renal cells. However, GGT leakage was transient and returned to normal after stopping the therapy.
• The study concluded that the conservative dosage of gentamicin did not lead to significant kidney damage in healthy ponies.

Bottom Line of the study

• This research contributes to our understanding of gentamicin’s nephrotoxicity in horses by shedding light on the underlying mechanisms and identifying potential markers (like GGT) for kidney damage.
• However, it is emphasized that even though elevated GGT levels were observed, it was a transient phenomenon, and the selected dosage regimen did not cause significant kidney damage in healthy ponies.