The investigation of the molecular changes of rhododendron honey on mice heart muscle using biophysical techniques

Rhododendron honey (RH), which is also known as "mad honey" in public, is obtained from Rhododendron plants widely grown especially in the Black Sea Region of Turkey. This honey induces toxic effects in people due to grayanotoxin found in it. However, it is commonly used for the treatment of some disorders like high blood pressure, gastrointestinal disorders, dental pain, common colds, etc. in public. Although it has been known that RH has some negative effects on heart, the structural and functional effects of it on heart muscle are unknown yet at molecular level. For this reason, in this study, we aimed to investigate the effects of different concentrations of RH and GTX-III, which is the most toxic type of GTXs, on mouse heart muscle tissue at molecular level. Male Mus musculus mice were divided into five groups, one being the control group and the others being the three different doses of RH (25, 50 and 75 mg/kg) and GTX-III (0.01 mg/kg) groups. The heart muscles of these mice were collected 24 h after the administration of RH and GTX-III and investigated using Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The results revealed that 25 mg/kg of RH didn't cause any significant alterations in the heart muscle except lipid peroxidation, however, significant differences were observed between 50 and 75 mg/kg RH and GTX-III treated groups and control group. For example, the total lipid content increased and the total protein content decreased significantly in 50 mg/kg RH-treated groups. Oppositely, in 75 mg/kg RH-treated and GTX-III-treated groups the total lipid content decreased and the total protein content increased. Unsaturated/saturated lipid ratio increased in all treated groups suggesting the presence of lipid peroxidation in the system. In addition, the treatment of 50, 75 mg/kg RH and GTX-III changed the content and conformation of nucleic acids, the secondary structure of proteins, decreased lipid order and increased membrane fluidity of heart muscle cells. These results revealed that RH and GTX-III causes significant alterations in the structure and function of heart muscle cells and these alterations depend on the dose consumed.