Endocrine Abstracts

The aim of the research was studying the influence of age and sex on the changes of bone mineral density detected on rats with experimental hyperthyroidism.

Research object: Research is conducted on 180 white females and males rats of ‘Wistar’ breed. Animals were arranged in the 12 groups: six controls groups (CG) of pre-pubertal, reproductive and old males and females; six age-dependent groups of males and females rats getting L-thyroxin injection in a dose of 25 μg/100 g of body weight/day i.m., during 30 days.

Research methods: Bone mineral density (BMD) was measured using dual energy X-ray densitometry (DXA). The index was calculated according to the formula: ΔBMD (%)=(ΔBMD/BMD ref.)×100, BMD ref.-initial indexes of bone mineral density of the entire body.

Research results: It was revealed that high doses of L-thyroxine injections in during 30 days caused the different changes of BMD of rats. Only of the pre-pubertal females increased the ΔBMD30 index with 15.83±1.99% in CG to 44.73±5.41%, Student’s t-criterion=4.49, P<0.0001, and does not change of ΔBMD30 index in the pre-pubertal male group. The maximum loss of ΔBMD30 index occurred in reproductive age, as for females rats (with 15.16±3.43% in CG to −10.04±2.32%, Student’s t-criterion=−6.22, P<0.0001), so for males (with 0.63±0.97% in CG to −4.31±2.63%, Student’s t-criterion=−4.17, P<0.0001). Not much was detected ΔBMD30 index at old males rats (with 1.43±1.20% in CG to 6.91±1.49%, Student’s t-criterion=2.73, P=0.012).

Conclusions: It is revealed that high doses of L-thyroxine injections during 30 days caused the different changes of BMD depending on sex and age rats.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.