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Published on: October 13, 2018
Effects of induced precocious puberty on cranial growth in female Wistar rats
Antonio de Moraes Izquierdo1, Fernanda Danielle Mishima, Vinícius Coelho Carrard
1Department of Odontopediatrics and Orthodontics, Federal University of Rio Grande do Sul (UFRGS) Dental School, Brazil.
Insights
Pharmacologically induced precocious puberty in Wistar rats showed some cranial growth differences, particularly in spheno-occipital synchondrosis width. However, danazol did not establish a consistent model for studying bone growth in precocious puberty at 30-day intervals.
Area of Science:
- Endocrinology
- Developmental Biology
- Cranioskeletal Biology
Background:
- Precocious puberty can impact skeletal development.
- Understanding cranial growth effects is crucial for pediatric endocrinology.
- Wistar rats are a common model for studying developmental processes.
Purpose of the Study:
- To investigate the effects of pharmacologically induced precocious puberty on cranial growth in female Wistar rats.
- To evaluate the efficacy of danazol as an inducer of precocious puberty for skeletal studies.
- To analyze changes in the spheno-occipital synchondrosis and bone deposition patterns.
Main Methods:
- Forty-eight female Wistar rats were divided into control and experimental groups.
- Precocious puberty was induced using danazol on day 5 post-birth.
- Craniometric measurements and histological analyses of the spheno-occipital synchondrosis were performed at 30, 60, 90, and 120 days.
- Alizarin staining was used to visualize bone deposition.
Main Results:
- Precocious puberty was successfully induced, evidenced by earlier maturation in experimental rats.
- A significant increase in total spheno-occipital synchondrosis width was observed in the E60 group compared to C60.
- Histomorphometric analysis revealed a statistically significant difference in total width between E60 (434.3 μm) and C60 (323.5 μm).
- No significant differences were found in body mass or macroscopic measurements.
Conclusions:
- Pharmacologically induced precocious puberty affects cranial growth, specifically the spheno-occipital synchondrosis, in Wistar rats.
- Danazol administration led to observable but not consistently significant changes in bone growth parameters at 30-day intervals.
- The study suggests that danazol at the tested dosage and intervals may not be an optimal model for comprehensively studying bone growth in precocious puberty.
Abstract:
This investigation examined the effects of pharmacologically induced precocious puberty on cranial growth in Wistar rats. Forty-eight female newborn Wistar rats were divided into two groups: a control group (C) and an experimental group (E), with four subgroups of six animals each. The time interval from birth until sacrifice differed between the subgroups, and was set at 30, 60, 90, and 120 days. An intramuscular single dose (300 μg) of steroid hormone danazol was administered on day 5 after birth, as a means of inducing precocious puberty. Alizarin (2 mg/100 g) was administered to three animals in each subgroup three days prior to sacrifice. Body mass and dates corresponding to the beginning of the oestrous cycle were recorded. Craniometric measurements were undertaken. Histological analysis using light and fluorescence microscopy was then carried out to qualitatively and quantitatively evaluate the spheno-occipital synchondrosis and to visualize bone deposition patterns. The results were analysed with a Student's t-test and analysis of variance. Precocious puberty was effectively induced and differences between groups denoted an earlier maturation in the experimental rats. In qualitative analysis, a significant increase of total synchondrosis width was noted only in group E60, in comparison with C60, and an increase in the E90 subgroup cortical bone width compared with the C90 subgroup. Histomorphometrically, a statistical difference between total width values of subgroups E60 (434.3 μm) and C60 (323.5 μm) was detected. However, body mass and macroscopic measurements did not show statistically significant differences. An appropriate model for studying bone growth associated with precocious puberty in Wistar female rats was not achieved using steroid hormone danazol, when evaluated at 30 day intervals.
