Journal Article

Effects of induced precocious puberty on cranial growth in female Wistar rats

Antonio de Moraes Izquierdo, Fernanda Danielle Mishima, Vinícius Coelho Carrard, Marcos Farina and Matilde da Cunha Gonçalves Nojima

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 34, issue 2, pages 133-140
Published in print April 2012 | ISSN: 0141-5387
Published online August 2011 | e-ISSN: 1460-2210 | DOI: http://dx.doi.org/10.1093/ejo/cjq130
Effects of induced precocious puberty on cranial growth in female Wistar rats

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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.

Journal Article.  3271 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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