The Effect of Two-Generation Exposure to a High-Fat Diet on Craniofacial Morphology in Rats

Abstract

This study aimed to examine the sexual dimorphism effect of two-generation exposure to a high-fat diet (HFD) on the craniofacial growth of rat offspring. Ten eleven-week-old pregnant Wistar rats were fed either a control or HFD from day 7 of pregnancy until the end of lactation. Twelve male and female offspring from the control-diet-fed mothers were assigned to the CM (control male, n = 6) and CF (control female, n = 6) groups. The other twelve from the HFD-fed mothers were assigned to the HFD male (HFDM, n = 6) and HFD female (HFDF, n = 6) groups. HFDM and HFDF rats continued with an HFD. The offspring's weight and fasting blood sugar levels were measured every two weeks. The craniofacial and dental morphologies were studied from lateral X-rays of the head at ten weeks old. The HFDM rats showed an increased body weight and larger neurocranial parameters compared with the CM group. Furthermore, there were slightly significant differences in body weight and viscerocranial parameters between the rats in the HFDF and CF groups. In conclusion, two-generational exposure to an HFD had a greater effect on the male offspring's body weight and craniofacial morphology.

Keywords: cephalometric analysis; craniofacial growth; high-fat diet; lactation; pregnancy.

Figure 1

Experimental design. Pregnant rats were fed either a control diet (CE2, Clea, Japan; 4.6% from fat, 3.402 kcal/g) or an HFD (HFD32, Clea, Japan; 32% from fat, 5.076 kcal/g) from day 7 of pregnancy until the end of the lactation period. Twenty-four offspring were selected and assigned to 4 groups: CM (control male, n = 6), CF (control female, n = 6), HFDM (high-fat diet male, n = 6), and HFDF (high-fat diet female, n = 6) groups. Cephalometric radiographs were taken at the age of 10 weeks, just before being sacrificed.

Figure 2

Cephalometric landmarks and linear measurements: (A) tracing and cephalometric landmarks on a radiograph; (B) linear measurements of the neurocranium consisting of Po–N: total skull length, Po–E: cranial vault length, Ba–E: total cranial base length, So–E: anterior cranial base length, Ba–CB1: occipital bone length, CB10–CB2: sphenoid bone length, Ba–So: posterior cranial base length, and Po–Ba: posterior neurocranium height; (C) linear measurements of the viscerocranium consisting of E–N: nasal length, Mu2–Iu: palate length, CB2–Iu: midface length, and E–Mu1: viscerocranial height; (D) linear measurements of the mandible consisting of Go–Mn: posterior corpus length, Ml–Il: anterior corpus length, Co–Il: total mandibular length, and Co–Gn: ramus height.

Figure 3

Dental landmarks and linear measurements. All molar crown widths were measured at the widest part of the molar’s dental crown mesiodistally. Um1: maxillary first molar crown width; Um2: maxillary second molar crown width; Um3: maxillary third molar crown width; Lm1: mandibular first molar crown width; Lm2: mandibular second molar crown width; Lm3: mandibular third molar crown width; Uil: maxillary incisor length, measured from the most prominent point between the incisal edges of the upper incisors (Ut) to the middle of the Pr–Iu line; Lil: mandibular incisor length, measured from the most prominent point between the incisal edges of the lower incisors (Lt) to the middle of the Il–Id line; UCH: maxillary first molar crown height, measured from the mesial cusp tip of the first maxillary molar to the cementoenamel junction (CEJ); URH: maxillary first molar mesial root length, measured from the CEF to the mesial root tip of the maxillary first molar; LCH: mandibular first molar crown height, measured from the mesial cusp tip of the first mandibular molar to the CEJ; LRH: mandibular first molar mesial root length, measured from the CEF to the mesial root tip of the mandibular first molar.

Figure 4

Fasting blood sugar level (A) and body weight (B) of the CM, HFDM, CF, and HFDF. All data are shown as the mean ± SD (two-way ANOVA). ** p ≤ 0.01. NS, not significant.

Figure 5

Cephalometric analyses: (A) changes in the neurocranial measurements of the CM, HFDM, CF, and HFDF groups; (B) changes in the viscerocranial measurements of the CM, HFDM, CF, and HFDF groups; (C) changes in the mandible measurements of the CM, HFDM, CF, and HFDF groups. All data are shown as the mean ± SD (two-way ANOVA followed by Tukey’s multiple comparisons test). * p < 0.05, ** p ≤ 0.01, and *** p ≤ 0.0001. NS, not significant.

Figure 6

Dental analyses. All data are shown as the mean ± SD (Kruskal–Wallis test). There was no significant difference in any dental measurements. NS, not significant.