Growth of functional cranial components in rats submitted to intergenerational undernutrition.

The aim of the present study was to discover how intergenerational undernutrition affects the growth of major and minor functional cranial components in two generations of rats. Control animals constituted the parental generation (P). The undernourished generations (F1 and F2) were fed 75% of the control diet. Animals were X-rayed every 10 days from 20 to 100 days of age. The length, width and height of the major (neurocranium and splanchnocranium) and minor (anterior-neural, middle-neural, posterior-neural, otic, respiratory, masticatory and alveolar) cranial components were measured on each radiograph. Volumetric indices were calculated to estimate size variations of these components. Data were processed using the Kruskal-Wallis and Kolmogorov-Smirnov tests for two samples. Impairment in splanchnocranial and neurocranial growth was found, the latter being more affected than the former in F1. Comparison between F2 and F1 animals showed cumulative effects of undernutrition in both major and minor components (anterior-neural, respiratory, masticatory and alveolar in males, and middle-neural and respiratory in females). Such differential effects on minor components may reflect a residual mechanical strain resulting from the linkage between components. This phenomenon was clearly observed in the neurocranium and could be understood as an adaptive response to the demands of the associated functional matrices.

Variation of functional cranial components in six Anthropoidea species.

Sixty male crania from three Platyrrhini and three Catarrhini genera were measured by means of the craniofunctional method. The aim was to analyze functional components of the skull and relate their function and the degree of encephalization to life history variables. We recognized two major and eight minor functional components. The objectives were to test (1) if within-taxa (Platyrrhini or Catarrhini) and/or between-taxa (Platyrrhini and Catarrhini) comparisons showed minor-component differentiation; and (2) if encephalization affects both primate groups differently. After standardization by size and scaling, 15 possible within-taxa and between-taxa comparisons were made. We found a strong phylogenetic signal, i.e., cranial differences were not randomly distributed, with the between-taxa variation being greater than within-taxa. Both hypotheses tested were accepted since: (1) There was no random variation between functional cranial components. They followed definite patterns for ancestral and derived traits. (2) Encephalization was present in all scaled comparisons, with Platyrrhini showing a higher degree of encephalization than Catarrhini. We conclude that major and minor craniofunctional components should be considered as correlated traits related to life history, because we found different patterns between platyrrhines and catarrhines, and within species of both taxa.

Sexual dimorphism and postnatal growth of intrauterine growth retarded rats.

The intrauterine growth retardation (IUGR) is a complex phenomenon since it causes variability in postnatal growth responses. The aim of the present study was to analyze the effects of lactational rehabilitation on body and cranial growth and sexual dimorphism in IUGR rats. IUGR model was carried out by means of uterine vessels bending in pregnant rats at the first day of pregnancy. Control and sham-operated animals were also included. During suckling, IUGR and sham-operated pups were cross-fostered to a control dam. The animals were x-rayed every four days, from birth to weaning. Body weight and length, and neural and facial variables were measured. The reduced placental blood flow delayed growth in pups. Facial growth was more impaired than the neural one. An incomplete catch up growth was found, since males reached sham values only in neurocranial height and females--except facial length and width--were similar to sham. Because of sex differences in growth recovery, normal sexual dimorphism in body and craniofacial pattern was not expressed in the IUGR group. This study suggests that reduced uteroplacental blood supply in the rat interferes with the full expression of normal dimorphism based on gender and confirms the impact of IUGR on postnatal growth.

Effect of undernutrition on the cranial growth of the rat. An intergenerational study.

The cumulative effect of undernutrition on successive generations was tested. The cranial growth of three generations of undernourished rats (F1, F2, F3) was compared to that of the parental generation (P), in order to (1). measure the extent to which the growth of each facial and neurocranial functional component was retarded when animals were undernourished and (2). determine whether any cumulative effect between generations can be found. The P generation was fed ad libitum, and the undernourished generations were fed 50% (F1) and 75% (F2 and F3) of the parental diet. Nine radiographs were taken from the age of 20-100 days. The length, width and height of the neurocranial and facial components were measured on each radiograph. Neurocranial (VNI), facial (VFI), and neurofacial (NFI) indices were calculated. Data were processed by the Kruskal-Wallis and Kolmogorov-Smirnov tests. An impairment in neurocranial and facial growth was found, the latter being more affected than the former in F1. At variance, the neurocranium was more affected than the face in F2 and F3, resulting in variations of the shape of the skull. A cumulative effect of moderate transgenerational undernutrition was evident and points to the need for further analysis on this topic.

Relative food intake of rats submitted to a moderate transgenerational undernutrition.

An experiment on rat undernutrition through seven generations was performed in order to see: (1) whether the nutritional stress on growth increases from one generation to the next, and (2) if an equilibrium point (AFP) in which the RFI--the amount of food intake (mg) per gram of body weight--reached is the same in both control and undernourished animals. The RFI values were calculated for each generation, between the 30th and 100th days of age. A moderate undernutrition was applied to the seven generations (F1 to F7) following the parental (P) one, which acted as controls. Undernourishment was made from conception to the end of the experiment (100 days old). The RFI values diminished with the age increment and increased through generations. There was, however, a clear AFP of 75.9 +/- 3.5 mg/g at 100 days of age in males, and of 78.7 +/- 4.2 mg/g at 90 days of age in females. A clear cumulative increment of RFI through the filial generations was also found at intermediate growth ages. The frequently argued nongenetic transmission of the nutritional deficiencies from parents to descendants was corroborated with the present results. Such cumulative effect was evident at ages before the AFP was reached; i.e., when the decrement in body mass of the undernourished animals was not yet equilibrated with the amount of available nutrients.

Efecto de las hormonoas gonadales sobre el dimorfismo sexual en substrato de desnutrición / Effect of gonodal hormones on the sexual dimorphism in malnutrition substrate

El efecto ambiental sobre el crecimiento y el dimorfismo sexual es mediado por disfunciones endócrinas. Se ha comprobado que la desnutrición compromete al eje hipotalámico-hipofisario-glandular. Se realizó una experiencia en ratas Wistar con objeto de determinar el efecto de la administración de hormonas gonadales sobre componentes craneanos funcionales cuyo dimorfismo sexual fue alterado por desnutrición postnatal y analizar el tipo de efecto que estas hormonas tienen sobre el dimorfismo sexual. Se constituyeron cuatro tratamientos: control con consumo de dieta stock ad-libitum; subnutrición (50 por ciento del consumo promedio control); subnutrición+hormonas con inyecciones periódicas de testosterona y estradiol a machos y hembras respectivamente y sham-operado, en el cual la hormona fue sustituida por el vehículo oleoso. Se realizó un estudio radiológico longitudinal entre los 20 y 80 días de edad. Sobre cada radiografía se relevaron longitud, ancho y altura neuro y esplacnocraneanas. Con los datos obtenidos se realizó análisis de varianza y test de Mann-Whitney por medio del programa SYSTAT7.0. Los resultados obtenidos indicaron que ambas hormonas restituyeron el dimorfismo craneano sexual ya sea estimulando (testosterona) o inhibiendo (estradiol) el crecimiento de los componentes craneanos.

Efecto de las hormonoas gonadales sobre el dimorfismo sexual en substrato de desnutrición / Effect of gonodal hormones on the sexual dimorphism in malnutrition substrate

El efecto ambiental sobre el crecimiento y el dimorfismo sexual es mediado por disfunciones endócrinas. Se ha comprobado que la desnutrición compromete al eje hipotalámico-hipofisario-glandular. Se realizó una experiencia en ratas Wistar con objeto de determinar el efecto de la administración de hormonas gonadales sobre componentes craneanos funcionales cuyo dimorfismo sexual fue alterado por desnutrición postnatal y analizar el tipo de efecto que estas hormonas tienen sobre el dimorfismo sexual. Se constituyeron cuatro tratamientos: control con consumo de dieta stock ad-libitum; subnutrición (50 por ciento del consumo promedio control); subnutrición+hormonas con inyecciones periódicas de testosterona y estradiol a machos y hembras respectivamente y sham-operado, en el cual la hormona fue sustituida por el vehículo oleoso. Se realizó un estudio radiológico longitudinal entre los 20 y 80 días de edad. Sobre cada radiografía se relevaron longitud, ancho y altura neuro y esplacnocraneanas. Con los datos obtenidos se realizó análisis de varianza y test de Mann-Whitney por medio del programa SYSTAT7.0. Los resultados obtenidos indicaron que ambas hormonas restituyeron el dimorfismo craneano sexual ya sea estimulando (testosterona) o inhibiendo (estradiol) el crecimiento de los componentes craneanos. (AU)