Article

Juvenile male rats display lower cortical metabolic capacity than females.

Departments of Psychology, Pharmacology and Toxicology, University of Texas at Austin, 1 University Station A8000, Austin, TX 78712, USA.
Neuroscience Letters (Impact Factor: 2.03). 09/2008; 440(3):255-9. DOI: 10.1016/j.neulet.2008.05.104
Source: PubMed

ABSTRACT The juvenile brain undergoes marked maturational changes accompanied by major sex hormone changes. In particular, sex differences in neural substrates could underlie male-specific dysfunction in behavioral responses related to the prefrontal cortex. Sex differences in regional metabolic capacity of the cerebral cortex were investigated in juvenile Sprague-Dawley rats. At 6 weeks of age the brains were processed for quantitative histochemistry of cytochrome oxidase, a rate-limiting enzyme in cellular respiration, which is an index of brain metabolic capacity. Quantitative image analysis revealed a main effect of sex with males displaying lower regional metabolic capacity than females in the dorsolateral and orbital prefrontal cortex and in the posterior parietal cortex. In addition, males separated for 6 h/day from their mothers as pups showed greater ambulatory behavior in the novel open field and higher metabolism in the posterior parietal cortex relative to males separated for 15 min/day. This is the first study to show sex differences in brain metabolic capacity in regions such as the prefrontal cortex that may be hypometabolic in juvenile males relative to females.

0 Bookmarks
 · 
73 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, we investigated the landmark identification errors on cone-beam computed tomography (CBCT)-derived cephalograms and conventional digital cephalograms. Twenty patients who had both a CBCT-derived cephalogram and a conventional digital cephalogram were recruited. Twenty commonly used lateral cephalometric landmarks and 2 fiducial points were identified on each cephalogram by 11 observers at 2 time points. The mean positions of the landmarks identified by all observers were used as the best estimate to calculate the landmark identification errors. In addition to univariate analysis, regression analysis of landmark identification errors was conducted for identifying the predicting variables of the observed landmark identification errors. To properly handle the multilayer correlations among the clustered observations, a marginal multiple linear regression model was fitted to our correlated data by using the well-known generalized estimating equations method. In addition to image modality, many variables potentially affecting landmark identification errors were considered, including location and characteristics of the landmark, seniority of the observer, and patient information (sex, age, metallic dental restorations, and facial asymmetry). Image modality was not the significant variable in the final generalized estimating equations model. The regression coefficient estimates of the significant landmarks for the overall identification error ranged from -0.99 (Or) to 1.42 mm (Ba). The difficulty of identifying landmarks on structural images with multiple overlapping--eg, Or, U1R, L1R, Po, Ba, UMo, and LMo--increased the identification error by 1.17 mm. In the CBCT modality, the identification errors significantly decreased at Ba (-0.76 mm). The overall landmark identification errors on CBCT-derived cephalograms were comparable to those on conventional digital cephalograms, and Ba was more reliable on CBCT-derived cephalograms.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 12/2011; 140(6):e289-97. · 1.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The interactions between a mother and her offspring during early postnatal life impact cognitive development in altricial species. The current study examined the influence of postnatal rearing conditions on subsequent cognitive functioning in male and female Long-Evans rats prior to puberty. Maternal conditions were manipulated by repeated separations of rat pups from their dams on postnatal days 2 though 14. In the early handling condition, pups were removed from mothers briefly for 15min daily, while in the maternal separation condition pups were separated from their mothers for 180min daily. Offspring from handled or separated litters were evaluated prior to puberty between days 25-36 of life on a battery of cognitive tasks that assessed several types of memory. Male rats separated from mothers for 180min were impaired in their non-spatial and spatial memory compared to early-handled males as indicated by their performance on an object recognition task, a Y-maze task, and reference and working memory versions of the water maze task. In contrast, maternally-separated females were not impaired, and in some cases performed better on memory tasks, compared to early-handled females. Results indicate that the biological sex of offspring moderated the effects of maternal conditions on diverse cognitive tasks. Because sex differences were evident prior to puberty, gonadal hormones likely had a limited influence on cognition. Although the bases for sex differences in the cognitive response to rearing conditions are unknown, disparities in maternal attentiveness directed toward male and female offspring may play a role.
    Neurobiology of Learning and Memory 07/2010; 94(1):91-9. · 3.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This is the first study to assess the effects of mother-infant separation on regional metabolic capacity in the preweanling rat brain. Mother-infant separation is generally known to be stressful for rat pups. Holtzman adolescent rats show a depressive-like behavioral phenotype after maternal separation during the preweanling period. However, information is lacking on the effects of maternal separation on the brains of rat pups. We addressed this issue by mapping the brains of preweanling Holtzman rat pups using cytochrome oxidase histochemistry, which reflects long-term changes in brain metabolic capacity, following two weeks of repeated, prolonged maternal separation, and compared this to both early handled and non-handled pups. Quantitative image analysis revealed that maternal separation reduced cytochrome oxidase activity in the medial prefrontal cortex and nucleus accumbens shell. Maternal separation reduced prefrontal cytochrome oxidase to a greater degree in female pups than in males. Early handling reduced cytochrome oxidase activity in the posterior parietal cortex, ventral tegmental area, and subiculum, but increased cytochrome oxidase activity in the lateral frontal cortex. The sex-dependent effects of early handling on cytochrome oxidase activity were limited to the medial prefrontal cortex. Regardless of separation group, females had greater cytochrome oxidase activity in the habenula and ventral tegmental area compared to males. These findings suggest that early life mother-infant separation results in dysfunction of prefrontal and mesolimbic regions in the preweanling rat brain that may contribute to behavioral changes later in life.
    Brain research 10/2010; 1367:198-206. · 2.46 Impact Factor

Full-text (2 Sources)

View
28 Downloads
Available from
May 30, 2014