GFAP Expression in Astrocytes of Suprachiasmatic Nucleus and Medial Preoptic Area are Differentially Affected by Malnutrition during Rat Brain Development

Maternal intake restriction programs the energy metabolism, clock circadian regulator and mTOR signals in the skeletal muscles of goat offspring probably via the protein kinase A-cAMP-responsive element-binding proteins pathway

The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood. We hypothesize that maternal intake restriction influences metabolic signals in the skeletal muscles of offspring via a glucagon-mediated pathway. Twenty-four pregnant goats were assigned to the control group (100% of the nutrients requirement, n = 12) and restricted group (60% of the control feed allowance from pregnant days 45 to 100, n = 12). Blood and L ongissimus thoracis muscle were sampled from dams (100 d of gestation), fetuses (100 d of gestation), and kids (90 d after birth) in each group. The data were analyzed using the linear MIXED model, with the multiple comparison method of SIDAK applied. Intake restriction reduced (P < 0.05) the total blood protein of dams and fetuses. Maternal restriction decreased (P < 0.05) the cAMP-responsive element-binding protein 1 (CREB1), CREB-binding protein (CREBBP), protein kinase A (PKA), aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1), protein kinase B (AKT1), mammalian target of rapamycin (mTOR), and regulatory-associated protein of mTOR (RPTOR) mRNA expression in the fetuses, and reduced (P < 0.05) the CREBBP, nuclear receptor subfamily 1 group H member 3 (NR1H3), D-box binding PAR bZIP transcription factor (DBP) and PKA mRNA levels in the kids, but increased (P < 0.05) the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1 A) and tuberous sclerosis 2 (TSC2) mRNA levels in the fetuses. The mRNA expression of clock circadian regulator (CLOCK) and TSC2 genes was increased (P < 0.05) in the restricted kids. The protein expression of total PKA and phosphorylated PKA in the restricted fetuses and kids were downregulated (P < 0.05), and the protein expression of total mTOR and phosphorylated mTOR were reduced (P < 0.05) in the restricted fetuses and kids. Maternal intake restriction regulated fat oxidation, protein synthesis, and circadian clock expression in the muscles of the offspring probably via the glucagon-mediated PKA-CREB pathway, which reveals a noteworthy molecular pathway that maternal undernutrition leads to metabolic adaptation of skeletal muscle in offspring.

Undernutrition - thirty years of the Regional Basic Diet: the legacy of Naíde Teodósio in different fields of knowledge

Undernutrition is characterized by an imbalance of essential nutrients with an insufficient nutritional intake, a disorder in which the clinical manifestations in most cases are the result of the economic and social context in which the individual lives. In 1990, the study by the medical and humanitarian Naíde Teodósio (1915-2005) and coworkers, which formulated the Regional Basic Diet (RBD) model for inducing undernutrition, was published. This diet model took its origin from the observation of the dietary habits of families that inhabited impoverished areas from the Pernambuco State. RBD mimics an undernutrition framework that extends not only to the Brazilian population, but to populations in different regions worldwide. The studies based on RBD-induced deficiencies provide a better understanding of the impact of undernutrition on the pathophysiological mechanisms underlying the most diverse prevalent diseases. Indexed papers that are analyzed in this review focus on the importance of using RBD in different areas of knowledge. These papers reflect a new paradigm in translational medicine: they show how the study of pathology using the RBD model in animals over the past 30 years has and still can help scientists today, shedding light on the mechanisms of prevalent diseases that affect impoverished populations.

Misadjustment of diurnal expression of core temperature and locomotor activity in lactating rabbits associated with maternal over-nutrition before and during pregnancy

Metabolic parameters ranging from circulating nutrient levels and substrate utilization to energy expenditure and thermogenesis are temporally modulated by the circadian timing system. During critical embryonic developmental periods, maternal over-nutrition could alter key elements in different tissues associated with the generation of circadian rhythmicity, compromising normal rhythmicity development. To address this issue, we determine whether maternal over-nutrition leads to alterations in the development of circadian rhythmicity at physiological and behavioral levels in the offspring. For this, female rabbits were fed a standard diet (SD) or high-fat and carbohydrate diet (HFCD) before mating and during gestation. Core body temperature and gross locomotor activity were continuously recorded in newborn rabbits, daily measurements of body weight and the amount of milk ingested was carried out. At the end of lactation, tissue samples, including brown adipose tissue (BAT) and white adipose tissue (WAT), were obtained for determining the expression of uncoupling protein-1 (UCP1) and cell death-inducing DNA fragmentation factor-like effector A (CIDEA) genes. HFCD pups exhibited conspicuous differences in the development of the daily rhythm of temperature and locomotor activity compared to the SD pups, including a significant increase in the daily mean core temperature, changes in the time when temperature or activity remains above the average, shifts in the acrophase, decrease in the duration and intensity of the anticipatory rise previous to nursing, and changes in frequency of the rhythms. HFCD pups exhibited a significant increase in BAT thermogenesis markers, and a decrease of these markers in WAT, indicating more heat generation by brown adipocytes and alterations in the browning process. These results indicate that maternal over-nutrition alters offspring homeostatic and chronostatic regulation at the physiological and behavioral levels. Further studies are needed to determine whether these alterations are associated with the changes in the organization of the circadian system of the progeny.

Improved survival and overt "dystonic" symptoms in a torsinA hypofunction mouse model

DYT1 dystonia is an inherited movement disorder without obvious neurodegeneration. Multiple mutant mouse models exhibit motor deficits without overt "dystonic" symptoms and neurodegeneration. However, some mouse models do. Among the later models, the N-CKO mouse model, which has a heterozygous Tor1a/Dyt1 knockout (KO) in one allele and Nestin-cre-mediated conditional KO in the other, exhibits a severe lack of weight gain, neurodegeneration, overt "dystonic" symptoms, such as overt leg extension, weak walking, twisted hindpaw and stiff hindlimb, and complete infantile lethality. However, it is not clear if the overt dystonic symptoms were caused by the neurodegeneration in the dying N-CKO mice. Here, the effects of improved maternal care and nutrition during early life on the symptoms in N-CKO mice were analyzed by culling the litter and providing wet food to examine whether the overt dystonic symptoms and severe lack of weight gain are caused by malnutrition-related neurodegeneration. Although the N-CKO mice in this study replicated the severe lack of weight gain and overt "dystonic" symptoms during the lactation period regardless of culling at postnatal day zero or later, there was no significant difference in the brain astrocytes and apoptosis between the N-CKO and control mice. Moreover, more than half of the N-CKO mice with culling survived past the lactation period. The surviving adult N-CKO mice did not display overt "dystonic" symptoms, and in addition they still exhibited small body weight. The results suggest that the overt "dystonic" symptoms in the N-CKO mice were independent of prominent neurodegeneration, which negates the role of neurodegeneration in the pathogenesis of DYT1 dystonia.

Reductions in hypothalamic Gfap expression, glial cells and α-tanycytes in lean and hypermetabolic Gnasxl-deficient mice

Background

Neuronal and glial differentiation in the murine hypothalamus is not complete at birth, but continues over the first two weeks postnatally. Nutritional status and Leptin deficiency can influence the maturation of neuronal projections and glial patterns, and hypothalamic gliosis occurs in mouse models of obesity. Gnasxl constitutes an alternative transcript of the genomically imprinted Gnas locus and encodes a variant of the signalling protein Gα_s, termed XLα_s, which is expressed in defined areas of the hypothalamus. Gnasxl-deficient mice show postnatal growth retardation and undernutrition, while surviving adults remain lean and hypermetabolic with increased sympathetic nervous system (SNS) activity. Effects of this knock-out on the hypothalamic neural network have not yet been investigated.

Results

RNAseq analysis for gene expression changes in hypothalami of Gnasxl-deficient mice indicated Glial fibrillary acid protein (Gfap) expression to be significantly down-regulated in adult samples. Histological analysis confirmed a reduction in Gfap-positive glial cell numbers specifically in the hypothalamus. This reduction was observed in adult tissue samples, whereas no difference was found in hypothalami of postnatal stages, indicating an adaptation in adult Gnasxl-deficient mice to their earlier growth phenotype and hypermetabolism. Especially noticeable was a loss of many Gfap-positive α-tanycytes and their processes, which form part of the ependymal layer that lines the medial and dorsal regions of the 3^rd ventricle, while β-tanycytes along the median eminence (ME) and infundibular recesses appeared unaffected. This was accompanied by local reductions in Vimentin and Nestin expression. Hypothalamic RNA levels of glial solute transporters were unchanged, indicating a potential compensatory up-regulation in the remaining astrocytes and tanycytes.

Conclusion

Gnasxl deficiency does not directly affect glial development in the hypothalamus, since it is expressed in neurons, and Gfap-positive astrocytes and tanycytes appear normal during early postnatal stages. The loss of Gfap-expressing cells in adult hypothalami appears to be a consequence of the postnatal undernutrition, hypoglycaemia and continued hypermetabolism and leanness of Gnasxl-deficient mice, which contrasts with gliosis observed in obese mouse models. Since α-tanycytes also function as adult neural progenitor cells, these findings might indicate further developmental abnormalities in hypothalamic formations of Gnasxl-deficient mice, potentially including neuronal composition and projections.

Electronic supplementary material

The online version of this article (doi:10.1186/s13041-016-0219-1) contains supplementary material, which is available to authorized users.

Effects of fractal surface on C6 glioma cell morphogenesis and differentiation in vitro

Neurons and glial cells in the brain are surrounded by a fractal environment. A fractal alkylketene dimmer (AKD) surface was shown to provide such a biomimetic environment for glial cell culture. However, little is known about the effects of fractal surface on the complexity of cell morphology. In particular, whether fractal surface induces glial cell differentiation remains to be elucidated. The present work, thus determined the fractal dimension (FD) of cell complexity with a geometrically calculational parameter, the expressions of GFAP gene and protein in C6 glioma cells on fractal AKD, non-fractal AKD and PLL-coated surfaces. Fractal surface suppressed the proliferation of glioma cell, and significantly increased the length and number of cell process. Furthermore, the enhanced values of FD were accompanied with the expressions of GFAP gene and protein, especially that of gene. However, cells on non-fractal and PLL surface proliferated gradually along with the culture time, showing the fibroblast-like morphology, and accompanied with the consistent expressions of GFAP gene and protein. These results suggested that C6 glioma cell differentiation can be induced by fractal AKD surface.

Immunoreactive vasoactive intestinal polypeptide and vasopressin cells after a protein malnutrition diet in the suprachiasmatic nucleus of the rat

The aim of the present study was to evaluate the effects of prenatal and postnatal protein deprivation on the morphology and density of vasopressin (VP) and vasoactive intestinal polypeptide (VIP) immunoreactive neurons in the suprachiasmatic nucleus (SCN) of young rats. Female Wistar rats were fed either 6% (malnourished group) or 25% (control group) casein diet five weeks before conception, during gestation and lactation. After weaning, the pups were maintained on the same diet until sacrificed at 30 days of age. The major and minor axes, somatic area and the density of VP- and VIP-immunoreactive neurons were evaluated in the middle sections of the SCN. The present study shows that chronic protein malnutrition (ChPM) in VP neurons induces a significant decrease in number of cells (–31%,) and a significant increase in major and minor axes and somatic area (+12.2%, +21.1% and +15.0%, respectively). The VIP cells showed a significant decrease in cellular density (–41.5%) and a significant increase in minor axis (+13.5%) and somatic area (+10.1%). Our findings suggest that ChPM induces abnormalities in the density and morphology of the soma of VP and VIP neurons. These alterations may be a morphological substrate underlying circadian alterations previously observed in malnourished rats.

Alteration of glial fibrillary acidic proteins immunoreactivity in astrocytes of the spinal cord diabetic rats

Diabetes affects retinal and nervous glial cells, especially the astrocytes. A key indicator of this response is the alteration in the level of intermediate filament glial fibrillary acidic protein (GFAP) and number of GFAP-immunoreactive astrocytes. To date, no study has investigated the effect of diabetes on the distribution of GFAP-immunoreactive astrocytes in the spinal cord. Therefore, the present study investigated the effect of diabetes on the number of GFAP-immunoreactive astrocytes in the gray matter of the spinal cord of streptozotocin-induced diabetic Wistar rats. Animals were divided into six groups (n = 7); 6 weeks and 12 weeks diabetic duration groups and their respective age-matched normal control and sham control groups. Our results demonstrated a significant (P < 0.001) decrease in the number of GFAP-immunoreactive astrocytes in different areas of the spinal cord sections of the 6 weeks and 12 weeks long diabetic rats when compared with the spinal cord of normal and sham control groups of comparable age. The mean percentage in total number of GFAP-immunoreactive astrocytes in the whole gray matter areas of the spinal cord of the 6 and 12 weeks diabetic groups were approximately 28% and 41% less than control groups. Furthermore, the 12 weeks diabetic group showed a significant (P < 0.001) reduction in the number of GFAP-immunoreactive astrocytes when compared with the 6 weeks diabetic animals. These results suggest that the induction of diabetes is associated with a reduction in GFAP-positive astrocytes in the spinal cord, which may affect the functional support and role of astrocytic cells in the nervous tissue. This in turn may contribute to the pathological changes associated with diabetic state in the central nervous system.