Thyroid hormone-induced morphological differentiation and maturation of astrocytes are mediated through the beta-adrenergic receptor

The molecular mechanisms associated with thyroid hormone (TH)-induced maturation of astrocytes have been studied using primary cultures. We have previously demonstrated that unlike normal astrocyte cultures, hypothyroid cultures fail to differentiate from flat polygonal cells with epithelioid morphology into mature process-bearing cells with stellate morphology. Addition of TH to the hypothyroid cells reverses the effect, and astrocytes transform into stellate cells. The beta-adrenergic receptor (beta-AR) agonist isoproterenol (ISP) has a similar effect, whereas simultaneous addition of the beta-adrenergic antagonist propranolol blocks the differentiation induced by TH or ISP. Addition of TH or ISP to hypothyroid cultures is also associated with a decrease in the level of filamentous cytoskeletal (F(i)) actin and an increase in the level of actin mRNA. Although addition of propranolol inhibited the decline in the level of F(i) actin in the TH- or ISP-supplemented cells as well as the induction of actin mRNA by TH, it partially inhibited the ISP-induced actin mRNA in these cultures. The hormone-induced maturation appears to be selectively regulated through the beta(2)-AR. The overall results indicate that the beta-adrenergic system plays an obligatory role in promoting TH-induced differentiation and maturation of astrocytes and in regulating the hormone-induced expression of actin and its intracellular organization in a way conducive to the morphological differentiation of the cells.     

Generation and characterization of a zebrafish muscle specific inducible Cre line

Zebrafish transgenic lines provide valuable insights into gene functions, cell lineages and cell behaviors during development. Spatiotemporal control over transgene expression is a critical need in many experimental approaches, with applications in loss- and gain-of-function expression, ectopic expression and lineage tracing experiments. The Cre/loxP recombination system is a powerful tool to provide this control and the demand for validated Cre and loxP zebrafish transgenics is high. One of the major challenges to widespread application of Cre/loxP technology in zebrafish is comparatively small numbers of established tissue-specific Cre or CreERT2 lines. We used Tol2-mediated transgenesis to generate Tg(CrymCherry;-1.9mylz2:CreERT2) which provides an inducible CreERT2 source driven by muscle-specific mylz2 promoter. The transgenic specifically labels the trunk and tail skeletal muscles. We assessed the temporal responsiveness of the transgenic by screening with a validated loxP reporter transgenic ubi:Switch. Further, we evaluated the recombination efficiency in the transgenic with varying concentrations of 4-OHT, for different induction time periods and at different stages of embryogenesis and observed that higher recombination efficiency is achieved when embryos are induced with 10 μM 4-OHT from 10-somites or 24 hpf till 48 or 72 hpf. The transgenic is an addition to currently available zebrafish transgenesis toolbox and a significant tool to advance muscle biology studies in zebrafish.     

Delayed but sustained induction of mitogen-activated protein kinase activity is associated with beta-adrenergic receptor-mediated morphological differentiation of astrocytes

Astroglial beta-adrenergic receptors (beta-ARs) are functionally linked to regulate cellular morphology. In primary cultures, the beta-AR agonist isoproterenol (ISP) can transform flat polygonal astrocytes into process-bearing, mature stellate cells by 48 h, an effect that can be blocked by the beta-AR antagonist, propranolol. ISP induced immediate activation of protein kinase A (PKA) which persisted up to 2 h, with no visible change in cell morphology. However, activation of PKA was sufficient to drive the process of transformation to completion, suggesting the involvement of downstream regulators of PKA. In addition to PKA inhibitors, the mitogen-activated protein kinase (MAPK) kinase inhibitor PD098059 also blocked ISP-induced morphological transformation. ISP treatment resulted in a biphasic response of cellular phosphorylated MAPK (phosphorylated extracellular signal-regulated kinase; p-ERK) level: an initial decline in p-ERK level followed by a sustained induction at 12-24 h, both of which were blocked by PKA inhibitor. The induction in pERK level coincided with initiation of morphological differentiation of the astrocytes and nuclear translocation of p-ERK. A long-lasting activation of p-ERK activity by ISP, at a later stage, appears to be critical for the transformation of astrocytes.     

Body mass index in Central India: inter district variation

Basic causes of poor state of nutrition and infections in developing countries are poverty, low level of hygienic conditions and little access to preventive and health care. Central India is known for its high rate of population growth and mortality, which persisted over time along with a low level of social, economic and infrastructure development. In the present study the body mass index (BMI) of 31 populations residing in 38 districts of Central India (comprising the States of Madhya Pradesh and Chhattisgarh) is assessed. Anthropometric data collected by the Anthropological Survey of India were utilized in this context. The mean body mass index values of the populations of total backward and non-backward districts are found to be lower than that of well-to-do individuals of India (Bharati 1989, Khongsdier 1997, Reddy 1998), but it is not as low as that found among the South Indian populations (Ferro-Luzzi et al. 1992). In the present investigation, it is also found that the majority of the backward districts fall in the category of different grade of chronic energy deficiency (CED), while in the non-backward districts a considerably less number of districts follows this trend. A better level of the nutritional status among the populations of the non-backward districts corroborates the findings of the Ministry of Health and Family Welfare (NFHS 1992). It reveals that the apparently healthy individuals with CED grade I in the present study may be thin but physically active and healthy. The present study, however, narrates further intensive investigations in these populations, because the BMI as a measure of the CED should incorporate the aspects like morbidity and health status of a population.     

The Tai-Phake of Assam, India--a morphometric study and population comparison with neighbouring groups

Morphometric characters of the adult males of the Tai-Phake and the nature and extent of morphometric variation among five neighboring mongoloid groups of Assam have been examined in the present study. For the sake of investigation 12 anthropometric measurements have been taken and five indices have been calculated. In order to obtain the distance values size, shape and biological distance are calculated. It revels that the Tai-Phake maintains a far distance with other five neighboring groups (Ahom, Deuri, Chutia, Mishing and Moran). The Ahom also maintain far distance with other five groups. While, the Mishing and Moran, and Deuri and Chutia maintain close distance among themselves.     

Brain-derived neurotrophic factor over-expression in the forebrain ameliorates Huntington's disease phenotypes in mice

Huntington's disease (HD), a dominantly inherited neurodegenerative disorder characterized by relatively selective degeneration of striatal neurons, is caused by an expanded polyglutamine tract of the huntingtin (htt) protein. The htt mutation reduces levels of brain-derived neurotrophic factor (BDNF) in the striatum, likely by inhibiting cortical BDNF gene expression and anterograde transport of BDNF from cortex to striatum. However, roles of the BDNF reduction in HD pathogenesis have not been established conclusively. We reasoned that increasing striatal BDNF through over-expression would slow progression of the disease if BDNF reduction plays a pivotal role in HD pathogenesis. We employed a Bdnf transgene driven by the promoter for the alpha subunit of Ca²⁺/calmodulin-dependent kinase II to over-express BDNF in the forebrain of R6/1 mice which express a fragment of mutant htt with a 116-glutamine tract. The Bdnf transgene increased BDNF levels and TrkB signaling activity in the striatum, ameliorated motor dysfunction, and reversed brain weight loss in R6/1 mice. Furthermore, it normalized DARPP-32 expression of the 32 kDa dopamine and cAMP-regulated phosphoprotein, increased the number of enkephalin-containing boutons, and reduced formation of neuronal intranuclear inclusions in the striatum of R6/1 mice. These results demonstrate crucial roles of reduced striatal BDNF in HD pathogenesis and suggest potential therapeutic values of BDNF to HD.     

Thyroid Hormone-Induced Maturation of Astrocytes Is Associated with the Expression of New Variants of Vimentin and Their Phosphorylation

The role of thyroid hormone (TH)-induced vimentin expression in promoting the maturation of astrocytes has been investigated. Comparative immunocytochemical staining with vimentin antibody demonstrated distinctly different patterns of expression of vimentin during the progressive maturation of astrocytes of normal and TH-deficient astrocyte cultures. [35S]Methionine labeling of cells showed a significant decline in the level of vimentin in the hypothyroid cultures at all ages from day 5 to 20. Western blot analysis suggested that the maturation of normal astrocytes was associated with the appearance of several acidic and basic variants of vimentin, whose expression was significantly delayed or reduced in the TH-deficient astrocytes. In normal astrocyte cultures, two acidic variants of vimentin, one of similar molecular weight and the other of lower molecular weight, were found to be phosphorylated during the final transformation of the epithelioid form into the mature stellate form. None of these phosphorylated forms was evident in the TH-deficient astrocytes. This was further confirmed by negative immunocytochemical staining of 5- to 18-day-old cultures of TH-deficient astrocytes with antibody TM71, specific to phosphorylated vimentin, compared with age-matched normal astrocytes, which displayed consistent positive staining. The overall results indicate that TH-induced expression of phosphorylated forms of vimentin may be essential for the intracellular organization of the cytoskeleton in a way conducive to the morphological maturation of astrocytes.     

Body mass index and chronic energy deficiency of adult males of Central Indian populations

Data on body weight, height, and sitting height from 11,496 adult males, age 18-62 years, belonging to 38 different populations of five major social groups (scheduled tribes, scheduled castes, "other backward castes," general castes, and Muslims) of Central India were taken for our analysis to assess the nutritional status of these groups. Cormic index and body mass index (BMI) were computed, and an analysis of variance (ANOVA) was carried out among different populations as well as among social groups separately on Cormic index and BMI. Shape, size, and generalized distances among the different social groups were computed and dendrograms were drawn. The level of malnutrition is the lowest among the general castes. The opposite is the case with the scheduled castes and scheduled tribes. Comparison of the coefficient of variation shows that there is variation in weight and BMI but that there is no marked variation in the other anthropometric variables. The ANOVA on Cormic index and BMI suggests that the people within a population are more homogeneous than the people between populations. There is a positive but statistically insignificant correlation between Cormic index and BMI. The five social groups differ more in size distance than in shape distance. According to the dendrogram of generalized distance values, the Muslims and the general castes can be grouped into one cluster and the scheduled castes, scheduled tribes, and other backward castes can be grouped into another cluster.