Effects of 6-month daily supplementation with oral beta-carotene in combination or not with benzo[a]pyrene on cell-cycle markers in the lung of ferrets

Epidemiological studies have demonstrated that people who eat more fruits and vegetables (rich in carotenoids) and people who have higher serum beta-carotene (BC) levels have a lower risk of cancer, particularly lung cancer. However, the two main human intervention studies of BC supplementation (the ATBC and the CARET trials) revealed an increased risk of lung cancer among smokers and asbestos workers. Previous studies carried out in the ferret have reported that BC effects are related to dose. Here, we treated ferrets with two concentrations of oral BC (0.8 and 3.2 mg/kg body weight per day) for 6 months, using BC in a formulation also containing dl-alpha-tocopherol and ascorbyl palmitate. The effect of the smoke-derived carcinogenic agent benzo[a]pyrene (BP), with or without low-dose BC, was also analysed. We determined the protein levels and mRNA expression levels of activator protein 1 (c-Jun and c-Fos), c-Myc, cyclin D1, proliferating cellular nuclear antigen and retinoic acid receptor beta. We did not find higher levels of cell proliferation markers in the lung of ferrets treated with BC or signals of squamous metaplasia lesions either. On the other hand, although no evident signals of pulmonary carcinogenesis were observed in animals exposed to BP, BC supplementation in these animals may prevent against excess cell proliferation, since this reestablishes Jun protein and cyclin D1 mRNA levels in the lung of BP-exposed animals. In summary, these results show that the combination of BC with alpha-tocopherol and ascorbyl palmitate does not induce pro-oxidant effects in the lung of ferrets.     

A large proportion of mediastinal and perirenal visceral fat of Siberian adult people is formed by UCP1 immunoreactive multilocular and paucilocular adipocytes

Journal of Physiology and Biochemistry - Many deleterious consequences for health of excessive fat accumulation are due to visceral fat. Browning of visceral fat is mainly cold dependent and has...     

CL316,243 and cold stress induce heterogeneous expression of UCP1 mRNA and protein in rodent brown adipocytes.

Uncoupling protein 1 (UCP1), the mammalian thermogenic mitochondrial protein, is found only in brown adipocytes, but its expression by immunohistochemistry is not homogeneous. Here we present evidence that the non-homogeneous pattern of immunostaining for UCP1 (referred to as the "Harlequin phenomenon") is particularly evident after acute and chronic cold (4C) stimulus and after administration of a specific beta(3)-adrenoceptor agonist (CL316,243). Accordingly, mRNA in situ expression confirmed the UCP1 non-homogeneous pattern of gene activation under conditions of adrenergic stimulus. Furthermore, morphometric analysis of immunogold-stained thin sections showed that UCP1-gold particle density was different among neighboring brown adipocytes with mitochondria of the same size and density. When the adrenergic stimulus was reduced in warm-acclimated animals (28C), UCP1 protein and mRNA expression was reduced and consequently the Harlequin phenomenon was barely visible. These data suggest the existence of an alternative and controlled functional recruitment of brown adipocytes in acute adrenergically stressed animals, possibly to avoid heat and metabolic damage in thermogenically active cells. Of note, the heat shock protein heme oxygenase 1 (HO1) is heterogeneously expressed in adrenergically stimulated brown adipose tissue and, specifically, cells expressing strong immunoreactivity for UCP1 also strongly express HO1.     

Expression of human alpha 2-adrenergic receptors in adipose tissue of beta 3-adrenergic receptor-deficient mice promotes diet-induced obesity

Catecholamines play an important role in controlling white adipose tissue function and development. beta- and alpha 2-adrenergic receptors (ARs) couple positively and negatively, respectively, to adenylyl cyclase and are co-expressed in human adipocytes. Previous studies have demonstrated increased adipocyte alpha 2/beta-AR balance in obesity, and it has been proposed that increased alpha 2-ARs in adipose tissue with or without decreased beta-ARs may contribute mechanistically to the development of increased fat mass. To critically test this hypothesis, adipocyte alpha 2/beta-AR balance was genetically manipulated in mice. Human alpha 2A-ARs were transgenically expressed in the adipose tissue of mice that were either homozygous (-/-) or heterozygous (+/-) for a disrupted beta 3-AR allele. Mice expressing alpha 2-ARs in fat, in the absence of beta 3-ARs (beta 3-AR -/- background), developed high fat diet-induced obesity. Strikingly, this effect was due entirely to adipocyte hyperplasia and required the presence of alpha2-ARs, the absence of beta 3-ARs, and a high fat diet. Of note, obese alpha 2-transgenic beta 3 -/- mice failed to develop insulin resistance, which may reflect the fact that expanded fat mass was due to adipocyte hyperplasia and not adipocyte hypertrophy. In summary, we have demonstrated that increased alpha 2/beta-AR balance in adipocytes promotes obesity by stimulating adipocyte hyperplasia. This study also demonstrates one way in which two genes (alpha 2 and beta 3-AR) and diet interact to influence fat mass.     

Tactile sensitivity,tactile acuity,and affective touch: from childhood to early adolescence

The development of somatosensation and affective touch acquires a central role throughout our lives, for several reasons. In adults, these functions are driven by different, neuroanatomically and functionally segregated fibres. To date, very little is known about the basic features of these fibres in childhood and this lack of knowledge is mirrored in the affective touch domain, where there are no studies on the main physiological features of the tactile processes linked to the stimulation of the hairy skin, namely the preferential site of affective touch. Thus, our study aims to analyze (1) tactile sensitivity and tactile acuity of children’s hairy forearms; (2) a possible dissociation between somatosensation and the affective touch; and (3) the presence/absence of the perception of affective touch already in childhood. To these aims, participants (160 children, aged 6 to 14?years), were administered with the Von Frey (tactile sensitivity) and the 2 Point Discrimination (tactile acuity) tests. Affective touch was measured following the classic protocol and pleasantness ratings were recorded. Our findings showed a correlation between age and somatosensation, suggesting a progressive reduction of sensitivity and acuity as age grows. Further, there was no overlap between affective touch and somatosensation, suggesting a behavioural segregation. Lastly, we found higher pleasantness ratings for Affective versus Neutral stimulations at all ages and an enhanced preference for Affective as age grows. We concluded that both somatosensation and affective touch are already present as two separate components of touch in childhood and change as a function of age.     

Hormone‐induced mitochondrial fission is utilized by brown adipocytes as an amplification pathway for energy expenditure

Adrenergic stimulation of brown adipocytes (BA) induces mitochondrial uncoupling, thereby increasing energy expenditure by shifting nutrient oxidation towards thermogenesis. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically‐induced changes in energy expenditure. The sympathetic neurotransmitter Norepinephrine (NE) induced complete and rapid mitochondrial fragmentation in BA, characterized by Drp1 phosphorylation and Opa1 cleavage. Mechanistically, NE‐mediated Drp1 phosphorylation was dependent on Protein Kinase‐A (PKA) activity, whereas Opa1 cleavage required mitochondrial depolarization mediated by FFAs released as a result of lipolysis. This change in mitochondrial architecture was observed both in primary cultures and brown adipose tissue from cold‐exposed mice. Mitochondrial uncoupling induced by NE in brown adipocytes was reduced by inhibition of mitochondrial fission through transient Drp1 DN overexpression. Furthermore, forced mitochondrial fragmentation in BA through Mfn2 knock down increased the capacity of exogenous FFAs to increase energy expenditure. These results suggest that, in addition to its ability to stimulate lipolysis, NE induces energy expenditure in BA by promoting mitochondrial fragmentation. Together these data reveal that adrenergically‐induced changes to mitochondrial dynamics are required for BA thermogenic activation and for the control of energy expenditure.     

Cellular and molecular large‐scale features of fetal adipose tissue: Is bovine perirenal adipose tissue Brown1685

Epidemiological and fetal programming studies point to the role of fetal growth in adult adipose tissue (AT) mass in large mammals. Despite the incidence of fetal AT growth for human health and animal production outcomes, there is still a lack of relevant studies. We determined the cellular and large-scale-molecular features of bovine fetal perirenal AT sampled at 110, 180, 210, and 260 days post-conception (dpc) with the aim of identifying key cellular and molecular events in AT growth. The increase in AT weight from 110 to 260 dpc resulted from an increase in adipocyte volume and particularly adipocyte number that were concomitant with temporal changes in the abundance of 142 proteins revealed by proteomics. At 110 and 180 dpc, we identified proteins such as TCP1, FKBP4, or HSPD1 that may regulate adipocyte precursor proliferation by controlling cell-cycle progression and/or apoptosis or delaying PPARγ-induced differentiation. From 180 dpc, the up-regulation of PPARγ-induced proteins, lipogenic and lipolytic enzymes, and adipokine expression may underpin the differentiation and increase in adipocyte volume. Also from 180 dpc, we unexpectedly observed up-regulations in the β-subunit of ATP synthase, which is normally bypassed in brown AT, as well as in aldehyde dehydrogenases ALDH2 and ALDH9A1, which were predominantly expressed in mouse white AT. These results, together with the observed abundant unilocular adipocytes at 180 and 260 dpc, strongly suggest that fetal bovine perirenal AT has much more in common with white than with brown AT.