Influence of high fat diet and resveratrol supplementation on placental fatty acid uptake in the Japanese macaque.

INTRODUCTION: Adequate maternal supply and placental delivery of long chain polyunsaturated fatty acids (LCPUFA) is essential for normal fetal development. In humans, maternal obesity alters placental FA uptake, though the impact of diet remains uncertain. The fatty fetal liver observed in offspring of Japanese macaques fed a high fat diet (HFD) was prevented with resveratrol supplementation during pregnancy. We sought to determine the effect of HFD and resveratrol, a supplement with insulin-sensitizing properties, on placental LCPUFA uptake in this model. METHODS: J. macaques were fed control chow (15% fat, n = 5), HFD (35% fat, n = 10) or HFD containing 0.37% resveratrol (n = 5) prior to- and throughout pregnancy. At ∼ 130 d gestation (term = 173 d), placentas were collected by caesarean section. Fatty acid uptake studies using (14)C-labeled oleic acid, arachidonic acid (AA) and docosahexanoic acid (DHA) were performed in placental explants. RESULTS: Resveratrol supplementation increased placental uptake of DHA (P < 0.05), while HFD alone had no measurable effect. Resveratrol increased AMP-activated protein kinase activity and mRNA expression of the fatty acid transporters FATP-4, CD36 and FABPpm (P < 0.05). Placental DHA content was decreased in HFD dams; resveratrol had no effect on tissue fatty acid profiles. DISCUSSION: Maternal HFD did not significantly affect placental LCPUFA uptake. Furthermore, resveratrol stimulated placental DHA uptake capacity, AMPK activation and transporter expression. Placental handling of DHA is particularly sensitive to the dramatic alterations in the maternal metabolic phenotype and placental AMPK activity associated with resveratrol supplementation.

Interaction between enkephalin and gamma-aminobutyric acid in the chicken retina: a double-label immunoelectron microscopic analysis.

In the present study, double-label immunoelectron microscopy was used to examine the synaptic relationships between amacrine cell populations in the chicken retina that contain either enkephalin or gamma-aminobutyric acid (GABA) or both enkephalin and GABA. The objectives of the present study were twofold. First, the ultrastructural features and synaptic organization of enkephalin and enkephalin/GABA amacrine cells were compared. Second, the synaptic interactions between these populations and the population of GABA amacrine cells were examined. A total of 475 synaptic arrangements were observed to involved enkephalin or enkephalin/GABA amacrine cell processes. The synaptic relationships of enkephalin and enkephalin/GABA amacrine cells were quite similar. Each population was pre- and postsynaptic to amacrine cells, postsynaptic to bipolar cells, and presynaptic to processes possibly originating from ganglion cells. A substantial percentage of each population's pre- and postsynaptic relationships were with the processes of GABAergic amacrine cells. Moreover, when enkephalin and enkephalin/GABA amacrine cell processes were postsynaptic to bipolar cells, their dyadic partner was observed frequently to be a GABA amacrine cell process. The present study suggests a diversity in the population of chicken enkephalin amacrine cells with respect to their expression of the classical inhibitory transmitter GABA. Moreover, a functional relationship between enkephalinergic and GABAergic pathways is indicated by studies showing that both enkephalin and enkephalin/GABA amacrine cells exhibit substantial synaptic interaction with GABA amacrine cells.

Localization of substance P and GABA in retinotectal ganglion cells of the larval tiger salamander.

The present study was performed as part of a systematic examination of the transmitter specificity of neuronal populations in the larval tiger salamander retina. Backfill-labeling of ganglion cells from the optic tectum was combined with double-label immunofluorescence histochemistry to determine if substance P and GABA are localized to ganglion cell populations in the tiger salamander retina. The triple-label analysis revealed the presence of substance P- and GABA-ganglion cells in both central and peripheral regions of the retina. Substance P-immunoreactive ganglion cells comprised 2% of the total population of backfill-labeled ganglion cells, while less than 1% of backfill-labeled ganglion cells expressed GABA immunoreactivity. Ganglion cells were not found to co-label for both substance P and GABA. Backfill-labeled displaced ganglion cells, which comprised 1.4% of the ganglion cell population, were not observed to be immunoreactive for either substance P or GABA. Forty-six point nine percent of substance P-cells in the ganglion cell layer were backfill-labeled and were identified as ganglion cells. GABA ganglion cells comprised less than 1% of GABA-immunoreactive cells in the ganglion cell layer. Therefore, the present study provides evidence for the presence of small populations of substance P- and GABA-ganglion cells in the larval tiger salamander retina. These observations suggest a functional diversity in the population of tiger salamander ganglion cells relative to their unique transmitter specificities.

Synaptic organization of dopaminergic amacrine cells in the larval tiger salamander retina.

The ultrastructural features and synaptic interactions of tyrosine hydroxylase-like-immuno-reactive amacrine cells in the larval tiger salamander retina were examined using routine immunoelectron microscopy. The somas of tyrosine hydroxylase-like-immunoreactive amacrine cells were immunostained evenly throughout their cytoplasm. Their nuclei were generally unstained and possessed indented nuclear membranes. The processes of tyrosine hydroxylase-like-immunoreactive amacrine cells were homogeneously stained with the exception of their mitochondria, whose morphology was often disrupted by the staining procedure. Tyrosine hydroxylase-like-immunoreactive amacrine cell processes were characterized by an occasional dense-cored vesicle(s), in addition to a generally homogeneous population of small, round, agranular synaptic vesicles. They formed conventional synaptic junctions that were characterized by symmetrical synaptic membrane densities. A total of 168 synapses were observed that involved tyrosine hydroxylase-like-immunoreactive amacrine cell processes. A large percentage (79.8%) of these synaptic arrangements were found in sublayer 1 of the inner plexiform layer, while substantially lower percentages were observed in sublayers 3 (9.5%) and 5 (10.7%). They served as pre- and postsynaptic elements 63.1 and 36.9% of the time, respectively. Tyrosine hydroxylase-like-immunoreactive amacrine cell processes were presynaptic to amacrine cell processes (36.9% of total synaptic involvement) and processes that lack synaptic vesicles and whose origin remains uncertain (26.2%). They received synaptic input primarily from amacrine cell processes (31.0%). Tyrosine hydroxylase-like-immunoreactive amacrine cell processes also received a few ribbon synapses from bipolar cells (5.9%). Each of these synaptic relationships were observed in each of sublayers 1, 3 and 5 of the inner plexiform layer, with the majority of each arrangement being found in sublayer 1.

Postnatal development of ganglion cells in the rabbit retina: characterizations with AB5 and GABA antibodies.

The use of cell-specific monoclonal antibodies provides a means by which the emergence, differentiation and maturation of retinal neurons can be studied. The present study investigates the labelling of ganglion cells in the developing rabbit retina by a ganglion cell-specific monoclonal antibody, AB5(12,13). AB5 labelling of ganglion cells was observed as early as day postnatal. By 6-8 days postnatal, AB5-labelled ganglion cells had begun differentiating into the various ganglion cell subtypes observed in the adult retina. This differentiation process appeared to continue throughout the first 3 weeks postnatal. The AB5 monoclonal antibody was also used in a double-label paradigm with an anti-gamma-aminobutyric acid (GABA) polyclonal antibody to differentiate the GABAergic ganglion cells from other GABAergic elements in the retina and to study their development. GABAergic ganglion cells were first observed at 3 days postnatal and by 6 days postnatal, it was possible to observe a wide variety of GABAergic ganglion cells ranging from small cells to large alpha-type cells. The appearance of AB5 labelling in ganglion cells at relatively early stages of development suggests that the AB5 monoclonal antibody may be a useful tool for studying the development of ganglion cell structure, distribution, synaptic relationships and neurochemical specificity.

Coexistence of somatostatin and neurotensin in amacrine cells of the chicken retina.

A comparison of previous immunocytochemical studies reveals a striking similarity in the morphologies of the populations of somatostatin-like and neurotensin-like immunoreactive amacrine cells in the chicken retina. A double-label analysis was performed to determine if these two neuroactive peptides coexist in chicken amacrine cells. An examination of retinal cryosections collected throughout the retina revealed that all labelled cells express both somatostatin- and neurotensin-like immunoreactivity. Therefore, these results indicate the presence of a single population of chicken amacrine cells whose members contain both of these neuroactive peptides.

Development of the subretinal space in the preterm human eye: ultrastructural and immunocytochemical studies.

To investigate the development of the subretinal space in the human infant, eyes were obtained from 12 live-born, anomaly-free, preterm infants from 20 to 32 weeks gestation and from one 3-month postterm infant. The retinas were studied by light microscopy, electron microscopy, and immunocytochemistry. The immunocytochemical studies utilized rabbit antiserum against purified bovine interstitial retinol binding protein (IRBP). A subretinal space containing IRBP was present in the central retina at 20 weeks and extended further into the periphery (expressed as a percentage of the distance from the optic disc to the ora serrata in the temporal hemisphere) as the retina developed. At 28 weeks, IRBP was absent only from the most peripheral 25% of the retina and reached the temporal ora serrata at 32 weeks. At 3 months postterm, IRBP immunofluorescence outlined fully developed photoreceptors, which were present from the optic disc to the ora serrata. The appearance of IRBP in the subretinal space correlated with the development of the first photoreceptor outer segment discs.

An extracellular retinol-binding glycoprotein in the rat eye-characterization, localization and biosynthesis.

We have identified and partially purified interstitial retinol-binding protein (IRBP) from the subretinal space of the rat. It appeared to be glycosylated. Its apparent mol. wt was 270,000 by gel-filtration and 144,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Rat IRBP cross-reacted with anti-bovine IRBP sheep and rabbit sera, bound all-trans-[15-(3)H] retinol and was bound by concanavalin A. IRBP was not detected in the cytosols of the neural retina or retinal pigment epithelium and choroid. This distribution was confirmed by immunocytochemistry using a fluorescence-labeled second antibody. Immunospecific fluorescence was most intense in the interphotoreceptor matrix in a 6.5 ?m band adjacent to the retinal pigment epithelium. It was less intense over the remainder of the rod outer segment layer and was comparatively faint over the inner segment region. Its occurrence in the interstitial space between the photoreceptors and retinal pigment epithelium coupled with the fact it bound all-trans-[15-(3)H] retinol supports the concept that it may be implicated in the transport of retinoids between the retina and the retinal pigment epithelium during the visual cycle. When incubated with [(3)H]leucine or [(3)H]glucosamine, isolated retinas (but not retinal pigment epithelium and choroid) secreted labeled IRBP into the medium. This suggests that the retina plays a role in regulating the amount of IRBP in the subretinal space.

An extracellular retinol-binding glycoprotein in the eyes of mutant rats with retinal dystrophy: development, localization, and biosynthesis.

Interstitial retinol-binding protein (IRBP) is a soluble glycoprotein in the interphotoreceptor matrix of bovine, human, monkey, and rat eyes. It may transport retinol between the retinal pigment epithelium and the neural retina. In light-reared Royal College of Surgeons (RCS) and RCS retinal dystrophy gene (rdy)+ rats, the amount of IRBP in the interphotoreceptor matrix increased in corresponding proportion to the amount of total rhodopsin through postnatal day 22 (P22). In the RCS-rdy+ rats, the amount increased slightly after P23. However, in the RCS rats there was a rapid fall in the quantity of IRBP as the photoreceptors degenerated between P23 and P29. No IRBP was detected by immunocytochemistry in rats at P28. The amount of rhodopsin fell more slowly. Although retinas from young RCS and RCS-rdy+ rats were able to synthesize and secrete IRBP, this ability was lost in retinas from older RCS rats (P51, P88) but not their congenic controls. The photoreceptor cells have degenerated at these ages in the RCS animals, and may therefore be the retinal cells responsible for IRBP synthesis. The putative function of IRBP in the extracellular transport of retinoids during the visual cycle is consistent with a defect in retinol transport in the RCS rat reported by others.

Characterization, localization, and biosynthesis of an interstitial retinol-binding glycoprotein in the human eye.

Human eyes contain an Mr 135K retinol-binding protein that is analogous to interstitial retinol-binding protein ( IRBP ) in the subretinal space of bovine eyes. It is a glycoprotein, because it binds 125I-concanavalin A, 125I-wheat germ agglutinin and 125I-Lens culinaris hemagglutinin. It does not bind Ricinus communis agglutinin I. After desialation, it binds Ricinus communis agglutinin I, but loses its capacity to bind wheat germ agglutinin. These observations, coupled with the known specificities of these lectins, suggest that at least one of the oligosaccharide chains is a sialated , biantennary complex type containing fucose. Both by direct analysis of dissected ocular tissues and by immunocytochemistry it was shown that human interstitial retinol binding protein is an extracellular protein that is confined predominantly to the subretinal space. Monkey retinas incubated in vitro in medium containing [3H]leucine were shown to synthesize and secrete this protein into the medium, a conclusion that was confirmed by immunoprecipitation with an immunoglobulin fraction prepared from rabbit antibovine IRBP serum. Virtually no other labeled proteins were detectable in the medium. It is concluded that interstitial retinol-binding protein meets many of the requirements for a putative transport protein implicated in the transfer of retinol between the pigment epithelium and retina during the visual cycle, and that the neural retina may play an important role in regulating its amount in the subretinal space.