Pamela J. Moore

Expression pattern of sigma receptor 1 mRNA and protein in mammalian retina.

Sigma receptors are nonopiate and nonphencyclidine binding sites that are thought to be neuroprotective due to modulation of N-methyl-D-aspartate (NMDA) receptors. Sigma receptor 1 expression has been demonstrated in numerous tissues including brain. Recently, studies using binding assays have demonstrated sigma receptor 1 in neural retina, however these studies did not demonstrate in which retinal cell type(s) sigma receptor 1 was present nor did they establish unequivocally the molecular identity of the receptor. The present study was designed to address these issues. Reverse transcription-polymerase chain reaction (RT-PCR) analysis amplified sigma receptor 1 in neural retina, RPE-choroid complex, and lens isolated from mice. A similar RT-PCR product was amplified also in three cultured cell lines, rat Müller cells, rat ganglion cells and human ARPE-19 cells. In situ hybridization analysis revealed abundant sigma receptor 1 expression in ganglion cells, cells of the inner nuclear layer, inner segments of photoreceptor cells and retinal pigment epithelial (RPE) cells. Immunohistochemical studies detected the sigma receptor 1 protein in retinal ganglion, photoreceptor, RPE cells and surrounding the soma of cells in the inner nuclear layer. These data provide the first cellular localization of sigma receptor 1 in neural retina and establish the molecular identity of sigma receptor 1 in retinal cells. The demonstration that sigma receptor 1 is present in ganglion cells is particularly noteworthy given the well-documented susceptibility of these cells to glutamate toxicity. Our findings suggest that retinal ganglion cells may be amenable to the neuroprotective effects of sigma ligands under conditions of neurotoxicity such as occurs in diabetes.

Analysis of Sigma Receptor (σR1) expression in retinal ganglion cells cultured under hyperglycemic conditions and in diabetic mice

The type 1 sigma receptor (sigmaR1) is a nonopiate and nonphencyclidine binding site that has numerous pharmacological and physiological functions. In some studies, agonists for sigmaR1 have been shown to afford neuroprotection against overstimulation of the NMDA receptor. sigmaR1 expression has been demonstrated recently in retinal ganglion cells (RGC). RGCs undergo apoptosis early in diabetic retinopathy via NMDA receptor overstimulation. In the present study we asked whether RGCs cultured under hyperglycemic conditions and RGCs of diabetic mice continue to express sigmaR1. RGCs were cultured 48 h in RPMI medium containing either 45 mM glucose or 11 mM glucose plus 34 mM mannitol (osmolar control). C57BL/6 mice were made diabetic using streptozotocin. The retina was dissected from normal and streptozotocin-induced diabetic mice 3, 6 and 12 weeks post-onset of diabetes. sigmaR1 was analyzed in cells using semiquantitative RT-PCR and in tissues by semiquantitative RT-PCR, in situ hybridization, Western blot analysis and immunolocalization. The RT-PCR analysis of cultured RGCs showed that sigmaR1 mRNA is expressed under hyperglycemic conditions at levels similar to control cells. Similarly, analysis of retinas of diabetic mice showed no difference in levels of mRNA encoding sigmaR1 compared to retinas of control mice. In situ hybridization analysis showed that expression patterns of sigmaR1 mRNA in the ganglion cell layer were similar between diabetic and control mice. Western blot analysis suggested that levels of sigmaR1 in retina were similar between diabetic and control retinas. Immunohistochemical analysis of sigmaR1 showed a similar pattern of sigmaR1 protein expression between control and diabetic retina. These studies demonstrate that sigmaR1 is expressed under hyperglycemic conditions in vitro and in vivo.

Relationship of Plasma Total Bilirubin, Apparent Unbound Bilirubin and Total Albumin with Cerebellar Glycogen and Abnormal Purkinje Cells in the Gunn Rat

Total plasma bilirubin, apparent unbound plasma bilirubin, cerebellar glycogen and Purkinje cells were quantified in heterozygous Gunn rats, homozygous Gunn rats and normal Wistar rats. Our results indicated that, in the Gunn rat, total bilirubin, apparent unbound bilirubin, and the bilirubin/albumin molar ratio are highly correlated with each other and with alterations in cerebellar Purkinje cells and accumulation of cerebellar glycogen. In addition, cerebella of heterozygous Gunn rats contained many abnormal Purkinje cells without intramitochondrial glycogen and cerebella of homozygous Gunn rats showed many Purkinje cells with intramitochondrial glycogen. Our results demonstrate previously unreported differences between heterozygous Gunn rats and controls. We suggest that population of Purkinje cells in the heterozygous Gunn rats may have received a cellular insult from fetal exposure to bilirubin.

Further observations on the effect of bilirubin encephalopathy on the Purkinje cell population in Gunn rats

Abstract Cerebella of young weanling Wistar rats and homozygous and heterozygous Gunn rats were prepared for electron microscopy. A number of immature-appearing cells were observed in the vicinity of mature and affected Purkinje cells in jaundiced homozygous Gunn rats suffering from bilirubin encephalopathy. Careful examination of these immature-appearing cells indicated that they were immature Purkinje cells whose maturation process had probably been delayed by excessive levels of bilirubin.

Some Effects of an Intrauterine Device on Glucosaminoglycans of the Hamster Uterus

The effect of an intrauterine device (IUD) on non-heparin sulfomucopolysaccharide (SMP) was studied in castrated, hormone-treated, and cycling hamsters by photographic densitometry of tissue sections stained specifically for SMP with Alcian blue. Non-heparin SMP increased slightly in the myometrium of IUD-containing uteri of all castrated groups, with the increase being significant in only the peanut oil-treated group. The endometrium also showed slight increases in sulfomucin in IUD-containing uteri of peanut oil, progesterone, and estrogen plus progesterone-treated animals. These increases, however, were not statistically significant. In cycling hamsters the IUD had little effect on uterine non-heparin SMP in most cycle stages.

The effect of an intrauterine device on mast cell numbers and distribution in the hamster uterus.

SummaryThe effect of an IUD on mast cell numbers and distribution in the uterus was studied in castrated, castrated hormone-treated and cycling hamsters. The device had a stimulatory effect on total mast cell numbers in those animals that received no treatment, peanut oil, or estrogen therapy and in all cycling animals. The device also apparently causes mast cells to be redistributed in the different areas of the uterus. The results indicate that the IUD alters the uterine mast cell response to exogenous hormones and cycle times.