Ovarian, Hypophyseal and Hypothalamic Hormones Coordinate Mammary Gland Remodeling in Adult Lagostomus maximus: a Rodent that Shows Pseudo-Ovulation at Mid-Gestation

Adult female mammary glands go through extensive tissue remodeling during pregnancy, lactation and after the weaning of the neonates. Here we characterize mammary gland morphology of adult females of Lagostomus maximus, a hystricomorph rodent with a pseudo-ovulatory event at mid-gestation, and describe how the glandular tissue changes its architecture in response to variations of the hormonal environment. At mid-gestation, pseudo-ovulation is seen as an essential event increasing the number of secondary corpora lutea and thus rising the circulating levels of progesterone that help to maintain pregnancy to term. As a side effect, mammary gland development is favored early during the long-lasting pregnancy of L. maximus, preparing females for the nutritional need of fully developed pups in this k-strategist species

Cold Shock Proteins Are Expressed in the Retina Following Exposure to Low Temperatures.

Hypothermia has been proposed as a therapeutic intervention for some retinal conditions, including ischemic insults. Cold exposure elevates expression of cold-shock proteins (CSP), including RNA-binding motif protein 3 (RBM3) and cold inducible RNA-binding protein (CIRP), but their presence in mammalian retina is so far unknown. Here we show the effects of hypothermia on the expression of these CSPs in retina-derived cell lines and in the retina of newborn and adult rats. Two cell lines of retinal origin, R28 and mRPE, were exposed to 32°C for different time periods and CSP expression was measured by qRT-PCR and Western blotting. Neonatal and adult Sprague-Dawley rats were exposed to a cold environment (8°C) and expression of CSPs in their retinas was studied by Western blotting, multiple inmunofluorescence, and confocal microscopy. RBM3 expression was upregulated by cold in both R28 and mRPE cells in a time-dependent fashion. On the other hand, CIRP was upregulated in R28 cells but not in mRPE. In vivo, expression of CSPs was negligible in the retina of newborn and adult rats kept at room temperature (24°C). Exposure to a cold environment elicited a strong expression of both proteins, especially in retinal pigment epithelium cells, photoreceptors, bipolar, amacrine and horizontal cells, Müller cells, and ganglion cells. In conclusion, CSP expression rapidly rises in the mammalian retina following exposure to hypothermia in a cell type-specific pattern. This observation may be at the basis of the molecular mechanism by which hypothermia exerts its therapeutic effects in the retina

Representative confocal microscopy images of the retina of newborn (A-F) and adult (G-O) rats exposed to either room temperature (A-C, G-I) or to a cold environment (D-F, J-O), and then to room temperature for 24h before sacrifice.

<p>Sections were exposed to antibodies against RBM3 (green, A,D,H,K,N) and CIRP (red, B,E,G,H,M). An overlay of both colors can be seen at (C,F,I,L,O). GCL = ganglion cell layer, IPL = inner plexiform layer, INL = inner nuclear layer. Bar for A-L = 25 μm. Bar for M-O = 10 μm.</p

Primary and secondary antibodies used in this study.

<p>Primary and secondary antibodies used in this study.</p

Modifications of core temperature in newborn (A) and adult (B) rats.

<p>Animals were exposed to room temperature (RT) or to a cold environment (8°C) for the indicated periods of time and their temperature was measured with a rectal probe. Each bar represents the mean ± SEM of 5–8 independent measurements. Asterisks indicate statistically significant differences with the animals kept at RT. ***: p<0.001.</p

Colocalization of retinal markers with RBM3 in adult retina.

<p>Representative confocal microscopy images of colocalizations in hypothermic adult rat retina between RBM3 (A,E,G) and cell specific markers calbindin (B), glutamine synthetase (D), and recoverin (H). The third column is a combination of the first two; a yellow hue represents colocalization. GCL = ganglion cell layer, IPL = inner plexiform layer, INL = inner nuclear layer, OPL = outer plexiform layer, ONL = outer nuclear layer. Bar for A-C = 50 μm. Bar for D-F = 25 μm. Bar for G-I = 25 μm.</p

Western blot analysis of CIRP (A,B) and RBM3 (C,D) in newborn (A,C) and adult (B,D) rats.

<p>Control (CTL) animals were kept at room temperature whereas test animals were subjected to a cold environment (8°C) for 15 min (newborns) or 3 h (adults), and then sacrificed at the indicated times. Bars represent the mean ± SD of the percentage ratio of protein expression divided by the expression of β-actin for all animals (n = 6). *: p<0.05.</p

Primers used for qRT-PCR.

<p>Primers used for qRT-PCR.</p