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Published on: January 26, 2011
Does light stimulus at eye opening of the developing rat influence retinal expression of GTP-binding protein (G(0))?
M Oguni1, H Shinohara, T Asano
1Department of Ophthalmology, Shimane Medical University, Shimane, Japan. oguni@shimane-med.ac.jp
Insights
Light exposure at eye opening does not influence GTP-binding protein G(0) expression in rat retinas. Dark-reared rats showed altered G(0) alpha levels, suggesting developmental factors, not light, regulate its expression.
Area of Science:
- Neuroscience
- Developmental Biology
- Ophthalmology
Background:
- GTP-binding protein G(0) alpha concentration increases rapidly in rat retinas between postnatal days 10 and 15.
- G(0) alpha distribution in the retina resembles adult patterns during this critical developmental window.
- Previous hypotheses suggested light stimulus at eye opening influences G(0) alpha expression.
Purpose of the Study:
- To investigate the effect of light stimulus at eye opening on GTP-binding protein G(0) alpha expression in rat retinas.
- To compare G(0) alpha expression and distribution in rats reared in darkness versus normal conditions.
Main Methods:
- Rats were reared in complete darkness from birth.
- Retinas were collected at various postnatal days (P10-P30) for analysis.
- Immunochemical and immunohistochemical methods using G(0) alpha antibody were employed.
Main Results:
- Dark-reared rats showed weaker G(0) alpha immunoreactivity in the inner nuclear layer compared to controls.
- G(0) alpha distribution remained similar between dark-reared and normally reared rats.
- While G(0) alpha increased from P10-P15 in dark-reared pups, its concentration was significantly lower at P22 and P30 compared to controls.
Conclusions:
- Light stimulus at eye opening does not appear to influence G(0) alpha expression in rat retinas.
- Developmental factors, rather than light exposure at eye opening, may regulate G(0) alpha expression.
- Altered G(0) alpha levels in dark-reared rats suggest a role in retinal development independent of immediate light stimulus.
Abstract:
We previously hypothesized that light stimulus at eye opening of rats on postnatal days (P) 13 or 14 has an effect on the expression of GTP-binding proteins (G(0) in the retina) because the concentration of G(0) alpha increased rapidly between P10 and P15. This hypothesis was also supported by the findings that the distribution of G(0) alpha in the retina was almost the same as that of adult rats between P10 and P15. In this study, pregnant rats were kept in a dark room after vaginal plugs were identified; they gave birth to their pups in the dark, and their pups were reared by their mothers in the dark. The postnatal rats were sacrificed at P10, P15, P18, P22, P24, P27, and P30. Their retinas were investigated immunochemically and immunohistochemically, using G(0) alpha antibody, and these results were compared with those of the rat pups reared normally. Only G(0) alpha immunoreactivity in the inner nuclear layer of rats reared in the dark room was weaker than in the controls; the distribution of G(0) alpha in the retina did not change, as compared with pups reared in normal conditions. In addition, in pups reared in the dark, G(0) alpha increased rapidly from P10 to P15. However, the concentration of G(0) alpha in the retina of rat pups reared in the dark was significantly low at P22 (p < 0.01) and P30 (p < 0.05), as compared with pups reared in normal conditions. Although the function of G(0) in the retina may have something to do with the light stimulus after eye opening, it appeared that the expression of G(0) was not influenced by light stimulus at eye opening.
