Diurnal and circadian variation of protein kinase C immunoreactivity in the rat retina

Abstract

We studied the dependence of the expression of protein kinase C immunoreactivity (PKC-IR) in the rat retina on the light:dark (LD) cycle and on circadian rhythmicity in complete darkness (DD). Two anti-PKC alpha antibodies were employed: One, which we call PKCαβ recognized the hinge region; the other, here termed PKCα, recognized the regulatory region of the molecule. Western blots showed that both anti-PKC antibodies stained an identical single band at approximately 80 kD. The retinal neurons showing PKC-IR were rod bipolar cells and a variety of amacrine neurons. After 3 weeks on an LD cycle, PKCαβ-IR in both rod bipolar and certain amacrine cells manifested a clear rhythm with a peak at zeitgeber time (ZT) of 06-10 hours and a minimum at ZT 18. No rhythm in total PKC-IR was observed when using the PKCα antibody, but, at ZT 06-10 hours, rod bipolar axon terminals showed increased immunostaining. After 48 hours in DD, with either antibody, rod bipolar cells showed increased PKC-IR. The PKCα antibody alone revealed that, after 48 hours, AII amacrine neurons, which lacked PKC-IR in an LD cycle, manifested marked PKC-IR, which became stronger after 72 hours. Light administered early in the dark period greatly increased PKCαβ-IR in rod bipolar and some amacrine neurons. Our data indicate that light and darkness exert a strong regulatory influence on PKC synthesis, activation, and transport in retinal neurons. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptThe daily light:dark cycle (LD) is a fundamental regulator of retinal activity. Most retinas have duplex function, meaning that rod photoreceptors and their associated circuitry are specialized for nocturnal vision, whereas cone photoreceptors and their circuits govern retinal function in bright light. The change from rod to cone vision is a complex process involving diurnal and circadian rhythms. Vertebrate retinas contain a circadian clock (Cahill et al., 1991;Tosini and Menaker, 1996). Among other functions, it governs melatonin synthesis, which in turn helps to regulate the production and release of dopamine (for review see Cahill and Besharse, 1995). The rhythms of melatonin and dopamine are in counterphase (Adachi et al., 1998), and these two intrinsic retinal neurochemicals are messengers for darkness and light, respectively (Cahill et al., 1991). The production of certain retinal proteins, for example, iodopsin (Pierce et al., 1993) and tryptophan hydroxylase (Green et al., 1995), also appears to be regulated by a circadian rhythm. Perhaps only a few critical proteins are directly under the control of the circadian clock; Green and Besharse (1996) found that only four of 2,000 retinal mRNAs examined showed a circadian rhythm of expression. Several important retinal activities also manifest a circadian rhythm, including photoreceptor outer segment disk shedding (La Vail, 1976), retinomotor movements (Levinson and Burnside, 1981), visual pigment synthesis (Von Schantz et al., 1999), relative expression of rod and cone signa...

The Retina of Asian and African Elephants: Comparison of Newborn and Adult

“…In accordance with previous studies [Greferath et al, 1990;Gabriel et al, 2001], protein kinase Cα (PKCα) immunoreactivity is mainly localized in rod bipolar cells (Fig. 6).…”

“…In addition to rod bipolars, PKCα is also expressed by a subpopulation of amacrine cells (Fig. 6), as previously observed in the rodent retina [Gabriel et al, 2001;Iandiev et al, 2007]. The somata of PKCα-expressing bipolar cells lie in the outer half of the INL; short (Fig.…”

Differential distribution of voltage‐gated calcium channels in dopaminergic neurons of the rat retina

“…Xu et al (2003) showed with use of the Alomone ␣1C antibody that the immunostaining appeared not as puncta, but rather was smooth, particularly in rod bipolar cells and in dopaminergic amacrines and some other amacrine neurons of unidentified subtype. The staining pattern and the reactive cells were remarkably like what has been reported for PKC␣ immunostaining in rat retina (Gabriel et al, 2001). Using the anti-␣1C antibody developed by McRory et al (2004), however, we observed that whether the immunostaining was smooth or punctate was a function of concentration and location.…”

The mammalian retina as a clock

“…Circadian rhythms have been also reported for the levels of mRNA encoding rod and cone photopigments (von Schantz et al 1999), for protein kinase C immunoreactivity (Gabriel et al 2001), and for GABA turnover rate and release (Jaliffa et al 2000). have demonstrated that, in the rat retina, the levels of several amino acid show a daily rhythm.…”