scispace - formally typeset
Search or ask a question
Topic

Pinealocyte

About: Pinealocyte is a research topic. Over the lifetime, 1605 publications have been published within this topic receiving 55609 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: Activation of D1‐dopamine receptor in bovine pinealocyte stimulates NAT activity and enhances melatonin level whereas activation of D2‐dipamine receptor leads to an inhibitory effect and these stimulatory and inhibitory effects act, in part, via a cAMP‐dependent transcription mechanism.
Abstract: D 1 - and D 2 -dopamine receptors in the bovine pineal gland were previously identified and characterized. The data indicate that the density of D 1 -dopamine receptors far exceeded that of D 2 -dopamine receptors. In our previous study, the mRNA for both the D 1 - and D 2 -dopamine receptors which elucidated the status of dopamine and its possible involvement in the pineal function was identified. A selective D 1 -agonist enhanced N-acetyltransferase (NAT) activity and increased the melatonin level, whereas, a selective D 2 -agonist inhibited NAT activity and decreased the melatonin level. An attempt has been made in the present study to clarify the mechanism of dopamine in controlling melatonin production in bovine pineal. The level of intracellular cyclic 3',5'-adenosine monophosphate (cAMP) was determined after a 2-hr incubation of bovine pinealocytes with selected combinations of drugs. SKF 38393, a selective D 1 -agonist, enhanced intracellular level of cAMP, and its effect was blocked by SCH 23390, a D 1 -selective antagonist. In contrast quinpirole, a selective D 2 -agonist, inhibited forskolin-stimulated intracellular level of cAMP while its effect was blocked by a D 2 -selective antagonist, spiperone. In addition, the dopamine-dependent phosphorylation of the transcription factors, cAMP responsive element-binding protein (CREB) was investigated. Immunoblots showed that SKF 38393 enhanced CREB phosphorylation and the stimulatory effect was abolished by SCH 23390 whereas quinpirole inhibited forskolin-stimulated phosphorylated CREB production and the inhibitory effect was prevented by spiperone. Taken together with our previous data, the results indicate that activation of D 1 -dopamine receptor in bovine pinealocyte stimulates NAT activity and enhances melatonin level whereas activation of D 2 -dopamine receptor leads to an inhibitory effect and these stimulatory and inhibitory effects act, in part, via a cAMP-dependent transcription mechanism.

12 citations

Journal ArticleDOI
TL;DR: Results indicate that MKP‐1 modulates the profile of AA‐NAT activity by selectively shaping the activation profile of p42/44MAPK but not that of p38MAPK.
Abstract: We recently reported a diurnal and norepinephrine (NE) -induced expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) in the rat pineal gland and postulated that this MKP-1 expression might impact adrenergic-regulated arylalkylamine-N-acetyltransferase (AA-NAT) activity via modulation of MAPKs. In this study, we investigated the effect of depletion of MKP-1 expression by using doxorubicin, a topoisomerase inhibitor that suppresses the expression of MKP-1 in other cell types and small interfering RNA targeted against Mkp1 in NE-stimulated pinealocytes. We found that both treatments were effective in inhibiting NE induction of MKP-1 expression. Moreover, both treatments also resulted in a prolonged activation of p42/44MAPK and an increase in AA-NAT induction by NE. In contrast, treatment of pinealocytes with PD98059, an inhibitor of MAPK kinase, reduced NE-stimulated AA-NAT activity. Interestingly, suppressing MKP-1 expression had no effect on the time profile of NE-stimulated p38MAPK activation. These results indicate that MKP-1 modulates the profile of AA-NAT activity by selectively shaping the activation profile of p42/44MAPK but not that of p38MAPK.

12 citations

Journal ArticleDOI
TL;DR: It is suggested that ceramide selectively inhibits cyclic nucleotide synthesis when theucleotide synthesis is potentiated by an increase in intracellular Ca2+ through L-type Ca2- channels and that the sphingomyelin cycle probably plays an important role in the regulation of these channels.

12 citations

Journal ArticleDOI
TL;DR: The data of the present study suggest that daily adjustment of retinal function combines clock-dependent regulation of genes responsible for phototransduction termination (Arr1, Arr4) and detoxification (Rdh12) in photoreceptors with light-dependentregulation of genesresponsible for retinoid recycling (Lrat, Rpe65, and Rdh5) in RPE.
Abstract: Purpose The aim of the present study was to identify candidate genes for mediating daily adjustment of vision. Methods Genes important for vision and genetically associated with severe retinal diseases were tested for 24-hour rhythms in transcript levels in neuronal retina, microdissected photoreceptors, photoreceptor-related pinealocytes, and retinal pigment epithelium-choroid (RPE-choroid) complex by using quantitative PCR. Results Photoreceptors of wildtype mice display circadian clock-dependent regulation of visual arrestins (Arr1, Arr4) and the visual cycle gene Rdh12, whereas cells of the RPE-choroid exhibit light-dependent regulation of the visual cycle key genes Lrat, Rpe65, and Rdh5. Clock-driven rhythmicity of Arr1, Arr4, and Rdh12 was observed also in rat pinealocytes, to persist in a mouse model of diabetic retinopathy (db/db) and, in the case of Arr1, to be abolished in retinae of mice deficient for dopamine D4 receptors. Therefore, the expression rhythms appear to be evolutionary conserved, to be unaffected in diabetic retinopathy, and, for Arr1, to require dopamine signaling via dopamine D4 receptors. Conclusions The data of the present study suggest that daily adjustment of retinal function combines clock-dependent regulation of genes responsible for phototransduction termination (Arr1, Arr4) and detoxification (Rdh12) in photoreceptors with light-dependent regulation of genes responsible for retinoid recycling (Lrat, Rpe65, and Rdh5) in RPE. Furthermore, they indicate circadian and light-dependent regulation of genes genetically associated with severe retinal diseases.

12 citations

Journal ArticleDOI
TL;DR: Data suggest that rhythmic expression of Lhx4 in the pineal gland is controlled via an adrenergic‐cyclic AMP mechanism and that Lh x4 acts to promote nocturnal melatonin synthesis.
Abstract: Homeobox genes generally encode transcription factors involved in regulating developmental processes. In the pineal gland, a brain structure devoted to nocturnal melatonin synthesis, a number of homeobox genes are also expressed postnatally; among these is the LIM homeobox 4 gene (Lhx4). We here report that Lhx4 is specifically expressed in the postnatal pineal gland of rats and humans. Circadian analyses revealed a fourfold rhythm in Lhx4 expression in the rat pineal gland, with rhythmic expression detectable from postnatal day 10. Pineal Lhx4 expression was confirmed to be positively driven by adrenergic signaling, as evidenced by in vivo modulation of Lhx4 expression by pharmacological (isoprenaline injection) and surgical (superior cervical ganglionectomy) interventions. In cultured pinealocytes, Lhx4 expression was upregulated by cyclic AMP, a second messenger of norepinephrine. By use of RNAscope technology, Lhx4 transcripts were found to be exclusively localized in melatonin-synthesizing pinealocytes. This prompted us to investigate the possible role of Lhx4 in regulation of melatonin-producing enzymes. By use of siRNA technology, we knocked down Lhx4 by 95% in cultured pinealocytes; this caused a reduction in transcripts encoding the melatonin-producing enzyme arylalkylamine N-acetyl transferase (Aanat). Screening the transcriptome of siRNA-treated pinealocytes by RNAseq revealed a significant impact of Lhx4 on the phototransduction pathway and on transcripts involved in development of the nervous system and photoreceptors. These data suggest that rhythmic expression of Lhx4 in the pineal gland is controlled via an adrenergic-cyclic AMP mechanism and that Lhx4 acts to promote nocturnal melatonin synthesis.

12 citations


Network Information
Related Topics (5)
Dopamine
45.7K papers, 2.2M citations
77% related
Dopaminergic
29K papers, 1.4M citations
77% related
Glutamate receptor
33.5K papers, 1.8M citations
76% related
Cerebral cortex
21.1K papers, 1.2M citations
75% related
NMDA receptor
24.2K papers, 1.3M citations
75% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202219
202116
202011
201915
201817