Effects of continuous light on rat parotid gland structure and reactivity

Chiarenza, A.P.; Sanz, Elizabeth; Vermouth, Nelia T.; Aoki, Agustı́n; Bellavía, S. L.

doi:10.1007/bf00319593

Cited by 5 publications

(4 citation statements)

References 17 publications

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“…In our previous study the loss of cell polarity accompanying the disruption of the acinar configuration ruled against optimal localization of a fluorescent signal to a specific cytoplasmic component of dispersed parotid cells [5]. In intact acini the basal pole expressed the highest levels of RyRs, where the ER is most concentrated [18,21], and the expression of receptors decreased through the apical pole where the ER is sparsely expressed, thus suggesting the ER as the locus of RyR expression. RyR expression has also been detected by immunofluorescence in the submandibular (salivary) gland, but in contrast with our findings its localization was confined to the luminal pole and basolateral membrane [22].…”

Section: Discussionmentioning

confidence: 93%

“…The three InsP $ R subtypes previously detected in exocrine pancreas and submandibular (salivary) glands were likewise localized in proximity to the apical (luminal) membrane [22,29]. Because Ins(1,4,5)P $ -sensitive Ca# + release is closely linked to the ER [30], the immunofluorescence data that identify the apical pole as a major site of the InsP $ R and therefore a primary locus of Ca# + signalling must be reconciled with morphological data revealing that apical ER is sparsely expressed in the resting parotid cell [18,21]. Whereas Ca# + -containing zymogen granules predominate in the apical pole, they do not appear to be responsible for any major contribution to Ca# + signalling in exocrine acinar cells, including parotid cells [29,31].…”

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confidence: 99%

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Ryanodine and inositol trisphosphate receptors are differentially distributed and expressed in rat parotid gland

Zhang

Wen

Bidasee

et al. 1999

Biochemical Journal

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The present study examines the cellular distribution of the ryanodine receptor/channel (RyR) and inositol 1,4,5-trisphosphate receptor (InsP3R) subtypes in parotid acini. Using fluorescently labelled 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-3-propionic acid glycyl-ryanodine (BODIPYtrade mark-ryanodine) and confocal microscopy, RyRs were localized primarily to the perinuclear region (basal pole) of the acinar cell. Ryanodine, Ruthenium Red, cAMP and cADP ribose (cADPR) competed with BODIPY-ryanodine, resulting in a reduction in the fluorescence signal. However, inositol 1,4, 5-trisphosphate [Ins(1,4,5)P3] did not alter the binding of BODIPY-ryanodine. Using receptor-subtype-specific antisera, InsP3Rs (types I, II and III) were located predominantly in the apical pole of the parotid cell. The presence of these three subtypes was confirmed using reverse transcriptase PCR with RNA-specific oligonucleotide probes. Binding studies using a parotid cell-membrane fraction identified and characterized RyRs and InsP3Rs in terms of binding affinity (Kd) and maximum binding capacity (Bmax) and confirmed that cADPR displaces ryanodine from its binding sites. Ruthenium Red and 8-Br-cADP-ribose blocked Ca2+ release in permeabilized acinar cells in response to cADPR and cAMP or forskolin, whereas Ins(1,4,5)P3-induced Ca2+ release was unaffected. The localization of the RyRs and InsP3Rs in discrete regions endow broad areas of the parotid cell with ligand-activated Ca2+ channels. The consequences of the dual activation of the RyRs and InsP3Rs by physiologically relevant stimuli such as noradrenaline (norepinephrine) are considered in relation to Ca2+ signalling in the parotid gland.

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Section: Discussionmentioning

confidence: 93%

mentioning

confidence: 99%

Ryanodine and inositol trisphosphate receptors are differentially distributed and expressed in rat parotid gland

Zhang

Wen

Bidasee

et al. 1999

Biochemical Journal

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“…In this respect, it is known that chemical-induced sympathectomy prevents fructose secretion in prostate and seminal vesicle of rats (Lamano et al, 1990). Moreover, previous works in our laboratory have shown that chronic exposure of rats to constant light promotes an alteration in sympathetic parotid and submaxillary glands secretory response (Chiarenza et al, 1989;Gallará and Bellavía, 1995). Whatever the effect of continuous lighting on the secretory activity of the epididymis it remains to be elucidated.…”

Section: Discussionmentioning

confidence: 90%

Lactate dehydrogenase activity of rat epididymis and spermatozoa: Effect of constant light

Ponce

Carriazo²,

Nt³

2009

Eur J Histochem

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During its passage through the epididymis, the gamete undergoes a process of “maturation” leading to the acquisition of its fertilizing ability. The epididymis displays regional variations in the morphology and metabolic properties of its epithelium which are relevant for the progressive development of mature sperm characteristics. The epididymis has spontaneous peristaltic contractions and receives sympathetic innervation that is modulated by melatonin, a hormone synthesized and released by the pineal gland. Constant lighting disrupts melatonin synthesis and secretion. We have studied the effect of constant light on lactate dehydrogenase (LDH; EC 1.1.1.27) and its isozyme C4 activities and protein content in whole epididymis, epididymal tissue and in spermatozoa from caput and cauda segments. Animals were exposed from birth to an illumination schedule of 14 h light: 10 h dark (group L:D). At 60 days of age one group of animals was submitted to constant light over 50 days (group L:L). In order to test the fertilizing ability, the rats of each group were mated with soliciting estrous females. The percentage of pregnancies in females mated with males maintained in L:L was remarkably lower than those in females mated with males maintained in the L:D photoperiod (44% and 88% respectively). Constant light increased protein concentration and LDH activity in caput as well as in cauda of total epididymis. On the contrary, in epididymal tissue, the protein content decreased in both epididymal sections compared with controls. When enzymatic activity was expressed in Units per spermatozoa, constant light induced a significant reduction of total LDH and LDHC4 in caput and cauda spermatozoa while LDH activity of epididymal tissue was not affected. In spite of the decrease in LDH per sperm cell when rats were exposed to constant light, in total epididymis (epididymis tissue plus sperm cells content) and in spermatozoa, values of enzyme activities expressed per weight unit were higher than those of controls. This is explained by the increase in the amount of stored spermatozoa, both in caput and cauda, produced by exposure of animals to constant light

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“…It was assumed that chronic exposure to constant light would increase the adrenergic changes usually produced by the light stimuli. In comparison to parotid gland from rats under a normal photoperiod, a 50% reduction in acinar cells rich in secretion granules was seen in glands from rats after 50 days of continuous light exposure (57). An increase in adrenergic responses was assumed, because in the rat parotid glands there is a clear correlation between cellular degranulation and sympathetic nerve activity (58).…”

Section: Chromic Exposure Of Rats To Constant Light • Effect On Ultramentioning

confidence: 99%

Role for the sympathetic nervous system in the control of salivary secretion by environmental stimuli

Bellavía¹,

Gallar²

1998

Biomedical Reviews

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• Saliva plays an important role in most biologic events cciuring in the oral cavity and contributes to the mainte nance of systemic health. Secretion occurs in response to a salivary reflex. During the fasting period, mouth dryness con trols basal secretion. Chewing is the main stimulus for secre tion. In human, salivary secretion can be influenced by light/ darkness and other environmental stimuli. Postganglionic fibers originated in the superior cervical ganglia provide sympathetic innervation to salivary and pineal glands. Postsynaptic a-and j3-adrenoceptors mediate salivary re sponses, including synthesis, storage and release of proteins. In mammals, the suprachiasmatic nuclei generate and syn chronize endogenous circadian rhythms and the sympathetic nervous system plays an important role in the propagation of circadian signals. In immature rats, parotid a-amylase and total soluble protein circadian rhythms are controlled by periodic factors whose timing is independent of that imposed by nocturnal chewing of solid food. In rats exposed to various environmental stimuli, such as photoperiod, constant dark ness or light, the submandibular secretory response and fine structure of parotid gland, suggest'that both presence and absence of light can induce adrenergic responses. Homeostatic mechanisms would be required for a differential cow

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Effects of continuous light on rat parotid gland structure and reactivity

Cited by 5 publications

References 17 publications

Ryanodine and inositol trisphosphate receptors are differentially distributed and expressed in rat parotid gland

Ryanodine and inositol trisphosphate receptors are differentially distributed and expressed in rat parotid gland

Lactate dehydrogenase activity of rat epididymis and spermatozoa: Effect of constant light

Role for the sympathetic nervous system in the control of salivary secretion by environmental stimuli

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