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The parotoid gland of bufonids is characterized as a specialized integument region, formed by different gland types. The secretion elaborated by the largest glandular alveoli has been related to animal chemical defense and is constituted by granular protein content, associated with a basophilic and alcianophilic material with features of glycoconjugates. This study aimed to identify and characterize the glycoconjugates in the secretion of the largest granular gland of the parotoid gland of Rinella icterica by histochemical and immunohistochemical techniques at light microscopy, biochemical methods, and nuclear magnetic resonance spectroscopy. Our results showed that the glycoconjugate content contains a mixture of chondroitin­6­sulfate (C6S) and chondroitin-non-sulfate (C0S). Thus, chondroitin sulfate probably plays an important role in gland physiology, probably protecting the protein content while inside the secretory portion.

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Amphibians have many skin poison glands used in passive defense, in which the aggressor causes its own poisoning when biting prey. In some amphibians the skin glands accumulate in certain regions forming macroglands, such as the parotoids of toads. We have discovered that the toad Rhaebo guttatus is able to squirt jets of poison towards the aggressor, contradicting the typical amphibian defense. We studied the R. guttatus chemical defense, comparing it with Rhinella marina, a sympatric species showing typical toad passive defense. We found that only in R. guttatus the parotoid is adhered to the scapula and do not have a calcified dermal layer. In addition, in this species, the plugs obstructing the glandular ducts are more fragile when compared to R. marina. As a consequence, the manual pressure necessary to extract the poison from the parotoid is twice as high in R. marina when compared to that used in R. guttatus. Compared to R. marina, the poison of R. guttatus is less lethal, induces edema and provokes nociception four times more intense. We concluded that the ability of R. guttatus to voluntary squirt poison is directly related to its stereotyped defensive behavior, together with the peculiar morphological characteristics of its parotoids. Since R. guttatus poison is practically not lethal, it is possibly directed to predators' learning, causing disturbing effects such as pain and edema. The unique mechanism of defense of R. guttatus may mistakenly justify the popular myth that toads, in general, squirt poison into people's eyes.

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This study assessed the effect of the antidepressants, Fluoxetine and Venlafaxine, on the size (GS), mass (M), cellular volume (CV), of rat parotid salivary glands and salivary flow rate (SFR), as well as the secretagogue action of pilocarpine on this flow. Ninety animals were divided into 9 treatment groups with the antidepressants, antidepressants associated with the application of pilocarpine, antidepressants and physiologic serum, physiologic serum (control) and pilocarpine (positive control). Thirty hours after the end of treatment, saliva collection began, to determine the SFR. Next, the salivary glands were removed, GS and M measured, and the specimens processes for histomorphometric analysis and CV determination. The variable GS presented statistically significant increase among the groups that were treated for 30 days with Fluoxetine (p=0.0002) and Venlafaxine (p=0.0112) when compared with the group treated with physiologic serum (control). The group treated with Fluoxetine for 30 days revealed increase in M (p=0.0190) and diminished SFR (p=0.0031), statistically significant, when compared with the control group. CV revealed increase in acinic cells between the Fluoxetine (30 days) (p=0.0005) and Venlafaxine (30 days) (p=0.0004) groups as well, when compared with the control group. The group treated with Venlafaxine for 60 days in association with pilocarpine presented SFR similar to the control group treated for 60 days. Both Fluoxetine and Venlafaxine reduced the SFR and caused increase in CV, resulting in hypertrophy of the glands, with Fluoxetine having a more pronounced anticholinergic action. The pilocarpine increased the SFR in the group that received Venlafaxine.

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We previously reported that mouse parotid acinar cells display anion conductance (I(ATPCl)) when stimulated by external ATP in Na+-free extracellular solutions. It has been suggested that the P2X7 receptor channel (P2X7R) might underlie I(ATPCl). In this work we show that I (ATPCl) can be activated by ATP, ADP, AMP-PNP, ATPgammaS and CTP. This is consistent with the nucleotide sensitivity of P2X7R. Accordingly, acinar cells isolated from P2X7R( -/- ) mice lacked I(ATPCl). Experiments with P2X7R heterologously expressed resulted in ATP-activated currents (I(ATP-P2X7)) partially carried by anions. In Na(+)-free solutions, I (ATP-P2X7) had an apparent anion permeability sequence of SCN(-) > I(-) congruent with NO3(-) > Br(-) > Cl(-) > acetate, comparable to that reported for I(ATPCl) under the same conditions. However, in the presence of physiologically relevant concentrations of external Na+, the Cl(-) permeability of I(ATP-P2X7) was negligible, although permeation of Br(-) or SCN(-) was clearly resolved. Relative anion permeabilities were not modified by addition of 1 mM: carbenoxolone, a blocker of Pannexin-1. Moreover, cibacron blue 3GA, which blocks the Na(+) current activated by ATP in acinar cells but not I(ATPCl), blocked I(ATP-P2X7) in a dose-dependent manner when Na+ was present but failed to do so in tetraethylammonium containing solutions. Thus, our data indicate that P2X7R is fundamental for I(ATPCl) generation in acinar cells and that external Na+ modulates ion permeability and conductivity, as well as drug affinity, in P2X7R.

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AIM: In this study, we have determined signalling pathways involved in adenosine A(1) receptor (A(1) receptor)-dependent stimulation of amylase release in rat parotid gland. METHODS: Amylase release, binding and cyclic adenosine monophosphate (cAMP) assays, inositol phosphates (IPs) production and nitric oxide synthase (NOS) activity in the presence of cyclopentyl-1,3-dipropylxanthine (CPA) alone or in the presence of different inhibitory drugs were performed. RESULTS: The binding parameters of specific A(1) antagonist [(3)H]-cyclopentyl 1,3-dipropilxanthine ([(3)H]-DPCPX) in parotid gland membranes show a population of high affinity sites with K(d) (nm) 0.53 +/- 0.06 and B(max) (fmol mg(-1) protein) 122.6 +/- 10.2. CPA stimulation of A(1) receptor exerts an increase in amylase release, IPs accumulation, cAMP production and NOS activity. All these A(1) agonist effects were blocked by the A(1) receptor antagonist DPCPX. Inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), protein kinase C (PKC), and adenylate cyclase, but not NOS, activities attenuated the CPA stimulatory effect on amylase release. The effect of CPA on amylase release significantly correlated with its action either on cAMP or on IPs accumulation. CONCLUSION: These results suggest that CPA activation of parotid gland A(1) receptor induces a stimulatory effect on amylase release associated with increased production of cAMP and IPs accumulation. The mechanism appears to occur secondarily to stimulation of phosphoinositide turnover via PLC activation. This, in turn, triggers cascade reactions involving CaM and PKC. The CPA stimulation of NOS does not appear to participate in amylase release.

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The effects of external anions (SCN(-), NO3-, I(-), Br(-), F(-), glutamate, and aspartate) on gating of Ca(2+)-dependent Cl(-) channels from rat parotid acinar cells were studied using the whole-cell configuration of the patch-clamp technique. Shifts in the reversal potential of the current induced by replacement of external Cl(-) with foreign anions, gave the following selectivity sequence based on permeability ratios ( P(x)/ P(Cl)): SCN(-)>I(-)>NO3->Br(-)>Cl(-)>F(-)>aspartate>glutamate. Using a continuum electrostatic model we calculated that this lyotropic sequence resulted from the interaction between anions and a polarizable tunnel with an effective dielectric constant of approximately 23. Our data revealed that anions with P(x)/P(Cl) > 1 accelerated activation kinetics in a voltage-independent manner and slowed deactivation kinetics. Moreover, permeant anions enhanced whole-cell conductance ( g, an index of the apparent open probability) in a voltage-dependent manner, and shifted leftward the membrane potential- g curves. All of these effects were produced by the anions with an effectiveness that followed the selectivity sequence. To explain the effects of permeant anions on activation kinetics and g(Cl) we propose that there are 2 different anion-binding sites in the channel. One site is located outside the electrical field and controls channel activation kinetics, while a second site is located within the pore and controls whole-cell conductance. Thus, interactions of permeant anions with these two sites hinder the closing mechanism and stabilize the channel in the open state.

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Calcium release via intracellular Ca2+ release channels is a central event underpinning the generation of numerous, often divergent physiological processes. In electrically non-excitable cells, this Ca2+ release is brought about primarily through activation of inositol 1,4,5-trisphosphate receptors and typically takes the form of calcium oscillations. It is widely believed that information is carried in the temporal and spatial characteristics of these signals. Furthermore, stimulation of individual cells with different agonists can generate Ca2+ oscillations with dramatically different spatial and temporal characteristics. Thus, mechanisms must exist for the acute regulation of Ca2+ release such that agonist-specific Ca2+ signals can be generated. One such mechanism by which Ca2+ signals can be modulated is through simultaneous activation of multiple second messenger pathways. For example, activation of both the InsP3 and cAMP pathways leads to the modulation of Ca2+ release through protein kinase A mediated phosphoregulation of the InsP3R. Indeed, each InsP3R subtype is a potential substrate for PKA, although the functional consequences of this phosphorylation are not clear. This review will focus on recent advances in our understanding of phosphoregulation of InsP3R, as well as the functional consequences of this modulation in terms of eliciting specific cellular events.

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O presente estudo teve por finalidade analisar e correlacionar as características anatômicas e a atividade funcional de glândulas parótidas saudáveis, empregando técnica sialográfica. O estudo anatômico foi realizado em 55 indivíduos, dos quais 37 participaram do exame funcional, que consistiu na verificaçäo da eliminaçäo da substância de contraste Lipiodol UF, em glândulas estimuladas e näo estimuladas. Os resultados demonstraram que a análise das imagens sialográficas pela observaçäo do sistema de ductos glandulares permitiu a constituiçäo de 5 grupos anatômicos distintos. Na avaliaçäo funcional, as glândulas estimuladas levaram períodos de tempo mais uniformes e curtos para a elimininaçäo do Lipiodol UF em relaçäo às näo estimuladas. A correlaçäo dos achados anatômicos e funcionais mostrou que a média do tempo de eliminaçäo da substância de contraste em glândulas estimuladas no Grupo I foi significantemente maior que as médias do Grupos II e III; o tempo máximo para o esvaziamento de glândulas estimuladas foi de 5 minutos em todos os Grupos, enquanto que as glândulas näo estimuladas näo apresentaram diferença estatística entre os Grupos. Ao final, concluiu-se que a avaliaçäo conjunta do modelo anatômico e da funçäo excretora de glândulas deve ser realizada com a utilizaçäo de estímulo

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Foram estudados os efeitos morfológicos e morfométricos em glândulas parótidas de ratos albinos, machos, de linhagem "Wistar", submetidos a dietas constituídas por diferentes níveis de proteína. Morfologicamente, observou-se, no grupo subnutrido, aumento no tamanho de suas células acinosas e diminuiçäo destas no grupo desnutrido, quando da comparaçäo com o grupo nutrido. Outro aspecto histológico evidenciado foi a intensa granulaçäo citoplasmática das células acinosas no grupo desnutrido. Ao estudo morfométrico, verificou-se näo existirem diferenças estatisticamente significativas entre os volumes nuclear, citoplasmático e celular das células acinosas entre os três grupos estudados. Quanto às células dos ductos intercalares, observou-se que, no grupo desnutrido, o volume nuclear dessas células apresentava-se diminuído em relaçäo aos grupos subnutrido e nutrido. Em relaçäo às células dos ductos estriados, observaram-se diferenças significantes quanto aos seus volumes citoplasmático e celular, que se apresentavam diminuídos no grupo desnutrido quando da comparaçäo com o grupo nutrido

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Quatro ratos albinos (Rattus norvegicus albinus), machos, foram submetidos a nutriçäo parenteral total (NPT) sem lipídeos durante 18 dias. O estudo ultra-estrutural da célula da glândula parótida demonstrou o retículo endoplasmático granular com cisternas dilatadas, pequenos grânulos de secreçäo dispersos por entre o mesmo e o núcleo deslocado da regiäo basal da célula. Tais achados, na ausência de desnutriçäo proteicocalórica, caracterizam menor atividade da célula acinar durante a NPT

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The authors have done a morphometric study by determination of mastocyte population of cutaneous wound's granulation tissue of parotidectomized rats and rats which were submitted to daily administration of 25 mg of 6-propyl-2-thiouracil (hypothyroid). The animals were sacrificed after four, eight and 12 post-operative days. The results analysis permitted to observe a statistically significant diminution of mastocyte population in the hypothyroid and parotidectomized animals granulation tissue in the fourth and 12th postsurgical days.

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Os autores estudaram, com métodos histoquímicos, a natureza do material elaborado pelas glândulas parótidas e sublingual do búfalo. Com base nos resultados obtidos, foi possível concluir que o produto de secreçäo das células acinares da glândula parótida contém muco-substância neutra e os seguintes radicais proteicos: alfa-amino, cisteína, tirosina, triptofano, cistina e argina. Nas células acinares da glândula sublingual foram observadas uma sulfosialomucina, o ácido hialurônico e muco-substâncias neutras: e nas semiluas serosas, além de muco-substância neutra, os radicais proteicos alfa-amino, cisteína, triptofano, cistina e arginina

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This work was carried out in order to investigate the influence of parotid glands on the metabolism of carbohydrates in the rat. The animals were selected by age (10, 20, 30 and 40 days-old) and distributed in 3 experimental groups as follows: Group I -- Parotidectomized animals; Group II -- Sham-parotidectomized animals; and Group III -- Control animals. The animals from all the groups were sacrificed 20 days after the beginning of the experiment. From the discussion of the results it was observed that the parotidectomized animals at 20, 30 and 40 days have presented significantly larger glycaemic means than control animals. These control animals, by the other hand, have also presented significantly larger glycaemic means than sham-parotidectomized animals. Concerning the 10 days-old animals, the statistical analysis have not showed any significance among the three groups. The results obtained from hepatic glycogen dosages, in the same animals, have showed a coherence, because the animals that have presented larger glycaemic levels, have also presented less hepatic glycogen content; contrarily, the animals that have presented a less glycaemic levels, have also presented a larger amount of hepatic glycogen.

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No remnants of adenohypophyseal tissue were found in 83% of the 70 dogs studied; in 17% of the animals remnants amounting to from 1 to 3% of normal hypophyseal tissue were found. These traces showed significant histological and cytological changes, and were most frequently found located on the floor of the sella turcica at some distance from their usual site. It is doubtful whether these residua have any functional significance, since the hypophysectomized dogs with such remnants had a survival time that corresponded to that of dogs with total hypophysectomy (6 months). The microscopic structure of the fragment of transplanted parotid (salivary gland) presents rich vascularization, changes in cellular distribution and a loss of the excretory duct. A better histological aspect was observed in the transplanted cells of the dogs with longer survival time. An important correlation exists between functional behavior of the operated animals and the histological state of the transplanted parotid tissue.

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