Inhibition of rat parotid gland growth response induced by chronic isoproterenol following treatment with quinolone antibiotics

Pefloxacin induced changes in serotonergic innervation and mast cell number in rat salivary glands

Pefloxacin is a second-generation fluoroquinolone antibiotic. Besides its advantageous characteristics, side effects including the hypofunction of salivary glands, decreased saliva production, and peripheral neuropathy were observed during the administration of pefloxacin. The aim of this study was to investigate the changes in the number of serotonergic immunoreactive fibers and mast cells after pefloxacin treatment in the parotid and sublingual glands of rats to detect the possible neurotoxic effect of pefloxacin. The adult female rats were treated with intraperitoneal (i.p.) injection of pefloxacin for three or seven days (at a concentration of 20 mg/100g body weight) and the serotonergic innervation pattern along with the change in mast cell number were evaluated by using histochemistry and immunohistochemistry in the parotid and sublingual glands. We found that a three-day treatment significantly increased the number of immunoreactive serotonergic nerve fibers, but after a seven-day treatment the number of serotonin positive nerve fibers decreased almost to values of the control group. The alteration of mast cell number was parallel with the changes of the serotonin positive fibers during the treatment. These results suggest that pefloxacin treatment can modify the finely controlled communication between the immune- and the peripheral nervous systems, resulting neurogenic inflammatory process. The background of this process is the altered serotonergic innervation and the increased number of activated mast cells releasing different mediators for example histamine, which can finally lead to reduced number of serotonin positive nerve fibers after a seven-day treatment of pefloxacin leading to atrophy and hypofunction of the salivary glands.

Bidirectional cross-regulation between ErbB2 and β-adrenergic signalling pathways

AIMS

Despite the observation that ErbB2 regulates sensitivity of the heart to doxorubicin or ErbB2-targeted cancer therapies, mechanisms that regulate ErbB2 expression and activity have not been studied. Since isoproterenol up-regulates ErbB2 in kidney and salivary glands and β2AR and ErbB2 complex in brain and heart, we hypothesized that β-adrenergic receptors (AR) modulate ErbB2 signalling status.

METHODS AND RESULTS

ErbB2 transfection of HEK293 cells up-regulates β2AR, and β2AR transfection of HEK293 up-regulates ErbB2. Interestingly, cardiomyocytes isolated from myocyte-specific ErbB2-overexpressing (ErbB2(tg)) mice have amplified response to selective β2-agonist zinterol, and right ventricular trabeculae baseline force generation is markedly reduced with β2-antagonist ICI-118 551. Consistently, receptor binding assays and western blotting demonstrate that β2ARs levels are markedly increased in ErbB2(tg) myocardium and reduced by EGFR/ErbB2 inhibitor, lapatinib. Intriguingly, acute treatment of mice with β1- and β2-AR agonist isoproterenol resulted in myocardial ErbB2 increase, while inhibition with either β1- or β2-AR antagonist did not completely prevent isoproterenol-induced ErbB2 expression. Furthermore, inhibition of ErbB2 kinase predisposed mice hearts to injury from chronic isoproterenol treatment while significantly reducing isoproterenol-induced pAKT and pERK levels, suggesting ErbB2's role in transactivation in the heart.

CONCLUSION

Our studies show that myocardial ErbB2 and βAR signalling are linked in a feedback loop with βAR activation leading to increased ErbB2 expression and activity, and increased ErbB2 activity regulating β2AR expression. Most importantly, ErbB2 kinase activity is crucial for cardioprotection in the setting of β-adrenergic stress, suggesting that this mechanism is important in the pathophysiology and treatment of cardiomyopathy induced by ErbB2-targeting antineoplastic drugs.

Permanent Peripheral Neuropathy: A Case Report on a Rare but Serious Debilitating Side-Effect of Fluoroquinolone Administration

The health risks and side effects of fluoroquinolone use include the risk of tendon rupture and myasthenia gravis exacerbation, and on August 15, 2013, the Food and Drug Administration updated its warning to include the risk of permanent peripheral neuropathy. We present a case of fluoroquinolone-induced peripheral neuropathy in a patient treated for clinically diagnosed urinary tract infection with ciprofloxacin antibiotic.

Modification of innervation pattern by fluoroquinolone treatment in the rat salivary glands

Fluoroquinolone antibiotics (FQAs) are widely used in dental and medical therapy. Despite their known severe adverse actions on the central and peripheral nervous system, little attention has been directed toward the potential toxic side effects of these compounds on the oral tissues. As the saliva secretion is controlled by the nervous system and neuropeptides, the neurotoxic effect of pefloxacin (PEF), a representative member of FQAs, was studied in rats in the present work. Previously, we demonstrated a significant weight loss of parotid gland tissue, a marked decrease in 3H-thymidine incorporation, a decreased volume of saliva and amylase activity of the glandular tissue in response to PEF. Animals received intraperitoneal injection of PEF (20 mg/100 g body weight daily) for 3 and 7 days. Normal histology, and neurofilament 200, substance P (SP) and calcitonin gene-related polypeptide (CGRP) containing nerve fibers were detected with immunohistochemical methods. A marked decrease of the weights in salivary glands and the acinar diameters were measured. Similarly, a strong and significant decrease of the number of SP and CGRP containing nerve fibers were detected. These findings suggest that the impaired morphology and innervation pattern of salivary glands is related to the neurotoxic adverse effect of FQA treatment.

Expressions of CCAAT-enhancer-binding proteins and c-Myc in the parotid gland of the rat: in vivo effects of isoprenaline, bethanechol, vasoactive intestinal peptide and food intake

Parotid glands of adult female rats were exposed to agonists mimicking sympathetic (isoprenaline, 1mg/kg, I.P.) or parasympathetic activity (bethanechol, 10 microg/kg/min i.v. for 30 min, and vasoactive intestinal peptide, VIP, 0.2 microg/kg/min, i.v. for 30 min) or they were reflexly activated by a meal demanding chewing. The stimulated glands were removed at varying times (15(30)-360 min) following the onset of the agonist administration or 75-300 min after the start of a 1h long feeding period, and a number of transcription factors was studied using Western blot. The protein bands were semi-quantitatively measured by densitometry. In response to isoprenaline, C/EBPalpha of 42, 38 and 30 kDa increased by 45-50% above control value, C/EBPbeta LAP (38/35 kDa) by 80% and C/EBPdelta (35 kDa) by 230%, while C/EBPbeta LIP (20 kDa) decreased by 45%. In response to VIP, C/EBPalpha of 42 kDa increased by 75% and C/EBPalpha of 30 kDa by 10%, C/EBPbeta LAP by 65% and C/EBPdelta by 410%, while C/EBPalpha of 38 kDa as well as C/EBPbeta LIP were not changed. In response to bethanechol, C/EBPalpha of 42 kDa increased by 105%, C/EBPbeta LAP by 40% and C/EBPdelta by 170%, while C/EBPalpha of 30 kDa decreased by 30% and C/EBPalpha of 38 kDa and C/EBPbeta LIP remained unchanged. c-Myc increased in response to isoprenaline and VIP by 40-55%, but not to bethanechol. In rats offered a pelleted diet, the parotid glands displayed increases in C/EBPalpha of 42 kDa by 105%, of 30 kDa by 40% and of 38 kDa, by 10%, in C/EBPbeta LAP by 65% and in C/EBPdelta by 215%, whereas C/EBPbeta LIP decreased by 25%. Thus, in parotid glands transcription factors of importance for growth and metabolism were shown to be influenced by autonomimetics as well as by nervous activity.

Structural and functional changes by Ciprofloxacin of rat submandibular gland

In the present study, the effects of Ciprofloxacin (Cipro), a fluoroquinolone antibiotic, on rat submandibular gland structure and function were examined in an acute experiment. Cipro was administered intraperitoneally at various doses (20, 40 and 80 mg/kg). Pure submandibular saliva was collected intraorally by micropolyethylene tubes under anaesthesia using a dissecting microscope. After collection of saliva, submandibular glands were removed and weighed. Flow rate, amylase activity, total protein and electrolyte concentrations were measured in saliva. Concentrations of DNA and protein were measured in the gland. All doses of Cipro (20, 40, 80 mg/kg) reduced salivary flow rate. Concentrations of salivary total protein and calcium and gland DNA were reduced by all doses of Cipro. Treatment by Cipro (80 mg/kg) induced an increase in salivary sodium and potassium concentrations. Histopathological examination of glands revealed that Cipro at doses of 40 mg/kg and 80 mg/kg induces morphological changes in the glands including irregular shape of the cerous and mucous bobbles, lack of nucleus in some cells, damage of the cytoplasmic and cell walls and presence of oncocytes in secretory ducts. It is concluded that Cipro inhibits rat submandibular gland functions consistent with structural damages to the gland that might be observed as a side effect in humans. Properties of fluoroquinolones to alter intracellular cAMP and their ability to suppress DNA and protein synthesis of acinar cells might be possible reasons for observed changes.

Inhibition of rat parotid and submandibular gland functions by ofloxacin, a fluoroquinolone antibiotic

While fluoroquinolones are widely used in the treatment of various infectious disease, not enough attention has been paid to their adverse effects on salivary glands functions. In the present study, the effects of ofloxacin, a fluoroquinolone antibiotic, on rat parotid and submandibular gland functions, were examined in an acute experiment. Ofloxacin (OFLX) was administered intraperitoneally at various doses (20, 40, and 80 mg/kg). Pure parotid and submandibular saliva were collected intraorally by microployethylene tubes under anaesthesia using a dissecting microscope. Flow rate, amylase activity, total protein, and calcium concentrations were reduced by all doses of OFLX (20, 40, 80 mg/kg, P < 0.01) in parotid saliva. In parotid saliva, sodium and potassium were increased by doses of 20 and 40 mg/kg (P < 0.01) and 20, 40, 80 mg/kg (P < 0.01) respectively. In submandibular saliva, flow rate, total protein and calcium concentrations were significantly reduced by all doses (20, 40, 80 mg/kg, P < 0.01). Sodium and potassium concentrations were also increased by a dose of 80 mg/kg, (P < 0.05) in submandibular saliva. It is concluded that ofloxacin inhibits rat salivary gland functions, which might be observed as a side-effect in humans. Properties of fluoroquinolones to alter intracellular cAMP and calcium levels and their ability to suppress DNA, RNA and protein synthesis of acinar cells might be possible reasons for the observed changes.