Morphological and biochemical alterations in growing rats induced by etretinate

Etretinate is an aromatic retinoid extensively used on Dermatology. Its toxic effects, however, reduce its application from a clinical point of view. In the present paper, we study etretinate intoxication of 48 growing Wistar rats. The intoxication was for 12 weeks using etretinate doses of 0.5 and 6 (mg/kg)/day. The concentrations of etretinate in plasma and liver were determined. Total seric cholesterol and triglyceride concentrations were analyzed. Structural and ultrastructural histological studies of liver samples were carried out. Continuous etretinate ingestions seem to produce an alteration in the detoxication of enzymatic complexes in the growing rats with both the concentrations, due to the increase in etretinate blood plasma observed during the study. There is a relationship between the etretinate dose and its blood plasma concentration and toxic effect, but there is not with etretinate concentration in the liver. The blood plasma concentration of cholesterol and triglycerides is not related to histological liver lesions. The histological study confirms hepatotoxicity with both doses. Nevertheless, the anatomopathological lesions observed do not seem to be related to the blood plasma and liver etretinate concentrations.     

Nickel-selenium interaction-time dependent biochemical alterations and metal decorporation in rats

The influence of selenium on the disposition of nickel and on Ni induced metallothionein levels was studied in female rats. Concomitant administration of Se (6.3 mumol/kg, intraperitoneally) and 63Ni (0.12 mmol/kg subcutaneously) lowered the Ni burden of all the soft organs and the plasma ceruloplasmin levels. Selenium caused no potentiating effect on the Ni induced hepatic MT. However, 3 days later, the lowered MT levels appeared related to the corresponding decrease in hepatic Ni content at day 6. The Ni selenide excretable complex and Ni-selenide protein complex appear to be probable mechanisms of the Ni-Se interaction in the present study.     

A glycogen storage disease in rats. Morphological and biochemical investigations

Liver and heart from a substrain of the NZR/Gd rat in which there is an inherited deficiency of liver phosphorylase b kinase was examined by light and electron microscopy and compared to material from a related, but normal substrain. Hepatic tissue differed markedly from that of control animals. Hepatocytes contained more than twice as much free glycogen and visible lipid. Glycogen particles had an abnormal appearance and some glycogen was sequestered within large, membrane-bound vesicles. Hepatocyte lysosomes were increased by a third and mean cell volume by more than half. Lobular architecture was distorted by the presence of enlarged, irregularly-shaped hepatocytes. Free glycogen was present in the space of Disse and sinusoids and within lysosomes in Kupffer cells. There were increased amounts of collagen in the space of Disse. The changes resemble those described in human glycogen storage disease IXa. A study of hepatic tissue from fasted rats showed that affected animals have an impaired ability to mobilise their liver glycogen stores. An increase in visible lipid also occurred in affected, fasted animals. Cardiac tissue appeared to be normal.     

Morphological alterations and NO-synthase expression in the heart after continuous light exposure of rats

Although exposure to continuous light is associated with hypertension and modulates the outcome of ischemia-reperfusion injury, less attention has been paid to its effects on cardiac morphology. We investigated whether 4-week exposure of experimental rats to continuous 24 h/day light can modify cardiac morphology, with focus on heart weight, fibrosis and collagen I/III ratio in correlation with NO-synthase expression. Two groups of male adult Wistar rats were studied: controls exposed to normal light/dark cycle (12 h/day light, 12 h/day dark) and rats exposed to continuous light. After 4 weeks of treatment the absolute and the relative heart weights were determined and myocardial fibrosis and collagen type I/III ratio were evaluated using picrosirius red staining. Endothelial and inducible NO-synthase expression was detected immunohistochemically. The exposure of rats to continuous light resulted in an increase of body weight with proportionally increased heart weight. Myocardial fibrosis remained unaffected but collagen I/III ratio increased. Neither endothelial nor inducible NO-synthase expression was altered in light-exposed rats. We conclude that the loss of structural homogeneity of the myocardium in favor of collagen type I might increase myocardial stiffness and contribute to functional alterations after continuous light exposure.     

Protective effect of nebivolol on reserpine-induced neurobehavioral and biochemical alterations in rats

Reserpine-induced orofacial dyskinesia is a model that shares some mechanists’ aspects with tardive dyskinesia whose pathophysiology has been related to oxidative stress. The present study was aimed to explore neuroprotective effects of nebivolol, an antihypertensive agent, on reserpine-induced neurobehavioral and biochemical alterations in rats. Reserpine (1 mg/kg, s.c.) was used to induce neurotoxicity. Administration of reserpine for 3 days every other day significantly increased the vacuous chewing movements (VCMs), tongue protrusions (TPs) and reduced the locomotor activity in rats. Pre-treatment with nebivolol (5 and 10 mg/kg, p.o. for 5 days) showed dose dependant decrease in VCMs and TP induced by reserpine. Nebivolol also showed significant improvement in locomotor activity. Reserpine significantly increased lipid peroxidation and reduced the levels of defensive antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD) and reduced glutathione (GSH) in rat brain. Nebivolol reversed these effects of reserpine on oxidative stress indices; indicating amelioration of oxidative stress in rat brains. The results of the present study indicated that nebivolol has a protective role against reserpine-induced orofacial dyskinesia. Thus, the use of nebivolol as a therapeutic agent for the treatment of tardive dyskinesia may be considered.     

The biochemical alterations following administration of Kalpaamruthaa and Semecarpus anacardium in mammary carcinoma

BACKGROUND: Breast cancer is one of the most common cancers in women of developed and developing countries. Lipids, lipoproteins and lipid-metabolizing enzymes have been associated with the risk of breast cancer. Kalpaamruthaa (KA) is a modified Siddha preparation, which contains Semecarpus anacardium Linn. (SA), Emblica officinalis (EO) and honey. OBJECTIVE: The present study was embarked to study the variations in lipids, lipid-metabolizing enzymes and lipoproteins in cancerous animals and the effect of KA on the lipid metabolism. MATERIALS AND METHODS: Breast cancer was induced in rats by administrating 7,12-dimethylbenz(a)anthracene orally (25 mg/kg body weight). After 90 days of induction, KA (300 mg/kg body weight) and SA (200 mg/kg body weight) were administered for 14 days, by gastric intubations. The levels of lipids and lipid-metabolizing enzymes were analysed in control and experimental animals. RESULTS AND CONCLUSION: The increased levels of total cholesterol, free cholesterol, phospholipids, triglycerides and free fatty acids and decreased levels of ester cholesterol in plasma, liver and kidney found in cancer suffering animals were reverted back to near normal levels on treatment with KA and SA. In mammary carcinoma bearing animals, the activities of total lipase, cholesterol ester synthase, and cholesterol ester hydrolase were significantly (p < 0.05) increased whereas lipoprotein lipase and lecithin cholesterol-acyl transferase were decreased. The levels of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) were increased and the level of high-density lipoprotein (HDL) was decreased. These alterations were recouped back upon treatment with KA as well as SA when compared to cancer animals. The effects of KA were found to be more effective than SA. No significant alterations were observed in herbal preparation control animals when compared to control animals.     

Persistent alterations to enteric neural signaling in the guinea pig colon following the resolution of colitis

Functional changes induced by inflammation persist following recovery from the inflammatory response, but the mechanisms underlying these changes are not well understood. Our aim was to investigate whether the excitability and synaptic properties of submucosal neurons remained altered 8 wk post-trinitrobenzene sulfonic acid (TNBS) treatment and to determine whether these changes were accompanied by alterations in secretory function in submucosal preparations voltage clamped in Ussing chambers. Mucosal serotonin (5-HT) release measurements and 5-HT reuptake transporter (SERT) immunohistochemistry were also performed. Eight weeks after TNBS treatment, colonic inflammation resolved, as assessed macroscopically and by myeloperoxidase assay. However, fast excitatory postsynaptic potential (fEPSP) amplitude was significantly increased in submucosal S neurons from previously inflamed colons relative to those in control tissue. In addition, fEPSPs from previously inflamed colons had a hexamethonium-insensitive component that was not evident in age-matched controls. AH neurons were hyperexcitable, had shorter action potential durations, and decreased afterhyperpolarization 8 wk following TNBS adminstration. Neuronally mediated colonic secretory function was significantly reduced after TNBS treatment, although epithelial cell signaling, as measured by responsiveness to both forskolin and bethanecol in the presence of tetrodotoxin, was comparable with control tissue. 5-HT levels and SERT immunoreactivity were comparable to controls 8 wk after the induction of inflammation, but there was an increase in glucagon-like peptide 2-immunoreactive L cells. In conclusion, sustained alterations in enteric neural signaling occur following the resolution of colitis, which are accompanied by functional changes in the absence of active inflammation.     

Age-related alterations in the biochemical and functional properties of the bladder in type 2 diabetic GK rats

Previous studies have demonstrated that experimental type 1 diabetes induced by streptozotocin causes alterations in the biochemical and functional properties of several receptor systems in the rat bladder. However, the exact mechanism involved in the pathophysiology of voiding dysfunction in type 2 diabetic patients is unknown. Because the GK rat is a widely accepted genetically determined rodent model for human type 2 diabetes, we investigated diabetes-induced changes in the bladder smooth muscle of the GK rats at several time points. Male GK rats and age-matched Wistar rats, as controls, were maintained for 4, 8, 16, and 32 weeks. Contractile responses to KCl, carbachol, ATP, and electrical field stimulation (EFS) were measured by using the isolated muscle bath techniques. Acetylcholine (ACh) release induced by EFS from bladder muscle strips was measured by using high-performance liquid chromatography coupled with a microdialysis procedure. Maximum contractile responses to carbachol and ATP, the release of ACh, and tissue sorbitol levels were similar in bladders from GK and control rats until 8 weeks of age. At 16 weeks of age, however, the contractile responses to carbachol and ATP, and tissue sorbitol levels were increased, and the EFS-induced ACh release was decreased in GK rats compared with controls. Although the maximum contractile responses to EFS were unchanged until 16 weeks of age, they were decreased in 32-week-old GK rats, compared with controls. Our data indicate the presence of age-related alterations in the biochemical and functional properties of the bladder in type 2 diabetic GK rats.     

BMP signaling in rats with TNBS-induced colitis following BMP7 therapy

Beyond stimulating bone formation, bone morphogenetic proteins (BMPs) are important in development, inflammation, and malignancy of the gut. We have previously shown that BMP7 has a regenerative, anti-inflammatory, and antiproliferative effect on experimental inflammatory bowel disease (IBD) in rats. To further investigate the BMP signaling pathway we monitored the effect of BMP7 therapy on the BMP signaling components in the rat colon during different stages of experimentally induced colitis by 2,4,6-trinitrobenzene sulfonic acid (TNBS). The results showed a significantly decreased BMP7 expression in the acute phase, followed by a significantly increased BMP2 and decreased BMP6 expression during the chronic phase of colitis. BMP7 therapy influenced the expression of several BMPs with the most prominent effect on downregulation of BMP2 and upregulation of BMP4 in the chronic phase of colitis. Importantly, connective tissue growth factor and noggin expression were elevated in the acute stage and significantly decreased upon BMP7 therapy. BMP receptor I expression was unchanged, whereas BMP receptor II was decreased at day 2 and increased at days 14 and 30 of TNBS inflammation. However, an opposite pattern of expression following BMP7 therapy has been observed. BMP7 increased the expression of BR-Smad including Smad3 and Smad4. Inhibitory Smads were increased in colitis and significantly decreased following BMP7 therapy at later stages of the disease. We suggest that BMP signaling was altered during TNBS-induced colitis and was recovered with BMP7 administration, suggesting that IBD is a reversible process.     

Morphological and biochemical characterization of remodeling in aorta and vena cava of DOCA-salt hypertensive rats

Arterial remodeling occurs in response to mechanical and neurohumoral stimuli. We hypothesized that veins, which are not exposed to higher pressures in hypertension, would demonstrate less active remodeling than arteries. We assessed remodeling with two standard measures of arterial remodeling: vessel morphometry and the expression/function of matrix metalloproteinases (MMPs). Thoracic aorta and vena cava from sham normotensive and DOCA-salt hypertensive rats (110 +/- 4 and 188 +/- 8 mmHg systolic blood pressure, respectively) were used. Wall thickness was increased in DOCA-salt vs. sham aorta (301 +/- 23 vs. 218 +/- 14 mum, P < 0.05), as was medial area, but neither measure was altered in the vena cava. The aorta and vena cava expressed the gelatinases MMP-2, MMP-9, transmembrane proteinase MT1-MMP, and tissue inhibitor of metalloproteinase-2 (TIMP-2). Immunohistochemically, MMP-2 localized to smooth muscle in the aorta and densely in endothelium/smooth muscle of the vena cava. Western and zymographic analyses verified that MMP-2 was active in all vessels and less active in the vena cava than aorta. In hypertension, MMP-2 expression and activity in the aorta were increased (59.1 +/- 3.7 and 74.5 +/- 6.1 units in sham and DOCA, respectively, P < 0.05); similar elevations were not observed in the vena cava. MMP-9 was weakly expressed in all vessels. MT1-MMP was expressed by the aorta and vena cava and elevated in the vena cava from DOCA-salt rats. TIMP-2 expression was significantly increased in the aorta of DOCA rats compared with sham but was barely detectable in the vena cava of sham or DOCA-salt hypertensive rats. These findings suggest that large veins may not undergo vascular remodeling in DOCA-salt hypertension.     

Atrial natriuretic peptide receptors in sympathetic ganglia: biochemical response and alterations in genetically hypertensive rats

High concentration of atrial natriuretic peptide (99-126) (ANP) receptors were localized by quantitative autoradiography in superior cervical and stellate ganglia from young and adult Wistar Kyoto (WKY) rats. ANP increased cyclic GMP formation in stellate ganglia from adult rats. Both young and adult spontaneously hypertensive rats (SHR) had a much lower number of ANP receptors in the sympathetic ganglia. In spite of low receptor concentration, the cyclic GMP response to ANP in SHR was unchanged. These results suggest the existence of physiologically active ANP receptors in the rat sympathetic ganglia. These receptors may also be involved in the pathophysiology of spontaneous hypertension.     

Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats

The objective of this study was to define further the role of the trigeminal motor nucleus (TMNu) in the postnatal ontogeny of the mammalian craniofacial skeleton. To that end, 42 male Sprague-Dawley rats underwent stereotaxic surgery at 40 days of age; 21 received small electrolytic lesions to their left-side TMNu (lesioned group) while 21 had TMNu stimulation with no actual electrolytic lesion produced (sham group). Seven rats from each group were killed at 28, 56, and 84 days postoperative to analyze trigeminal motoneuron (TMNe) count, masticatory muscle weight, and osteological growth vector data. At all three time periods, lesioned animals showed significant differences 1) between the surgery and nonsurgery sides, and 2) from sham animals. However, sham animals also demonstrated significant between-side differences for medial pterygoid muscle weight (56 days), mandibular height (28 and 56 days), and mandibular length data (84 days); these data suggested that even relatively slight damage to TMNe can create morphological changes within the craniofacial complex. Snout deviation in a lesioned rat towards the opposite side from all other lesioned animals was correlated with unique damage to its pontine reticular formation; this suggested that the observed morphological alterations of the craniofacial complex may have been due not only to TMNu damage, but also to changed expressions of the masticatory central pattern generator (CPG). Morphological alterations of the craniofacial skeleton resulting from lesions to the TMNu were likely due to changed neuromuscular activity patterns of the masticatory muscles and their biomechanical effects upon bone.     

Permanent alterations of spinal cord reflexes following nerve lesion in newborn rats

Sciatic nerve lesion in newborn rats is known to cause degeneration of a large number of axotomized motoneurones and spinal ganglion cells. Some of the surviving motoneurones exhibit abnormal firing properties and the projection pattern of central terminals of sensory neurones is altered. We report here on long-term changes in spinal cord reflexes in adult rats following neonatal nerve crush. In acutely spinalized and anaesthetized adult rats 4-6 months old in which the sciatic nerve had been crushed on one side at birth, the tibial nerve, common peroneal nerve or sural nerve were stimulated on the reinnervated and control side and reflex responses were recorded from the L5 ventral spinal roots. Ventral root responses (VRRs) to tibial and peroneal nerve stimulation on the side of the nerve lesion were significantly smaller in amplitude representing only about 15% of the mean amplitude of VRRs on the control side. The calculated central delay of the first, presumably monosynaptic component of the VRR potential was 1.6 ms on the control side while the earliest VRR wave on the side of the nerve lesion appeared after a mean central latency of 4.0 ms that seems too long to be of monosynaptic origin. These results suggest that neonatal sciatic nerve injury markedly alters the physiological properties and synaptic connectivity in spinal cord neurones and causes a marked depression of spinal cord responses to peripheral nerve stimulation.     

Malignant alterations following early blockade of nitric oxide synthase in hypertensive rats

Nitric oxide (NO) is important for the homeostasis of organ functions. We studied the structural and functional changes in the cardiovascular (CV) and renal systems following early NO deprivation by various nonspecific and specific NO synthase (NOS) inhibitors: N-nitro-L-arginine methyl ester (L-NAME), N-nitro-L-arginine (L-NA), S-methyl-isothiourea (SMT), and L-N6-(1-iminoethyl)-lysine (L-Nil). The aim is to elucidate the involvement of NO through endothelial or inducible NOS (eNOS and iNOS). Drugs were given to spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar Kyoto rats (WKY) from a young age (5-wk-old). Physiological, biochemical, and pathological examinations were performed. L-NAME and L-NA treatment caused a rapid increase in tail cuff pressure (TCP). The TCP of SHR reached a malignant level within 30 days with signs of stroke, proteinuria [corrected] severe glomerular sclerosis, and moderate ventricular hypertrophy (VH). The plasma nitrite/nitrate was reduced, while creatinine, urea nitrogen and uric acid were elevated. The renal tissue cyclic guanosine monophosphate (cGMP) was decreased with an elevated collagen content. The numbers of sclerotic glomeruli, arteriolar and glomerular injury scores were markedly increased, accompanied by reduction in renal blood flow, filtration rate, and fraction. Plasma endothelin-1 was increased following L,-NAME or L-NA treatment for 10 days. The expression of eNOS and iNOS mRNA was depressed by L-NAME and L-NA. The relevant iNOS inhibitors, SMT and L-Nil depressed the iNOS expression, but did not produce significant changes in CV and renal systems. The continuous release of NO via the eNOS system provides a compensatory mechanism to prevent the genetically hypertensive rats from rapid progression to malignant phase. Removal of this compensation results in VH, stroke, glomerular damage, renal function impairment, and sudden death.     

Sesamin attenuates behavioral,biochemical and histological alterations induced by reversible middle cerebral artery occlusion in the rats

Restoration of blood flow to an ischemic brain region is associated with generation of reactive oxygen species (ROS) with consequent reperfusion injury. ROS cause lipid peroxidation, protein oxidation, and DNA damage, all of which are deleterious to cells. So diminishing the production of free radicals and scavenging them may be a successful therapeutic strategy for the protection of brain tissue in cerebral stroke. The present study investigated the neuroprotective effect of sesamin (Sn) to reduce brain injury after middle cerebral artery occlusion (MCAO). The middle cerebral artery (MCA) of adult male Wistar rat was occluded for 2 h and reperfused for 22 h. Sesamin is the most abundant lignan in sesame seed oil is a potent antioxidant. Sesamin (30 mg/kg) was given orally twice, 30 min before the onset of ischemia and 12 h after reperfusion. The initial investigations revealed that sesamin reduced the neurological deficits in terms of behavior and reduced the level of thiobarbituric acid reactive species (TBARS), and protein carbonyl (PC) in the different areas of the brain when compared with the MCAO group. A significantly depleted level of glutathione and its dependent enzymes (glutathione peroxidase [GPx] and glutathione reductase [GR]) in MCAO group were protected significantly in MCAO group treated with sesamin. The present study suggests that sesamin may be able to attenuate the ischemic cell death and plays a crucial role as a neuroprotectant in regulating levels of reactive oxygen species in the rat brain. Thus, sesamin may be a potential compound in stroke therapy.     

Morphological and biochemical correlates in the characterization of Sarcocystis spp

Isoenzyme electrophoretic techniques were applied to the characterization of seven Sarcocystis spp. that had been identified by conventional morphological studies. Cystozoites were harvested from macroscopic cysts from sheep, cattle, and mice and from microscopic cysts from sheep, cattle, and goats. Soluble cystozoite extracts were subjected to cellulose acetate gel electrophoresis and characterized at 15 of the 39 enzyme loci examined. Genetic relationships among isolates were examined by simple phenetic clustering. Two different morphological types of macroscopic cysts from sheep, identified as S. gigantea (syn. S. ovifelis) and S. medusiformis, consistently differed at 40% of the loci examined. Such genetic divergence confirms their separate morphotypic classification. Both differed from microscopic cyst isolates from sheep at 87% of the loci examined; however, two different morphotypes of microscopic cysts were found in the sheep sampled (thick-walled and thin-walled cysts). Until sufficient numbers of each type can be isolated and examined separately, both were regarded as belonging to the species S. tenella (syn. S. ovicanis). Macroscopic and microscopic cysts from cattle consistently differed at 80% of the loci thereby supporting their separate classification as S. hirsuta (syn. S. bovifelis) and S. cruzi (syn. S. bovicanis), respectively. Isolates from goats (microscopic cysts identified as S. capracanis) differed from S. tenella and S. cruzi at 20% and 47% of the loci, respectively. All macroscopic cyst isolates from the various host animal species (including S. muris from mice) differed from each other at nearly all loci. Isoenzyme electrophoretic techniques therefore provided genetic evidence supporting the classification of these various Sarcocystis spp. by their morphological characteristics.