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PubMed1988

Effect of chronic cysteamine treatment on mouse liver aryl hydrocarbon hydroxylase activity.

Patients receive chronic cysteamine in the management of nephropathic cystinosis. In a previous report our results indicated that acute cysteamine treatment inhibited cytochrome P-450. Cysteamine (85 mg/kg i.p.) was administered daily to female Swiss mice for 1.5 and 8.5 months. Cysteamine treatment (8.5 months) did not affect hepatic microsomal aryl hydrocarbon hydroxylase (AHH) activity compared with controls. A small decrease in liver AHH activity was seen after 1.5 months of treatment with cysteamine. Liver histology, body weight, liver and spleen weights, and serum aminotransferase activity after chronic and subchronic treatment did not differ from controls. Chronic in vivo cysteamine treatment, unlike acute in vitro treatment did not decrease AHH activity. Incubation of isolated murine hepatocytes with cysteamine significantly inhibited AHH activity compared with controls. The inhibition occurred in a concentration-related manner, with 65% inhibition at 8.8 mM (1 mg/mL) (equivalent to the predicted plasma concentration using the maximally tolerable human dose), and 100% inhibition at 44 mM (5 mg/mL). The concentrations used in vitro were not cytotoxic. This suggests that chronic cysteamine treatment may not result in drug interactions and that in vitro results are not always good indicators of in vivo effects.

Animals↗
PubMed1992

Cysteamine enhances the procoagulant activity of Factor VIII-East Hartford, a dysfunctional protein due to a light chain thrombin cleavage site mutation (arginine-1689 to cysteine).

We have recently identified the molecular defect responsible for cross-reacting material-positive hemophilia A in two unrelated patients in which the substitution of cysteine for arginine-1689 (Factor VIII-East Hartford[FVIII-EH]) abolishes a critical Factor VIII light chain thrombin cleavage site. As other mutant proteins with a cysteine for arginine substitution have been modified in the presence of cysteamine, we have determined the effect of this and other reducing agents on FVIII-EH function. Cysteamine concentrations between 0.1 and 10 mM caused dose- and time-dependent increases in FVIII-EH VIII:C activity, as much as 14-fold (to 35 and 62 U/dl for the two patients tested). Comparable data were obtained in a standard one-stage VIII:C coagulation assay and in a chromogenic substrate assay measuring Factor Xa generation. Thrombin cleavage of the FVIII-EH light chain in the presence of cysteamine was documented by immunoadsorption and analysis. Cystamine and cysteamine-S-phosphate, similar compounds that do not possess a free thiol group, had no effect. Cysteamine augmentation of FVIII-EH VIII:C was abolished by the simultaneous addition of N-ethyl maleimide or iodoacetamide, but these sulfhydryl blocking agents did not prevent the VIII:C increase and light chain cleavage by thrombin if the plasma samples were dialyzed to remove the inhibitors before adding the cysteamine. However, incubation with DTT before iodoacetamide prevented the cysteamine effect after dialysis. These data suggest that when isolated from patient plasma, FVIII-EH cysteine-1689 is present in a disulfide bond. This bond is cleaved by cysteamine to form a new mixed disulfide, a pseudolysine that restores a thrombin cleavage site that is essential for procoagulant function.

Blood Coagulation↗
PubMed1981

Pantetheinase activity and cysteamine content in cystinotic and normal fibroblasts and leukocytes.

Cysteamine is the most effective agent known for the reduction of the elevated cystine content of cells from patients with cystinosis. A defect in endogenous cysteamine generation could account for many of the metabolic features of this disorder. To test this hypothesis, we have developed improved methods for measuring pantetheinase (cysteamine-generating) activity and intracellular cysteamine levels and used these methods to measure such parameters in cystinotic and normal leukocytes and cultured skin fibroblasts. Pantetheinase activity as defined in the test was similar in extracts of cystinotic and normal cells [leucocytes, normal, 78 +/- 15 (S.E.), cystinotic, 56+/- 6.4; fibroblasts, normal, 9.4 +/- 1.5; cystinotic, 7.7 +/- 1.7]. Cysteamine levels were normal in leukocytes from cystinotics receiving no cysteamine or doses of oral cysteamine too low to reduce leukocyte cystine content. The results indicate that the cause of cystinosis is unlikely to be related to a failure to generate of sustain normal intracellular cysteamine levels.

Amidohydrolases↗
PubMed1989

Epidermal growth factor inhibits cysteamine-induced duodenal ulcers in rats.

We examined the pathogenesis of cysteamine-induced duodenal ulcers in rats, especially with reference to epidermal growth factor (EGF). Control, cysteamine (400 mg/kg, s.c.), cysteamine + EGF (20 micrograms/kg/day, i.p.) submandibular resection (SMR), SMR + cysteamine, and SMR + cysteamine + EGF groups were examined for duodenal ulceration. With submandibular resectioning, endogenous EGF decreased, and with the administration of EGF (i.p.), endogenous EGF increased. In the SMR + cysteamine group, serum gastrin increased and the intragastric pH decreased remarkably compared to in the normal control group. The administration of exogenous EGF suppressed this change. Mucosal blood flow, the potential difference and hexosamine, as defensive factors, decreased markedly in the SMR + cysteamine group, but the administration of exogenous EGF reversed these changes. These results suggested that a decrease in EGF is involved in the pathogenesis of cysteamine-induced duodenal ulcers in rats.

Animals↗
PubMed1978

Experimental acetaminophen-induced hepatic necrosis: biochemical and electron microscopic study of cysteamine protection.

In an attempt to elucidate the biochemical mechanism of acetaminophen-induced hepatic necrosis, the present study in hamsters was undertaken to evaluate the possible changes in lipid peroxidation and microsomal enzyme activities. The protective action of cysteamine was likewise assessed in the light of these biochemical variables and the fine structural features of the liver were seen by electron microscopy. One group of golden Syrian hamsters was administered a toxic dosage of acetaminophen (600 mg . per kg . intraperitoneally) while another group was treated with the same dosage of acetaminophen, followed 1 hour later by cysteamine (200 mg . per kg . intraperitoneally). The animals were sacrificed at 6, 12, 18, and 24 hours. Microsomal fractions were isolated for biochemical assays, and liver sections were prepared for electron microscopy. Results showed that significant enhancement of lipid peroxidation occurred in the untreated acetaminophen-poisoned group, as compared to the cysteamine-treated group. Glucose 6-phosphatase activity was markedly suppressed at 6, 12, and 18 hours after acetaminophen administration. Cysteamine treatment completely prevented the curtailment of NADPH-cytochrome c reductase and glucose 6-phosphatase activities in the protected group, and partially maintained aniline hydroxylase activity. Cytochrome P-450 level was unaffected in both the cysteamine-treated and the untreated groups at the respective time intervals. Electron microscopic examination showed progressive loss of the structural integrity of the endoplasmic reticulum, lipid infiltration, and vacuolation in the untreated acetaminophen-poisoned group. At 18 and 24 hours, sinusoidal congestion and myeloid figure formation were prominent. In the cysteamine-protected group, polysomes reassembled around the granular endoplasmic reticulum at 18 hours. It is postulated that lipid peroxide formed in vivo may facilitate the microsomal oxidation of acetaminophen to the toxic metabolite. NADPH-cytochrome c reductase is likely to be the locus within the NADPH-cytochrome P-450 electron transport chain susceptible to lipoperoxidation. The free radical-related lipoperoxidation may mediate the impairment of in vitro drug metabolism, as reflected by the depressed aniline hydroxylase activity. The abnormal phospholipid metabolism is manifested at the fine structural level by the myeloid body formation. The protective effects of cysteamine as seen in the attenuated lipid peroxidation and the consequent derangement of microsomal enzymes correlate well with the morphologic observations. Cysteamine protection is discussed in terms of its role as an inhibitor of the toxic metabolite formation.

Acetaminophen↗
PubMed1991

Attenuating effect of the monoamine oxidase inhibitor furazolidone on the anti-carcinogenetic effect of cysteamine on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effect of furazolidone on inhibition by cysteamine of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in inbred Wistar rats. After oral treatment with MNNG for 25 weeks, rats received cysteamine, furazolidone, or both compounds. In week 52, rats treated with cysteamine had a significantly decreased incidence of gastric cancers. Concomitant treatment with furazolidone significantly attenuated the inhibitory effect of cysteamine on gastric carcinogenesis. Administration of furazolidone alone significantly increased the number, but not the incidence, of gastric cancers. The norepinephrine concentration of the antral portion of the gastric wall and the labelling index of the antral mucosa were significantly reduced in rats treated with cysteamine, and significantly higher in rats treated with both compounds than in those treated with cysteamine alone. These findings indicate that the cysteamine-induced inhibition of gastric carcinogenesis is mediated by catecholamines.

Adenocarcinoma↗
PubMed2003

Capacity of adult and prepubertal mouse oocytes to undergo embryo development in the presence of cysteamine.

The present study was carried out to study de novo glutathione (GSH) synthesis and to evaluate the effect of stimulating GSH synthesis during in vitro maturation (IVM) of adult and prepubertal mouse oocytes on the embryo developmental rate. Adult (8 weeks old) and prepubertal mice (24-26 days old) were primed with 5 IU of PMSG and oocytes were retrieved from the ovary 48 hr later for IVM. After IVM (18 hr) Cumulus oocyte complexes (COC) were in vitro fertilized (IVF) and in vitro culture (IVC) in order to observe embryo development. The IVM medium was supplemented with: 0, 25, 50, 100, or 200 microM of cysteamine. To study the novo GSH synthesis, 5 mM BSO was added during IVM of adult or prepubertal oocyte. Developmental rates up to blastocyst were recorded for each group. Experiments also included a group of ovulated oocytes (in vivo matured) after priming with PMSG and HCG. After IVM of adult mice oocytes, an improvement was observed on embryo development in all the supplemented groups when compared with the untreated group (P < 0.05). No differences were observed in blastocyst rate among IVM oocytes with cysteamine and ovulated oocytes. Prepubertal IVM mouse oocytes had a lower cleavage rate compared with ovulated oocytes (P < 0.05). Cysteamine failed to improve prepubertal oocytes developmental rates (P > 0,05). 2-cell embryos, coming from IVM prepubertal oocytes and ovulated oocytes had the same preimplantation developmental rate up to the blastocyst stage. In prepubertal, and adult oocytes an inhibition of embryo development was observed when buthionine sulfoximide (BSO), a specific inhibitor of the gamma-glutamylcysteine synthetase, was added during oocyte maturation (P < 0.01). In conclusion, an improvement in mouse embryo development was observed when cysteamine was added to the IVM medium of adult mice oocytes. In prepubertal oocytes cysteamine addition during oocyte maturation failed to improve embryo developmental rates. The presence of BSO lowered or completely blocked blastocyst development. This proves that, de novo GSH synthesis during oocyte maturation of adult and prepubertal oocytes undoubtedly plays an important role in embryo development. The improvement on oocyte competence observed in adult mice oocytes is probably related to intracellular GSH synthesis stimulated by cysteamine. Nevertheless the reason why cysteamine failed to improve prepubertal oocytes competence remains as an open question.

Animals↗
PubMed1995

Effect of cysteamine on glutathione level and developmental capacity of bovine oocyte matured in vitro.

The present study was carried out to evaluate if the addition of cysteamine to the culture medium during in vitro maturation of bovine oocytes increased the glutathione (GSH) levels in the mature oocytes, and if these changes may promote an improvement on in vitro development to the blastocyst stage. Follicular oocytes from slaughterhouse ovaries were matured in TCM 199 supplemented with 10% (v/v) fetal calf serum, hormones, and O (control), 25, 50, or 100 muM of cysteamine for 24 hr. After in vitro maturation the oocytes were fertilized and cultured for 8 days. The percentage of embryos that developed to the blastocyst stage was significantly higher (P < 0.01) for oocytes matured in medium containing 100 muM of cysteamine than for those matured in control medium. Moreover, the intracellular GSH levels were increased (P < 0.05) in oocytes matured with 100 muM of cysteamine with respect to control. No differences were observed in maturation and cleavage rates, and in the mean cell numbers per blastocyst among treatments (P > 0.05). These results indicate that the addition of thiol compounds such as cysteamine to maturation medium increases the efficiency of in vitro blastocyst production from immature bovine oocytes. The higher levels of GSH in oocytes matured in the presence of cysteamine suggest that the beneficial effects of cysteamine on in vitro maturation and subsequent development after in vitro fertilization are mediated by GSH.

Animals↗
PubMed1996

Effect of cysteamine on gastric nerve fibers containing gastrin-releasing peptide in the rat.

In rats, changes in gastric nerve fibers containing gastrin-releasing peptide (GRP) in cysteamine-induced duodenal ulcer were investigated in relation to the dynamics of gastrin-producing cells (G-cells). Marked increases in gastric acid secretion and serum gastrin level were observed from 2 h after the administration of cysteamine. The number of G-cells was significantly decreased from 2 h after the injection of cysteamine. Two and 4 h after the administration of cysteamine, the G-cells showed ultrastructural changes characterized by a markedly decreased number of secretory granules. Circulating GRP levels were significantly elevated from 2 h after the administration of cysteamine. In the control group given vehicle only, nerve fibers showing immunoreaction for GRP formed a fine network in the gastric wall and were densely distributed in the oxyntic mucosa, located close to capillaries and demonstrated varicosities that contained either small clear vesicles or GRP-immunopositive vesicles with large cores. Eight h after the administration of cysteamine, there was depleted GRP immunoreactivity, evidenced by a markedly decreased number of vesicles, with large electron-dense cores, in the oxyntic mucosa. These findings suggest that, in cysteamine-induced duodenal ulcer, alterations in gastric nerve fibers containing GRP may be related to hypergastrinemia.

Animals↗
PubMed1987

Mechanism of action of cysteamine on duodenal alkaline phosphatase.

A single s.c. injection of cysteamine-HCl, a potent duodenal ulcerogen, drastically decreased duodenal alkaline phosphatase (DAP) activity in mucosal cells. The effect was detectable 4 hr after the injection of cysteamine, it was the most prominent at 12 hr and lasted less than 24 hr after the ulcerogen administration. Under the same experimental conditions cysteamine did not affect alkaline phosphatase activity in the liver. Furthermore, ethanolamine, the toxic but nonulcerogenic derivate of cysteamine, had no effect on the DAP activity if given in equimolar quantities. Thus, the effect of DAP activity seems to be a property of the duodenal ulcerogen, related only to the target organ, i.e. duodenal mucosa. Since cimetidine administration and pylorus ligation, which both abolish HCl hypersecretion provoked by cysteamine, did not "protect" the enzyme from the depletion, it is hard to believe that gastric acid hypersecretion could be responsible for the enzyme depletion provoked by the ulcerogen. Dopamine metabolism disorders, induced by cysteamine administration in the brain and duodenal mucosa, are not causally related to DAP-depletion either. Cysteamine most probably inhibits the DAP activity by three different mechanisms, by one acting directly on the enzyme molecules and by two others acting indirectly, through its adrenocorticolytic and stresogenic effects.

Adrenalectomy↗
PubMed1987

Cysteamine-induced depletion of central somatostatin-like immunoactivity: effects on behavior, learning, memory and brain neurochemistry.

The effects of a wide range of doses of systemically administered cysteamine were studied on locomotor behavior, passive avoidance memory, cortical and cerebrospinal fluid somatostatin-like immunoactivity and cortical levels of dopamine and norepinephrine. High doses of cysteamine (200 and 250 mg/kg s.c.) led to sustained locomotor activation. Doses of 150 mg/kg and above resulted in head and neck tremor and increased defecation. When cysteamine was administered immediately following the acquisition of a passive avoidance response, doses of 50 mg/kg and above resulted in significant attenuation of passive avoidance retention test performance. Cysteamine in doses of 50 mg/kg and above depleted cortical somatostatin-like immunoactivity by approximately 50%. The depletion of cortical somatostatin-like immunoactivity was accompanied by a rapid rise in somatostatin-like immunoactivity in cerebrospinal fluid. In addition to the depletion of somatostatin-like immunoactivity, high doses of cysteamine (150 mg/kg and above) produced changes in cortical levels of norepinephrine and dopamine, reminiscent of dopamine-beta-hydroxylase inhibition. The results of this series of experiments suggest that somatostatin, in addition to its effects on hormonal regulation, may play an important role in behavior and passive avoidance learning and memory. It is possible that the amnesia produced by cysteamine may have been due to the release of somatostatin into CSF from tissue stores, rather than somatostatin depletion per se. It is also possible that the catecholaminergic effects of high doses of cysteamine contribute to the behavioral deficits observed.

Animals↗
PubMed1988

Somatostatin and SMS 201-995 reverse the impairment of cognitive functions induced by cysteamine depletion of brain somatostatin.

The involvement of somatostatin in the organization of cognitive functions was studied. We assessed changes in learning and memory processes by studying the effects of cysteamine, a compound that decreases somatostatin-like immunoreactivity in the brain, somatostatin and the potent somatostatin analogue, SMS 201-995, on active avoidance behaviour, assessed with a shuttle box apparatus, or on passive avoidance behaviour. Cysteamine induced a loss of the conditioned active avoidance response acquired after 3 weeks of daily trials. The effect was observed 2 h (-29%) and 4 h (-51%) after cysteamine treatment (300 mg/kg s.c.) and disappeared after 24 h. Intracerebroventricular administration of somatostatin or SMS 201-995 to cysteamine-treated rats significantly reversed the cysteamine effects on the conditioned avoidance responses. Similar results were obtained on passive avoidance behaviour. We also investigated the effect of cysteamine treatment on brain somatostatin-sensitive adenylate cyclase. We observed that adenylate cyclase activity in the frontal cortex of cysteamine-pretreated animals was more sensitive to inhibition by the SRIF analogue, SMS 201-995, than it was in control animals. This effect was observed at concentrations of SMS 201-995 that were ineffective in control tissue. These results show that disruption of somatostatinergic transmission affects cognitive functions of rats.

Adenylyl Cyclases↗
PubMed1984

Morphologic effects of cysteamine on the rat adenohypophysis.

In pituitary lactotrophs of female Sprague-Dawley rats given cysteamine (300 mg/kg, per os/day) for 7 days, forming granules were increased in number and contained many separate electron-dense structures suggesting crinophagy. Compared to control values, cysteamine treatment caused no change in blood prolactin (PRL) levels, measured by radioimmunoassay (RIA). 17 beta-Estradiol (50 micrograms, sc/day) for 7 days, induced lactotroph hyperplasia and increased blood PRL levels which were unaffected by simultaneous cysteamine administration. The ultrastructural changes did not reflect those due to bromocriptine suppression of secretory activity, and supported the concept that cysteamine altered lactotroph morphology by an unknown mechanism. In pituitary gonadotrophs following cysteamine treatment, increased electron lucency of luminal contents of dilated rough endoplasmic reticulum was noted; however, blood luteinizing hormone (LH) levels did not differ from those of control values. In ovariectomized rats, cysteamine suppressed castration cell formation and reduced blood LH levels, suggesting an interference with the cell's ability to respond to GnRH stimulation. The morphologic effects of cysteamine appeared to be selective to lactotrophs and gonadotrophs, and were not secondary to vascular impairment, as capillary endothelial cells were undamaged.

Animals↗
PubMed1981

Cysteamine inhibition of [15N]-glycine turnover in cystinosis and of glycine cleavage system in vitro.

In order to clarify the hyperglycinemic effect of cysteamine treatment in children with nephropathic cystinosis, we measured [15N]-glycine turnover in three affected patients. Administration of cysteamine lowered the glycine flux and the glycine metabolic clearance rate but did not alter the glycine pool size. Formation of [15N]-serine from [15N]-glycine was lower in untreated patients than in control subjects and was reduced still further by cysteamine. Studies in vitro with isolated rat liver mitochondria and acetone extracts of mitochondria indicated that even low cysteamine concentrations (0.1 mM) inhibited the glycine cleavage system in both the direction of glycine oxidation and glycine synthesis. Cysteamine was a more potent inhibitor of the glycine cleavage system than any other sulfhydryl containing compound. Although no ill effects of cysteamine treatment were immediately apparent, patients receiving cysteamine should be monitored carefully for the appearance of any neurologic symptoms which might be referable to inhibition of the glycine cleavage system.

Coenzyme A↗
PubMed1983

Somatostatin depletion of the gut and pancreas induced by cysteamine is not prevented by vagotomy or by dopamine agonists.

The role of endogenous somatostatin in the pathogenesis of duodenal was investigated in the present study by using the cysteamine animal model of the disease. Our previous studies showed a rapid and multiorgan depletion of somatostatin immunoreactivity (SIR) in rats given a single dose of duodenal ulcerogen cysteamine. We now determined whether acetylcholinergic and dopaminergic modulation (both known to influence the development of duodenal ulcer) are accompanied by modification of cysteamine-induced SIR depletion in rat organs. Vagotomy performed either 1 or 18 h before cysteamine administration did not interfere with the chemically induced SIR decrease in pancreas, gastric and duodenal mucosa. Vagal denervation alone had no marked influence on SIR levels but if combined with cysteamine, the SIR depletion in the stomach was significantly more pronounced than after the duodenal ulcerogen alone. Pretreatment with the dopamine agonists bromocriptine or lergotrile (known to prevent the chemically induced duodenal ulcers) did not influence the SIR depletion by cysteamine. Thus cysteamine depletes endogenous somatostatin in peripheral organs (e.g., stomach, duodenum, pancreas) by mechanisms independent of both vagus nerve and dopamine agonists. A role of central somatostatin depletion leading to disinhibition of vagus is also considered in the pathogenesis of experimental duodenal ulcer.

Animals↗
PubMed2006

Capillary electrophoresis method development for determination of impurities in sodium cysteamine phosphate samples.

A capillary electrophoresis method for determination of impurities in sodium cysteamine phosphate-an alternative drug to use in place of cysteamine (Cystagon), Mylan Laboratories Inc.) in the treatment of cystinosis-was developed. The administration of cysteamine, divided in four doses due to the short half-life of this drug, is a helpful treatment, but several patients show intolerance, due to the very unpleasant odor and taste of cysteamine. Sodium cysteamine phosphate is less organoleptic aversive and also has a larger active time, allowing the compression of the doses to 2 per day, increasing the acceptance of the drug. In the developed method the two main decomposition products of sodium cysteamine phosphate, cystamine and cysteamine, can be determined with LOQs of 30 microg/ml (0.2%) and 16 microg/ml (0.1%), respectively. The background electrolyte is 15 mM ammonium acetate (pH 8.85) with 10% methanol and the separation takes less than 4 min. UV detection is performed at 195 nm. This volatile method was developed with the purpose of further hyphenation to a mass spectrometer.

Cysteamine↗
PubMed1997

Influence of growth hormone on cysteamine-induced gastro-duodenal lesions in rats: the involvement of somatostatin.

It is known that cysteamine ulcerogenic effect depends, among others, on a depletion of somatostatin in the gastro-intestinal tract. Since growth hormone (GH) causes the release of hypothalamic somatostatin (SRIH) and potentiates the ulcerogenic action of cysteamine we have studied the influence of GH on gastro-duodenal mucosa levels of SRIH, and its relevance for the ulcerogenic action of cysteamine. Female rats of the Sprague-Dawley strain were pretreated with GH (0.25, 0.5 or 1 mg/kg) and subjected to cysteamine-induced gastric lesions. These animals showed an increased mortality and severity of gastric lesions. The measurement of gastric and duodenal barrier mucus levels revealed that GH administration was followed by a decrease in mucus production. Pretreatment with SRIH (25 or 50 microg/kg) was followed by a decreased percent incidence and severity of gastric mucosa lesions induced by cysteamine. The mucus production was increased by SRIH administration. GH pretreatment was followed by a reduction of SRIH-like immunoreactivity in gastro-duodenal mucosa and an increase of insulin plasma levels. Acute injection of cysteamine per se was also followed by a decrease of gastro-duodenal SRIH and an increase in insulin plasma levels. These results suggest that high levels of plasma GH, as induced by exogenous GH administration, may cause a decrease of SRIH gastro-intestinal content and this in turn may potentiate the ulcerogenic activity of cysteamine.

Animals↗
PubMed2000

Effect of cysteamine during in vitro maturation on buffalo embryo development.

The purpose of this study was to evaluate whether the addition of cysteamine during in vitro maturation (IVM) of buffalo oocytes enhances embryo development. Cumulus-oocyte complexes (COC) from slaughterhouse ovaries were matured in vitro in TCM 199 supplemented with 10% fetal calf serum (FCS), 0.5 microg mL(-1) FSH, 5 microg mL(-1) LH, 1 microg mL(-1) 17 beta estradiol and 0 (control), 50, 100 or 200 micromol L(-1) of cysteamine for 24 hours. The matured oocytes then were fertilized and cultured for 7 days. No beneficial effect on maturation and cleavage rate was related to the addition of cysteamine. However, the percentage of embryos that developed to compact morula and blastocyst stage was significantly higher (P < or = 0.01) for oocytes matured in medium containing 50 micromol L(-1) of cysteamine than it was for oocytes matured with 0, 100 and 200 micromol L(-1) cysteamine (22.6% vs 14.9%, 15.7% and 13% respectively); moreover, the addition of 50 micromol L(-1) of cysteamine during IVM significantly (P < or = 0.01) increased the proportion of transferable quality (Grades 1 and 2) embryos (19.3% vs 11.3%, 11.6% and 11.2% respectively). The present study showed that adding a thiol compound (such as cysteamine) to the IVM medium improves buffalo in vitro embryo production (IVEP) efficiency, which so far has been unsatisfactory.

Animals↗