Cyanide Poisoning Compromises Gene Pathways Modulating Cardiac Injury in Vivo.

Smoke inhalation from a structure fire is a common route of cyanide poisoning in the U.S. Cyanide inhibits cellular respiration, often leading to death. Its rapid distribution throughout the body can result in injuries to multiple organs, and cyanide victims were reported to experience myocardial infarction and other cardiac complications. However, molecular mechanisms of such complications are yet to be elucidated. While FDA-approved CN antidotes such as sodium thiosulfate and hydroxocobalamin are clinically used, they have foreseeable limitations during mass casualty situations because they require intravenous administration. To facilitate the development of better antidotes and therapeutic treatments, a global view of molecular changes induced by cyanide exposure is necessary. As an exploratory pursuit, we performed oligonucleotide microarrays to establish cardiac transcriptomes of an animal model of nose-only inhalation exposure to hydrogen cyanide (HCN), which is relevant to smoke inhalation. We also profiled cardiac transcriptomes after subcutaneous injection of potassium cyanide (KCN). Although the KCN injection model has often been used to evaluate medical countermeasures, this study demonstrated that cardiac transcriptomes are largely different from that of the HCN inhalation model at multiple time points within 24 h after exposure. Pathway analysis identified that HCN-induced transcriptomes were enriched with genes encoding mediators of pathways critical in modulation of cardiac complications and that a large number of such genes were significantly decreased in expression. We utilized the upstream regulatory analysis to propose drugs that can be potentially employed to treat cyanide-induced cardiac complications.

Oxidative damage mediated iNOS and UCP-2 upregulation in rat brain after sub-acute cyanide exposure: dose and time-dependent effects.

Cyanide-induced chemical hypoxia is responsible for pronounced oxidative damage in the central nervous system. The disruption of mitochondrial oxidative metabolism has been associated with upregulation of uncoupling proteins (UCPs). The present study addresses the dose- and time-dependent effect of sub-acute cyanide exposure on various non-enzymatic and enzymatic oxidative stress markers and their correlation with inducible-nitric oxide synthase (iNOS) and uncoupling protein-2 (UCP-2) expression. Animals received (oral) triple distilled water (vehicle control), 0.25 LD50 potassium cyanide (KCN) or 0.50 LD50 KCN daily for 21 d. Animals were sacrificed on 7, 14 and 21 d post-exposure to measure serum cyanide and nitrite, and brain malondialdehyde (MDA), reduced glutathione (GSH), glutathione disulfide (GSSG), cytochrome c oxidase (CCO), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CA) levels, together with iNOS and UCP-2 expression, and DNA damage. The study revealed that a dose- and time-dependent increase in cyanide concentration was accompanied by corresponding CCO inhibition and elevated MDA levels. Decrease in GSH levels was not followed by reciprocal change in GSSG levels. Diminution of SOD, GPx, GR and CA activity was congruent with elevated nitrite levels and upregulation of iNOS and UCP-2 expression, without any DNA damage. It was concluded that long-term cyanide exposure caused oxidative stress, accompanied by upregulation of iNOS. The upregulation of UCP-2 further sensitized the cells to cyanide and accentuated the oxidative stress, which was independent of DNA damage.

Assessing the efficacy of aqueous garlic extract, sodium nitrite and sodium thiosulfate against prolonged oral cyanide exposure in rabbits.

This study was aimed to compare the efficacy of aqueous garlic extract, sodium nitrite (SNT), sodium thiosulfate (STS) and hydroxocobalamin against oral cyanide exposure in rabbits. For this purpose, forty two adult male rabbits were divided randomly into 7 groups of 6 animals (A-G) each. Rabbits in group A were offered feed only and served as negative control, while the rabbits in group B received feed plus potassium cyanide (KCN) at 3mg/kg orally and were kept as positive control. Animals in group C received feed, KCN and intraperitoneal injection (IP) of aqueous garlic extract at 500mg/kg. Rabbits in group D were given feed, KCN and IP injection of STS at 600mg/kg. Members in group E received feed, KCN and IP injection of both aqueous garlic extract at 500mg/kg and SNT at 20mg/kg. Animals in group F were given feed, KCN and IP injection of both STS at 600mg/kg and SNT at 20mg/kg, while the rabbits in group G received feed, KCN and IP injection of hydroxocobalamin at 300mg/kg. The treatments were given to respective groups for 40 days. The efficacy of the antidotes was measured on the basis of changes in biochemical profile of rabbits in each group. In this study, hydroxocobalamin was found to be significantly more effective cyanide (CNI) antidote than garlic, STS, SNT plus garlic extract, or SNT and STS, either alone or in combination. A combination of SNT and garlic extract was the second most effective CNI antidote. The efficacy of garlic alone was significantly higher than STS alone or in combination with SNT. The efficacy of combined SNT and STS was superior to STS alone in treating rabbits with CNI toxicity. In conclusion, aqueous garlic extract alone or in combination with STS can effectively be used against cyanide toxicity.

Histopathological changes induced in liver, kidney, heart and pancreas of rabbits by prolonged oral cyanide exposure.

The aim of the present study was to determine the deleterious effects of prolonged oral cyanide insult on various organs and tissues in rabbits. For this purpose, 12 locally bred adult male rabbits were allocated into two groups of 6 viz. control and experimental. Rabbits in control group were offered feed only while the rabbits in experimental group received feed plus potassium cyanide (KCN) at 3 mg/kg body weight orally for a period of 40 days. None of the rabbit in both the groups demonstrated any of the gross changes in any organ on postmortem examination. Liver was normal in size, shape, texture and color. Kidneys were also normal in size and color. Histopathological examination revealed severe hepatocyte vacuolation and degeneration in liver of rabbits in experimental group. There was also excessive congestion in liver and bile duct of rabbits in experimental group. Kidneys of rabbits in experimental group demonstrated severe glomerular and tubular necrosis and congestion. In the tubular epithelial cells, pyknotic nuclei were also present. On the other hand, heart and pancreas of rabbits in both control and experimental group did not show any histopathological change in microscopic structures. In conclusion, prolonged oral cyanide administration could have harmful effects on liver and kidney functions.

Neurobehavioral and Cardiovascular Effects of Potassium Cyanide Administered Orally to Mice.

The Food and Drug Administration Animal Rule requires evaluation of cardiovascular and central nervous system (CNS) effects of new therapeutics. To characterize an adult and juvenile mouse model, neurobehavioral and cardiovascular effects and pathology of a single sublethal but toxic, 8 mg/kg, oral dose of potassium cyanide (KCN) for up to 41 days postdosing were investigated. This study describes the short- and long-term sensory, motor, cognitive, and behavioral changes associated with oral dosing of a sublethal but toxic dose of KCN utilizing functional observation battery and Tier II CNS testing in adult and juvenile mice of both sexes. Selected tissues (histopathology) were evaluated for changes associated with KCN exposure with special attention to brain regions. Telemetry (adult mice only) was used to evaluate cardiovascular and temperature changes. Neurobehavioral capacity, sensorimotor responsivity or spontaneous locomotor activity, and rectal temperature were significantly reduced in adult and juvenile mice at 30 minutes post-8 mg/kg KCN dose. Immediate effects of cyanide included bradycardia, adverse electrocardiogram arrhythmic events, hypotension, and hypothermia with recovery by approximately 1 hour for blood pressure and heart rate effects and by 2 hours for body temperature. Lesions consistent with hypoxia, such as mild acute tubular necrosis in the kidneys corticomedullary junction, were the only histopathological findings and occurred at a very low incidence. The mouse KCN intoxication model indicates rapid and completely reversible effects in adult and juvenile mice following a single oral 8 mg/kg dose. Neurobehavioral and cardiovascular measurements can be used in this animal model as a trigger for treatment.

Toxicokinetic aspects of thiocyanate after oral exposure to cyanide in female Wistar rats in different physiological states.

Cyanide (CN) is an ion that has been well studied in toxicology and has been associated with several intoxication episodes: the ingestion of contaminated foods and water, chemical war, suicides, homicides, occupational exposures and the use of certain medicines. The aim of the present study was to determine the toxicokinetic parameters of thiocyante (SCN), the main metabolite of CN, after oral administration of potassium cyanide (KCN) to female rats at diestrus, gestational and lactational periods. Female Wistar rats were divided into three equal groups: virgins in the diestrus phase of the estrus cycle, females at the 14th day of gestation and females at the 14th day of lactation. Each group of rats received 3.0 mg of potassium cyanide per kilogram (KCN/kg body weight) by gavage, and blood was collected at several time points. We also collected amniotic fluid from pregnant rats and milk from the nursing rats to analyze thiocyanate concentration. The results showed that SCN levels were significantly increased in serum, milk and amniotic fluid after administration of KCN. In conclusion, the results of the present study evidence that the metabolism of CN varies greatly considering the physiologic state of the female rat, being females at estrus probably more exposed by these substances than at gestation and lactation because in these states there are other compartments, fetus and milk, which may capture these substances, as demonstrated by the V(d) values.

[Experimental models of lysosomal phase reactivity in blood leukocytes exposed to low doses of potassium cyanide].

Cytochemical analysis of acid phosphatase was used to evaluate lysosomal membranes stability under oral intake of potassium cyanide by rats over one month in daily doses of 1.30 mg/kg (1/10 LD50) and 0.65 mg/kg (1/20 LD50). The authors demonstrated phase-related dose-dependent changes in the lysosomal state, and the main response feature was associated with functional activation that usually followed the membrane alteration.

Serotonin nerve terminals in the dorsomedial medulla facilitate sympathetic and ventilatory responses to hemorrhage and peripheral chemoreflex activation.

Serotonin neurons of the caudal raphe facilitate ventilatory and sympathetic responses that develop following blood loss in conscious rats. Here, we tested whether serotonin projections to the caudal portion of the dorsomedial brain stem (including regions of the nucleus tractus solitarius that receive cardiovascular and chemosensory afferents) contribute to cardiorespiratory compensation following hemorrhage. Injections of the serotonin neurotoxin 5,7-dihydroxytryptamine produced >90% depletion of serotonin nerve terminals in the region of injection. Withdrawal of ∼21% of blood volume over 10 min produced a characteristic three-phase response that included 1) a normotensive compensatory phase, 2) rapid sympathetic withdrawal and hypotension, and 3) rapid blood pressure recovery accompanied by slower recovery of heart rate and sympathetic activity. A gradual tachypnea developed throughout hemorrhage, which quickly reversed with the advent of sympathetic withdrawal. Subsequently, breathing frequency and neural minute volume (determined by diaphragmatic electromyography) declined below baseline following termination of hemorrhage but gradually recovered over time. Lesioned rats showed attenuated sympathetic and ventilatory responses during early compensation and later recovery from hemorrhage. Both ventilatory and sympathetic responses to chemoreceptor activation with potassium cyanide injection were attenuated by the lesion. In contrast, the gain of sympathetic and heart rate baroreflex responses was greater, and low-frequency oscillations in blood pressure were reduced after lesion. Together, the data are consistent with the view that serotonin innervation of the caudal dorsomedial brain stem contributes to sympathetic compensation during hypovolemia, possibly through facilitation of peripheral chemoreflex responses.

Can isosorbide dinitrate oral spray serve as an immediate bridging therapy for a mass cyanide poisoning?

OBJECTIVE: In this proof-of-concept study, the aim was to evaluate the short-term clinical effectiveness of isosorbide dinitrate (ISDN) oral spray in non-anaesthetized cyanide-poisoned swine. METHODS: A comparative study was conducted using domestic swine. Animals were intravenously poisoned with potassium cyanide (KCN), either 2 mg/kg or 4 mg/kg dose. Two control groups (one for each cyanide dose) were not further treated. Two other groups (one for each cyanide dose) were treated within 1 min after poisoning with ISDN oral spray: 3 spray actuations (averaging a total of 3.75 mg) after the lower cyanide dose and 4 spray actuations (averaging a total of 5.0 mg) after the higher dose. The study outcomes were clinical score, time to death, and blood tests including pH, lactate, and methemoglobin levels. RESULTS: All the animals started to convulse within 20 to 30 sec after KCN poisoning, then became unresponsive and hemodynamically depressed after another 20 to 30 sec. After the KCN 2 mg/kg dose, 3 of 4 control animals survived, while all treated animals survived. Compared with control animals, ISDN-treated animals displayed significantly better clinical scores starting 5 min after KCN poisoning. Acidosis was significantly more pronounced in the untreated animals. After the KCN 4 mg/kg dose, similar survival rates were observed for control and ISDN-treated groups (1/4), but treated animals had longer time to death and better pH and lactate levels. CONCLUSION: ISDN oral spray administration following KCN poisoning in this porcine model did not result in statistically significant increased survival. However, based on clinical scores and clinical laboratory values, ISDN may benefit as a bridging countermeasure until currently-available specific cyanide antidotes can be administered. Further research is warranted to better characterize this potential role of ISDN in cyanide poisoning.

Protective role of alpha-ketoglutarate against massive doses of cyanide in rats.

Cyanide is a highly toxic cellular poison that requires immediate and aggressive treatments. Combination of sodium nitrite (SN) and sodium thiosulfate (STS) is the treatment of choice but oral treatment of alpha-ketoglutarate (A-KG) has also been shown to significantly antagonize cyanide poisoning in laboratory animals. This study reports the efficacy of various treatment regimens as: (i) repeated doses of A-KG after simultaneous treatment of A-KG and STS, (ii) repeated doses of A-KG after pre-treatment of SN, STS and A-KG, (iii) repeated doses of STS after pre-treatment of SN, STS and A-KG, and (iv) repeated doses of A-KG and STS after pretreatment of SN, STS and A-KG on mortality of female rats exposed to massive doses of potassium cyanide. A maximum of 40-folds protection was observed when A-KG at 1.0 g kg(-1) after 2 hr and 0.5 g kg(-1) after 4 hr was repeated following the pre-treatment of SN (0.025 g kg(-1); subcutaneous;-45 min), STS (1.0 g kg(-1); intraperitoneal; -15 min) andA-KG (2.0 g kg(-1); oral; -10 min). Similar protection was also conferred by repeating 0.5 g kg(-1) each of A-KG and STS 2 hr after pre-treatment of SN, STS and A-KG. Also, 38-folds protection after simultaneous administration of 20 g kg(-1) A-KG and 1.0 g kg(-1) STS, followed by 2.0 g kg(-1) A-KG after 2 hr was noteworthy The results indicate that repeated treatment of A-KG alone after simultaneous treatment of A-KG and STS or repeated treatment of A-KG alone or with STS after pre-treatment of A-KG, SN and STS have immense potential in challenging extremely high doses of cyanide as compared to the antidotes given once. The study has implications in the development of A-KG as an alternate treatment for cyanide poisoning.

Characterization of a Swine (Sus scrofa) Model of Oral Potassium Cyanide Intoxication.

Cyanide is a readily available and potentially lethal substance. Oral exposure can result in larger doses, compared with other routes. Currently, there are no antidotes specific for use in the treatment of oral cyanide poisoning, and studies cannot be done in humans. We report on a new large animal model of oral cyanide toxicity to evaluate potential antidotes. Six female swine (Sus scrofa; weight, 45 to 55 kg) were anesthetized, intubated, and instrumented. Animals received a KCN bolus of either 5 or 8 mg/kg delivered via orogastric tube. Time to apnea was recorded; parameters monitored included heart rate, respiratory rate, blood pressure, pulse oximetry, end-tidal CO2, arterial blood gasses, and lactate concentrations. The Welch t test was used to calculate confidence intervals, mean, and standard deviation, and a Kaplan-Meier survival curve was used to compare survival between the 2 groups. At baseline, all animals in both groups were similar. Animals in the 5-mg/kg group had a more rapid time to apnea (5.1 ± 2.1 min), longer time to death (48.5 ± 38.1 min), and a greater rate of survival than the 8-mg/kg group (apnea, 10.6 ± 10.7 min; death, 26.1 ± 5.8 min). All animals displayed signs of toxicity (acidemia, hyperlactatemia, hypotension, apnea). We here report a large animal (swine) model of oral cyanide poisoning with dose-dependent effects in regard to time to death and survival rate. This model likely will be valuable for the development of medical countermeasures for oral cyanide poisoning.

On the Efficacy of Cardio-Pulmonary Resuscitation and Epinephrine Following Cyanide- and H2S Intoxication-Induced Cardiac Asystole.

This study was aimed at determining the efficacy of epinephrine, followed by chest compressions, in producing a return of spontaneous circulation (ROSC) during cyanide (CN)- or hydrogen sulfide (H2S)-induced toxic cardiac pulseless electrical activity (PEA) in the rat. Thirty-nine anesthetized rats were exposed to either intravenous KCN (n = 27) or H2S solutions (n = 12), at a rate that led to a PEA within less than 10 min. In the group intoxicated by CN, 20 rats were mechanically ventilated and received either epinephrine (0.1 mg/kg i.v. n = 10) followed by chest compressions or saline (n = 10, "control CN") when in PEA. PEA was defined as a systolic pressure below 20 mmHg and a pulse pressure of less than 5 mmHg for 1 min. In addition, seven spontaneously breathing rats were also exposed to the same CN protocol, but infusion was stopped when a central apnea occurred; then, as soon as a PEA occurred, epinephrine (0.1 mg/kg IV) was administered while providing manual chest compressions and mechanical ventilation (CPR). Finally, 12 rats were intoxicated with H2S, while mechanically ventilated, and received either saline (n = 6, "control H2S") or epinephrine (n = 6) with CPR when in PEA. None of the control-intoxicated animals resuscitated (10 rats in the control CN group and 6 in the control H2S group). In contrast, all the animals intoxicated with CN or H2S that received epinephrine followed by chest compressions, returned to effective circulation. In addition, half of the spontaneously breathing CN-intoxicated animals that achieved ROSC after epinephrine resumed spontaneous breathing. In all the animals achieving ROSC, blood pressure, cardiac output, peripheral blood flow and [Formula: see text]O2 returned toward baseline, but remained lower than the pre-intoxication levels (p < 0.01) with a persistent lactic acidosis. Epinephrine, along with CPR maneuvers, was highly effective in resuscitating rodents intoxicated with CN or H2S. Since epinephrine is readily available in any ambulance, its place as an important countermeasure against mitochondrial poisons should be advocated. It remains critical to determine whether the systematic administration of epinephrine to any victims found hypotensive following CN or H2S intoxication could prevent PEA, decrease post-ischemic brain injury and increase the efficacy of current antidotes by improving the circulatory status.

Cyanide-induced cytochrome a,a3 oxidation-reduction responses in rat brain in vivo.

The sensitivity of the brain to cyanide-induced histotoxic hypoxia and the protective effects of known cyanide antagonists, have been assessed in vivo by reflectance spectrophotometry. Cyanide-related changes in cytochrome a,a3 (cytochrome c oxidase) oxidation-reduction (redox) state, tissue hemoglobin saturation, and local blood volume were continuously monitored in cerebral cortex of rats. Noncumulative, dose-dependent inhibition of the in situ mitochondrial respiratory chain was evaluated directly by measuring increases in reduction levels of the terminal oxidase. These transient cytochrome a,a3 reductions were accompanied by increases in regional cerebral hemoglobin saturation and blood volume. Cytochrome redox responses were not altered either in magnitude or kinetics by hyperoxia; however, the cyanide-cytochrome dose-response curve was greatly shifted to the right by pretreatment with sodium nitrite, and the recovery rate of cytochrome a,a3 from cyanide-induced reduction was enhanced fourfold by pretreatment with sodium thiosulfate.

Peripheral chemoreceptor activation enhances 5-hydroxytryptamine release in the locus coeruleus of conscious rats.

Intravenous bolus injection of KCN (40 microg) elicited brief but pronounced tachypnea, bradycardia and pressor response, and led to a 37% increase in 5-hydroxytryptamine (serotonin) (5-HT) release in the locus coeruleus (LC) of freely moving rats. Slow infusion of KCN (15 microg/min) for 10 min induced only a slight pressor response, but increased the respiration rate (+39 breaths/min), as well as 5-HT release in the LC (+60%) throughout the infusion. In rats with transected chemoreceptor afferents, neither injection or infusion of KCN changed 5-HT release, suggesting that in intact animals, the effect on extracellular 5-HT was due to activation of peripheral chemoreceptors. In summary, we report that peripheral chemoreceptor activation enhances 5-HT release in the LC, indicating that 5-HT might be involved in the modulation of LC activity by ascending chemosensory information.

Antagonism of cyanide toxicity by isosorbide dinitrate: possible role of nitric oxide.

In a search for improved cyanide antidotes, the efficacy of isosorbide dinitrate (ISDN), was compared with that of the known cyanide antidote, NaNO2. ISDN was as effective as an optimal dose of NaNO2 in protecting mice against cyanide lethality. To study the mechanism involved, the extent of formation of the cyanide scavenger, methemoglobin, in the action of ISDN was determined. ISDN (300 mg/kg, p.o.) increased methemoglobin from 5 to 10% of total hemoglobin, while, in contrast, NaNO2 (100 mg/kg, i.p.) increased methemoglobin levels to 50% of total hemoglobin. Lowering the dose of NaNO2 to 30 mg/kg reduced methemoglobin levels to approximately 10% of total hemoglobin and in turn nearly abolished its antidotal effect. Decreasing methemoglobin to less than control levels using methylene blue failed to abolish cyanide antagonism by ISDN. Thus, methemoglobin formation by ISDN does not account for its antidotal action. Further studies comparing the respiratory depressant effects of cyanide in the presence of ISDN or NaNO2 also indicated that these two antidotes have different mechanisms of action. Efforts to produce tolerance to the antidotal effect of ISDN against cyanide toxicity were unsuccessful. It is suggested that the well-known ability of ISDN to generate nitric oxide may account for the noted cyanide antagonism.

Effect of atropine on cyanide-induced acute lethality in mice.

The effects of atropine on acute lethality induced by cyanide were investigated in mice. The LD50 value of cyanide (s.c. injection) was 8.4 (7.6-9.3) mg/kg. However, the LD50 value of cyanide (s.c.) was significantly increased by 1.5-fold when atropine (32 mg/kg) was injected s.c. in mice. Furthermore, the combined administration of atropine (32 mg/kg), Ca2+ (500 mg/kg) and sodium thiosulfate (1 g/kg) tremendously increased the LD50 value by 5.6-fold in mice although sodium thiosulfate or Ca2+ alone increased the LD50 2.5- or 1.5-fold. On the other hand, although the LD50 value of cyanide (intracerebroventricular injection (i.v.t.)) was 52.0 (47.4-57.0) micrograms/brain, the LD50 value of cyanide (i.v.t.) was significantly increased by 1.3- or 1.61-fold in mice 10 min after s.c. injection of atropine (32 mg/kg) or Ca2+ (500 mg/kg). Furthermore, the combined administration of atropine and Ca2+ increased the LD50 value of cyanide by 2.1-fold. These results suggest that atropine inhibits cyanide-induced acute lethality and promotes the antagonistic effect of thiosulfate and Ca2+ in mice.

Antagonistic effect of melatonin against cyanide-induced seizures and acute lethality in mice.

The effect of melatonin on potassium cyanide-induced neurotoxicity was investigated in vivo. The ED50 value of potassium cyanide, as measured by induction of tonic and clonic seizures, was significantly increased by 1.5- or 1.8-fold by s.c. preinjection of melatonin (20, 100 or 345 mg/kg) in mice. The preventive effect of melatonin against potassium cyanide-induced seizures was dose dependent. The LD50 value of potassium cyanide, based on 24-h mortality, was also significantly increased by 1.3-fold by preinjection of melatonin. Potassium cyanide (8 mg/kg, s.c.) increased lipid peroxidation in whole brain of mice, and the increased lipid peroxidation was completely abolished when cyanide-induced seizures were stopped by preadministration of melatonin. These results suggest that melatonin, a pineal hormone, may protect against cyanide-induced neurotoxicity with its free radical scavenging effects in mice.

Neuropathologic study of long term cyanide administration to goats.

Cyanogenic glycosides, which release cyanide, are present in several plant species of high importance for animal production, such as cassava and sorghum. Several human neurological diseases have been associated with chronic cyanide exposure. On the other hand, these effects in ruminants are almost unknown. Thus, the objective of the present study was to determine the long-term lesions of the central nervous system (CNS) caused by daily administration of potassium cyanide (KCN) to goats. Thirty-four male goats were divided into five groups, respectively treated orally with 0 (control), 0.3, 0.6, 1.2 or 3.0 mg KCN/kg/day for 5 months. At the end of the experiment, the whole CNS of each animal was collected for histopathology and immunohistochemistry for apoptotic markers (BAX, BCl2 and CPP32) and for glial fibrillary acid protein (GFAP; vimentin). The results showed the presence of spheroids in the pons, medulla oblongata, and ventral horn of the spinal cord, gliosis and spongiosis in medulla oblongata, gliosis in the pons, and damaged Purkinje cells in the cerebellum from goats that received the higher cyanide dose. In goats from the 1.2 mg KCN/kg group we observed congestion and hemorrhage in the cerebellum, and spheroids in the spinal cord. Gliosis was confirmed by GFAP protein expression. Immunohistochemistry for apoptotic markers and typical apoptotic morphology suggested apoptosis did not participate in the pathogenesis of the observed lesions. Thus, chronic cyanide exposure can promote neuropathological lesions also in goats, and this species can be a useful ruminant model to study the neurotoxic effects of long-term cyanide exposure.

A comparative study of effect of oral chronic cyanide administration on some rabbit tissue ATPases.

The effect of oral KCN administration on Na(+)-K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase activities was studied in some rabbit tissues. Generally, the order of activity of the enzymes was kidney > liver > ileum > colon. There were significant decreases (P < 0.05) in the activities of all the ATPases in the tissues of KCN-treated rabbits relative to controls. The decreases in Na(+)-K(+)-ATPase and Ca(2+)-ATPase activities were most pronounced in liver and kidney. The decreases in ATPases suggest impairment of membrane function as a result of the toxic effect of cyanide.

Prenatal toxicity of cyanide in goats--a model for teratological studies in ruminants.

Although exposure to cyanogenic plants or cyanide during pregnancy has adverse effects, no teratological study with cyanide has been conducted in goats or any other ruminant. The objective of the present study was to evaluate the effects of the maternal exposure to potassium cyanide (KCN) during pregnancy on both dams and offspring and furthermore, to develop a model for prenatal toxicological studies in ruminants. Twenty-six pregnant goats were allocated into four groups and given 0, 1.0, 2.0, or 3.0mg KCN/kg body weight per day orally (administered via twice-daily gavage) from Day 24 of pregnancy to term. However, one control dam and another from the 3.0mg KCN/kg per day group were sacrificed on Day 120. At birth, the kids were examined carefully for gross abnormalities. Three months after birth, the male kids and one dam from each group were sacrificed for histopathological study. Although clinical signs of poisoning were observed in dams, cyanide treatment did not alter the length of gestation or the number of live kids. Two prognata kids were born in the 3.0mg KCN/kg group, and one dam from the same group aborted two fetuses. There were histological lesions only in the KCN-treated dam (and its fetuses) sacrificed on Day 120; these consisted of an increased number of resorption vacuoles of thyroid follicular colloid, and status spongiosis of nervous white matter. This study proposes a new animal model for teratogenic trials that could be important to evaluate the effects of chemicals throughout pregnancy in goats and potentially other ruminants.