Metoclopramide-induced central nervous system depression in the chicken

Phytotherapeutic Approach in the Management of Cisplatin Induced Vomiting; Neurochemical Considerations in Pigeon Vomit Model

Cisplatin induced vomiting involves multiple mechanisms in its genesis and a single antiemetic agent do not cover both the phases (acute & delayed) of vomiting in clinics; necessitating the use of antiemetics in combination. Cannabis sativa and other selected plants have ethnopharmacological significance in relieving emesis. The aim of the present study was to investigate the intrinsic antiemetic profile of Cannabis sativa (CS), Bacopa monniera (BM, family Scrophulariaceae), and Zingiber officinale (ZO, family Zingiberaceae) in combinations against vomiting induced by highly emetogenic anticancer drug-cisplatin in pigeons. We have analysed the neurotransmitters which trigger the vomiting response centrally and peripherally. Electrochemical detector (ECD) was used for the quantification of neurotransmitters and their respective metabolites by high performance liquid chromatography in the brain stem (BS) and area postrema (AP) while peripherally in the small intestine. Cisplatin (7 mg/kg i.v.) induced reliable vomiting throughout the observation period (24 hrs). CS-HexFr (10 mg) + BM-MetFr (10 mg)–Combination 1, BM-ButFr (5 mg) + ZO-ActFr (25 mg)–Combination 2, ZO-ActFr (25 mg) + CS-HexFr (10 mg)–Combination 3, and CS-HexFr (10 mg) + BM-ButFr (5 mg)–Combination 4; provided ~30% (30 ± 1.1), 70% (12 ± 0.4; P < 0.01), 60% (19 ± 0.2; P < 0.05) and 90% (05 ± 0.1; P < 0.001) protection, respectively, against cisplatin induced vomiting as compared to cisplatin control. Standard MCP (30 mg) provided ~50% (23 ± 0.3) protection (P > 0.05). CS Hexane fraction (10 mg/kg), BM methanolic (10 mg/kg) and bacoside rich n-butanol fraction (5 mg/kg) and ZO acetone fraction (25 mg/kg) alone provided ~62%, 36%, 71%, and 44% protection, respectively, as compared to cisplatin control. The most effective and synergistic combination 4 was found to reduce 5HT and 5HIAA (P < 0.05–0.001) in all the brain areas area postrema (AP)+brain stem (BS) and intestine at the 3^rd hour of cisplatin administration. In continuation, at the 18^th of cisplatin administration reduction in dopamine (P < 0.001) in the AP and 5HT in the brain stem and intestine (P < 0.001) was observed. The said combination did not change the neurotransmitters basal levels and their respective metabolites any significantly. In conclusion, all the tested combinations offered protection against cisplatin induced vomiting to variable degrees, where combination 4 provided enhanced attenuation by antiserotonergic mechanism at the 3^rd hour while a blended antidopaminergic and antiserotonergic mechanism at the 18^th hour after cisplatin administration.

Suppression of Cisplatin-Induced Vomiting by Cannabis sativa in Pigeons: Neurochemical Evidences

Cannabis sativa (CS, family Cannabinaceae) has been reported for its anti-emetic activity against cancer chemotherapy-induced emesis in animal models and in clinics. The current study was designed to investigate CS for potential effectiveness to attenuate cisplatin-induced vomiting in healthy pigeons and to study the impact on neurotransmitters involved centrally and peripherally in the act of vomiting. High-performance liquid chromatography system coupled with electrochemical detector was used for the quantification of neurotransmitters 5-hydroxytryptamine (5HT), dopamine (DA) and their metabolites; Di-hydroxy Phenyl Acetic acid (Dopac), Homovanillic acid (HVA), and 5-hydroxy indole acetic acid (5HIAA) centrally in specific brain areas (area postrema and brain stem) while, peripherally in small intestine. Cisplatin (7 mg/kg i.v.) induce emesis without lethality across the 24 h observation period. CS hexane fraction (CS-HexFr; 10 mg/kg) attenuated cisplatin-induced emesis ∼ 65.85% (P < 0.05); the reference anti-emetic drug, metoclopramide (MCP; 30 mg/kg), produced ∼43.90% reduction (P < 0.05). At acute time point (3^rd h), CS-HexFr decreased (P < 0.001) the concentration of 5HT and 5HIAA in the area postrema, brain stem and intestine, while at 18^th h (delayed time point) CS-HexFr attenuated (P < 0.001) the upsurge of 5HT caused by cisplatin in the brain stem and intestine and dopamine in the area postrema. CS-HexFr treatment alone did not alter the basal neurotransmitters and their metabolites in the brain areas and intestine except 5HIAA and HVA, which were decreased significantly. In conclusion the anti-emetic effect of CS-HexFr is mediated by anti-serotonergic and anti-dopaminergic components in a blended manner at the two different time points, i.e., 3^rd and 18^th h in pigeons.

Anti-emetic mechanisms of Zingiber officinale against cisplatin induced emesis in the pigeon; behavioral and neurochemical correlates

BACKGROUND

Zingiber officinale (ZO, family Zingiberaceae) has been reported for its antiemetic activity against cancer chemotherapy induced emesis in animal models and in clinics. Current study was designed to investigate ZO for potential usefulness against cisplatin induced vomiting in pigeon and its effects on central and peripheral neurotransmitters involved in the act of vomiting.

METHODS

Zingiber officinale acetone fraction (ZO-ActFr) was investigated for attenuation of emesis induced by cisplatin in healthy pigeons. Neurotransmitters DA, 5HT and their metabolites DOPAC, HVA and 5HIAA were analyzed using High Performance Liquid Chromatography system coupled with electrochemical detector in area postrema, brain stem and intestine. Antiemetic effect of ZO-ActFr was correlated with central and intestinal neurotransmitters levels in pigeon.

RESULTS

Cisplatin (7 mg/kg i.v.) induced emesis without lethality upto the observation period. ZO-ActFr (25, 50 & 100 mg/kg) attenuated cisplatin induced emesis ~ 44.18%, 58.13% (P < 0.05) and 27.9%, respectively; the reference drug, metoclopramide (MCP; 30 mg/kg), produced ~ 48.83% reduction (P < 0.05). ZO-ActFr reduced (P < 0.05 - 0.001) 5-hydroxytryptamine (5HT) concentration in the area postrema, brain stem and intestine at 3(rd) hour of cisplatin administration, while at the 18(th) hour ZO treatments attenuated the dopamine upsurge (P < 0.001) caused by cisplatin in the area postrema and 5HT concentration (P < 0.01 - 0.001) in the brain stem and intestine. ZO treatments alone did not altered the basal neurotransmitters and their metabolites in the brain areas and intestine.

CONCLUSION

The behavioral study verify the antiemetic profile of ZO against cisplatin induced emesis in the pigeon, where central and peripheral neural evidences advocate the involvement of serotonergic mechanism at initial time point (3(rd) hr), while the later time point (18(th) hr) is associated with serotonergic and dopaminergic component in the mediation of its antiemetic effect.

Central depressant effects and toxicity of propofol in chicks

Propofol is an ultra-short acting anesthetic agent. The information on the pharmacological and toxicological effects of propofol in the chicken is rather limited. This study examines the toxicity and pharmaco-behavioral effects of propofol given intraperitoneally in 7–10 day-old chicks. The median effective doses of propofol for the induction of sedation, analgesia to electric stimulation and sleep in the chicks were 1.82, 2.21 and 5.71 mg/kg, respectively. The 24-h median lethal dose of propofol in chicks was 57.22 mg/kg. The therapeutic indices of propofol for sedation, analgesia and sleep were 31.4, 25.9 and 10, respectively. Propofol at 0.5 and 1 mg/kg reduced the locomotor activity and increased the duration of tonic immobility in chicks. Propofol at 2 and 4 mg/kg caused analgesia to electric stimulation as well as analgesia and anti-inflammatory responses against formalin test in chicks. Propofol at 5, 10 and 20 mg/kg induced sleep in chicks for 8.4 to 25 min. Physostigmine shortened the sleep duration of propofol. Data suggest that propofol induces anti-inflammatory action and central nervous system depression in chicks resulting in sedation, analgesia and anesthesia with wide safety margin. These effects could form the basis of further pharmacological and toxicological studies on propofol in the young chick model, and the drug could be safely applied clinically in the chicken.

Effects of hydrogen peroxide on diazepam and xylazine sedation in chicks

Oxidative stress may cause various neuronal dysfunctions and modulate responses to many centrally acting drugs. This study examines the effects of oxidative stress produced by hydrogen peroxide (H₂O₂) on sedation induced by diazepam or xylazine as assessed in 7–14 day-old chicks. Day-old chicks were provided with either plane tap water (control group) or H₂O₂ in tap water as 0.5% v/v drinking solution for two weeks in order to produce oxidative stress. Spectrophotometric methods were used to determine glutathione and malondialdehyde concentrations in plasma and whole brain. Drug-induced sedation in the chicks was assessed by monitoring the occurrence of signs of sedation manifested as drooping of the head, closed eyelids, reduced motility or immotility, decreased distress calls, and recumbency. The latency to onset of sedation and its duration were also recorded. H₂O₂ treatment for two weeks significantly decreased glutathione and increased malondialdehyde concentrations in plasma and whole brain of the chicks on days 7, 10 and 14 as compared with respective age-matched control groups. H₂O₂ decreased the median effective doses of diazepam and xylazine for the induction of sedation in chicks by 46% and 63%, respectively. Injection of diazepam at 2.5, 5 and 10 mg/kg, i.m. or xylazine at 2, 4 and 8 mg/kg, i.m. induced sedation in both control and H₂O₂-treated chicks in a dose dependent manner, manifested by the above given signs of sedation. H₂O₂ significantly decreased the latency to onset of sedation in chicks treated with diazepam at 5 and 10 mg/kg, increased the duration of sedation and prolonged the total recovery time in comparison with respective non-stressed control chicks. A similar trend occurred with xylazine in the H₂O₂-treated chicks, though the differences from control counterparts did not attain the statistical significance, except for the recovery time of the lowest dose of the drug. The data suggest that H₂O₂-induced oxidative stress sensitizes the chicks to the depressant action of the sedatives diazepam and xylazine. Further studies are needed to examine the potential role of oxidative stress in modulating the actions of therapeutic agents on the brain.

Metoclopramide protection of diazinon-induced toxicosis in chickens

The efficacy of metoclopramide for preventing organophosphate insecticide-induced (diazinon) toxicosis was evaluated in 7~14 days old chicks. Injection of metoclopramide at 25 mg/kg, s.c. 15 min before diazinon increased the oral 24 h median lethal dose of the insecticide in the chicks by 80%. Metoclopramide alone inhibited the in vitro and in vivo plasma and whole brain cholinesterase activities of the chicks. Metoclopramide pretreatment at 100 mg/kg, s.c. reduced the extent of cholinesterase inhibition that was caused by diazinon (10 mg/kg, p.o.) in the plasma and whole brain by 24% and 7%, respectively. Diazinon at 10 mg/kg, p.o. produced signs of cholinergic toxicosis in the chicks, and these signs included salivation, lacrimation, gasping and convulsions within 2 h, and the 2-h and 24-h lethalities were 88 and 100%, respectively. Metoclopramide at the dose rates of 12.5, 25, 50, 100 and 200 mg/kg, s.c. given 15 min before diazinon (10 mg/kg, p.o.) variably decreased the occurrence of toxic manifestations in the chicks. The highest dose of metoclopramide (200 mg/kg, s.c.) reduced the 2-h and 24-h lethality of diazinon to 75% each and it reduced the overall toxicity score of diazinon by 32%. The data suggest that metoclopramide pretreatment only partially protected chicks against the acute toxicity of diazinon.