Enhancement of malathion toxicity to the hybrid red-legged partridge following exposure to prochloraz

Johnston, Gail; Collett, G. C.; Walker, C.H.; Dawson, A.; Boyd, I. A.; Osborn, Dan

doi:10.1016/0048-3575(89)90108-9

Cited by 32 publications

(20 citation statements)

References 25 publications

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“…Subsequent oral dosing of malathion to control and prochloraz-treated birds also revealed selectivity between these two groups. Over a 24 h Volume 21 P-450 Biotechnology period, birds that had been dosed with prochloraz showed considerably greater serum butyrylcholinesterase depression than did controls [4]. The same effect was found after dosing with 90 mg/kg, although the difference between the control and the prochloraz-treated birds was smaller (G. Johnston [4].…”

Section: Potentiation Due To Increased Activationsupporting

confidence: 51%

“…Over a 24 h Volume 21 P-450 Biotechnology period, birds that had been dosed with prochloraz showed considerably greater serum butyrylcholinesterase depression than did controls [4]. The same effect was found after dosing with 90 mg/kg, although the difference between the control and the prochloraz-treated birds was smaller (G. Johnston [4]. After dosing with dimethoate, prochloraz-treated birds also showed a greater inhibition of serum butyrylcholinesterase than did controls.…”

Section: Potentiation Due To Increased Activationmentioning

confidence: 50%

“…In a study with red-legged partridges (Alectoris rufa cross), the induction of cytochrome P-450 with EBIs was related to the toxicity of organophosphorus insecticides that are activated by this haemoprotein [4]. After 24 h from dosing with 180 mg/kg of prochloraz, there was a 3-fold increase in the cytochrome P-450 content of microsomes, a 4-fold increase in aldrin epoxidase activity and a 20-fold increase in ethoxyresorufin-o-de-ethylase activity, the last two being expressed in terms of kg of body weight [4, 51.…”

Section: Potentiation Due To Increased Activationmentioning

confidence: 99%

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Potentiation of pesticide toxicity in birds: role of cytochrome P-450

Walker

Johnston

1993

Biochemical Society Transactions

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Section: Potentiation Due To Increased Activationsupporting

confidence: 51%

Section: Potentiation Due To Increased Activationmentioning

confidence: 50%

Section: Potentiation Due To Increased Activationmentioning

confidence: 99%

See 1 more Smart Citation

Potentiation of pesticide toxicity in birds: role of cytochrome P-450

Walker

Johnston

1993

Biochemical Society Transactions

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“…Other interactions include potential inhibition of hepatic cytochrome P450 enzymes. For instance, EBI fungicides are capable of reducing the activity of certain forms of cytochrome P450 by binding to the haem moiety (Johnston et al, 1989), and EBDC fungicides denature P450s either through interactions with the sulfydryl group or because of their metal-chelating properties (Siddiqui et al, 1991). If these enzymes in tree swallows were inhibited, it is also possible that hepatic monodeiodiase enzymes were inhibited, thereby preventing the metabolism and conversion of T 4 to T 3 .…”

Section: Discussionmentioning

confidence: 97%

Thyroid Function in Nestling Tree Swallows and Eastern Bluebirds Exposed to Non-Persistent Pesticides and p, p?-DDE in Apple Orchards of Southern Ontario, Canada

Mayne

Bishop²,

Martin³

et al. 2005

Ecotoxicology

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This study examined the associated effects of pesticides and persistent residues of p,p'-DDE on thyroid function in 16-day-old tree swallows (Tachycineta bicolor) and 12-day-old eastern bluebirds (Sialia sialis). Apple orchards sprayed with pesticides in current use and reference sites were chosen for study in southern Ontario, Canada, during 2000-2001. We assessed thyroid hormone concentrations (plasma and muscle thyroxine [T4], and triiodothyronine [T3]) and the response to a challenge with thyroid stimulating hormone (TSH) as well as parameters of thyroid histology. Individual nests were exposed to as many as seven individual pesticide applications and up to five pesticide mixtures. Concentrations of p,p'-DDE in eggs from both species were highest in orchard sites, and ranged from 0.05 to 5.44 mg/kg wet weight for tree swallows, and from 0.17 to 95.4 mg/kg for eastern bluebirds. In 2000, tree swallows from sprayed orchards had elevated plasma T4 concentrations, and thyroid glands with collapsed follicles, hypertrophic epithelia, and higher follicular epithelial cells relative to chicks from reference sites. Plasma T4 concentration was positively correlated with the total number of pesticide mixtures applied during egg incubation through chick rearing. In 2001, basal plasma T3 concentration in tree swallow chicks did not differ between orchard and reference sites, though there were differences among orchards; T3 was positively correlated with total number of individual sprays applied during egg incubation through chick rearing. Tree swallows challenged with TSH showed no significant difference in thyroid hormone concentration or follicular epithelial cell height between exposure groups; however, a significantly greater proportion of chicks from reference sites were found to have thyroids with focal or diffuse hypertrophic epithelia relative to orchard chicks. In 2001, bluebirds from sprayed orchards had significantly higher T3 concentrations in response to TSH challenge; this response was positively correlated with the total number of pesticides applied during egg incubation through chick rearing.

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“…The ChE activity in brain and serum was measured by the calorimetric method of Ellman et al (1961), as adapted by Johnston et al (1989) except that 0.287 mM acetylthiocholine iodide was used as a substrate in the reaction cuvette in the present study. Activity was determined in 5 µl serum samples and 20 µl brain homogenate, the final assay volumes being 3.0 ml and 3.015 ml respectively.…”

Section: Methodsmentioning

confidence: 99%