Enzyme Induction in the Process of Development

Dickerson, J. W. T.; Basu, Tapan K.

doi:10.1007/978-1-4615-8954-9_2

Cited by 5 publications

(4 citation statements)

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“…The biological and immunological activity of TRH was measured following incubations of TRH with plasma from rats 4 days, 16 days, and about I year old. Immunoreactive TRH was measured by a radioimmunoassay for TRH similar to that of Bassiri and Utiger (12).…”

mentioning

confidence: 99%

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Thyrotropin Releasing Hormone: Development of Inactivation System During Maturation of the Rat

Neary

Kieffer

Federico

et al. 1976

Science

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Whereas thyrotropin releasing hormone is rapidly and extensively degraded by plasma of adult rats, no appreciable loss of biological or immunological activity is caused by plasma from rats 4 or 16 days old. The plasma of neonatal rats does not appear to contain an inhibitor of thyrotropin releasing hormone peptidase or a peptidase with altered substrate affinity. The development of an active peptidase in rat plasma suggests a physiological role for inactivation of thyrotropin releasing hormone.

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mentioning

confidence: 99%

“…SCIENCE, VOL. 193 zyme activities in fetal and neonatal tissues has been studied (16), little is known about the development of plasma peptidases or proteases. However, plasma renin activity in sheep (17) and plasma vasopressinase activity in monkeys (18) are reported to be higher in fetal and newborn animals than in maternal or nonpregnant animals.…”

mentioning

confidence: 99%

Thyrotropin Releasing Hormone: Development of Inactivation System During Maturation of the Rat

Neary

Kieffer

Federico

et al. 1976

Science

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“…This presumably reflects the greater sensitivity of the developing rat to 3MCtype inducing agents (45). Firstly, in the liver, 3MC-sensitive P,-450-dependent enzymes were elevated earlier than the PB-sensitive P-450 dependent enzymes.…”

Section: Effects Of Pbbs On Mfo Activity In Neonatal Animalsmentioning

confidence: 94%

Characteristics of Cytochrome P-450 and Mixed Function Oxidase Enzymes Following Treatment with PBBs

Dent¹

1978

Environmental Health Perspectives

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. . The National Institute of Environmental Health Sciences (NIEHS) and Brogan & Partners are collaborating with JSTOR to digitize, preserve and extend access to Environmental Health Perspectives. The mixture of PBBs in FireMaster BP-6 has been demonstrated to constitute potent inducers of hepatic and extrahepatic mixed function oxidase (MFO) enzymes. Chronic dietary administration of PBBs to mature female rats results in a "mixed" pattern of induction, with increases in both cytochrome P-450 and P,-450 associated enzymes. Acute administration of PBBs (150 mg/kg IP) to mature female rats resulted in a time-dependent induction of MFO activities; the P-450-dependent enzymes were simulated early (24-48 hr after administration) while the P,-450 dependent enzymes reached maximal activities at later time points. However, studies of the kinetics and patterns of inhibition of the induced enzymes along with gel electrophoresis studies of the microsomal proteins indicate that PBBs may induce different proteins from those induced by the classical P-450 and P,-450 inducers, phenobarbital and 3methylcholanthrene. In addition, the pattern of enzyme induction caused by PBBs in developing ratsdiffers from that in adults, in that the P,-450-associated enzymes are stimulated prior to the P-450associated enzymes. The overall pattern of enzyme induction in extrahepatic tissue differs from that seen in the liver and sex differences in enzyme induction have also been demonstrated. As modifications of MFO activity may alter the toxicity of chemicals, these findings suggest that the toxicity of chemicals may be altered in animals exposed to PBBs and that these toxicities may exhibit age, sex, and organ specificities different from those seen in control animals.

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“…Enzyme inducing agents have been shown to modify the toxicity of chemicals (44)(45)(46)(47)(48)(49). Both PB and 3MC modify the toxicity of agents such as CCl4, acetaminophen, and bromobenzene.…”

Section: Toxicological Consequences Of Mixed Function Oxidase Stimulamentioning

confidence: 99%

Characteristics of cytochrome P-450 and mixed function oxidase enzymes following treatment with PBBs.

Dent¹

1978

Environ Health Perspect

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The mixture of PBBs in FireMaster BP-6 has been demonstrated to constitute potent inducers of hepatic and extrahepatic mixed function oxidase (MFO) enzymes. Chronic dietary administration of PBBs to mature female rats results in a "mixed" pattern of induction, with increases in both cytochrome P-450 and P1-450 associated enzymes. Acute administration of PBBs (150 mg/kg IP) to mature female rats resulted in a time-dependent induction of MFO activities; the P-450-dependent enzymes were simulated early (24-48 hr after administration) while the P1-450 dependent enzymes reached maximal activities at later time points. However, studies of the kinetics and patterns of inhibition of the induced enzymes along with gel electrophoresis studies of the microsomal proteins indicate that PBBs may induce different proteins from those induced by the classical P-450 and P1-450 inducers, phenobarbital and 3-methylcholanthrene. In addition, the pattern of enzyme induction caused by PBBs in developing rats differs from that in adults, in that the P1-450-associated enzymes are stimulated prior to the P-450-associated enzymes. The overall pattern of enzyme induction in extrahepatic tissue differs from that seen in the liver and sex differences in enzyme induction have also been demonstrated. As modifications of MFO activity may alter the toxicity of chemicals, these findings suggest that the toxicity of chemicals may be altered in animals exposed to PBBs and that these toxicities may exhibit age, sex, and organ specificities different from those seen in control animals.

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Enzyme Induction in the Process of Development

Cited by 5 publications

References 231 publications

Thyrotropin Releasing Hormone: Development of Inactivation System During Maturation of the Rat

Thyrotropin Releasing Hormone: Development of Inactivation System During Maturation of the Rat

Characteristics of Cytochrome P-450 and Mixed Function Oxidase Enzymes Following Treatment with PBBs

Characteristics of cytochrome P-450 and mixed function oxidase enzymes following treatment with PBBs.

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