Potentiation of acoustic-trauma-induced audiogenic seizure susceptibility by salicylates in mice

Summary Combined exposure to noise and salicylates was found to produce greater acoustic trauma induced audiogenic seizure risk than exposure to the noise alone. The result suggests that salicylates could make the mouse cochlea more vulnerable to the traumatic action of noise.This work was supported by grants from the Australian Research Grants Committee.     

Rapid development of acoustic trauma-induced audiogenic seizure risk in 3 strains of seizure-resistant mice

Summary Audiogenic seizure risk can be induced in genetically seizure resistant mice by exposure to an intense noise a few days prior to testing for seizure. This experiment demonstrates that the priming induced seizure risk can develop within 6–16 h after priming. It was argued that this finding suggested an alternative hypothesis of priming involving peripheral auditory mechanisms.This study was supported by funds from Australian Research Grants Committee. I am grateful for the assistance of Miss Clare Aberdeen.     

Experimentally induced otitis and audiogenic seizure in the mouse

Summary Audiogenic seizures can be induced in genetically non-susceptible 17-day-old mice (Rb/3 strain) with various results. Priming only induced 9% of seizures, auditory insulation 3,8%, while experimental otitis leads to 79%. The hypothesis concerning disuse supersensitivity subsequent to acoustic deprivation was not confirmed by the experiment. However, modification of acoustic transmission at middle ear lever induced by otitis, or ear physical damage during the maturation period, exposes the upper nervous centers to intense stimulation to which the reaction is a recruiting response.     

Effect of diabetes on the enzymes of the cholinergic system of the rat brain

Summary Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities were determined in several brain regions of normal and streptozotocin-induced diabetic rats. The diabetic rats exhibited significant increase in ChAT activity (p<0.05) in all brain regions studied except for the cortex and the midbrain. Meanwhile, the diabetes condition was associated with significant increase (p<0.05) in AChE activity of the bulbus olfactorius, medulla oblongata and cerebellum. These data suggest that uncontrolled diabetes is associated with significant alterations in the brain cholinergic systems.To whom requests of reprints should be addressed.This work was supported by grants from the National Aeronautics and Space Administration (NSG 2183 and NAG-2-411), a grant from the National Institutes of Health (NIH Grant RR0811) and a grant from the Division of Research Resources, National Institutes of Health (NIH Grant RR03020).     

Effect of diabetes on the enzymes of the cholinergic system of the rat brain

Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities were determined in several brain regions of normal and streptozotocin-induced diabetic rats. The diabetic rats exhibited significant increase in ChAT activity (p less than 0.05) in all brain regions studied except for the cortex and the midbrain. Meanwhile, the diabetes condition was associated with significant increase (p less than 0.05) in AChE activity of the bulbus olfactorius, medulla oblongata and cerebellum. These data suggest that uncontrolled diabetes is associated with significant alterations in the brain cholinergic systems.     

Influence of treatment duration on audiogenic seizure susceptibility during barbiturate withdrawal in rats

Barbiturate withdrawal seizure susceptibility in rats increased with increasing duration of treatment during a 15-day treatment period in which the animals were given an i.p. dose of sodium barbital every 12 h. This method of producing dependence has clear advantages over previously described methods.     

Influence of treatment duration on audiogenic seizure susceptibility during barbiturate withdrawal in rats

Summary Barbiturate withdrawal seizure susceptibility in rats increased with increasing duration of treatment during a 15-day treatment period in which the animals were given an i.p. dose of sodium barbital every 12 h. This method of producing dependence has clear advantages over previously described methods.     

Effect of adrenalectomy on sound-induced seizure susceptibility and intensity in genetically susceptible rats

Summary Neither seizure susceptibility nor intensity was altered by sham-operation or by adrenalectomy in adult rats that are genetically susceptible to sound-induced seizures. Thus, sound-induced seizures in genetically susceptible rats are analogous to those in genetically susceptible mice to the extent that removal of the adrenal glands does not alter established seizure characteristics in either species.     

Altered brain cholinergic enzymes activity in the genetically obese rat

Genetically obese male Zucker rats (fa/fa) and their lean littermates (Fa/-) were used in this experiment. Fourteen-week-old obese and lean littermates were sacrificed and choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) enzymes were assayed in specific brain regions. The assays of these enzymes indicate that obese animals had a significantly lower ChAT activity in the cerebellum, pons, and cerebral cortex and a significant increase in ChAT activity in the thalamus and hypothalamus. Meanwhile, the cerebral cortex, cerebellum, midbrain, thalamus and hypothalamus of the obese animals showed significantly higher AChE activity than their lean littermates. It was concluded from this study that obesity may be associated with changes in the enzymes of the brain cholinergic system.     

Altered brain cholinergic enzymes activity in the genetically obese rat

Summary Genetically obese male Zucker rats (fa/fa) and their lean littermates (Fa/-) were used in this experiment. Fourteen-week-old obese and lean littermates were sacrificed and choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) enzymes were assayed in specific brain regions. The assays of these enzymes indicate that obese animals and a significantly lower ChAT activity in the cerebellum, pons, and cerebral cortex and a significant increase in ChAT activity in the thalamus and hypothalamus. Meanwhile, the cerebral cortex, cerebellum, midbrain, thalamus and hypothalamus of the obese animals showed significantly higher AChE activity than their lean littermates. It was concluded from this study that obesity may be associated with changes in the enzymes of the brain cholinergic system.This work was supported by a grant from the National Aeronautics and Space Administration (NAG 2-411), a grant from the National Institutes of Health (NIH RR 0811), and a grant from the Division of Research Resources, National Institutes of Health (NIH Grant RR 03020).     

Activity of some enzymes in experimental hypertension in the rabbit

Zusammenfassung Bei durch Nierenarterien-Drosselung nach kontralateraler Nephrektomie chronisch hypertonischen Kaninchen wird mit Antirenin regelmässig eine bestimmte hypotensive Wirkung erzeugt. Auffallend niedrige Reninblutwerte, stark herabgesetzte Monoaminoxydase-Aktivität und deutlich gesteigerte Dopadecarboxylase-Aktivität sind charakteristisch. Der Befund zeigt die Bedeutung der Niere in der Erzeugung der Blutdruckamine im Laufe einer chronischen Hypertonie.

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This investigation was aided in part by grants from the Office of the Surgeon General, United States Army (no. DA-49-007-MD-429), and from the National Health Institute, United States Public Health Service (no. H-444 (C 10)).     

Corticosteroid effects on cholinergic enzymes in ethanol-treated fetal brain cell cultures

Summary In the presence of ethanol, corticosterone and dexamethasone inhibit choline acetyltransferase and acetylcholinesterase activities in cultured fetal brain cells of the rat. These results suggest that corticosteroids may have an important influence on the activity of cholinergic enzymes in the fetal brain and may antagonize the effects of ethanol in this setting.     

Corticosteroid effects on cholinergic enzymes in ethanol-treated fetal brain cell cultures

In the presence of ethanol, corticosterone and dexamethasone inhibit choline acetyltransferase and acetyl-cholinesterase activities in cultured fetal brain cells of the rat. These results suggest that corticosteroids may have an important influence on the activity of cholinergic enzymes in the fetal brain may antagonize the effects of ethanol in this setting.     

Activity of orotate metabolizing enzyme complex and various urea-cycle enzymes in mutant mice with ornithine transcarbamylase deficiency

Summary The overall activity of the enzyme complex consisting of orotate phosphoribosyl transferase and orotidine monophosphate decarboxylase, and of various enzymes of the urea cycle, has been studied in sparse-fur (spf) mutant mice with ornithine transcarbamylase deficiency. The enzyme complex has a lower overall activity, which could be caused by disturbed pyrimidine metabolism due to hyperammonemia. Other enzymes of the urea cycle do not show any significant change.Acknowledgments. The research was supported by a grant from the Conseil des Clubs Sociaux and Fondation Justine Lacoste Beaubien, Montréal. The authors wish to thank Ms Louise Poulin and Ms Francine Poisson for technical assistance.     

Regional changes of the cholinergic system in the guinea-pig's brain after physostigmine

Riassunto L'eserina 0.2–5 mg/kg aumenta la ACh totale del cervello di cavia soprattutto nel telencefalo. Dopo trattamento sub-acuto, l'attività colinoacetilasica aumenta, forse per stimolazione mediata dei neuroni colinergici.     

Frequency distribution ofTrypanosoma cruzi in macrophages from resistant and susceptible strains of mice

Summary The frequency distribution ofTrypanosoma cruzi inside macrophages from normal of chronically infected resistant and susceptible mice obeys a negative binomial type of distribution. This implies that an aggregating mechanism operates inT. cruzi: macrophage interaction.Acknowledgments. We thank Dr Sylvio T. Torres for providing the inbred strains of mice. The work was supported by the Brazilian Research Council (CNPq) and the Financiadora de Estudos e Projectos (FINEP).