Effects of aminergic drugs and glutamic acid on audiogenic seizures induced by early exposure to ethanol

Whole transcriptome analysis in offspring whose fathers were exposed to a developmental insult: a novel avian model

Although the effects of paternal exposure to insults on the offspring received limited attention in the past, it is currently gaining interest especially after understanding the mechanisms which may mediate such exposure effects. In the current study, the well-controlled avian model (Fayoumi) was utilized to investigate the effects of paternal exposure to the developmental insult, chlorpyrifos on the offspring's gene expression via mRNA and small RNA sequencing. Numerous mRNA gene expression changes were detected in the offspring after paternal exposure to the developmental insult, especially in genes related to neurogenesis, learning and memory. qPCR analysis of several genes, that were significantly changed in mRNA sequencing, confirmed the results obtained in mRNA sequencing. On the other hand, small RNA sequencing did not identify significant microRNA genes expression changes in the offspring after paternal exposure to the developmental insult. The effects of the paternal exposure were more pronounced in the female offspring compared to the male offspring. The results identified expression alterations in major genes (some of which were pertinent to the functional changes observed in other forms of early developmental exposure) after paternal insult exposure and provided a direction for future studies involving the most affected genes.

Parental Preconception and Pre-Hatch Exposure to a Developmental Insult Alters Offspring's Gene Expression and Epigenetic Regulations: An Avian Model

Parental exposure to insults was initially considered safe if stopped before conception. In the present investigation, paternal or maternal preconception exposure to the neuroteratogen chlorpyrifos was investigated in a well-controlled avian model (Fayoumi) and compared to pre-hatch exposure focusing on molecular alterations. The investigation included the analysis of several neurogenesis, neurotransmission, epigenetic and microRNA genes. A significant decrease in the vesicular acetylcholine transporter (SLC18A3) expression was detected in the female offspring in the three investigated models: paternal (57.7%, p < 0.05), maternal (36%, p < 0.05) and pre-hatch (35.6%, p < 0.05). Paternal exposure to chlorpyrifos also led to a significant increase in brain-derived neurotrophic factor (BDNF) gene expression mainly in the female offspring (27.6%, p < 0.005), while its targeting microRNA, miR-10a, was similarly decreased in both female (50.5%, p < 0.05) and male (56%, p < 0.05) offspring. Doublecortin's (DCX) targeting microRNA, miR-29a, was decreased in the offspring after maternal preconception exposure to chlorpyrifos (39.8%, p < 0.05). Finally, pre-hatch exposure to chlorpyrifos led to a significant increase in protein kinase C beta (PKCß; 44.1%, p < 0.05), methyl-CpG-binding domain protein 2 (MBD2; 44%, p < 0.01) and 3 (MBD3; 33%, p < 0.05) genes expression in the offspring. Although extensive studies are required to establish a mechanism-phenotype relationship, it should be noted that the current investigation does not include phenotype assessment in the offspring.

Embryonic exposure to ethanol increases the susceptibility of larval zebrafish to chemically induced seizures

Prenatal ethanol exposure is known to cause neurodevelopmental disorders. While high prevalence of epilepsy is observed among the children whose mothers abused alcohol during pregnancy, the results from animal studies are conflicting. Here, we investigated whether embryonic exposure to ethanol can increase the susceptibility to pentylenetetrazole (PTZ)-induced seizures in larval zebrafish. Embryos at 3 hours post-fertilization (hpf) were exposed to ethanol at the concentrations ranging from 0.25% to 1% for 21 hours. Control and ethanol-exposed larvae were challenged with PTZ at 7 days post-fertilization (dpf) at the concentrations of 2.5, 5 or 15 mM. The seizure behavior of larvae was recorded and analyzed using EthoVision XT 11. We found that embryonic ethanol exposure increased the percentage of larvae exhibiting typical stage II and III seizure and resulted in a significant reduction in stage I, II and III seizure latency in an ethanol concentration-dependent manner. Embryonic exposure to ethanol also significantly increased the severity of PTZ-induced seizures in larvae, as demonstrated by increased total distance traveled and the duration of mobility. This is the first demonstration that ethanol exposure during early embryonic stage can reduce the threshold for chemically induced seizures and increase the severity of seizure behavior in larval fish.

Alcohol, auditory functioning and deafness

This paper reviews studies of alcohol and auditory impairment and the treatment of deaf people with alcohol problems and concludes that: (a) alcohol affects auditory functioning, (b) prenatal exposure to alcohol is a risk factor for hearing impairment in FAS children,

Prenatal ethanol exposure: susceptibility to convulsions and ethanol's anticonvulsant effect in amygdala-kindled rats

The present experiments assessed the effects of prenatal ethanol exposure on the susceptibility to convulsions and on the anticonvulsant effect of ethanol using the electrical kindling model of epilepsy in rats. Adult male Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF), and ad libitum-fed control (C) treatment groups were tested following the implantation of a stimulation electrode in the left amygdala complex. The same rats were tested in four consecutive experiments. Both E and PF rats showed a slightly slower rate of kindling than C rats, as measured by convulsion class but not as measured by forelimb clonus duration (experiment 1). However, the groups did not differ significantly in the electrical stimulation threshold for kindled convulsions (experiment 2). Furthermore, prenatal ethanol exposure had no significant effect on the dose-response curve for ethanol's (0, 0.9, 1.1, 1.3, and 1.5 g/kg, ip) anticonvulsant effect (experiment 3), or on the rate of tolerance development to ethanol's (1.5 g/kg, ip) anticonvulsant effect (experiment 4) on kindled convulsions. Thus, prenatal exposure to ethanol does not appear to have long-term effects on the susceptibility to convulsions or on the anticonvulsant effect of ethanol in adult male rats in the kindling model as used in the present experiments.

Hippocampal cholinergic alterations and related behavioral deficits after early exposure to ethanol

The present study was designed to ascertain septohippocampal cholinergic alterations and their related behavioral deficits after early exposure to ethanol. Mouse pups were exposed to ethanol, 3 g/kg by daily subcutaneous injection on postnatal days 2-14. At age 50 days, the ethanol-exposed mice had significant reductions from control levels in eight-arm maze performance. For example, on the fourth testing day, the number of correct entries in the ethanol group was 21% below control levels (P < 0.05) and the number of trials needed to enter all arms was 48% above control (P < 0.001). It took the ethanol-exposed mice twice the time to reach criterion than it did control (P < 0.01). A 33% increase from control level in muscarinic receptor number (Bmax) was found in the treated mice of age 22 days and a 64% increase at age 50 days (P < 0.001). However, no differences between control and treated groups could be detected in the presynaptic component of the cholinergic innervation, choline acetyltransferase activity. The results suggest that early ethanol exposure acts on hippocampal function similarly to phenobarbital, probably via alterations in postsynaptic processes in the septohippocampal cholinergic pathways.

Prenatal alcohol exposure attenuates pentylenetetrazol-induced convulsions in rats

Female rats prenatally exposed to alcohol were tested at 35 days of age for susceptibility to pentylenetetrazol (PTZ)-induced convulsions. There was a significant dose-response effect of PTZ. Contrary to expectations, alcohol-exposed females were slightly but still significantly less convulsion-prone than pair-fed controls. These results suggest prenatal alcohol exposure reduces the susceptibility to convulsions in rats.

Audiogenic seizure susceptibility and auditory brainstem responses in rats prenatally exposed to alcohol

Rats prenatally exposed to alcohol (0%, 17.5%, or 35% ethanol-derived calories) were tested for audiogenic seizure susceptibility on one of postnatal days 18 to 23, then retested 5 days later. Prenatal alcohol exposure did not influence audiogenic seizure susceptibility or severity. There was, however, a significant increase in seizure incidence on the retest day for all groups, suggesting a priming effect. Auditory brainstem response (ABR) data suggested that prenatal alcohol exposure and acoustic trauma (i.e., exposure to an alarm bell used for eliciting audiogenic seizures) induced measurable sensorineural hearing loss, and that the combined exposure to alcohol and acoustic trauma interacted additively to produce greater hearing loss than either alone.

Pharmacological effects of phenylalanine on seizure susceptibility: an overview

The effects of excessive doses of phenylalanine on seizure susceptibility were examined in animal models in the past, primarily because of their relevance to phenylketonuria. It was thought that such effects might involve brain monoaminergic mechanisms. Recently, this issue has been pursued with a renewed interest but for a different reason. The dipeptide sweetener, aspartame, contains a phenylalanine residue. In the last three years, a number of studies involving as many as nine animal models of seizures have reexamined the effects of phenylalanine (and aspartame) on seizure thresholds. Data from these studies are in general agreement that aspartame at dosage levels below 1,000 mg/kg, or phenylalanine at equimolar doses, is without an effect on seizure susceptibility in animals. When the dosage level of aspartame reaches 1,000 mg/kg, the findings between various laboratories and from different animal models of seizures are inconsistent, showing either no effect or a proconvulsant effect. The Acceptable Daily Intake of aspartame in humans set by the Food and Drug Administration is 50 mg/kg/day. Thus, the data from the excessive bolus doses in rodents do not appear to be relevant to human use. This article provides a detailed review of the data from both early and recent studies and points out the methodological problems apparent at such high doses.

Increased tolerance in mice following prenatal exposure to barbiturate

HS/Ibg (heterogeneous stock) mice dams were fed milled mouse food containing 3 g/kg phenobarbital (PhB) in acid form and water as their only nutritional source from gestation days 9--19. Control females received milled food and water. Blood PhB levels of treated females and fetuses were 40--200 micrograms/ml blood. At the age of 50 days, male offspring were injected with C14 -sodium pentobarbital (PenB) (50 mg/kg). Sleep time and temperature loss were monitored and, in randomly selected individuals, brain PenB levels were determined upon awakening. The experiment was repeated on the same animals for 3 consecutive days. All offspring developed functional (central nervous system) tolerance during the 3 testing days as evidenced by the daily decrease in sleep time while brain levels of PenB upon awakening increased (P less than 0.001). Offspring who received PhB prenatally had generally shorter sleep times, less temperature loss, and higher brain PenB levels upon awakening than controls. The differences were most pronounced on the second day (sleep time reduced 27%, P less than 0.001; temperature loss 47%, P less than 0.001; brain PhB levels increased 23%, P less than 0.01).

The permissive role of glucocorticoids in the development of ethanol dependence and tolerance

In mice chronically treated with ethanol (in a liquid diet containing 6% ethanol ad libitum for 2 weeks), brain tryptophan hydroxylase (TPH) activity was increased (by 30-45% in whole brain), while brain tyrosine hydroxylase activity remained unchanged. Such chronic ethanol treatment also induced susceptibility to audiogenic seizures during withdrawal (60% incidence). When ethanol treatment was given to adrenalectomized (Adx) mice, the increase of brain TPH activity and the development of withdrawal audiogenic seizures were both prevented. In Adx mice receiving daily injections of corticosterone (0.5 mg/mouse), the ethanol-induced increase of brain TPH activity and the occurrence of withdrawal audiogenic seizures were both restored. Similarly, the ethanol-induced increase of liver alcohol dehydrogenase activity (by 60%) was prevented in Adx mice and restored by corticosterone replacement. It was noted that in all three cases replacement with such large doses of the corticoid did not enhance the ethanol effects, but merely restored the effects to the levels observed in intact mice. Apparently, glucocorticoids are required in a permissive role in order for the ethanol effects to occur.

Long term reduction of male agonistic behavior in mice following early exposure to ethanol

A system was developed to study the ability of early (pre- and neonatal) ethanol input to induce long lasting neural and behavioral changes. Ethanol was administered to E7b1/10bg and DBA/1Bg offspring through their parents who received 10% ethanol as their only liquid supply either before and during pregnancy, or from delivery until 14 days post partum, or during both periods. Thus, the offspring received ethanol transplacentally and/or through the mother's milk. The present paper is concerned with the male agonistic behavior at age 50 days of the treated offspring as compared with their pair fed controls. Early ethanol input resulted in a 23% increase in latency to attack in C57 mice and 58% in DBA, as well as a 49% (C57) and 38% (DBA) decrease in time spent fighting. The sensitive period to ethanol effect was apparently postnatal. Prenatal administration had no effect on agonistic behavior. DBA offspring were more aggressive than C57 and the scores of C57 offspring were more variable, thus indicating a lower phenotypic buffering in this strain.

Suppressant effects of alcohol on audiogenic seizures

Genetically seizure susceptible DBA/1/Bg mice fed 10% ethanol in their drinking water exhibited a marked diurnal variation in blood alcohol levels. At peak levels, sound-induced seizures were significantly reduced. At trough levels, seizures remained unaffected. Ethanol administered during early development enhanced seizures at post-weaning age. Such alcohol-augmented seizures were suppressed by ethanol feeding during the testing period, to the same base level as in animals not pretreated with ethanol in early life.