Effects of maternal consumption of ethanol, barbital, or chlordiazepoxide on the behavior of the offspring

Primidone-induced embryolethality and DRL deficits in surviving offspring

Pregnant Sprague-Dawley rats were administered primidone (PRM) by oral gavage on gestation days 8-20 in doses of 0 or 120 mg/kg. This dose did not produce body weight differences in the dams during the dosing period nor were there differences in the birth weights of the offspring. PRM was embryolethal with only 43% of drug-treated dams maintaining their pregnancies, whereas 100% of the pregnant controls produced offspring. An analysis of resorption sites in PRM-treated dams that did not deliver showed a nearly identical number of implantation sites (12.6) compared to the litter size of controls (12.8) that delivered pups. There were no overall differences in exploratory activity levels between PRM-treated and control animals. However, in the PRM-treated females there was an absence of the sexually dimorphic increase in activity seen in control females when compared to control males. The PRM-treated males showed an impairment in the acquisition of a DRL-20 (differential reinforcement of low rates) operant schedule over a 9-week acquisition period. There were no differences in the total response rates between the groups, suggesting that this is a specific learning deficit and not a performance deficit. The results of these experiments provide evidence that prenatal PRM exposure can be embryolethal and also impair behavior in the surviving rat offspring.

Developmental and behavioral effects of prenatal primidone exposure in the rat

Pregnant Sprague-Dawley rats were administered primidone (PRM) by oral gavage on gestation days 8-17 in doses of 0.40, and 80 mg/kg. Although these doses of PRM did not produce significant differences in litter size, birth weight, mortality, date of attainment of developmental landmarks or measures of preweaning reflex and motor development, there were a number of significant differences that developed as the animals approached and entered adulthood. When tested as adults, the 80 mg/kg male rats showed a deficit in the performance of an eight-arm radial maze task. These same animals showed a significant reduction in open field activity when tested as adults. In addition, both male and female PRM-treated animals showed reduced body weights at different periods corresponding to onset of sexual maturation during development. These findings are consistent with the larger body of literature reporting on the neurobehavioral teratology of phenobarbital, including its ability to produce lesions in the hippocampus and endocrine dysfunction resulting in reproductive deficits. These results suggest that PRM produces its adverse effects as a result of its metabolism to phenobarbital, which in turn affects the limbic system.

Effects of chronic prenatal, neonatal and adult exposure to barbiturates on mitochondrial benzodiazepine receptors in mouse testis

In the present study we investigated the effect of chronic exposure to phenobarbital, administered to mice during the prenatal or neonatal period, as well as to adult mice, on mitochondrial benzodiazepine receptors in the testis. Three modes of treatment were investigated: (1) offspring of pregnant mice receiving food containing 3 g/kg phenobarbital until gestational day 18 were killed at 22 or 50 days of age and assayed for receptor binding (prenatal group); (2) offspring of untreated mice were injected subcutaneously once daily with 50 mg/kg phenobarbital on days 2-21 of age and killed at 22 or 50 days of age (neonatal group); (3) adult mice were injected subcutaneously once daily for 3 weeks with 50 or 100 mg/kg phenobarbital (adult group). Prenatal or neonatal exposure to phenobarbital did not alter the testicular weight in all groups (except for the neonatally exposed group killed at 22 days of age), or the mitochondrial benzodiazepine receptor binding characteristics. However, the maximal number of these receptors in the testes of mice in the adult group receiving 100 mg/kg phenobarbital was significantly increased (42%, P < 0.05), compared to controls. The administration of 50 mg/kg phenobarbital to the adult group also induced an increase (27%, non-significant) in testicular mitochondrial benzodiazepine receptors. Phenobarbital administration did not affect the receptor affinity values or the weight of the testis. It is unclear whether these receptor alterations due to chronic phenobarbital exposure of adult mice reflect functional changes in the testis.

Effects of prenatal ethanol exposure on later sensitivity to the low-dose stimulant actions of ethanol in mouse offspring: possible role of catecholamines

The purpose of this study was to examine whether prenatal ethanol (EtOH) exposure alters later sensitivity to the low-dose stimulant effects of EtOH. Because the locomotor stimulant effects of EtOH are thought to be mediated, at least in part, by activation of brain monoamine systems, and because prenatal EtOH exposure has been shown to alter brain monoamine activity, it was hypothesized that prenatal EtOH exposure may alter sensitivity to the stimulant actions of EtOH. To test this hypothesis, sensitivity to the locomotor stimulant effects of various challenge doses of EtOH was examined in male and female offspring from prenatal alcohol (A), pair-fed (PF), and lab chow (LC) groups at different ages. In addition, to address the hypothesis further, sensitivity to the catecholamine synthesis inhibitor alpha-methyl-p-tyrosine (AMPT) was examined in these offspring, as well. Results indicated that male offspring prenatally exposed to EtOH exhibited reduced baseline activity and a blunted stimulant response to all challenge doses of EtOH (0.75-1.5 g/kg) in comparison with control offspring at 30 days of age, but these effects appeared to "normalize" at 70 days of age. Female EtOH-exposed offspring also exhibited a reduced baseline level of activity relative to control offspring, as well as a blunted stimulant response to the lowest challenge dose of EtOH (0.75 g/kg) at 30 days of age, and these effects persisted into adulthood. The stimulant response to higher doses of EtOH did not significantly differ among prenatal treatment groups in young or adult female offspring. However, because baseline activity was significantly lower in female EtOH-exposed offspring than control offspring, the stimulant response to these doses of EtOH (1.125 and 1.5 g/kg) was relatively greater than that for PF and LC offspring. Importantly, none of the differences in performance among the prenatal treatment groups could be attributed to an alteration in EtOH pharmacokinetics, because blood EtOH levels measured immediately following the 10-min test session were similar for all prenatal treatment groups across all of the EtOH test doses. Further, a similar response profile as that observed following EtOH challenge at 70 days of age was obtained following phenobarbital challenge (10-40 mg/kg). Finally, whereas AMPT (50-400 mg/kg) dose-dependently antagonized the stimulant effects of EtOH in all prenatal treatment groups, this effect of AMPT was significantly greater in mice prenatally exposed to EtOH in comparison with control offspring.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of prenatal phenobarbital on benzodiazepine receptor development

Phenobarbital (PB) was administered to pregnant mice during days 9-21 of gestation. Forebrain and cerebellar [3H]flunitrazepam ([3H]FLU) binding was assayed in the offspring at birth and at 21 days of age. Prenatal treatment produced a decrease in the number (Bmax) of [3H]FLU receptors in both the forebrain and cerebellum at birth. A small decrease in the [3H]FLU dissociation constant (KD) values in the forebrain was also detected at birth, but no changes were seen in the [3H]FLU KD values in the cerebellum. No changes were observed in forebrain and cerebellar [3H]FLU Bmax or KD values at 21 days of age, indicating that the effects of prenatal exposure to PB on [3H]FLU binding are eliminated during the postnatal development of the forebrain and cerebellum. The receptor affinity for the triazolopyridazine CL 218,872, which distinguishes the type I and type II benzodiazepine (BDZ) receptors, was not altered by prenatal PB treatment. The coupling of the BDZ receptor to the gamma-aminobutyric acid and pentobarbital binding sites was unaffected by exposure to PB in utero.

Benzodiazepines and the developing rat: a critical review

This paper reviews: the development of benzodiazepine binding-sites and the GABA system; the evidence that prenatal exposure to benzodiazepines can cause malformations; other persisting effects of developmental exposure to benzodiazepines; and the behavioral effects of benzodiazepines (and other relevant drugs) in immature animals. The review concentrates on the rat, since fundamental work in other species is scarce. The data on neurochemical development are found to be generally consistent; however, reports that the enhancement of benzodiazepine binding by GABA varies with age are controversial. The physical development of the rat is disturbed only by extremely high doses of benzodiazepines. The evidence for persisting effects after early exposure to benzodiazepines is impressive at first sight, but in most studies, confounding variables have not been eliminated. Startle and some learning tasks are affected by prenatal diazepam; submissiveness is affected by neonatal lorazepam; social behaviour and convulsions are affected by neonatal CGS 8216. Benzodiazepines inhibit chemically-induced seizures in neonatal rats, but the developmental profile of sensitivity to the convulsants is disputed. Benzodiazepines stimulate motor behavior in the neonatal rat.

Short-, medium-, and long-term effects of prenatal oxazepam on neurobehavioural development of mice

A benzodiazepine (oxazepam) was given to nulliparous mice on days 12-16 of pregnancy, and the development and young adult behaviour of the offspring were studied. Experiment 1, using 5, 15, and 50 mg/kg doses given PO twice daily, showed a dose-dependent retardation of postnatal development of several responses such as righting, bar holding, limb placing, and auditory startle. These changes were maximal in the first 2 postnatal weeks and then were markedly attenuated, or disappeared, being apparently related to a temporary retardation of body growth. A reduction of locomotor activity at 60 days was found only in the 50 mg/kg group. The effects of the 15 mg/kg dose on postnatal body growth and neurobehavioural development were replicated in Experiments 2 and 3. Moreover, in these experiments prenatal oxazepam reduced open field activity at 14-16 days and attenuated the hyperactivity induced by dl-amphetamine sulphate (2 mg/kg IP). On the other hand activity, habituation, and response to a scopolamine challenge (2 mg/kg IP) at 21-23 days were not significantly different from those of appropriate controls. Experiment 3, using a cross-fostering procedure, showed that postnatal maternal effects were not responsible for the changes so far mentioned. Experiment 2 also investigated the acquisition of several go-no go avoidance discriminations in a shuttle-box, using either light (L) or buzzer noise (N) as the "go" signal, a compound "no go" signal (NL in the L-"go" groups and LN in the N-"go" groups), and either an extinction or a passive avoidance contingency during the "no go" signal (4 weeks of training, starting at 60 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence and potentiation of external and internal fetal anomalies resulting from chlordiazepoxide and amitriptyline alone and in combination

The teratogenic potential of a combination of chlordiazepoxide (Cdz) and amitriptyline (Amt) was examined with regard to both internal and external anomalies. Timed pregnant golden hamsters were given a single intraperitoneal injection on day 8 of gestation of one of the following: chlordiazepoxide hydrochloride (28.5 mg/kg), amitriptyline hydrochloride (70.3 mg/kg), Cdz-Amt combination (28.5 mg/kg Cdz + 70.3 mg/kg Amt, in order to retain the 1:2.5 dose ratio utilized in a clinically-used preparation of these agents), or saline vehicle (control). Fetuses were recovered on gestation day 15 following maternal sacrifice. Cranial malformations were analyzed in Bouin's-fixed fetuses by making 1-mm coronal sections through each head, whereas visceral anomalies were examined following general dissection of each body. Amt alone produced a significant (P less than 0.05) incidence of bent tail and encephalocele, whereas Cdz significantly (P less than 0.05) altered the male:female ratio of surviving fetuses when compared with saline-injected controls. The Cdz-Amt combination caused significant increases in cranial malformations, open eye, bent tail, abnormal lung, and urogenital anomalies. The teratogenic effects of potentiation between the components of this combination are discussed in terms of external and internal malformations.

Effects of combined alcohol and benzodiazepine: a review

Both human and animal studies relating to the combined effects of alcohol and benzodiazepine (BZD) are reviewed. Although the combination of alcohol and BZD is sometimes associated with drug-induced deaths, drug overdoses and traffic accidents or fatalities, epidemiological information is lacking on the true extent of the combined abuse and on the patterns and prevalence of use of these two drugs. Since BZD are widely used for the short- and long-term treatment of alcoholics, these patients are deemed more at risk of developing BZD or alcohol/BZD dependence than the general population. There is a dire need for large-scale controlled studies concerning the efficacy of BZD in the long-term treatment of alcoholics. Compared to men, women are at a higher risk as far as the potential for BZD addiction is concerned, since they tend to use BZD more often. Epidemiologic studies on the patterns of use of BZD, alcohol or alcohol/BZD in pregnant women are called for. Animal models are also needed to ascertain whether prenatal exposure to both alcohol and BZD can impart long-lasting behavioral changes in the progeny. It is possible that BZD can exacerbate the damaging prenatal effects of alcohol.

Chronic neonatal treatment with CGS 8216: effects on the behaviour of adolescent rats

The behaviour of male adolescent rats was studied after neonatal administration of CGS 8216 (2.5 or 10 mg/kg/day). The pups were cross-fostered, and drug treatment (in a split-litter design) lasted from postnatal day 7 to day 28; behavioural tests began on day 31. In the social interaction test, neonatally-treated adolescents displayed an unusual profile of behaviour that was the opposite to the profile caused by acute CGS 8216 in adults. Their response to challenge doses of CGS 8216 was not significantly different from that of neonatal controls. In the holeboard test of exploratory behaviour, there was little sign of effects of the neonatal treatment, and the response to challenge doses of Ro 15-1788 or chlordiazepoxide was not differentially affected. However, neonatally-treated animals were less sensitive to the convulsant effects of pentylenetetrazole and picrotoxin. Lasting effects of neonatal CGS 8216 have been detected in adults; the effects seen in adolescents appear not to be identical, since a proconvulsant effect occurs in adults.

Exposure to ethanol during pregnancy in mice: potential importance of dose for the development of tolerance in offspring

CD-1 albino mice were given Portagen-10 percent ethanol (ETOH) or isocaloric Portagen-sucrose during pregnancy to determine if tolerance developed in utero and to describe the temporal pattern of its decline postnatally. ETOH mothers did not significantly increase their consumption of ETOH but gained in body weight during pregnancy, showed no signs in the open field of withdrawal from ETOH shortly after delivery and showed less pup-caring behavior than pair-fed controls (PFC). Among offspring 1, 3, 10, 25 and 60 days old, only 25-day old ETOH pups metabolized and cleared an anesthetic dose of ETOH more efficiently than PFC animals, suggesting the absence of Dispositional Tolerance in the other animals. PFC offspring 10 days old took significantly longer to lose the righting reflex than their ETOH counterparts following the anesthetic dose of ETOH, the difference being opposite that which would suggest the occurrence of Adaptive Tolerance. Data are discussed primarily in terms of decreases in dose of ETOH to which mothers and fetuses were exposed during pregnancy.

Long-lasting effects of early barbiturates on central nervous system and behavior

Forty years of prescribing barbiturates to pregnant women and infants, and thirty years of animal research have shown that barbiturates affect the developing central nervous system (CNS) and behavior. This paper compiles and reviews animal and selected human literature in this research area. Early barbiturate exposure in animals reduces brain weight with related changes in brain biochemistry and neuromorphology. Significant changes may be found in surviving adult offspring. Evidence of CNS and behavioral damage in human beings due to early barbiturate exposure is not clearcut, however, confounded by the conditions for which the drugs are prescribed. In animals, early drug exposure significantly reduces levels of hormones, vitamins, and other biologically active macromolecules via (long-lasting) induction of hepatic metabolizing enzymes. Whether or not in humans treated with barbiturates, hormone levels remain within the normal range (by-feed-back regulation) and, also, if vitamin deficiencies can be simply corrected by supplements is still being debated. Early barbiturates administered to animals is associated with long-lasting disturbances in activity, learning performance, sexual behavior, and reproductive function, but not in a simple dose-exposure related manner. Animal studies show that long-lasting functional tolerance to drugs develops following early barbiturate exposure. Although infants become "passively addicted" following in utero exposure, there is as yet no data on subsequent development of human adult tolerance. Drug related damage must, in any case, be weighed against therapeutic benefits of drug administration and the results of failure to treat.

Prenatal ethanol exposure permanently reduces the number of pyramidal neurons in rat hippocampus

The effect of prenatal ethanol exposure in the rat on the development of dorsal hippocampal pyramidal and dentate gyrus granule cells was examined. Ethanol was administered in a nutritionally adequate liquid diet to pregnant rats during days 10--21 of gestation. Control groups were either pair-fed the same liquid diet, except for equicaloric substitution of sucrose for ethanol, or received free access to pelleted laboratory food. The brains of 60-day-old offspring exposed to ethanol during gestation were found to have 20% fewer dorsal hippocampal pyramidal cells than did those of controls. Prenatal ethanol exposure, however, did not affect the number of dentate gyrus granule cells. Prenatal exposure to ethanol permanently reduced the number of prenatally formed hippocampal neurons without altering physical growth, which suggested that the developing nervous system is particularly sensitive to the toxic effects of ethanol.

Fetal exposure to ethanol enhances pituitary-adrenal and temperature responses to ethanol in adult rats

Long lasting effects of perinatal ethanol exposure were studied in adult rats who were the offspring of dams fed a 5.0% w/v ethanol-containing liquid diet ad libitum or pair-fed the isocaloric control diet during gestation weeks 2 and 3 or during postnatal week 1. Fetal exposure to ethanol reduced body weight of pups at birth unless the ethanol diet was supplemented with casein; neonatal exposure to the ethanol or pair-fed diets, casein supplemented or not, reduced pup weights until day 21 postnatally when weights of all fetally or neonatally exposed pups were normal. Between 52 and 120 days of age females were tested for pituitary-adrenal and temperature responses to a challenge dose of ethanol. Prenatally ethanol-exposed rats showed significantly higher plasma corticosterone titers and developed a greater hypothermia in response to an intraperitoneal injection of ethanol (0.75--1.5 g/kg) than did pair-fed controls. Similar responses enhancement did not occur in the postnatally ethanol-exposed rats. Temporal patterns of blood ethanol levels after an intraperitoneal injection of ethanol (1.5 g/kg) were similar in prenatally ethanol-exposed females and their pair-fed controls. The data indicate that exposure to ethanol in utero exerts persistent effects on the offspring, rendering them more responsive to the hypothermic and pituitary-adrenal activating effects of alcohol as adults.

Effects of prenatal ethanol exposure on avoidance conditioning in high- and low-avoidance rat strains

Two lines of rats selected for high- and low-avoidance performance consumed a nutritious liquid diet containing 35% ethanol-derived calories through days 5--18 of gestation. Control dams were pair-fed an identical liquid diet except for isocaloric substitution of sucrose for ethanol or ad libitum laboratory chow and water. Subsequently, the offspring of the low-avoider dams fed ethanol were found to be impaired ona two-way shock-avoidance conditioning when compared to the pair-fed and ad libitum controls from the same line. In contrast, the offspring of the high-avoider dams fed ethanol displayed similar levels of avoidance, responding to their controls. These results demonstrate that the effects on avoidance conditioning of in utero ethanol exposure are dependent upon the line of rat studied.