Gestational caffeine modifies offspring behaviour in mice

Behavioral profile assessment in offspring of Swiss mice treated during pregnancy and lactation with caffeine

The association between caffeine consumption and various psychiatric manifestations has long been observed. The objective was to assess the behavioral profile in offspring of Swiss mice treated during pregnancy and lactation with caffeine. For this purpose, two groups (n = 6 each and BW ~ 35 g) of female mice were treated during pregnancy and lactation by: tap water and caffeine solution at a concentration of 0.3 mg/mL through oral route. The offspring obtained, by completing 70 days of life, was underwent a behavioral battery test. Statistical analysis was performed by student t test and the different significance adopted was p < 0.05. According to our results, it was not found any significant differences in tail suspension and forced swimming tests. In anxiety related responses however, the mice of caffeine group had greater number of fecal pellets (178 %, p = 0.001) in the open field test, higher number of attempts (51 %, p = 0.03) in light-dark box and decreased percentage of entries in open arms (41 %, p = 0.01) in elevated plus maze test. Moreover, in the marble burying test, there was a significant decrease in the number of buried marbles compared with controls (110 %, p = 0,002). In the meantime, in the von Frey test, it was observed an exacerbation of mechanical allodynia both in basal conditions and after the carrageenan administration (p < 0.001). Furthermore, caffeine treatment during pregnancy and lactation causes long-term behavioral changes in the mice offspring that manifest later in life.

The Janus face of caffeine

Caffeine is certainly the psychostimulant substance most consumed worldwide. Over the past years, chronic consumption of caffeine has been associated with prevention of cognitive decline associated to aging and mnemonic deficits of brain disorders. While its preventive effects have been reported extensively, the cognitive enhancer properties of caffeine are relatively under debate. Surprisingly, there are scarce detailed ontogenetic studies focusing on neurochemical parameters related to the effects of caffeine during prenatal and earlier postnatal periods. Furthermore, despite the large number of epidemiological studies, it remains unclear how safe is caffeine consumption during pregnancy and brain development. Thus, the purpose of this article is to review what is currently known about the actions of caffeine intake on neurobehavioral and adenosinergic system during brain development. We also reviewed other neurochemical systems affected by caffeine, but not only during brain development. Besides, some recent epidemiological studies were also outlined with the control of "pregnancy signal" as confounding variable. The idea is to tease out how studies on the impact of caffeine consumption during brain development deserve more attention and further investigation.

Caffeine intake during pregnancy and risk of problem behavior in 5- to 6-year-old children

BACKGROUND AND OBJECTIVE

Human studies that have investigated the association between caffeine intake during pregnancy and offspring's behavioral outcomes are scant and inconclusive. We prospectively investigated the association between maternal caffeine intake during pregnancy and children's problem behavior at age 5 to 6 years. Mediation by fetal growth restriction and gestational age as well as effect modification by the child's gender and maternal smoking was tested.

METHODS

In a community based multiethnic birth cohort, dietary caffeine intake (coffee, caffeinated tea, and cola) was measured (maternal self-report, n = 8202) around the 16th week of gestation. At age 5, children's overall problem behavior, emotional problems, conduct problems, hyperactivity/inattention problems, peer relationship problems, and prosocial behavior were rated by both mother and teacher (n = 3439) with the Strengths and Difficulties Questionnaire. Analyses were adjusted for maternal age, ethnicity, cohabitant status, education, smoking and alcohol consumption during pregnancy, child's gender, family size, and prenatal maternal anxiety.

RESULTS

Caffeine intake was not associated with a higher risk for behavior problems or with suboptimal prosocial behavior. No evidence was found for mediation by fetal growth restriction or gestational age, nor for effect modification by the child's gender.

CONCLUSIONS

Results did not provide evidence for developmental programming influences of intrauterine exposure to caffeine on offspring's problem behavior at age 5. Present results give no indication to advise pregnant women to reduce their caffeine intake to prevent behavior problems in their children.

Increased emotional reactivity in rats following exposure to caffeine during adolescence

From 45 to 55 days after birth, male and female rats were treated via daily intraperitoneal injections with either isotonic saline, or 15 or 30 mg/kg caffeine. When 72-82 and 112-122 days old, their activity and emotional reactivity were assessed by means of frequencies of rearing, ambulation, immobility, defecation and urination recorded in an open field, as well as their occupancy of corners and center squares of the field, and their partial emergence and latencies to fully emerge from a small darkened chamber into a brightly lit arena. Rats treated with caffeine were probably more emotionally reactive than untreated controls as suggested by more immobility and defecation and urination. There were also effects on rearing and ambulation that might have arisen from increased impulsivity. Further evidence of caffeine treatment-induced higher emotional reactivity was found in the heavier adrenal glands of a small number of 10 months-old males. This occurred in the absence of any caffeine treatment effects on spatial reference memory measured by ability to identify a novel Y-maze arm. Changes between the two testing ages in rearing and emergence latencies, and sex-dependent changes in ambulation, defecation and corner and center squares occupancy, along with immobility for 30 mg/kg caffeine-treated subjects, were discussed in the light of possible changes in emotional reactivity. Sex differences in open-field rearing and ambulation, and testing age-dependent sex differences in corner and center squares occupancy were ascribed to higher emotional reactivity in males.

Teratogen update: evaluation of the reproductive and developmental risks of caffeine

Caffeine is a methylated xanthine that acts as a mild central nervous system stimulant. It is present in many beverages, including coffee, tea, and colas, as well as chocolate. Caffeine constitutes 1-2% of roasted coffee beans, 3.5% of fresh tea leaves, and approximately 2% of mate leaves (Spiller, '84; Graham, '84a,b). Many over-the-counter medications, such as cold and allergy tablets, headache medicines, diuretics, and stimulants also contain caffeine, although they lead to relatively minimal intake (FDA, '86). In epidemiological studies, it is assumed that one cup of coffee contains < or =100 mg of caffeine, and soft drinks, such as colas, contain 10-50 mg of caffeine per 12-ounce serving. The per-capita consumption of caffeine from all sources is estimated to be about 3-7 mg/kg per day, or approximately 200 mg/day (Barone and Roberts, '96). Consumption of caffeinated beverages during pregnancy is quite common (Hill et al., '77) and is estimated to be approximately 144 mg/day, or 2.4 mg/kg for a 60-kg human (Morris and Weinstein, '81). However, pregnant women appear to consume slightly less than do other adults, approximately 1 mg/kg per day (Barone and Roberts, '96). This decrease may be interrelated with taste aversion (Hook, '76; Little, '82). The medical literature contains many varied references that appear to indicate that human adverse reproductive/developmental effects are produced by caffeine. If caffeine indeed causes such effects, the reproductive consequences could be very serious because caffeine-containing foods and beverages are consumed by most of the human populations of the world, and consumption in the United States is estimated to be 4.5-kg/person/year (Narod et al., '91). Therefore, the medical literature dealing with developmental and reproductive risks of caffeine was reviewed, and the biological plausibility of the epidemiological and animal findings, as well as the methods and conclusions of previous investigators, were evaluated. The epidemiological studies describe exposures of women to caffeine during pregnancy, as well as the occurrence of congenital malformations, fetal growth retardation, small-for-date babies, miscarriages (spontaneous abortions), behavioral effects, and maternal fertility problems that presumably resulted from the caffeine consumption. A few epidemiological studies were concerned with the genetic effects of preconception exposures to caffeine. Animal studies, conducted mostly in pregnant rats and mice, were designed to produce malformations. The objectives of the present review are to summarize the findings from the various clinical and animals studies, objectively discuss the merits and/or faults inherent in the studies and establish a global reproductive risk assessment for caffeine consumption in humans during pregnancy. It should be noted that evaluation of the developmental risks of caffeine based solely on epidemiological studies is difficult because the findings are inconsistent. Even more important, is the fact that caffeine users are subject to multiple confounding factors that make analyses difficult and prevent investigators from reaching definitive conclusions. For example, the caffeine content of foods and beverages can vary considerably, which can interfere with obtaining valid interpretations from many human studies. Isolated epidemiological studies dealing with the risk of abortion, without evaluating other developmental and reproductive effects, are the most difficult to interpret, because they present special problems that are sometimes ignored in epidemiological studies. The results of animal studies are probably most helpful in solving some of the dilemmas created by the epidemiological studies. An animal study reported in 1960 first focused our attention on the potential developmental effects of caffeine. However, the exposure reported by Nishimura and Nakai ('60) was an intraperitoneal dosage of 250 mg/kg in the mouse, an extremely high dosage that would result in a blood plasma level that could never be obtained from consuming caffeine containing products. More recent animal studies have demonstrated, that depending on the method of administration and species, the developmental NOEL in rodents is approximately 30 mg/kg per day, the teratogenic NOEL is 8,100 mg/kg per day, and the reproductive NOEL approximately 80-120 mg/kg per day. Lack of biological plausibility to support the concept that caffeine has been responsible for human malformations is another important part of this analysis. For example, no one has described the Caffeine "teratogenic syndrome," a cluster of malformations associated with caffeine ingestion. Proven human teratogens have an identifiable syndrome. The malformations described in the animal studies at very high doses fit the description of vascular disruptive types of malformations. (ABSTRACT TRUNCATED)

Maternal caffeine intake has minor effects on adenosine receptor ontogeny in the rat brain

Maternal caffeine intake has been suggested to influence the offspring. We have studied the effects of maternal caffeine intake on adenosine and GABA receptors, targets for caffeine, during development of the rat brain. Caffeine (0.3 g/L) was added to the drinking water of rat dams during pregnancy and early postnatal life. Adenosine A1 and A2A and GABAA receptor development was studied using receptor autoradiography and in situ hybridization. Pups were examined on embryonic d 14 (E14), E18, E21, 2 h after birth (P2h), P24h, postnatal d 3 (P3), P7, P14, and P21. Adenosine A, receptor mRNA was detected at E14 and receptors at E18. A1 mRNA levels increased from the level reached at E18 between P3 and P14 (maximally a doubling), whereas A, receptors, studied by [3H]-1,3-dipropyl-8-cyclopentyl xanthine binding, increased later and to a much larger extent (about 10-fold) postnatally. Caffeine treatment had no significant effect on adenosine A1 receptors or on A1 receptor mRNA. A2A mRNA had reached adult levels by E18, whereas receptor levels were low or undetectable before birth and increased dramatically until P14. Caffeine did not influence A2A receptors or A2A receptor mRNA at any stage during development. [3H]-flunitrazepam binding, representing GABAA receptors, showed large regional variations during ontogeny, but there were no clear differences between the caffeine-exposed and the nonexposed pups. Thus, exposure to a low dose of caffeine during gestation and postnatal life had only minor effects on development of adenosine A, and A2A receptors and GABAA receptors in the rat brain.

Can Prenatal Caffeine Exposure Affect Behavioral Inhibition?

Given the widespread use of caffeine and its potential nonoptimal effects during pregnancy, it is remarkable and distressing that almost nothing is known about the long-term effects of prenatal caffeine exposure in humans. Research on nonhumans reveals that prenatal caffeine exposure is associated with an enduring tendency toward a profile of fearfulness, hypoactivity, and exaggerated stress in uncertain situations. A similar pattern of behavioral inhibition has been observed in humans and has been attributed to various causes such as inborn temperament or environmental influences. The author's conjecture is that prenatal caffeine exposure could be an additional factor contributing to the tendency toward behavioral inhibition. One mechanism for this effect is that caffeine causes an upregulation of adenosine receptors, thus creating a vulnerability to adenosine-induced inhibition of neuronal firing and neurotransmitter release.

Neonatal caffeine alters passive avoidance retention in rats in an age- and gender-related manner

Chronic administration of an adenosine receptor antagonist disturbs spatial learning and memory in adult mice and neonatal caffeine exposure results in long-term behavioral and biochemical sequelae in mice and rats. We thus postulated that early treatment with caffeine would have latent effects on learning and memory as measured in a passive avoidance paradigm. Rats were not handled or received caffeine (15-20 mg/kg/day) by gavage over postnatal days 2-6. At 28 or 70-90 days of age, rats were trained to avoid an electrified grid and tested for retention 24 h, 72 h, and 7 days later. At 28 days, caffeine-exposed rats required more trials to meet criterion than did control rats, regardless of gender. There was minimal effect on retention of either neonatal treatment or gender at this age. At 70-90 days, there was no effect of either gender or treatment on learning; however, there was a significant effect of gender (P < 0.05) on retention at 24 h that was more pronounced in neonatally caffeine-treated rats (P < 0.01). At 72 h, the effect of caffeine on retention differed between male and female rats. Neonatal caffeine exposure significantly improved retention in females (P < 0.01) and significantly decreased retention in males (P < 0.05). Thus, caffeine exposure limited to the first week of life resulted in alterations in passive avoidance retention that became apparent over pubertal development. These changes were a function of the gender of the animal.

Demonstration of congenital anomalies in the joints of the forelimbs and hindlimbs caused by several pharmacological agents

In this study, fetal joint abnormalities caused by cytosine arabinoside, caffeine, sodium salicylate, and retinyl acetate administration during pregnancy, were investigated. In the cytosine-arabinoside-administered group, complete disappearance of joint spaces in the forelimbs, and narrowing or complete disappearance of joint spaces in the hindlimbs was highly noticeable. In the caffeine group, in all forelimb joints starting from art, humeri, there were abnormal fusions in bones, together with occasional disappearance of the joint space. In hindlimbs, similar findings were observed. In the sodium salicylate group, the complete disappearance of joint space and surfaces among humerus-radius and ulna was striking, and occasional fusions in tarsometatarsal joints were also present. Severe narrowing of the same joint space in the retinyl acetate group was striking. Total disappearance of the articulation manus and carpometacarpal joints was observed, together with hindlimb joint and bone findings.

Potential teratogenic and neurodevelopmental consequences of coffee and caffeine exposure: a review on human and animal data

The teratogenic effect of caffeine has been clearly demonstrated in rodents. The sensitivity of different animals species is variable. Malformations have been demonstrated in mice at 50-75 mg/kg of caffeine, whereas the lowest dose usually needed to induce malformations is 80 mg/kg in rats. However, when caffeine is administered in fractioned amounts during the day, 330 mg/kg/day are necessary to reach teratogenicity in rats. In rodents, the most frequently observed malformations are those of the limbs and digits, ectrodactyly, craniofacial malformations (labial and palatal clefts) and delays in ossification of limbs, jaw and sternum. Nevertheless, even in rodents, caffeine can be considered as a weak teratogenic agent, given the quite large quantities of caffeine necessary to induce malformations and the small number of animals affected. In humans, caffeine does not present any teratogenic risk. The increased risk of the most common congenital malformations entailed by moderate consumption of caffeine is very slight. However, caffeine potentiates the teratogenic effect of other substances, such as tobacco, alcohol, and acts synergistically with ergotamine and propranolol to induce materno-fetal vasoconstrictions leading to malformations induced by ischemia. Therefore, even though caffeine does not seem to be harmful to the human fetus when intake is moderate and spread out over the day, some associations, especially with alcohol, tobacco, and vasoconstrictive or anti-migraine medications should be avoided. Maternal consumption of caffeine affects brain composition, especially in case of a low-protein diet and also seems to interfere with zinc fixation in brain. Maternal exposure to caffeine induces also long-term consequences on sleep, locomotion, learning abilities, emotivity, and anxiety in rat offspring, whereas in humans, more studies are needed to ascertain long-term behavioral effects of caffeine ingestion by pregnant mothers.

Consequences on the newborn of chronic maternal consumption of coffee during gestation and lactation: a review

The present review is devoted to effects on the newborn of maternal ingestion of caffeine during gestation and lactation. In rodents, caffeine is able to induce malformations, but usually at high doses never encountered in humans; indeed, when caffeine is administered in fractioned quantities during the day, as it is the case with human caffeine intake, caffeine is no longer a teratogen in rodents. Caffeine ingested during gestation induces a dose-dependent decrease in body weight, but only for large doses (> 7 cups/day of coffee), whereas it has no effect at moderate doses. Maternal caffeine consumption during gestation affects hematologic parameters in both rat and human infants and induces long-term effects on sleep, locomotion, learning abilities, emotivity and anxiety in rodent offspring, whereas in humans, more studies are needed to determine the consequences of early caffeine exposure on behavior. Investigators do not agree on the quantities of the methylxanthine found in breast milk, but caffeine does not change breast milk composition, and rather, stimulates milk production. We conclude in this review that maternal caffeine consumption in moderate amounts during gestation and lactation has no measurable consequences on the fetus and newborn infant. Pregnant mothers, however, should be advised to consume coffee and caffeinated beverages in moderation, especially because of the prolonged half-life of caffeine both during the last trimester of pregnancy and in the newborn infant.

Caffeine does not increase synthesis of heat shock proteins in rat embryos

Caffeine exposure in utero in rats is known to result in intrauterine growth retardation and lowered birth weight as well as changes to behaviour and brain biochemistry. We have investigated whether caffeine's embryotoxicity is a result of the events associated with increased hsp synthesis, i.e., disruption to normal protein synthesis. Caffeine (30 mg/kg) was administered orally to pregnant rats as single or repeated doses. Embryos were removed 3 h after dosing on gestation day (GD) 9, 10, 11 and 12 and total embryonic protein and RNA analysed. There was no change in the mRNA or protein levels of hsp 88, 71/73, and 25 after acute or chronic treatment. To separate the direct effect of caffeine from those mediated through the mother, whole rat embryo culture was used. Caffeine (50 micrograms/ml) for 90 min did not increase hsp 88, 73 or 25 mRNA levels in 9.5, 10.5 and 11.5 GD cultured embryos. We conclude that in vivo or in vitro treatment of 9-12 GD rat embryos with moderate to high doses of caffeine does not increase the synthesis of the major mammalian hsps. Hence, hsp induction is unlikely to play a role in the embryotoxic actions of caffeine.

Behavioral and biochemical consequences of perinatal exposure of mice to instant coffee: a correlative evaluation

In the present study, the lasting effects of prepartum and perinatally consumed instant coffee by female mice on the behavior as well as on the level of activities of certain enzymes in the tissues of their male offspring have been investigated. The behavioral observations of nonsocial investigation, defense, displacement, latency to threat and naso-nasal contact has decreased significantly in offspring of treated mothers, while the threat, attack, latency to threat and attack and number of fights have increased significantly. Hence, coffee has proven to be an inducer of hyperactive behavior in these offspring. Such effects are both dose dependent and duration-of-treatment dependent. Moreover, variations were detected in the level of AChE activity in the brain tissues of these offspring together with variations in the levels of AcPase and AlPase activities in their liver, kidneys and testes. Such variations in these organs have developed in utero, making these enzymes convenient markers in teratological studies.

Behavioral effects of exposure to caffeine during gestation, lactation or both

Open-field behavior and latencies of emergence from a darkened chamber to a brightly lit arena were recorded at 1, 2, 4 and 6 months after birth in male and female rats that had been exposed to 26 or 45 mg/kg/day caffeine ingested by dams in their drinking water during gestation, 25 or 35 mg/kg/day during lactation or to the two low or high doses ingested during both gestation and lactation. One or both of the gestational or lactational doses reduced locomotor activity and increased defecation in the open field at all ages for males only. Rearing was decreased for both sexes by 25 mg/kg/day lactational caffeine. Numbers of rats that failed to or took longer than 1 min to emerge into the brightly lit arena were increased by 26 mg/kg/day gestational caffeine. All rats that had been exposed to either dose combination of caffeine during both gestation and lactation showed less locomotor and rearing activity, reduced tendencies to emerge within 1 min and, at 6 months of age only, more defecation in the open field. It was concluded that the effects of gestational and lactational exposure to caffeine were additive in their modification of the developing brain as reflected in decreased motor activity possibly arising from heightened emotional reactivity to the testing situation. Hypersensitivity of males to caffeine exposure during either gestation or lactation separately seemed to diminish when exposure was increased for all rats through experience of the drug during both gestation and lactation. Possible involvement of caffeine-induced increases in adenosine receptors in the type of results obtained was discussed.

Prenatal exposure to AVP or caffeine but not oxytocin alters learning in female rats

Rats whose mothers had been treated with 1 microgram of arginine vasopressin (AVP) or oxytocin (OXT), 15 mg of caffeine, or saline on days 13-19 of gestation were given training on a passive avoidance response as adults. Female rats whose mothers had been exposed to either AVP or caffeine demonstrated enhanced retention of the response. No effects were found for male rats or for exposure to oxytocin. These results suggest that prenatal exposure to AVP or caffeine produced sexually dimorphic effects on learning and that the effects are specific to the structure of AVP.

Sex-and age-dependent effects of prenatal exposure to caffeine on open-field behavior, emergence latency and adrenal weights in rats

Pregnant rats were provided with drinking water containing 0, 0.23 or 0.3 mg/ml of caffeine throughout gestation. These concentrations gave rise to daily doses of 0, 28 and 36 mg/kg. Open-field behavior and latencies to emerge from a darkened chamber were observed in offspring at regular intervals from 1 to 8 months after birth. The main results revealed increases in open-field locomotor and rearing activity with 28 but not 36 mg/kg/day. The opposite pattern characterized emergence latency. These changes were more typical of male rats particularly when older. Combining the present results with those of an earlier study by the authors strengthened the curvilinear trends observed and led to the conclusion that, low doses of prenatal caffeine increase activity and decrease emotionality. Higher doses may have the opposite effects to the point that the significant differences from control subjects reported earlier can occur. When 8 months old, female but not male rats prenatally exposed to 36 mg/kg/day of caffeine had significantly heavier adrenal glands than controls.

Preliminary indications that functional effects of fetal caffeine exposure can be expressed in a second generation

Caffeine, added to the drinking water of males used for impregnation and gestant BALB/c mice such that their daily caffeine intake was 60 mg/kg, modified the passive avoidance behavior of the offspring when tested as adults. Caffeine-treated and control mice of the F1 generation were then cross-mated. The F2 generation was not exposed to caffeine but, when tested as adults, there were significant differences in passive avoidance latencies among the F2 mice. These data are a preliminary indication that effects resulting from fetal caffeine exposure in the F1 mice can be expressed in a second generation. Some cross-fostered groups of mice were tested in both the F1 and F2 generations as an initial control for postnatal maternal effects. F1 caffeine-treated mice also carried significantly smaller litters, implying that prenatal caffeine exposure could have affected the reproductive ability of these mice. It is tentatively concluded that a changed uterine environment, possibly interacting with an effect on the germ line, may be reflected in neurobehavioral effects in the second generation.

Prenatal caffeine causes long lasting behavioral and neurochemical changes

The effects of prenatal exposure to caffeine were studied on later physical development, behavior and brain neurochemistry. Daily doses (150, 300 or 450 mg/L) of caffeine were given to rat dams during the last week of pregnancy. Prenatal caffeine exposure resulted in a number of behavioral and neurochemical changes in the offspring which were long lasting and dose related. The low dose (150 mg/L) of prenatal caffeine caused hyperactivity in an open-field. The high dose of caffeine caused learning disabilities in complex visual and auditory discrimination learning paradigms while simple motor learning or a spatial orientation task were not affected. Both male and female offspring showed some behavioral effects of caffeine exposure. The medium and high doses of caffeine resulted in weight gain that was observable as early as 35 days of age and increased progressively with age. This weight gain was associated with increased food intake. The neurochemical studies carried out at 2-3 months of age revealed an increase in choline uptake in hippocampus, mainly in the animals treated with the lower doses of caffeine and higher protein concentration (microgram/mg wet tissue) in the cortex or hippocampus of offspring exposed to the higher doses of caffeine. At 15 months of age, choline uptake in the frontal cortex was significantly reduced in the animals prenatally exposed to the 300 and 450 mg/L dose.

Behavioral effects of prenatal exposure to caffeine in rats

For the first ten days of gestation, rats received daily intraperitoneal injections of 10-40 mg/kg of caffeine. Open field behavior of their fostered offspring was observed 61, 145 and 188 days after birth. While there were no obvious physical effects of the prenatal experience, at 61 days caffeine exposure led to an increase in the number of times seen walking for males only and increased ambulation (distance travelled) for both sexes. At 145 days occupancy of centre squares of the apparatus and latencies of emergence from a dark box into an illuminated arena were higher for caffeine-exposed males only. When 188 days old, rats exposed to 20 mg/kg of caffeine tended to exhibit less locomotor activity and more grooming behavior while spending more time in corners of the apparatus. Male rats prenatally exposed to 20 mg/kg of caffeine avoided the centre squares of the apparatus. It was concluded that prenatal caffeine had modified the development of mechanisms controlling voluntary motor activity in the youngest rats. However, at older ages, the prenatal effect was probably manifested as increased timidity or emotional reactivity. Males were often affected differently from females by the prenatal treatment.

Protein-energy malnutrition during pregnancy alters caffeine's effect on brain tissue of neonate rats

We studied whether protein-energy malnutrition changed brain susceptibility to a small dose of caffeine in newborn rats. Since we had demonstrated previously that caffeine intake during lactation increased the brain neuropeptide on newborns, we investigated further the effects of the prenatal administration of caffeine on TRH and cyclo (His-Pro). From day 13 of gestation to delivery day, pregnant rats in one group were fed either a 20% or a 6% protein diet ad libitum, and those in the other group were pair-fed with each protein diet supplemented with caffeine at an effective dose of 2 mg/100 g body weight. Upon delivery, brain weight, brain protein, RNA, DNA and the neuropeptides thyrotropin-releasing hormone (TRH) and cyclo (His-Pro) were measured in the newborn rats. A 6% protein without caffeine diet caused reductions in brain weights and brain protein, RNA and DNA contents, but did not alter brain TRH and cyclo (His-Pro) concentrations in the newborn animals. In the offspring from dams fed a 6% protein diet, caffeine administration significantly elevated brain weights and brain contents of protein, RNA and DNA. In contrast, these values were similar between noncaffeine and caffeine-supplemented animals in a 20% protein diet group. Brain TRH and cyclo (His-Pro) concentrations were not changed by caffeine administration. These data suggest that caffeine augments protein synthesis in the newborn rat brain when malnourished, but that the same dose of caffeine did not affect protein synthesis in brains of newborn rats from normally nourished dams. Therefore, the present findings indicate that the nutritional status of mothers during pregnancy has important implication in the impact of caffeine on their offspring's brains.

Long-lasting tolerance to stimulatory effects of perinatal caffeine treatment

Pregnant rats were treated with caffeine in their drinking water at doses of 136.3 mg/kg/day during gestation and 222.2 mg/kg/day during lactation. The resulting offspring at 60 days of age (40 days after drug withdrawal) were tested in an activity monitor cage. Spontaneous locomotor activity and that induced by caffeine (10, 30, 60 mg/kg/day) were observed. Treated rats showed apparent tolerance to caffeine-induced motility. Therefore perinatal caffeine treatment seems to induce long-lasting tolerance. This finding contrasts with those previously reported for chronic caffeine treatment in adult rats, where tolerance disappears after only 2-3 weeks following drug withdrawal.