Persisting effects on adult brain monoamines of neonatal distress and carbon monoxide exposure

Effect of perinatal stress on the biogenic amine neurotransmitter level of the adult rat's brain

The amount of biogenic amines (dopamine and serotonin) and their metabolites (DOPAC, HVA, 5-HIAA, and 5-HTOL) in five regions of the brain (frontal cortex, hypothalamus, hippocampus, striatum, and brainstem) was studied in the male and female offspring of control and perinatally (48 h before birth or 48 h after birth) food and water deprived dams, when they were three months old, by using HPLC-EC determination. The increase of amine or metabolite level was dominant (19 values increased and 10 decreased related to control). Before-birth stress caused increase in 9 case and only 2 decreased, while in the case of after-birth stress 10 increased and 8 decreased. However, though there is no possibility to decide an exact tendency of direction, the after-birth stress (transmitted by milk) has more expressed effect. Striatum and brainstem were the most touched regions. There was a gender dependence with the dominance of males, except striatum. Blood plasma nociceptin level was also studied and there was a significant elevation in males after pre- and postnatal deprivation, while in females only after postnatal deprivation. The importance of the results in correlation with other stress effects is discussed.

Sexual behavior, neuroendocrine, and neurochemical aspects in male rats exposed prenatally to stress

The present study was designed to examine some short- and long-term effects of maternal restraint stress--during the period of sexual brain differentiation--on reproductive and endocrine systems, sexual behavior, and brain neurotransmitters in male rat descendants. Pregnant rats were exposed to restraint stress for 1 h/day from gestational days (GDs) 18 to 22. Prenatal stress did not influence the wet weight of sexual organs and the quantity of germ cells in adult male pups; however, these animals showed reduced testosterone levels, delayed latency to the first mount and first intromission, and also decreased number of ejaculations. Additionally, there was an increase in the dopamine and serotonin levels in the striatum. Our results indicate that prenatal stress had a long-term effect on neurotransmitter levels and sexual behavior. In this sense, reproductive problems caused by injuries during the fetal period can compromise the later success of mating as well as the capacity to generate descendants.

Prenatal influence of ischemia-hypoxia-induced intrauterine growth retardation on brain development and behavioral activity in rats

The effects of intrauterine growth retardation (IUGR) on brain histological or functional development were examined in rats. IUGR was induced by ligating the bilateral uterine arteries at day 17 of pregnancy. On day 22 of pregnancy, cesarean section was performed, and pups with a birth weight of <2 SD of the mean birth weight of control pups were regarded as IUGR rats. Morphological changes of the brain were studied by Nissl's staining at different timepoints during prenatal and postnatal periods. For behavioral study, an open-field test was performed at 5, 7 and 10 weeks after birth. Histological studies showed the migration disorder of the neurons in the cerebral cortex from embryonic day 17 to postnatal day (PD) 49. The open-field test revealed locomotor disturbance at PD49 in male IUGR rats, but not in female IUGR rats or control rats. It is concluded that IUGR due to antenatal ischemia-hypoxia causes morphological changes in the central nervous system, and induces behavioral impairment, particularly in male rats.

The effect of prenatal exposure to carbon monoxide on breathing and growth of the newborn guinea pig

In utero hypoxia may affect the development of the brain and result in altered respiratory responses postnatally. Using a barometric plethysmograph, we examined the effects of exposing pregnant guinea pigs to 200 ppm carbon monoxide (CO) for 10 h/d from d 23-25 of gestation until term (approximately 68 d) on the ventilatory responses of their 4-5-d-old neonates at rest, and during progressive asphyxia and steady state hypercapnia. Exposure to this concentration of CO produced significantly higher levels of carboxyhemoglobin (COHb) in maternal (8.53 +/- 0.6% versus 0.25 +/- 0.1%) and fetal blood (13.0 +/- 0.4% versus 1.6 +/- 0.1%) from CO-treated animals when compared with controls. Hematocrit was significantly higher in the CO-treated neonates (46.3 +/- 1.0% versus 41.3 +/- 0.9%) at 5-6 d of age, although no difference existed between the groups for COHb at this time. There was no difference between the groups for length of gestation, litter size, or birth weight, but CO-treated neonates were significantly smaller at 4 d of age (102.4 +/- 3.7 g) compared with controls (132.0 +/- 5.0 g). At 4-5 d of age there was no difference between the groups for either tidal volume (VT), respiratory frequency (f), or minute ventilation (VE) at rest, but during steady state hypercapnia (4 and 6% CO2) the CO-treated neonates had a significantly greater VT and VE (but not f) than did controls. During progressive asphyxia, CO-treated animals had a significantly greater VT than did controls from 1-8% CO2. There was a significant fall in f at 1 and 3% CO2 in CO-treated animals; however, this effect did not persist, resulting in a significantly increased VE from 3 to 8% CO2. The inspiratory flow rate (VT/expiratory time) was significantly increased in the CO-treated neonates during progressive asphyxia; this occurred in the absence of a difference in inspiratory time between the groups. These results indicate that prenatal exposure to CO increases CO2 sensitivity in 4-5-d-old guinea pigs. This may be due to developmental alterations in the areas of the brainstem responsible for respiratory control.

Carbon monoxide intoxication during pregnancy: a case presentation and pathophysiologic discussion, with emphasis on molecular mechanisms

In carbon monoxide (CO) poisoning, the mortality and morbidity risk does not always correlate with the level of carboxyhemoglobin (COHb). Recent studies confirm that the mitochondrial cytochrome portion of the respiratory chain is susceptible to CO toxicity at concentrations traditionally considered nontoxic. These laboratory findings correlate with subtle neurologic symptoms detected by psychometric studies in individuals many days from the time of acute intoxication. Additionally, in the pregnant patient, a time lag for both uptake and elimination of CO between the mother and fetus has been demonstrated, with the fetus at risk for hypoxia even when the mother's blood level of CO is nontoxic. Hyperbaric oxygen (HBO) therapy in pregnant patients has not been shown to have adverse effects on the fetus. We present a case of CO intoxication in late pregnancy treated with HBO therapy without adverse consequences.

Behavioral sequelae in young rats of acute intermittent antenatal hypoxia

Several studies have examined behavioral sequelae of acute or chronic pre- or postnatal hypoxia. However, few of these tested a large battery of behavioral functions, particularly those following relatively mild, intermittent hypoxia. Also, in few studies were the hypoxic pups cross-fostered or the experimenter blinded as to experimental group. In addition, in almost no studies were concomitant hypoxic-induced brain biochemicals measured. The present study tested the hypotheses that mild, intermittent antenatal hypoxia can lead to long-term alterations in neurobehavioral development, as well as neurochemical changes.

Effects of prenatal stress on vulnerability to stress in prepubertal and adult rats

This study investigated the hypotheses that unpredictable prenatal stress has effects on the offspring, similar to those induced by perinatal administration of glucocorticoids and increases the vulnerability to stressful situations at adulthood. Rats were exposed to random noise and light stress throughout pregnancy. Offspring were tested for the development of spontaneous alternation behavior (SA) and at adulthood, their response to novel or aversive situations, open field, extinction and punishment following acquisition of an appetitive response and two-way active avoidance, were assessed. In prenatally stressed rats, the development of SA was significantly delayed. On repeated exposure to an open field they were less active; control rats had elevated plasma corticosterone (CCS) on days 2 and 4 of open field exposure, while prenatally stressed rats had significantly raised plasma CCS after each exposure (days 1-8). Furthermore, punishment-induced suppression of an appetitive response was enhanced. Acquisition of active avoidance was faciliated in female but reduced in male prenatally stressed offspring. It is suggested that random prenatal noise and light stress may cause impairment of development of hippocampal function which lasts into adulthood. This impairment is manifested as an increase in vulnerability and a decrease in habituation to stressful stimuli.

Neurotransmitter alterations in a model of perinatal hypoxic-ischemic brain injury

Vulnerability of neurotransmitter-specific neurons to hypoxia-ischemia was examined in the immature rat corpus striatum. Carotid artery ligation plus 2 hours of 8% oxygen atmosphere at 1 week of age produced ipsilateral striatal injury and reduced hemisphere mass 2 and 6 weeks later. Striatal injury was always more severe than damage to overlying cortex. Over half the animals had status marmoratus, a neuropathological change seen in the basal ganglia and thalamus after hypoxic-ischemic injury in full-term human infants. Two weeks after the insult, markers for cholinergic, dopaminergic, and gamma-aminobutyric acid-containing neurons were all reduced, but the reduction in cholinergic markers was greater than that for the other two transmitters. Muscarinic cholinergic receptors were relatively preserved, but their distribution was disrupted. In adult animals specific activity of cholinergic neuronal markers was normal, suggesting that the balance of neurotransmitters was restored after the early insult.