Effects of postnatal exposure to cocaine on the development of the rat corpus callosum

Progesterone as a Postnatal Prophylactic Agent for Encephalopathy Caused by Prenatal Hypoxic Ischemic Insult

Brain damage caused by hypoxic ischemic insult during the perinatal period causes hypoxic ischemic encephalopathies (HIEs). Therapeutic hypothermia is indicated for HIE, but because the therapeutic burden is large for its limited therapeutic effectiveness, another strategy is needed. Progesterone (P4) plays a neuroprotective role through the actions of its metabolite, allopregnanolone (Allo), on P4 receptor, γ-aminobutyric acid type A receptors or both. We examined the therapeutic potential of P4 using a newborn rat model of HIE. Fetal rats were exposed to transient ischemic hypoxia by 30-minute bilateral uterine artery clamping on gestational day 18. After spontaneous birth, newborn pups were subcutaneously injected with P4 (0.10 or 0.01 mg), medroxyprogesterone acetate (MPA; 0.12 mg), or Allo (0.10 mg) through postnatal days (PDs) 1 to 9. Brain damage in the rats was assessed using the rotarod test at PD50. The HIE insult reduced the rats' ability in the rotarod task, which was completely reversed by P4 and Allo, but not by MPA. Histological examination revealed that the HIE insult decreased neuronal (the cortex and the hippocampal CA1 region) and oligodendroglial cell density (the corpus callosum) through PD0 to PD50. The axon fiber density and myelin sheath thickness in the corpus callosum were also reduced at PD50. The time-course study revealed that P4 restored oligodendroglial cells by PD5, which was followed by neuroprotective action of P4 that lasted long over the injection period. These results suggest that P4 protects the neonatal brain from HIE insult via restoration of oligodendroglial cells.

Corpus callosum in adolescent offspring exposed prenatally to maternal cigarette smoking

Teratogens, such as alcohol or anti-epileptic drugs, affect the size of the corpus callosum. Here we report findings obtained in a case-control study that investigated possible effects of teratogens contained in cigarette smoke on the size and structural properties of this structure. We recruited and scanned with magnetic resonance imaging a total of 408 adolescents (12 to 18 years of age); a subsample of 300 adolescents is considered in this report. Cases (n=146) were exposed to maternal cigarette smoking during pregnancy; non-exposed controls (n=154) were matched to cases by maternal education. We measured the size of corpus callosum (CC) and its sections (corrected for brain size), as well as mean values of magnetization-transfer ratio (MTR) in each CC section. Corpus callosum, and especially its posterior part, was smaller in the exposed vs. non-exposed female adolescents; no significant effects were found in males. Exposed and non-exposed subjects did not differ in the MTR-based index of myelination in either gender in any CC section. Given the lack of exposure effect on the myelination index, this finding might reflect a lower number of inter-hemispheric connections in female offspring of mothers who smoked during pregnancy.

Shape changes of the corpus callosum in abstinent methamphetamine users

The objective of the current study was to evaluate structural changes of the corpus callosum (CC) in abstinence methamphetamine (MA) users. Shape and size of the CC in 27 MA users were compared to those of 18 healthy comparison subjects. To define the local curvature and width of the CC, medial model-based shape analysis was performed using CC skeletons extracted from a distance map. To define the local displacement of the CC, a boundary model-based shape analysis was performed. In addition, the size of regional areas of the CC was measured according to the Witelson's definition for comparison. In the medial model-based shape analysis, increased curvature in the genu (curvature angle difference = 4.1 degrees) and decreased width in posterior midbody (width difference = 0.77 mm) and isthmus area (width difference = 0.86 mm) of the CC were observed in MA users relative to healthy comparison subjects. In the boundary model-based shape analysis, significant displacement was observed in MA users where there were differences in shape/width patterns by the medial model-based shape analysis. There were no differences in the size of regional areas of the CC between groups. Findings suggest that MA use is associated with regional changes in interhemispheric white matter tracts, which connect frontal and parietal cortices and that these frontal and parietal abnormalities may underlie clinical manifestations of the MA abuse.

Fatal "crack" cocaine ingestion in an infant

This report describes a 10-month-old infant girl who died of cocaine poisoning. The infant was found apneic and in ventricular fibrillation after the parents summoned rescue personnel and claimed she had ingested rat poison. The parents later admitted that 2 hours before calling for assistance, the infant's 2-year-old brother was found eating "crack" cocaine and also feeding it to the infant. Investigators found "crack" cocaine throughout the house and in the infant's crib. At autopsy, the infant had two pieces of "crack" cocaine in the duodenum. The brain exhibited a markedly thinned corpus callosum. Toxicologic examination showed high concentrations of cocaine in the blood and in other specimens. The manner of death was classified as homicide because the infant was willfully placed in a hazardous environment with an easily accessible toxic substance, medical attention was deliberately delayed for 2 hours, and medical personnel were deceived when they were falsely told she had ingested rat poison. These features were thought to constitute neglect. The toxicologic characteristics of this case are unique. There are numerous reports of passive cocaine inhalation in infants and children less than 5 years of age, but ingestion of cocaine in this age group has rarely been documented. This age group also has no reported deaths due to cocaine ingestion and no cases of "crack" cocaine ingestion. The high concentrations of cocaine seen in this case, combined with the "crack" cocaine found in the duodenum, indicate ingestion as the route of exposure. The thinned corpus callosum in this case may be a consequence of intrauterine cocaine exposure.

Evaluation of neonatal exposure to cocaine on learning, activity, startle, scent marking, immobility, and plasma cocaine concentrations

Prenatal cocaine treatment produces equivocal effects on spatial learning and memory; however, no data are available on neonatal treatment as a model of human third-trimester exposure. Sprague-Dawley rats were treated on postnatal days (P) 1-10 or 11-20 with cocaine (15 mg/kg x 4 per day at 2-h intervals) or saline (P1-P20) and evaluated as adults in the Morris water maze and on tests of activity, startle, scent marking, swimming immobility, and sequential learning. Neonatal cocaine had no effect on mortality; however, early treatment reduced body weight, whereas later treatment did not. Neonatal cocaine had no effects on exploratory activity, swimming ability, sequential learning, multiday activity rhythms, scent marking, or swimming immobility, but augmented acoustic startle amplitude in the early-treated group. Neonatal cocaine also produced an interaction on spatial learning in which the cocaine early-treated males performed slightly more efficiently than controls. Plasma cocaine concentrations were significantly higher in the early-treated group than the later-treated group despite receiving the same weight-adjusted doses. It was concluded that neonatal cocaine, when administered during a stage of brain development analogous to human third trimester, induces few behavioral effects based on the assessments used in this study.