Influence of neonatal vitamin A or vitamin D treatment on the concentration of biogenic amines and their metabolites in the adult rat brain.

Newborn male rats were treated with a single dose of 3 mg vitamin A (retinol) or 0.05 mg vita-min D (cholecalciferol), and three months later five brain regions (frontopolar cortex, hypothalamus, hippocampus, striatum, and brainstem) were studied for tissue levels of dopamine (DA), serotonin (5HT), and metabolites such as homovanillic acid (HVA), as well as 5-hydroxyindole-3-acetic acid (5HIAA). Vitamin A treatment as hormonal imprinting significantly decreased 5HIAA levels in each brain region. Vitamin D imprinting significantly elevated DA only in the brainstem and HVA levels in striatum and hypothalamus. Present and earlier brain-imprinting results (with brain-produced substances), show that the profound and life-long effect of neonatal hormonal imprinting on neurotransmitter production of the adult brain seems to be well established. As prophylactic treatment with these vitamins is frequent in the perinatal period, the imprinting effect of vitamin A and vitamin D must be taken into consideration.

Effect of beta-endorphin imprinting during late pregnancy on the brain serotonin and plasma nocistatin levels of adult male rats.

Female rats were treated with 10 microg of beta-endorphin on the 19th day of pregnancy. Offspring were studied when five months old. Serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content in four brain regions were determined by HPLC-EC and the nocistatin levels of blood plasma using RIA methods. In each brain region studied, the 5-HT levels were highly significantly reduced and that of 5-HIAA in three regions was highly significantly increased. When 5HIAA/5HT ratios, as a measure of serotonin turnover, were calculated, imprinted animals showed extremely high values. Plasma nocistatin level was also significantly elevated. The results call attention to the effect of perinatal endorphin imprinting and its long-term consequences (e.g., setting of aggressiveness, pain tolerance).

Prolonged effect of stress at weaning on the brain serotonin metabolism and sexuality of female rats.

Weanling female rats were stressed (by water and food deprivation for two days) and three months later the following indexes were studied: 5-HT and 5-HIAA levels in five brain regions, blood plasma and cerebrospinal fluid (CSF), sexual activity and nocistatin level of the plasma and CSF. The 5-HIAA content of hypothalamus and brainstem was significantly decreased (in the brainstem with one third) and in the striatum significantly increased. Plasma nocistatin level was significantly increased. Meyerson index and lordosis quotient were similar to control, but the estrus frequency almost doubled in the stressed animals. Much more defense reactions were observed in the stressed females during trials of mating. The results demonstrate that, 1) the perinatal period is not only sensitive to the remote-effects of stress but later could also be stress-sensitive critical periods, and 2) the continuously differentiating (e.g. bone marrow) cells are sensitive to late imprinting by stress, as well as to the brain and the sexual system.