Monoamines and their metabolites in the amphibian (Ambystoma tigrinum) brain: quantitative changes during metamorphosis and captivity.

1. Monoamine neurotransmitters (epinephrine, norepinephrine, dopamine, serotonin and some of their metabolites (DOPEG, MHPG, DOPAC, 5-HIAA) were measured by HPLC in extracts from telencephalon (TEL) and diencephalon-midbrain (DM) before, during at the end of metamorphosis. 2. During metamorphosis MHPG increased and 5-HIAA decreased in TEL and DM while DOPEG decreased only in DM. 3. Monoamine levels were greater in the TEL and a larger increase in MHPG occurred there. 4. Captivity without metamorphosis also caused a significant depression of 5-HIAA in TEL and depression of DOPEG, MHPG and DOPAC in DM.

Activation of the serotonergic system in chick spinal cord during hatching.

The objectives of the present study were to determine the levels of serotonin (5-HT), its major catabolic metabolite, 5-hydroxyindoleacetic acid (5-HIAA), and norepinephrine (NE) in chick spinal cord before, during, and after hatching and also to determine if changes in the levels of these chemicals are directly related to the hatching behavior. The levels of 5-HT, 5-HIAA, and NE were measured by high performance liquid chromatography with electrochemical detection in whole spinal cords of 20-day-old "pre-hatching" embryos, 21-day-old "normal hatching" embryos, 0-day-old "post-hatching" chicks, and 0-day-old "glass egg hatching" chicks. NE was measured but no significant differences were found in NE levels among experimental groups. The concentration of 5-HT was elevated in chick embryo spinal cords during normal hatching compared to pre-hatching embryos and post-hatching chicks. The concentration of 5-HIAA was elevated during and after normal hatching compared to pre-hatching embryos. However, neither 5-HT nor 5-HIAA levels were found to be elevated in chick spinal cords during glass egg hatching compared to pre-hatching embryos or post-hatching chicks. Therefore, there appears to be an activation of the serotonergic system in chick spinal cord related to the specific event of hatching but this activation is not directly related to the movements common to both hatching and glass egg hatching.

Monoamine neurotransmitters and metabolites during the estrous cycle, pregnancy, and the postpartum period.

A wide variety of behavioral changes in the female rat have been associated with the estrous cycle, pregnancy, and the postpartum period and their accompanying hormonal fluctuations. Since monoamine systems have been implicated in the control of these behaviors, the present study examined the tissue concentrations of norepinephrine (NE), dopamine (DA), and serotonin (5HT) and their primary metabolites dihydroxyphenylglycol (DHPG), 3-methoxy-4-hydroxyphenylglycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5HIAA) in the anterior cerebral cortex, hippocampus, and cerebellum during the estrous cycle, late pregnancy, and the early postpartum period. Results show no significant differences in neurotransmitter or metabolite levels during the estrous cycle in any of the three brain regions examined. However, profound differences were observed between samples from late pregnancy, early postpartum, and the estrous cycle. In general, NE and 5HT levels in all three brain regions fell from normal values during late pregnancy and rose in the early postpartum period; levels of their metabolites rose in postpartum samples. Conversely, DA levels were elevated in late pregnancy and depressed in the early postpartum period in anterior cortex, while DOPAC levels were depressed in both late pregnancy and the early postpartum period. The finding of changes in monoamine metabolism associated with pregnancy and its termination could be important in understanding the increased susceptibility to affective illness in women during the postpartum period.