Emotional reactivity modulates autonomic responses to an acoustic challenge in quail.

Emotional reactivity modulates autonomic responses to an acoustic challenge in quail. Physio Behav 00(0) 000-000, 2006. This study investigated the relationship between emotional reactivity and behavioral and autonomic responses to an acoustic stimulus in quail. It was hypothesized that birds with high emotional reactivity would have higher motor inhibition combined with higher sympathetic activation than birds with low emotional reactivity. Two experiments were performed. The first looked for correlations between emotional reactivity, evaluated by a tonic immobility test, and motor and Heart Rate Variability in relation to an acoustic stimulus. The second experiment compared the motor and autonomic responses to the acoustic stimulus of quail selected on either long (LTI) or short (STI) duration of tonic immobility. The first experiment showed that the acoustic stimulation induced motor inhibition and cardiac activation. Correlations were found between tonic immobility duration and both autonomic activity before stimulation and sympathovagal balance after stimulation. In the second experiment, LTI quail showed strong sympathetic activation, whereas STI quail showed parasympathetic and sympathetic activation. The activation of the parasympathetic system induced by the noise in STI quail can be explained by the predominance of this system at rest in this line. In conclusion, both the basal autonomic activity and the autonomic responses differed according to the emotional reactivity, and changes in autonomic activity appear to be related to the genetic selection process.

N-Methyl-D-aspartate receptor subunits NR1 and NR2C are overexpressed in the inferior colliculus of audiogenic mice.

Some non-DBA2 Albino Swiss mice exhibit noise induced epileptic seizures during a short period of postnatal development. Because N-methyl-D-aspartate (NMDA) glutamate ionotropic receptors are involved in the occurrence of audiogenic seizures, we investigated by in situ hybridization methods, the expression of the different subunits (NR1, NR2A, NR2B, NR2C) of this receptor in the central nucleus of the inferior colliculus (IC), a main relay of the auditory pathways. At postnatal day 20, the NR2C subunit is highly expressed in the IC of convulsive mice, while in non-convulsive mice a slight signal is only found for NR1, NR2A, and NR2B. In adult mice, the NR1 and NR2A signals are observed while the NR2B signal is almost undetectable. The audiogenic susceptibility may be related to the transient expression of the NR2C subunit during a brief neonatal period during which synaptic reorganization happens.

Transfer of maternal testosterone to the guinea pig fetus during the last third of pregnancy.

Testosterone (T) transfer from mother to fetuses was explored in anesthetized guinea pigs on Days 48 and 67 of pregnancy using a constant intravenous infusion of tritium-labeled T ([3H]T). Labeled dihydrotestosterone ([3H] DHT), androstenedione ([3H] delta 4) and [3H] T were estimated after celite chromatography in maternal plasma, umbilical venous plasma, fetal arteriovenous plasma and fetal tissue homogenates including liver, genital tract with gonads, hypothalamic area, hypophysis and remaining brain. Total radioactivity was measured by counting a part of the homogenates. Results indicate that very low concentrations of [3H] T and [3H] delta 4 were found in umbilical and fetal plasma, whereas [3H] DHT levels were relatively high. A minute part of maternal T was transferred to male and female fetuses: 0.7 to 1.9 pg/ml, and that represented 0.4 to 5.6% of fetal T. The difference observed between umbilical and fetal [3H] T showed that 80% of the fetal T coming from the mother was metabolized by the fetuses. This result is discussed in relationship to the high radioactive concentrations present in fetal liver. Concentrations of total radioactivity were high in fetal tissues, and the three nervous tissues exhibited a significant difference in their capacity to fix radioactivity. There was a complete absence of the three labeled androgens in the hypophysis. However, [3H] DHT was present in all other tissues, and gonads + genital tract in the male fetus exhibited [3H] DHT concentrations significantly higher than those detected in the female fetus.(ABSTRACT TRUNCATED AT 250 WORDS)