Neuroscience
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Comparative Study
Molecular and functional analysis of hyperpolarisation-activated nucleotide-gated (HCN) channels in the enteric nervous system.
Hyperpolarisation-activated non-specific cation currents (Ih currents) are important for the regulation of cell excitability. These currents are carried by channels of the hyperpolarisation-activated nucleotide-gated (HCN) family, of which there are four known subtypes. In the enteric nervous system (ENS), the Ih current is prominent in AH neurons. ⋯ There was no correlation between the magnitude of the Ih and intensity of channel immunoreactivity. Our results indicate that HCN1, 2 and 4 genes and protein are expressed in the ENS. AH/Dogiel type II neurons, which have a prominent Ih, express HCN2 and 4 in guinea-pig and HCN1 and 2 in mouse and rat.
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Comparative Study
Sex differences in the effect of ethanol injection and consumption on brain allopregnanolone levels in C57BL/6 mice.
The pharmacological profile of allopregnanolone, a neuroactive steroid that is a potent positive modulator of gamma-aminobutyric acidA (GABAA) receptors, is similar to that of ethanol. Recent findings indicate that acute injection of ethanol increased endogenous allopregnanolone to pharmacologically relevant concentrations in male rats. However, there are no comparable data in mice, nor has the effect of ethanol drinking on endogenous allopregnanolone levels been investigated. ⋯ The sex differences in the effect of ethanol administration on endogenous allopregnanolone levels suggest that the hormonal milieu may impact ethanol's effect on GABAergic neurosteroids. Importantly, these data are the first to report the effect of ethanol drinking on allopregnanolone levels and indicate that ethanol consumption and ethanol injection can produce physiologically relevant allopregnanolone levels in male mice. These results have important implications for studies investigating the potential role of endogenous allopregnanolone levels in modulating susceptibility to ethanol abuse.
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The neuropeptide, corticotropin-releasing hormone (CRH), has been shown to play a role in behavioral and neurobiological effects of drugs of abuse. An important modulator of CRH, the CRH binding protein (CRH-BP), has not, on the other hand, been assessed for its role in drug-associated effects. The primary objective of the present experiment was to assess whether prior, chronic exposure to cocaine modulates expression of CRH-BP, and to compare expression of the BP with that of the peptide itself. ⋯ In the CeA, cocaine pre-exposure increased both CRH and CRH-BP mRNA expression 1 day post-treatment. In the dorsal BNST, cocaine pre-exposure elevated levels of CRH-BP, but not CRH, mRNA 3 days post-treatment. Taken together, the results suggest that withdrawal-induced changes in the expression of the CRH-BP, and CRH itself, are relatively short-lived and that a dysregulation in basal expression of either gene is not likely responsible for long-lasting behavioral effects noted with cocaine and other drugs of abuse.
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Comparative Study
Detection and mapping of quantitative trait loci that determine responsiveness of mice to nitrous oxide antinociception.
Exposure to 70% N(2)O evokes a robust antinociceptive effect in C57BL/6 (B6) but not in DBA/2 (D2) inbred mice. This study was conducted to identify quantitative trait loci (QTL) in the mouse genome that might determine responsiveness to N(2)O. Offspring from the F(2) generation bred from B6 and D2 progenitors exhibited a broad range of responsiveness to N(2)O antinociception as determined by the acetic acid-induced abdominal constriction test. ⋯ Combined results revealed two significant QTL that influence responsiveness to nitrous oxide on proximal chromosome 2 and distal chromosome 5, and one suggestive QTL on midchromosome 18. The chromosome 2 QTL was evident only in males. A significant interaction was found between a locus on chromosome 6 and another on chromosome 13 with a substantial effect on N(2)O antinociception.
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Comparative Study
Serotonergic response to social stress and artificial social sign stimuli during paired interactions between male Anolis carolinensis.
Serotonergic activity is influenced by social status and manipulation of social signals. In the lizard Anolis carolinensis, eyespot formation, i.e. darkening of postorbital skin from green to black, appears during stressful and agonistic situations, forming first in males that become dominant. To assess the effect of eyespots on central serotonergic activity during social interaction, males were paired by weight and painted postorbitally with green or black paint. ⋯ Decreased hypothalamic serotonin was associated with increased aggressive behavior. These results, when compared with previous studies, suggest some flexibility in central serotonergic systems, which may shape dominant and subordinate rank acquisition, and appear to be influenced by the completion of social role formation. Furthermore, social status and central serotonergic activity was influenced by a visual cue, the presence or absence of postorbital eyespots on an opponent.