ISSN:
1365-2826
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
A2A receptor knockout (A2AR−/−) mice are more anxious and aggressive, and exhibit reduced exploratory activity than their wild-type littermates (A2AR+/+). Because α-melanocyte-stimulating hormone (α-MSH) influences anxiety, aggressiveness and motor activity, we investigated the effect of A2AR gene disruption on α-MSH content in discrete brain regions and pro-opiomelanocortin (POMC) expression in the hypothalamus and pituitary. No modification in α-MSH content was observed in the hypothalamus and medulla oblongata where POMC-expressing perikarya are located. In the arcuate nucleus of the hypothalamus, POMC mRNA levels were not affected by A2AR disruption. Conversely, in A2AR−/− mice, a significant increase in α-MSH content was observed in the amygdala and cerebral cortex, two regions that are innervated by POMC terminals. In the pars intermedia of the pituitary, A2AR disruption provoked a significant reduction of POMC mRNA expression associated with a decrease in α-MSH content. By contrast, in the anterior lobe of the pituitary, a substantial increase in POMC mRNA and adrenocorticotropin hormone concentrations was observed, and plasma corticosterone concentration was significantly higher in A2AR−/− mice, revealing hyperactivity of their pituitary-adrenocortical axis. Together, these results suggest that adenosine, acting through A2A receptors, may modulate the release of α-MSH in the cerebral cortex and amygdala. The data also indicate that A2A receptors are involved in the control of POMC gene expression and biosynthesis of POMC-derived peptides in pituitary melanotrophs and corticotrophs.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2826.2003.01116.x
