Differential time course of angiotensin-induced AP-1 and Krox proteins in the rat lamina terminalis and hypothalamus
ABSTRACT We studied the time course of expression of the inducible transcription factors (ITF) c-Fos, FosB, c-Jun, JunB, JunD, Krox-20 and Krox-24, induced by a single intracerebroventricular injection of angiotensin II, in the subfornical organ (SFO), median preoptic nucleus (MnPO) paraventricular nucleus (PVN) and supraoptic nucleus (SON). c-Fos and Krox-24 were expressed rapidly in neurons of all four areas but completely disappeared after 4 h. FosB showed a delayed but persistent expression between 4 h and 24 h in the MnPO and PVN. c-Jun was induced in the MnPO, SFO and PVN after 1.5 h and in the SON after 4 h. JunB was selectively expressed in the MnPO and SFO and the level of JunD did not change. The expression of the pre-existing transcription factors SRF, CREB and ATF-2 which contribute to the transcriptional control of jun, fos and krox genes, was not affected by Ang II. Thus, we could show for the first time that an acute stimulation of AT receptors results in continual changes in ITF expression over 24 h.
- [Show abstract] [Hide abstract]
ABSTRACT: Exercise training (ExT) has been shown to reduce sympathetic drive during heart failure (HF). The subfornical organ (SFO) is involved in neural control of sympathetic drive. We hypothesized that an activated SFO contributes to enhanced sympathetic activity in HF. We also postulated that ExT would reduce the activation of the SFO and its contribution to sympathetic drive during HF. Sprague-Dawley rats were subjected to coronary artery ligation to induce HF. Rats were assigned to ExT for 3-4 weeks. Rats with HF had a 2.5-fold increase in FosB-positive cells in the SFO compared to sham rats, and this was normalized by ExT. Microinjection of Angiotensin (Ang) II (100 pmol) into the SFO resulted in a greater increase in renal sympathetic nerve activity (RSNA), blood pressure, and heart rate in HF than in sham group. These responses were normalized after ExT (ΔRSNA: 23 ± 3 vs. 8 ± 2%). ExT also abolished the decrease in RSNA in HF rats after Losartan microinjection (200 pmol) into the SFO (-21 ± 4 vs. -2 ± 3%). Finally, there was elevated mRNA (5-fold) and protein expression (43%) of AT1 receptors in the SFO of rats with HF, which were reversed after ExT. These data suggest that the enhanced activity of the SFO by elevated tonic Ang II contributes to the enhanced sympatho-excitation exhibited in HF. The decrease in AT1 receptor expression in the SFO by ExT may be responsible for reversing the neuronal activation in the SFO and SFO-mediated sympatho-excitation in rats with HF.AJP Heart and Circulatory Physiology 10/2013; · 4.01 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Repeated mating over a period of 6 h facilitates pair-bond formation in monogamous prairie voles. Using this paradigm, we examined fos expression in brain areas implicated in social behavior in voles. We hypothesized that the presence of the fos protein after a period of time sufficient for pair bonding to occur may indicate brain areas that are especially important in pair bond formation. We found elevated levels of fos immunoreactivity in the medial and cortical amygdala, medial preoptic area (MPOA), and bed nucleus of the stria terminalis (BNST) in females that mated several times over a 6-h period as compared to a variety of unmated controls. No treatment effects were found in the central amygdala, nucleus accumbens (NAcc), or lateral septum (LS). We suggest that areas that show evidence of fos expression after sufficient time for pair bonding to occur may be important in the formation of associations between the partner and mating stimuli.Physiology & Behavior 10/2003; 80(1):95-101. · 3.03 Impact Factor