, 2003 and Li and Pan, 2005). Treatment with ANG II also decreased the amplitude of evoked IPSCs and the frequency of miniature IPSCs in neurons of the dorsolateral periaqueductal gray, an effect blocked by losartan, but not by
the AT2 antagonist PD123319 (Xing et al., 2009). Treatment with ANG II had no effect on excitatory post synaptic currents in the PVN neurons or in the dorsolateral STA-9090 periaqueductal gray (Li et al., 2003, Li and Pan, 2005 and Xing et al., 2009). In contrast, another study showed that the amplitude of the IPSCs in the MnPO was reduced by the treatment with losartan, suggesting a post synaptic action of endogenous ANG II that facilitated the effect of the GABAergic input to the MnPO (Henry et al., 2009). Considering the effects of the activation of GABAA receptors in the LPBN on hypertonic NaCl and water intake (Callera et al., 2005 and De Oliveira et al., 2007) and the results of previous studies showing that AT1 receptor activation may modulate the action of the GABAergic mechanisms (Henry et al.,
2009, Li et al., 2003, Li and Pan, 2005 and Xing et al., 2009), in the present study we investigated the effects of injections of the specific AT1 receptor antagonist, losartan, learn more into the LPBN on water and hypertonic NaCl intake induced by the activation of GABAA receptors by muscimol injections into the LPBN in fluid replete or FURO + CAP-treated rats. Fig. 1 is a photomicrograph of a transverse section of the brainstem of one rat, representative of the groups tested, showing the typical bilateral injection sites in the LPBN. The injections were centered in the central lateral and dorsal lateral portions of the LPBN (see Fulwiler and Saper, 1984 for definitions of LPBN subnuclei). In some rats, LPBN injections reached the ventral lateral
Meloxicam and external lateral portions, as well as the Kölliker–Fuse nucleus. The sites of injections were similar to those in previous studies that showed the effects of LPBN injections of methysergide, proglumide, moxonidine or muscimol on water and 0.3 M NaCl intake (Andrade et al., 2006, Callera et al., 2005, De Gobbi et al., 2001, De Luca et al., 2003 and De Oliveira et al., 2007). In some rats, injections spread to the brachium (superior cerebellar peduncle), or slightly ventral to this structure, reaching the dorsal portions of the medial parabrachial nucleus (MPBN) uni- or bilaterally. There was no difference in the effects if the injections were restricted to the LPBN or if they spread to the ventral structures described above. ANOVA showed significant differences between treatments for 0.3 M NaCl [F(3, 21) = 20.7; P < 0.001] and water intake [F(3, 21) = 9.05; P < 0.