Panicolytic-like effect induced by the stimulation of GABAA and GABAB receptors in the dorsal periaqueductal grey of rats

Cellular and subcellular localization of the GABAB receptor 1a/b subunit in the rat periaqueductal gray matter

“…Activation of GABA B receptors in this PAG subdivision impairs one-way escape in the elevated T-maze test, which is consistent with an anxiolytic or panicolytic effect (Bueno et al, 2005).…”

Effects of reversible inactivation of the dorsomedial hypothalamus on panic- and anxiety-related responses in rats

“…The results observed with the DMH are very similar to those obtained with another neuroanatomic region implicated in defense, i.e., the dorsal periaqueductal gray (dPAG). When administered intra-dPAG, muscimol also impaired escape, without altering ETM-inhibitory avoidance (19). In fact, the similarities of the role played by the medial hypothalamus and the dPAG in the modulation of defense were previously pointed out by Schmitt et al (8), who showed that both intra-dPAG and intramedial hypothalamus administrations of SR 95103, a GABA-A receptor antagonist, produced a dose-dependent behavioral activation together with jumps.…”

Role of GABA in anxiety and depression

“…Reduced panic-like behavior in rats by intra-DPAG injection of muscimol and baclofen, and increased panic by benzodiazepine inverse agonist FG 7142 [Bueno et al, 2005a]. Increased anxiety by prior electrical stimulation of the inferior colliculus in rats [Pandossio et al, 2000].…”

“…For example, the GABA-B agonist baclofen was found to be ineffective in several animal anxiety tests [Umezu, 1999;Dalvi and Rodgers, 1996;Zarrindast et al, 2001], but revealed anxiolytic-like properties (similar to GABA-A agonists) in several other studies [File et al, 1991[File et al, , 1992Shephard et al, 1992;Bueno et al, 2005a]. Baclofen was ineffective in the FST depression test, increased learned helplessness, and attenuated the effects of ADs in rats [Nakagawa et al, 1996a,b], but reduced depressiveness and reversed reserpine effects in the FST in mice [Aley and Kulkarni, 1989; see similar data in rats in Hilakivi et al, 1988].…”

“…The midbrain tectum is rich in GABAergic neurons [Pandossio et al, 2000;Bueno et al, 2005a] and a number of animal studies have shown GABAergic drugs affect the midbrain tectum and alter stressrelated anxiety-like behavioral responses, while certain neurochemical or morphological alterations in this brain area have been found in animal depression-like states (Table 6). As such, although clinical studies are still needed to confirm this notion, it seems possible Clinical data Amygdala a Activation in patients with posttraumatic stress disorder [Rauch et al, 1996], during anticipatory anxiety [Phelps et al, 2001], in adults and adolescents viewing fearful faces; also positive correlation of amygdalar activation and social anxiety scores [Morris et al, 1998;Killgore and Yurgelun-Todd, 2005].…”