Dorsal periaqueductal gray stimulation facilitates anxiety-, but not panic-related, defensive responses in rats tested in the elevated T-maze

Abstract

The escape response to electrical or chemical stimulation of the dorsal periaqueductal gray matter (DPAG) has been associated with panic attacks. In order to explore the validity of the DPAG stimulation model for the study of panic disorder, we determined if the aversive consequences of the electrical or chemical stimulation of this midbrain area can be detected subsequently in the elevated T-maze. This animal model, derived from the elevated plus-maze, permits the measurement in the same rat of a generalized anxiety- and a panic-related defensive response, i.e., inhibitory avoidance and escape, respectively. Facilitation of inhibitory avoidance, suggesting an anxiogenic effect, was detected in male Wistar rats (200-220 g) tested in the elevated T-maze 30 min after DPAG electrical stimulation (current generated by a sine-wave stimulator, frequency at 60 Hz) or after local microinjection of the GABAA receptor antagonist bicuculline (5 pmol). Previous electrical (5, 15, 30 min, or 24 h before testing) or chemical stimulation of this midbrain area did not affect escape performance in the elevated T-maze or locomotion in an open-field. No change in the two behavioral tasks measured by the elevated T-maze was observed after repetitive (3 trials) electrical stimulation of the DPAG. The results indicate that activation of the DPAG caused a short-lived, but selective, increase in defensive behaviors associated with generalized anxiety.

Involvement of non-NMDA glutamate receptors of the hypothalamic paraventricular nucleus in the cardiovascular response to the microinjection of noradrenaline into the dorsal periaqueductal gray area of rats

“…There are previous studies showing that either electrical or chemical stimulation with the broad-spectrum excitatory amino acid dl-homocysteic acid (DLH) or glutamate (200 nL) or NMDA (200 nL) in the dPAG induce a panic-related defensive response and/or anxiety-like behavior in animals (Ballesteros et al, 2014;Camplesi et al, 2012;de Almeida et al, 2006;Dean, 2011;Krieger and Graeff, 1985;Reimer et al, 2012). However, another set of studies have demonstrated that there is a behavior-related distinction between columns of the PAG, suggesting that the lateral and dorsolateral (dlPAG) regions (Bandler and Shipley, 1994;Bandler et al, 2000;Carrive, 1993;da Silva et al, 2006) are associated with behavioral reactions, while the dorsomedial region (dmPAG) is not (Pelosi et al, 2012).…”

Glutamate and modeling of schizophrenia symptoms: Review of our Findings: 1990–2014

“…Taking into account only the most recent studies, animal models have been used to study anxiety [7][8][9][10], panic attack [11,12], depressive disorders [13,14], and even mania [15]. Other approaches focused on schizophrenia and mania [16].…”