Basal amygdaloid facilitation of midbrain periaqueductal gray elicited defensive rage behavior in the cat is mediated through NMDA receptors.
The present study tested the hypotheses that: (1) defensive rage behavior elicited from the midbrain periaqueductal gray (PAG) in the cat is facilitated from the basal complex of amygdala; and (2) such facilitation from this region of amygdala is mediated via a pathway in which excitatory amino acids acting upon NMDA receptors within the PAG are utilized as a neurotransmitter. In the first phase of this study, cannula electrodes were implanted into PAG sites for the elicitation of defensive rage behavior as well as for drug delivery. Then, a second monopolar electrode was implanted into the basal nucleus of amygdala from which facilitation of defensive rage could be obtained. As a result of dual stimulation of the basal amygdala and PAG, response latencies for defensive rage were significantly lowered relative to PAG stimulation alone (P < 0.01). In the second phase of this experiment, 3 doses of a selective NMDA receptor antagonist, AP-7 (0.1, 0.5, 1.0 mg/kg), were peripherally (i.p.) administered in 5 animals. The results indicated a significant decrease in the facilitatory effects of amygdaloid stimulation in a dose and time dependent manner (P < 0.001). In the third phase, AP-7 was administered intracerebrally into PAG defensive rage sites in doses of 0.2 and 2.0 nmol. It was noted that intracerebral microinjections of AP-7 at the higher dose (2.0 nmol) also significantly suppressed the facilitatory effects of amygdaloid stimulation (P < 0.01); however, these effects were somewhat less potent then those observed following peripheral drug administration. A fourth phase of the study was conducted at the completion of the pharmacological experiments.(ABSTRACT TRUNCATED AT 250 WORDS)
Shaikh
M B
MB
Department of Neurosciences, New Jersey Medical School, Newark 07103.
Schubert
K
K
Siegel
A
A
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives*; D000596:Amino Acids / Q000008:administration & dosage / Q000502:physiology*; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001481:Basal Metabolism; D002415:Cats; D002552:Cerebral Ventricles; D004558:Electric Stimulation; D005260:Female; D007263:Infusions, Parenteral; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology*; D010487:Periaqueductal Gray / Q000502:physiology*; D011889:Rage / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology*
D000596:Amino Acids; D018377:Neurotransmitter Agents; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate; C031231:2-amino-7-phosphonoheptanoic acid