Fu X W, Brudzynski S M
Department of Clinical Neurological Sciences, University of Western Ontario, University Hospital, London, Canada.
Pharmacol Biochem Behav. 1994 Dec;49(4):835-41. doi: 10.1016/0091-3057(94)90231-3.
Direct injection of glutamate, a neuroexcitatory agent, into the anterior hypothalamic-preoptic area of the rat brain induced ultrasonic vocalization. This vocalization was characterized by short-duration calls (below 60 ms) of high sound frequency (pitch), mostly above 40 kHz, and was similar to the known 50-kHz vocalization observed in natural situations. The glutamate-induced vocalization was dose dependent within the dose range of 16.9-67.6 micrograms and was antagonized by local pretreatment with MK-801, an NMDA antagonist. The increasing dosage of glutamate induced more calls and had a significant influence on frequency and intensity of emitted ultrasound. The average sound frequency increased whereas the mean sound intensity decreased with the dosage of glutamate. On the other hand, the mean duration of a single call and the bandwidth did not significantly change with doses of glutamate. Injection of carbachol, a muscarinic cholinomimetic agent, into the same brain sites as glutamate, induced a different type of ultrasonic vocalization with low sound frequency and long call duration, known as 22-kHz calls. The results suggest that high sound frequency, short-duration calls (50 kHz) and low sound frequency, long-duration calls (22 kHz) have different neurophysiological and neurochemical mechanisms.
将神经兴奋性递质谷氨酸直接注射到大鼠脑的下丘脑前视前区会诱发超声发声。这种发声的特点是持续时间短（低于60毫秒）、声音频率（音高）高，大多高于40千赫，与在自然情况下观察到的已知50千赫发声相似。在16.9 - 67.6微克的剂量范围内，谷氨酸诱发的发声呈剂量依赖性，并且可被NMDA拮抗剂MK - 801局部预处理所拮抗。谷氨酸剂量增加会诱发更多叫声，并对发出的超声频率和强度有显著影响。随着谷氨酸剂量增加，平均声音频率升高，而平均声音强度降低。另一方面，单次叫声的平均持续时间和带宽并未随谷氨酸剂量显著变化。将毒蕈碱拟胆碱剂卡巴胆碱注射到与谷氨酸相同的脑区，会诱发一种不同类型的超声发声，其声音频率低、叫声持续时间长，即所谓的22千赫叫声。结果表明，高频、短持续时间叫声（50千赫）和低频、长持续时间叫声（22千赫）具有不同的神经生理和神经化学机制。
