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Biomedical subjects

A R Allen

Publications and source records attributed to A R Allen.

22 records · Page 2Linked to original sources
PubMedDate not supplied

The 5-HT1A receptor antagonist p-MPPI blocks responses mediated by postsynaptic and presynaptic 5-HT1A receptors.

The present experiments examined the ability of the novel 5-HT1A receptor antagonist to block responses mediated by postsynaptic and presynaptic 5-HT1A receptors in vivo. Pretreatment with p-MPPI reduced or blocked the effect of the 5-HT1A receptor agonist 8-OH-DPAT on two responses mediated by postsynaptic 5-HT1A receptors, reduction of body temperature and the 5-HT behavioral syndrome. Administration of p-MPPI alone did not alter body temperature or produce symptoms of the 5-HT syndrome. Pretreatment with p-MPPI also blocked the ability of 8-OH-DPAT to reduce extracellular 5-HT in the striatum, a response mediated by presynaptic 5-HT1A receptors in the dorsal raphe nucleus, but did not alter striatal 5-HT when administered alone. These results indicate that p-MPPI is an effective 5-HT1A receptor antagonist in vivo with no intrinsic activity. p-MPPI may prove to be a useful pharmacological tool for studying 5-HT1A receptors and their involvement in anxiety and affective disorders.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMedDate not supplied

Effect of click rate on the latency of auditory brain stem responses in humans.

Auditory brain stem responses are the far-field reflections of electrical activity originating in the auditory pathway in its course from the cochlea to cortex that can be recorded from scalp electrodes using computer averaging techniques. There are seven components in the initial 10 msec following a click signal which have been shown to have an orderly change in latency as a function of signal intensity. The results of this study show that click repetition rate can also significantly affect the response latency measure. Responses were measured in six normal hearing subjects at click rates of 10, 30, 50 and 100/sec and af four intensity levels (30, 40, 50, and 60 dB sensation level). The mean latency shift of component V was approximately 0.5 msec when the responses at 10 and 100/sec were compared. This is equivalent to a 15-20 dB decrease in signal intensity at the 10/sec click rate. An analysis of the time of occurrence of this shift using brief click trains at 100/sec showed the shift in latency to be complete by the fifth click. The latency shift was similar at the four signal levels tested. The latency shift was similar at the four signal levels tested. The latency shift of component V appeared to be a monaural and therefore a potentially peripheral process. The results are interpreted as an objective measure of adaptation in the human auditory system with implications for the measurement in disorders of hearing.

Acoustic Stimulation↗