Responsiveness of non-IHS migraine and tension-type headache to sumatriptan.

In a long-term efficacy and safety study, 424 patients were treated with sumatriptan (6 mg sc) for 1,904 migraine attacks. The patients were diagnosed with migraine based on IHS criteria but individual migraine attacks treated in the study were physician diagnosed; not necessarily required to meet IHS criteria. A re-analysis of the treatment response to open label sumatriptan (6 mg sc) indicated that 43 patients had treated at least one migraine that fulfilled IHS criteria for tension-type headache. Analysis of this population revealed they treated 232 headaches. Of these headaches, 114 were classified per IHS criteria as migraine; 76 as tension-type; and 42 as non-IHS migraine (not classifiable as IHS migraine or IHS tension-type headache). Of the 114 migraines, a positive response to sumatriptan occurred in 109 (96%) cases; of the 76 tension-types, 73 responded to sumatriptan (97%); of the 42 non-IHS migraine, 40 (95%) responded to sumatriptan. An equivalent response to sumatriptan among three diagnostic groups of headache supports the concept of a common biologic mechanism involving 5HT1 receptors that spans a range of clinical presentations.

Observations of novel behaviors as indices of ethanol withdrawal-induced anxiety.

One of the prominent symptoms in alcoholics during withdrawal is an intense feeling of anxiety. Recently new tests have become available which may index anxiety in rodents. We have evaluated two such tests in our model of withdrawal from ethanol (ET) in rats. Rats were given either ET in milk (7-13 g/kg/4 days) or equicaloric dextrin maltose in milk via implanted gastric cannuli. Rats were scored for classical withdrawal symptoms (tremors, convulsions, stereotyped behavior), for stimulus-elicited ultrasonic vocalizations (USVs), and in one study for exploration of novel objects placed in their home cage at various points after the last dose of ET. In Sprague-Dawley rats, classical withdrawal symptoms were highest between 8-12 hours, and disappeared by 36 hours. Latency to explore a novel object was unchanged, but duration was depressed between 10-30 hours, and was recovered by 70 hours. Following a less intense Day 1 treatment regimen in Long-Evans rats, the vocalizations were greatly increased in number, and peak response occurred sooner (6 hours post-infusion) and was of shorter overall duration (50 hours). Pretreatment with diazepam (1.25-5.0 mg/kg) depressed the number of vocalizations during ET withdrawal (ETW), which suggests that this measure could index anxiety in animal models of withdrawal from ET.

Disruption of noradrenergic, but not serotonergic or opiate, functioning blocks both cardiac and behavioral components of the orienting response in preweanling rats.

Previous work in this laboratory established that selective attention, as measured by the behavioral and autonomic expressions of the orienting response (OR), is not disrupted by either dopaminergic or cholinergic receptor blockade. The present experiments extended this pharmacological analysis of the OR. In Experiment 1, preweanling rats were injected with methysergide maleate, a serotonin receptor blocker. Neither the behavioral nor the heart rate (HR) component of the OR was attenuated. In Experiment 2, the opiate receptor blocker naltrexone also failed to inhibit the HR and behavioral expressions of the OR. alpha-1 adrenergic receptor blockade with WB-4101 in Experiment 3 abolished both the HR and behavioral ORs to the pulsating tone. In Experiment 4, clonidine, which inhibits release of norepinephrine by stimulating alpha-2 autoreceptors, attenuated both behavioral and HR ORs to the pulsating tone in a dose-dependent manner. These data, in combination with the prior findings, suggest that norepinephrine is critically involved in the central process underlying the OR in the rat. Dopaminergic, cholinergic, serotonergic, and opiate receptor blockades do not impair selective attention as indexed by HR and behavioral ORs to an auditory stimulus. In contrast, disruption of noradrenergic functioning via either alpha-1 receptor blockade or alpha-2 receptor stimulation disrupts both the HR and behavioral components of the OR. These results indicate that integrity of central noradrenergic functioning is essential for expression of the OR and for stimulus-directed attention.

Disruption and recovery of the orienting response following shock or context change in preweanling rats.

Previous research has shown that placement of preweanling rats in an unfamiliar environment inhibits both heart rate and behavioral orienting responses to an auditory stimulus, and that the orienting response gradually reappears during the following 15 min. Four experiments designed to evaluate two potential explanations of this effect were conducted. If the arousal induced by an unfamiliar environment disrupts sensory information processing, so should the arousal induced by mild electric shock. In two experiments, the orienting response was inhibited in proportion to number of shocks received and rate of recovery was comparable to that observed in the unfamiliar environment. New environments also contain many unfamiliar stimuli which may overload the rats' limited information processing capacity. In two experiments a change in environmental stimulation was shown to inhibit the orienting response. Recovery of the orienting response followed the same time course as that seen following shock or placement in an unfamiliar environment. Although the results of this study clearly demonstrate environmental inhibition of the orienting response, they provide little support for either the "arousal" or the "information overload" hypotheses of orienting response inhibition. The implications of these data for current theoretical conceptualizations of the orienting response are discussed.