This article reviews experimental evidence and theoretical constructs that implicate serotonin (5-HT) modulation of defensive behavior within the midbrain periaqueductal gray in panic disorder (PD). Evidence with conflict tests in experimental animals indicates that 5-HT enhances anxiety, whereas results with aversive stimulation of the dorsal periaqueductal gray point to an anxiolytic role of ...

The use of Cannabis sativa by humans dates back several thousand years, for both its psychotomimetic and potential medicinal properties. As scientific research methods developed, the cannabinoids present in this herb were characterized, as well as their complex interface with the human central nervous system, provided by the activation of specific receptors. The subsequent description of an end...

Rett syndrome (RTT) is caused by mutations in the X-linked gene MECP2. While patients with RTT show widespread changes in brain function, relatively few studies document changes in brain structure and none examine in detail whether mutations causing more severe clinical phenotypes are linked to more marked changes in brain structure. To study the influence of MeCP2-deficiency on the morphology ...

Sexual behavior is suppressed by various types of stressors. We previously demonstrated that an alarm pheromone released by stressed male Wistar rats is a stressor to other rats, increases the number of mounts needed for ejaculation, and decreases the hit rate (described as the number of intromissions/sum of the mounts and intromissions). This deterioration in sexual behavior was ameliorated by...

Pain is an unpleasant sensory and emotional experience usually triggered by stimulation of peripheral nerves and often associated with actual or potential tissue damage. It is well known that pain perception for patients and normal subjects can be modulated by psychological factors, such as attention, stress, and arousal. Our understanding of how this modulation occurs at a neuroanatomical leve...

The habenula, located in the posterior thalamus, is implicated in a wide array of functions. Animal anatomical studies have indicated that the structure receives inputs from a number of brain regions (e.g., frontal areas, hypothalamic, basal ganglia) and sends efferent connections predominantly to the brain stem (e.g., periaqueductal gray, raphe, interpeduncular nucleus). The role of the habenu...

In an effort to correlate the recently cloned MOR-1 receptor with the pharmacological actions of morphine and morphine-6beta-glucuronide (M6G), we have used an antisense paradigm. Rats were injected intracerebroventricularly (i.c.v.) with antisense oligodeoxynucleotides on days 1, 3 and 5 and tested for analgesia on day 6 after administration of morphine or M6G i.c.v. or after microinjection of...