Differential effects of electrical stimulation of the central amygdala and lateral hypothalamus on fos-immunoreactive neurons in the gustatory brainstem and taste reactivity behaviors in conscious rats.

Projections from the central amygdala (CeA) and lateral hypothalamus (LH) modulate the activity of gustatory brainstem neurons, however, the role of these projections in gustatory behaviors is unclear. The goal of the current study was to determine the effects of electrical stimulation of the CeA or LH on unconditioned taste reactivity (TR) behaviors in response to intra-oral infusion of tastants. In conscious rats, electrical stimulation of the CeA or LH was delivered with and without simultaneous intra-oral infusion of taste solutions via an intra-oral cannula. Immunohistochemistry for the Fos protein was used to identify neurons in the gustatory brainstem activated by the electrical and/or intra-oral stimulation. In the absence of intra-oral infusion of a tastant, electrical stimulation of either the CeA or the LH increased the number of ingestive, but not aversive, TR behaviors performed. During intra-oral infusions of taste solutions, CeA stimulation tended to increase aversive behaviors whereas LH stimulation dramatically reduced the number of aversive responses to quinine hydrochloride (QHCl). These data indicate that projections from the CeA and LH alter TR behaviors. A few of the behavioral effects were accompanied by changes in the number of Fos-immunoreactive neurons in the gustatory brainstem, suggesting a possible anatomical substrate for these effects.

Transcendental meditation, hypertension and heart disease.

BACKGROUND: Accumulating evidence that stress contributes to the pathogenesis and expression of coronary heart disease has led to the increasing use of stress reduction techniques in its prevention and treatment. The most widely used and tested technique is transcendental meditation. OBJECT: To describe transcendental meditation and review research on its use in the treatment and prevention of coronary heart disease. DISCUSSION: Transcendental meditation shows promise as a preventive and treatment method for coronary heart disease. Transcendental meditation is associated with decreased hypertension and atherosclerosis, improvements in patients with heart disease, decreased hospitalisation rates and improvements in other risk factors including decreased smoking and cholesterol. These findings cannot be generalised to all meditation and stress reduction techniques as each technique differs in its effects. Further research is needed to delineate the mechanisms involved and to verify preliminary findings concerning atherosclerosis and heart disease and the findings of short term hypertension studies.