Tulane, LSU team on stress-related shutdown
The team from Tulane and Louisiana State Universities, led by Shi Di, found that in both physiological and psychological stress situations, stress hormones act on the brain to stimulate the release of endogenous cannabinoids from neurons in the hypothalamus, which act as a local messenger within the hypothalamus to shut down the neuroendocrine stress response.
One explanation for this hormone feedback regulation of the stress response might be to prepare the brain to mount another response in case of the onset of another possible stressor. The endogenous cannabinoids may serve to link the stress response with other neuroendocrine functions controlled by the hypothalamus, such as feeding.
Di says that the "actions of the endocannabinoids on the synaptic circuits that control the activity of the hypothalamic neurons serve to rapidly inhibit hormone secretion from the pituitary gland, providing a rapid negative feedback mechanism for the regulation of neuroendocrine function during stress."
Japanese team finds inhibition of excitatory and inhibitory synaptic transmission
In an in vitro study, a multi-center Japanese team led by Atsushi Soya focused on the supraoptic nucleus (SON) where vasopressin and oxytocin are synthesized. They found that a synthesized cannbinoid (CP55,940) inhibited both excitatory and inhibitory synaptic transmission and that a balanced input can produce sustained changes in neuronal activity without damage to neuronal homeostasis.
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19-Jul-2005