We conducted experiments with receptor antagonists in rats. Opioid receptor and dopaminergic Dl or D2 receptor do not play an essential role in neuroendocrine or behavioural fear responses. Histaminergic H2 receptor is involved in the vasopressin and prolactin but not ACTH, oxytocin or behavioural fear responses. Both purinergic P2 and adrenergic alpha1 receptors are essential for behavioural and neuroendocrine fear responses. Adrenergic beta1 receptor is selectively involved in the vasopressin and beta2 receptor is in the prolactin fear responses.
Benzodiazepine receptor is involved in the neuroendocrine fear responses.
NMDA subclass of glutamate receptor is essential for emotional memory associated with neuroendocrine fear responses. Histaminergic H2 receptor is selectively involved in the vasopressin but not in the oxytocin responses to novelty stress. None of the other receptor antagonists used did not impair the responses to novelty stress. We conclude that adrenergic alpha1 and NMDA receptors are essential for fear but not anxiety responses and that there may be distinctive signal pathways in the brain for mediating emotional responses in individual physiological parameters. Managed by Traffic Interactive .