The recently identified histamine H4 receptor has revealed a potential new complexity for the role of histamine in the immune system. To begin to understand the role of this receptor in humans, one must first determine whether homologs exist and can be studied in lower species. To address this, we cloned the rat, mouse, and guinea pig cDNAs corresponding to the recently identified human histami...

The present study investigated the effects of intra-dentate gyrus microinjection of naloxone (an opioid antagonist) and thioperamide (an antagonist of histamine H3 receptors) in the formalin test in rats. Subcutaneous injection of formalin (50 μl, 2.5 %) in the ventral surface of right hind paw produced a biphasic pattern (first phase: 0-5 min and second phase: 15 - 60 min) of licking/biting an...

After unilateral vestibular neurectomy (UVN) many molecular and neurochemical mechanisms underlie the neurophysiological reorganizations occurring in the vestibular nuclei (VN) complex, as well as the behavioral recovery process. As a key regulator, the histaminergic system appears to be a likely candidate because drugs interfering with histamine (HA) neurotransmission facilitate behavioral rec...

Myocardial ischemia activates cardiac spinal afferents that transmit the nociceptive information leading to chest pain and elicit excitatory cardiovascular reflexes. Previous studies have shown that histamine is increased in coronary sinus blood during myocardial ischemia and that this autacoid stimulates abdominal visceral afferents. The present investigation evaluated the role of endogenous h...

Histamine, in vitro, via H2-receptor activation, exerts an inhibitory effect on polymorphonuclear (PMN) chemotaxis and T-lymphocyte proliferation. The aim of this study was to verify these histamine inhibitory effects in man. Healthy and asymptomatic asthmatic volunteers inhaled a histamine (0.1%), methacholine (0.1%) or saline aerosol for 3 min. Asthmatics were selected on the basis of low bro...

Non-reinforced retrieval induces memory extinction, a phenomenon characterized by a decrease in the intensity of the learned response. This attribute has been used to develop extinction-based therapies to treat anxiety and post-traumatic stress disorders. Histamine modulates memory and anxiety but its role on fear extinction has not yet been evaluated. Therefore, using male Wistar rats, we dete...

objective: the nucleus accumbens (nac) receive histaminergic neurons from tuberomammillary nuclei. there are reports indicating that central histamine systems are involved in many physiological behavioral processes, including anxiety. the aim of the present study was to assess whether the histaminergic system of the nac is involved in anxiety-related behaviors. methods:   rats   were   anesthet...

in the present study, the effects of intracerebroventricular (icv) administration of normal saline (control), histamine, mepyramine (a histamine h1-receptor antagonist) and ranitidine (a histamine h2-receptor antagonist) were investigated on the formalin-induced pain in rabbits. subcutaneous (sc) injection of a formalin (100 μl, 5%) solution into the ventral surface of the right hind paw was pe...