Influence of Intracerebroventricular Administration of Histaminergic Drugs on Morphine State-Dependent Memory in the Step-Down Passive Avoidance Test

Central histaminergic transmission modulates the expression of chronic nicotine withdrawal induced anxiety-like and somatic behavior in mice

The present study investigated the plausible modulatory role of central histaminergic transmission on the expression of nicotine withdrawal induced anxiety and somatic behavior in mice. Abrupt cessation of chronic nicotine (2 mg/kg, i.p. × 3/day) treatment for 12 days to mice, expressed increased anxiety in light & dark test and total abstinence (somatic) score at 24 h post nicotine withdrawal time. The somatic signs includes a composite score of all behaviors such as grooming, rearing, jumping, body shakes, forelimb tremors, head shakes, abdominal constrictions, scratching, empty mouth chewing or teeth chattering, genital licking, tail licking. Mice exhibited higher expression to nicotine withdrawal induced anxiety in light & dark test at 24 h post-nicotine withdrawal time on pre-treatment centrally (i.c.v) with histaminergic agents like histamine (0.1, 50 μg/mouse), histamine H₃ receptor inverse agonist, thioperamide (2, 10 μg/mouse), histamine H₁ receptor agonist, FMPH (2, 6.5 μg/mouse) or H₂ receptor agonist amthamine (0.1, 0.5 μg/mouse) or intraperitoneally (i.p.) with histamine precursor, l-histidine (250, 500 mg/kg) as compared to control nicotine withdrawn animals. Furthermore, mice pre-treated with all these histaminergic agents except histamine H₁ receptor agonist, FMPH shows exacerbated expression to post-nicotine withdrawal induced total abstinence (somatic) score in mice. On the other hand, central injection of selective histamine H₁ receptor antagonist, cetirizine (0.1 μg/mouse, i.c.v.) or H₂ receptor antagonist, ranitidine (50 μg/mouse, i.c.v) to mice 10 min before 24 h post-nicotine withdrawal time completely alleviated the expression of nicotine withdrawal induced anxiety and somatic behavior. Thus, it can be contemplated that the blockade of central histamine H₁ or H₂ receptor during the nicotine withdrawal phase could be a novel approach to mitigate the nicotine withdrawal associated anxiety-like manifestations. Contribution of endogenous histamine via H₁ or H₂ receptor stimulation in the nicotine withdrawal induced anxiety and somatic behavior is proposed.

Peripheral Adenosine A3 Receptor Activation Causes Regulated Hypothermia in Mice That Is Dependent on Central Histamine H1 Receptors

Adenosine can induce hypothermia, as previously demonstrated for adenosine A1 receptor (A1AR) agonists. Here we use the potent, specific A3AR agonists MRS5698, MRS5841, and MRS5980 to show that adenosine also induces hypothermia via the A3AR. The hypothermic effect of A3AR agonists is independent of A1AR activation, as the effect was fully intact in mice lacking A1AR but abolished in mice lacking A3AR. A3AR agonist-induced hypothermia was attenuated by mast cell granule depletion, demonstrating that the A3AR hypothermia is mediated, at least in part, via mast cells. Central agonist dosing had no clear hypothermic effect, whereas peripheral dosing of a non-brain-penetrant agonist caused hypothermia, suggesting that peripheral A3AR-expressing cells drive the hypothermia. Mast cells release histamine, and blocking central histamine H1 (but not H2 or H4) receptors prevented the hypothermia. The hypothermia was preceded by hypometabolism and mice with hypothermia preferred a cooler environmental temperature, demonstrating that the hypothermic state is a coordinated physiologic response with a reduced body temperature set point. Importantly, hypothermia is not required for the analgesic effects of A3AR agonists, which occur with lower agonist doses. These results support a mechanistic model for hypothermia in which A3AR agonists act on peripheral mast cells, causing histamine release, which stimulates central histamine H1 receptors to induce hypothermia. This mechanism suggests that A3AR agonists will probably not be useful for clinical induction of hypothermia.

Ameliorating effect of histamine on impairment of cued fear extinction induced by morphine withdrawal in histidine decarboxylase gene knockout mice

AIM

Histamine plays an important role in morphine addiction and memory-dependent behavior. However, little is known about the effect of histamine on the impairment of memory after morphine withdrawal. This study was designed to investigate the effect of histamine on memory impairment induced by morphine withdrawal in histidine decarboxylase knockout (HDC-KO) and wild-type (WT) mice.

METHODS

WT and HDC-KO mice were given subcutaneous morphine or saline twice daily for 5 consecutive days. The mice received a cued or contextual fear conditioning session 7 days after the last injection. During subsequent days, mice received 4 cued or contextual extinction sessions (one session per day). Western blot was used to assess extracellular signal-regulated kinase (ERK) phosphorylation in the amygdala and hippocampus.

RESULTS

Morphine withdrawal did not affect the acquisition of cued or contextual fear responses. It impaired cued but not contextual fear extinction. The acquisition of cued and contextual fear responses was accelerated in HDC-KO mice. Histamine deficiency aggravated the impairment of cued fear extinction induced by morphine withdrawal, whereas histamine (icv, 5 μg/mouse) reversed this effect. Morphine withdrawal decreased ERK phosphorylation in the amygdala after cued fear extinction, especially in HDC-KO mice.

CONCLUSION

These results suggest that morphine withdrawal specifically impairs cued fear extinction and histamine ameliorates this impairment. Its action might be mediated by the modulation of ERK phosphorylation in the amygdala. Histamine should be explored for possible roles in the prevention or treatment of morphine abuse and relapse.

Withdrawal from repeated administration of morphine alters histamine-induced anxiogenic effects produced by intra-ventral hippocampal microinjection

In the present study, the influence of withdrawal from repeated administration of morphine on intra-ventral hippocampal microinjection of histamine-induced anxiety-like behavior was investigated in male Wistar rats. Three days subcutaneous administration of morphine (5-10 mg/kg) followed by five days free of the drug decreased the percentage open arm time and the percentage open arm entries. Intra-ventral hippocampal administration of histamine (2.5-7.5 microg/rat) decreased percentage open arm time and percentage open arm entries. Intra-ventral hippocampal histamine-induced anxiogenic effect was reversed in animals that had previously received the three days morphine (7.5 mg/kg) followed by five days free of the drug. Intra-ventral hippocampal administration of pyrilamine (5-20 microg/rat) or ranitidine (10-40 microg/rat) decreased percentage open arm time and percentage open arm entries. Pyrilamine- or ranitidine-induced anxiogenic effect was not changed in animals that had previously received the three days morphine (7.5 mg/kg) followed by five days free of the drug. Intra-ventral hippocampal injections of clobenpropit increased percentage open arm time. The percentage open arm time and percentage open arm entries were decreased in the morphine-treated animals compared with non-morphine-treated controls. Percentage open arm entries and locomotor activity was reduced with some doses of clobenpropit. It can be concluded that the histamine system is involved in anxiety-like behavior, and repeated injections of morphine followed by five days free of the drugs interact with histamine receptor mechanism.

Tramadol-induced seizurogenic effect: a possible role of opioid-dependent histamine H1 receptor activation-linked mechanism

The present study has been designed to investigate the role of opioid receptors, mast cells, and histamine receptors (H(1) subtype) in the seizurogenic effect of tramadol on pentylenetetrazole-treated mice. A single injection of pentylenetetrazole (80 mg kg(-1)) was used to elicit seizure activity in mice. Seizures were assessed in terms of the time latency of the onset of Straub-like tail, onset of jerky movements of whole body, convulsions, and death. Tramadol administration (50 mg kg (-1)) caused a marked increase in seizurogenic activity of pentylenetetrazole as measured in terms of a significant decrease in the time latency of the onset of Straub-like tail, jerky movements of whole body, convulsions, and death. Moreover, prior administration of naloxone (2 mg kg(-1)), fexofenadine (100 mg kg(-1)), cetrizine, sodium cromoglycate, and ketotifen (10 mg kg(-1)), respectively, attenuated the seizurogenic activity that tramadol exerted on pentylenetetrazole-treated mice. Therefore, it may be suggested that tramadol exerts a seizurogenic effect on mice via an H(1) receptor activation-linked pathway possibly through an opioid receptor-dependent release of histamine from the mast cells.

Effects of Clozapine and Sulpiride on Morphine State-Dependent Memory in the Step-Down Passive Avoidance Test

The effects of antipsychotic drugs sulpiride and clozapine on morphine state-dependent memory of passive avoidance task were examined in mice. Post-training administration of morphine (5 mg/kg) led to state-dependent learning with impaired memory retrieval on the test day which was reversed by pre-test administration of the same dose of the opioid (5 mg/kg). In animals where memory was impaired by post-training morphine, the administration of either sulpiride or clozapine before pre-test morphine reduced the improvement of memory produced by the opioid. Co-administration of sulpiride with clozapine did not potentiate their antagonistic response. In conclusion, the inhibition of improvement of memory retrieval by morphine treatment on the test day by the two dopamine receptor antagonists seems to be induced through two different receptor mechanisms.

Endogenous opiates and behavior: 2005

This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17).

Influence of morphine- or apomorphine-induced sensitization on histamine state-dependent learning in the step-down passive avoidance test

Effects of morphine- or apomorphine-induced sensitization on histamine state-dependent memory of passive avoidance task were examined in mice. Pre-training intracerebroventricular (i.c.v.) administration of histamine (20 microg/mouse) decreased the learning of a one-trial passive avoidance task. Pre-test administration of histamine (10 and 20 microg/mouse) reversed amnesia induced by pre-training of histamine, with maximum response at 20 microg/mouse. Pre-training histamine-induced amnesia was also reversed in morphine- or apomorphine-sensitized mice that had previously received once daily injections of morphine (20 and 30 mg/kg) or apomorphine (0.5 and 1 mg/kg) for 3 days. The reversion of histamine-induced amnesia in morphine-sensitized mice was decreased by once daily administration of naloxone (0.5 and 1 mg/kg), SCH 23390 (0.05 and 0.1 mg/kg) or sulpiride (25, 50 and 100 mg/kg) prior to injection of morphine (30 mg/kg/day, 3 days). Furthermore, once daily administration of sulpiride (50 and 100 mg/kg) but not SCH 23390 (0.01, 0.05 and 0.1 mg/kg) prior to apomorphine (1 mg/kg, for 3 days) decreased the reversion of pre-training histamine-induced amnesia by apomorphine. The results suggest that apomorphine or morphine sensitization affects the impairment of memory induced by histamine and thus it is postulated that opioid and dopamine receptors may play an important role in this effect.

Influence of intracerebroventricular administration of cannabinergic drugs on morphine state-dependent memory in the step-down passive avoidance test

The effects of cannabinergic drugs on morphine state-dependent memory of passive avoidance task were examined in mice. Pre-training (0.25, 0.5 and 5 mg/kg) and post-training (5 mg/kg) administration of morphine impaired memory retrieval on the test day. Impairment of memory retrieval by morphine (5 mg/kg) on the test day was reversed by pre-test administration of the same dose of the opioid. The pre-test intracerebroventricular administration of the cannabinoid CB1/CB2 receptor agonist (WIN55,212-2) (0.75 and 1 microg/mouse) not only mimicked the effect of pre-test morphine treatment, but also increased this action of the opioid. Furthermore, the pre-test intracerebroventricular administration of CB1 receptor antagonist (AM251) (20 and 100 ng/mouse) prevented the restoration of memory by morphine. Pre-training administration of WIN55,212-2 (1 microg/mouse) led to state-dependent learning with impaired memory retrieval on the test day as well, which was reversed by pre-test administration of the drug (0.5, 0.75 and 1 microg/mouse) or morphine (1 and 5 mg/kg). Restoration of impairment induced by WIN55,212-2 was decreased by both the opioid receptor antagonists, naloxone (0.01 microg/mouse) and AM251 (20 and 100 ng/mouse). In conclusion, the improvement of memory retrieval by morphine treatment on the test day seems to be induced, at least in part, by the cannabinoid CB1 receptors.

Effects of intracerebroventricular administration of ultra low doses of histaminergic drugs on morphine state-dependent memory of passive avoidance in mice

The effects of intracerebroventricular (i.c.v.) administration of ultra low doses (ULDs) of histamine, clobenpropit and pyrilamine are studied on morphine state-dependent (STD) memory in mice. Although pre-test administration of different doses of histamine and clobenpropit showed no effect on impairment of memory induced by pre-training morphine, when the above drugs were co-administered with morphine, they inhibited the restoration of memory by morphine. These effects were opposite to microgram doses of the same drugs.

Cross state-dependent retrieval between histamine and lithium

Histamine and lithium state-dependent (StD) retrieval of passive avoidance task and their interactions was examined in mice. The pre-training or pre-test intracerebroventricular (i.c.v.) injection of histamine (20 microg/mouse) impaired retrieval when it was tested 24 h later. In the animals, in which retrieval was impaired due to histamine pre-training administration, pre-test administration of histamine, with the same dose, restored retrieval. The H1 blocker, pyrilamine (20 microg/mouse, i.c.v.), but not the H(2) blocker; ranitidine prevented the restoration of retrieval by pre-test histamine. The pre-training (5 and 10 mg/kg) or pre-test (5 mg/kg) injection of lithium also impaired retrieval, when it was tested 24 h later. In the animals that received lithium (5 mg/kg) or histamine (20 microg/mouse) as pre-training treatment, administration of histamine, clobenpropit or lithium, respectively, resulted in restoration of memory retrieval. Neither pyrilamine nor ranitidine prevented the restoration of retrieval by pre-test lithium. In conclusion, histamine or lithium can induce state-dependent retrieval and a cross-StD exists between these drugs, which may be mediated through the inositol pathway.