Does histamine interact with cholinergic neurones in its cataleptogenic action in the rat?

Histamine and the striatum

The neuromodulator histamine is released throughout the brain during periods of wakefulness. Combined with an abundant expression of histamine receptors, this suggests potential widespread histaminergic control of neural circuit activity. However, the effect of histamine on many of these circuits is unknown. In this review we will discuss recent evidence for histaminergic modulation of the basal ganglia circuitry, and specifically its main input nucleus; the striatum. Furthermore, we will discuss recent findings of histaminergic dysfunction in several basal ganglia disorders, including in Parkinson's disease and most prominently, in Tourette's syndrome, which has led to a resurgence of interest in this neuromodulator. Combined, these recent observations not only suggest a central role for histamine in modulating basal ganglia activity and behaviour, but also as a possible target in treating basal ganglia disorders. This article is part of the Special Issue entitled 'Histamine Receptors'.

Effects of prenatal diphenhydramine exposure on dopaminergic function in adult rats

Female pregnant rats were treated with 20.0 mg/kg diphenhydramine (DPH) or the same volume of saline solution (NaCl 0.9%), SC, daily during pregnancy. As adults, male pups were tested for stereotyped behavior in response to apomorphine (1 mg/kg, SC) administration. No differences between DPH-exposed and control rats were evident. In another group of rats, dopamine (DA) and homovanillic acid (HVA) levels were quantified in striatal samples. DA levels were equivalent, but increased levels of HVA were observed. Based upon these data we suggest that prenatal exposure to DPH, a histamine (H1) receptor antagonist, reduces presynaptic dopaminergic mechanisms without altering postsynaptic dopaminergic function in adulthood.

Pharmacological characteristics of catalepsy induced by intracerebroventricular administration of histamine in mice: the importance of muscarinic step in central cholinergic neurons

Histamine-induced catalepsy was antagonized potently by scopolamine, an antimuscarinic drug, and partially blocked by sparteine. Neither methylatropine nor antinicotinic drugs could reverse histamine-induced catalepsy. These results indicate the greater importance of muscarinic receptors rather than their nicotinic counterparts in histamine-induced catalepsy. Various antiparkinson drugs, i.e. biperiden and trihexyphenidyl, which have antimuscarinic activity or dopamine agonists, i.e. L-dopa, amantadine and bromocriptine, could antagonize the histamine-induced catalepsy to various degrees. Thus, catalepsy induced by icv histamine can be evoked not only by an activation of the histamine receptor, but also indirectly due to cholinergic and dopaminergic imbalance.

Biphasic effects of intra-accumbens histamine administration on spontaneous motor activity in the rat; a role for central histamine receptors

1. The effect of intra-accumbens injection of histamine and related compounds on the spontaneous motor activity of the rat has been investigated. 2. Microinjections of histamine (1-200 micrograms) induced dose-dependent, biphasic changes in rat activity consisting of an initial brief hypoactivity response followed by a marked hyperactivity phase. The histamine metabolite, n-tele-methylhistamine was without effect. 3. Pretreatment with the H1-receptor antagonist mepyramine (10 micrograms) blocked the hypoactivity response and markedly attenuated histamine-induced hyperactivity. In contrast, pretreatment with the H2-receptor antagonist SKF93479 had no effect on histamine-induced behaviour. 4. Microinjection of the H1-receptor agonist 2-thiazolylethylamine induced a marked hyperactivity response, but unlike the response to histamine, there was no initial hypoactivity. The H2-receptor agonist dimaprit had no apparent behavioural effects following intra-accumbens injection. 5. Intra-accumbens injection of the non-selective histamine agonists n alpha-methylhistamine or n alpha, n alpha-dimethylhistamine induced both marked hypoactivity and hyperactivity responses which were comparable with the effects of histamine. 6. The present results demonstrate a histamine, H1-receptor-mediated arousal in the nucleus accumbens which follows transitory hypoactivity, possibly due to activation of presynaptic H3-receptors.

Role of central histaminergic mechanism in behavioural depression (swimming despair) in mice

The role of the central histaminergic system in depression was studied by using swimming despair test in mice - a behavioural model of depression. In this test, immobility of mice reflects a state of depression. Intracerebral (ic) injection of histamine (50-200 micrograms) increased significantly the immobility. The H1-receptor blocker mepyramine (2.5-20 mg/kg ip) had no effect while H2-receptor blocker cimetidine (100-200 micrograms ic) caused a significant decrease in immobility. The histamine induced facilitation was blocked completely by cimetidine and antidepressant drugs-imipramine and desipramine, but remained unaffected in mice pretreated with mepyramine or atropine. The H2 agonist impromidine (20-40 micrograms ic) also enhanced significantly, the immobility which was blocked by cimetidine and antidepressant drugs. It has been concluded that central H2-receptors facilitate depression and antidepressant drugs block central H2-receptors.

Possible neuronal mechanisms involved in neurotensin-induced catalepsy in mice

The neuronal mechanisms of neurotensin (NT)-induced catalepsy were investigated in mice. NT administered intracerebroventricularly (ICV 0.5, 1.0 and 2.0 micrograms) produced catalepsy in a dose-dependent fashion. A significant effect was observed at 2.0 micrograms and a maximal effect 2-3 h after injection. The NT-induced catalepsy was inhibited by pretreatment with atropine, trihexyphenidyl or biperiden (each drug, 0.8-5.0 mg/kg, IP), anticholinergic drugs, and L-DOPA (100, 200 mg/kg, IP). However, the catalepsy was not significantly antagonized by p-chlorphenylalanine (300 mg/kg X 3 days, IP) or methysergide (5, 10 mg/kg, IP), antiserotonergic drugs, and was not potentiated by the GABAergic drugs, aminooxyacetic acid (25 mg/kg, IP) or muscimol (1 mg/kg, IP). In addition, the NT-induced catalepsy was dose-dependently reduced by antihistamines, such as diphenhydramine (0.8-10 mg/kg, IP) and tripelennamine (0.4-5.0 mg/kg, IP) and was potentiated after treatment with histidine (250, 500 mg/kg, IP), a precursor of brain histamine. NT-induced catalepsy was also reduced by ICV pretreatment with diphenhydramine (1-5 micrograms/rat), a H1 antagonist, but not by cimetidine (5, 20 micrograms/rat), a H2 antagonist. These findings suggest that the catalepsy induced by NT may involve not only central cholinergic and dopaminergic mechanisms but also a histaminergic mechanism mediated via H1-histamine receptors, and seems to differ from the catalepsy induced by neuroleptics.

Studies on the site and mechanism of the inhibitory action of intracerebral histamine on the cold-stimulated thyrotropin secretion in male rats

The locus of the inhibitory action of histamine on cold-stimulated TSH secretion was studied in male rats. Various histaminergic drugs were given either into the median eminence (ME), the third ventricle, the rostral and caudal part of anterior hypothalamus (rAH and cAH) or the posterior hypothalamus (PH) of conscious rats. When infused into ME, histamine (5 and 10 micrograms/rat) decreased and mepyramine (2.5 micrograms) increased the cold-stimulated TSH secretion while a larger dose of mepyramine (10 micrograms/rat), impromidine (0.05 and 0.1 microgram/rat), 2-pyridylethylamine (2-PEA; 5 and 10 micrograms/rat) and cimetidine (2.5 and 7.5 micrograms/rat) had no effect. The inhibitory action of histamine (5 micrograms/rat) was most marked 30 min after the infusion into ME and it remained significant for at least 50 min. Neither cimetidine (50 and 100 mg/kg i.p.) nor mepyramine (10 and 20 mg/kg i.p.) antagonized the inhibitory action of histamine (5 micrograms/rat) in ME. Histamine (10 micrograms/side) inhibited the cold-stimulated TSH secretion likewise when infused bilaterally either into rAH, cAH or PH. TSH secretion induced by exogenous TRH (100 ng i.p.) was also inhibited by histamine (1 microgram/rat) given into the third ventricle. In conclusion, histamine seems to have an inhibitory action on the cold-stimulated TSH secretion. This action is apparently mediated through areas close to the third ventricle. The mechanism of this action seems to be fairly non-specific, i.e. it is mediated through neither H1- nor H2-receptors.

Analgesic effect of histamine induced by intracerebral injection into mice

Three methods were used to study the analgesic effect of intracerebral injection of histamine (Hi) on mice: the writhing test (acetic acid and phenylquinone), the electrical stimulation of the tail and the hot plate test. At doses higher than 2 micrograms, Hi inhibited the writhing syndrome significantly, and at doses of 10 micrograms or higher, Hi displayed a marked analgesic effect during both the electrical stimulation and hot plate methods. The saline injection produced only a negligible effect. Simultaneous application of Hi and 10 micrograms of diphenhydramine, pyrilamine or promethazine, apparently causing no analgesic effect from a single administration, caused a parallel shift of the dose-response curve of Hi to the right. ED50 of Hi was increased approximately 2, 2.8 and 3.8 times, respectively. However, cimetidine did not reveal any antagonistic effect on Hi-induced analgesia. Subcutaneously administered, 3 mg/kg of morphine augmented the analgesic effect of Hi. In accordance with this, pretreatment of naloxone (0.005 mg/kg) antagonized the analgesic action of Hi almost completely. When 5 mg/kg of leucine-enkephalin, less than the minimum effective dose, was given prior to Hi injection, the analgesic effect of Hi was enhanced. In addition, 10 and 20 micrograms of Hi increased the morphine analgesia markedly and parallel shifted the dose-response curve of morphine to the left.

Regional differences in the turnover of neuronal histamine in the rat brain

The turnover rate of histamine (HA) and the half-life of neuronal HA were estimated in 9 regions of the rat brain following pargyline-induced accumulation of tele-methylhistamine (t-MH). The turnover rate was the highest in the hypothalamus (108.7 ng/g/hr). The striatum also showed a high turnover rate (80.2 ng/g/hr) despite much lower levels of HA and t-MH, as compared with the levels in the hypothalamus. The turnover rate was relatively high in the thalamus, cerebral cortex, amygdala and midbrain, but it was very low in the cerebellum. t-MH accumulation in the spinal cord was nil. The HA levels were reduced to various degrees (from nil to less than 40% of the control) by (S)-alpha-fluoromethylhistidine, depending on the regions studied. The neuronal HA content of each brain region was subsequently estimated, and the half-life of neuronal HA in each region was calculated. The half-life of neuronal HA was the shortest (7.7 min) in the striatum, while it was long (about 50 min) in the hypothalamus and thalamus. Half-life values of about 20 min were obtained in other regions. These results show the high levels of histaminergic activity in some parts of the telencephalon, thalamus and midbrain as well as the hypothalamus.

An appraisal of the value of vitamin B12 in the prevention of motion sickness

Unpublished reports have suggested that hydroxycobalamin (B12, i.m.) prevents motion sickness. Some biomedical evidence supports this contention in that B12 influences the metabolism of histidine and choline; dietary precursors to neurotransmitters with established roles in motion sickness. Susceptibility to motion sickness was evaluated after B12 (1000 micrograms, i.m.). Subjects initially completed vestibular function and motion sickness susceptibility tests to establish normal vestibular function. The experimental motion stressor was a modified coriolis sickness susceptibility test. Subjects executed standardized head movements at successively higher RPM until a malaise III endpoint was reached. Following two baseline tests with this motion stressor, subjects received a B12 injection, a second injection two weeks later, and a final motion sickness test three weeks later. No significant differences in susceptibility were noted after B12. Hematological parameters revealed no B12 deficiency before injection. The possibility that patients with B12 deficiencies are more susceptible to motion sickness cannot be ruled out.

Is the brain histamine involved in cataleptogenic action of analgesics and haloperidol?

L-Histidine, histamine ivc, and amodiaquine (inhibitor of histamine catabolism) enhanced catalepsy induced by morphine, codeine and fentanyl. Haloperidol catalepsy was increased only by ivc histamine. H1 (but not H2) receptor antagonists have shown anticataleptic effect in the action of analgesics and haloperidol.

Involvement of histaminergic mechanisms in the cataleptogenic effect of morphine in mice

Intraperitoneally administered morphine induced catalepsy in mice. Morphine pretreatment however, failed to antagonize apomorphine-induced cage climbing behaviour thereby ruling out the possibility of its possessing DA receptor blocking activity. Pretreatment with L-histidine, a precursor of histamine, and atropine, potentiated the cataleptic effect of morphine whilst pretreatment with chlorcyclizine, an H1 receptor blocker, and naloxone, a morphine antagonist, antagonized morphine-catalepsy. Pretreatment with metiamide, an H2 receptor blocker, and methysergide, a 5-HT antagonist, did not significantly alter the cataleptic effect of morphine. The results with L-histidine and chlorcyclizine suggest an involvement of central histaminergic mechanisms in the cataleptogenic effect of morphine in mice. Further, as the cataleptic effect of morphine was also antagonized by naloxone it appears that the interaction of morphine with the central histaminergic mechanisms is mediated through specific opiate receptors.

Evidence for central histaminergic mechanism in foot shock aggression

The role of central histaminergic system in foot shock induced aggression was studied in mice. Histamine administered by intracerebral (IC) injection (25-200 micrograms) produced a significant increase in fighting episodes in a dose dependent manner. It was observed that mepyramine (H1 blocker) given intraperitoneally (IP) significantly increased and metiamide (H2 blocker) given IC decreased significantly the fighting response. To determine the nature of receptors involved in histamine induced facilitation of aggressive behaviour, histamine was administered IC in mice pretreated with mepyramine or metiamide. Mepyramine pretreatment further increased the facilitatory effect of histamine while metiamide blocked the enhancement of aggressiveness by histamine. Combined pretreatment with metiamide and mepyramine decreased significantly the fighting counts which remained unaffected after histamine. Haloperidol did not block the enhancement of aggression by histamine or mepyramine. However, atropine pretreatment partially inhibited the histamine induced increase in the fighting counts. Results of pretreatment with metiamide and atropine were similar to those obtained with pretreatment of metiamide and mepyramine. Metiamide alone or in combination with atropine failed to affect the facilitatory effect of amphetamine on the foot-shock aggression. It is concluded that central histamine H2 receptors have a facilitatory role and H1 receptors an inhibitory role on aggressive behaviour in mice induced by foot-shock. Since histamine per se had a facilitatory effect on foot-shock induced aggression, the central H2 receptors seem to dominate over the H1 receptors.

Inhibition of diamine oxidase by antimalarial drugs

The antimalarial drugs amodiaquine, quinacrine and chloroquine inhibit the catabolism of putrescine by the rat. Amodiaquine, the most potent of the three, does so in a dose-dependent fashion. This is attributed to the action in vivo of the drugs on diamine oxidase, an enzyme that is inhibited by them in vitro.

Influence of histamine on the serotonergic system of rat brain

Both histamine and 4-methylhistamine, after intraventricular injection into normal rats, reduced the levels of serotonin and increased those of 5-hydroxyindoleacetic acid in hypothalamus; after injection into tranylcypromine-treated rats, head twitches were induced which were blocked by antiserotonin agents. 2-Pyridylethylamine, an agonist of histamine H1 receptors, neither influenced serotonin level in hypothalamus nor evoked behavioural changes. It is concluded that injected histamine may release serotonin from the hypothalamus and that this produces the behavioural changes.