Pharmacological evaluation of catalepsy in low calcium and/or magnesium deficient feeding mice

Populations from the Kii peninsula of Japan and Guam present a high incidence of amyotrophic lateral sclerosis and parkinsonism-dementia complex. It is thought that the low levels of calcium (Ca) and magnesium (Mg) in the drinking water are involved in the pathogenesis of these diseases. The present study aimed to test the hypothesis that catalepsy, a behavioral immobility and one of the Parkinsonian symptoms, may result from functionally impaired dopaminergic neurons in low Ca and Mg (LCa/Mg) fed mice. A group of mice fed with an LCa/Mg diet for 6 weeks was compared to a control group on a standard diet. Cataleptic symptoms such as akinesia and rigidity were measured using the bar test. The antiparkinsonian drugs dopamine (DA) precursor L-3, 4-dihydroxy phenylamine (L-DOPA), the selective DA receptor D2 agonist bromocriptine and the DA releaser amantadine were tested for their effects on the induced catalepsy. Mice developped catalepsy after 3 weeks on the LCa/Mg diet. LCa/Mg diet-induced catalepsy was improved by the administration of either L-DOPA (50 - 200 mg/kg i.p.) in combination with benserazide (25 mg/kg i.p.), bromo- criptine (0.25 - 4 mg/kg i.p.) or amantadine (5 - 20 mg/kg i.p.). These results suggest that catalepsy in LCa/Mg mice might result from a hypofunction of dopaminergic neurons. Moreover, our results support the hypothesis that LCa/Mg in-take may be one etiological factor in neurodegenerative disorders including Parkinson’s disease.

Females adopt sexual catalepsy to facilitate mating

Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner.Female sexual cannibalism,a particularly dramatic illustration of this conflict,is widespread in certain animal taxa including spiders.Nevertheless,females of some funnel weaving spiders that are generally aggressive to conspecifics enter a cataleptic state after male courtship,ensuring the males can mate without risk of attack.In this study,we demonstrated that the physical posture and duration,metabo-lites,and central neurotransmitters of females of Aterigena aculeata in sexual catalepsy closely resemble females in thanatosis but are distinct from those in anesthesia,indicating that the courted females feign death to eliminate the risk of potentially aggressive responses and thereby allow preferred males to mate.Unlike the taxonomically widespread thanatosis,which generally represents a deceptive visual signal that acts against the interest of the receivers,sexual catalepsy of females in the funnel weaving spiders may deliver a sexual-receptive signal to the courting males and thereby benefit both the signal senders and receivers.Therefore,sexual catalepsy in A.aculeata may not reflect a conflict butrather a confluence of interest betweenthe sexes.

Atypical neuroleptic properties of l-stepholidine -Electrophysiological and behavioral studies

Intravenous administration of l-stepholidine (SPD), a dopamine (DA) receptor antagonist, in-creased the firing rate of DA neurons located in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNC) in both anaesthetized and paralyzed rats. However, with the increase of dose, SPD selectively inhibited the fir-ing activity of DA neurons in the VTA but not in the SNC. The inhibition was reversed by the DA agonist apomor-phine (APO), suggesting that it may be via the mechanism of depolarization inactivation (DI). In rats, chronic admin-istration of SPD for 21 d dose-dependently decreased the number of spontaneously active DA neurons in the VTA, of which effect was reversed by APO (i. v. ). In contrast, the same treatment failed to affect the population of DA neu-rons in the SNC. Similarly, the acute treatment of SPD also decreased the number of spontaneously firing DA neurons in the VTA, but not in the SNC. SPD per se only induced very weak catalepsy. Its catalepsy which was not in pro-portion to dosage was only observed in the dose range of 10-40 mg/kg and lasted 15 min. SPD effectively antago-nized the APO (2 mg/kg, i.p. )-induced stereotypy. The above-mentioned results suggest that SPD selectively inacti-vates the DA neurons in the VTA not in the SNC. SPD may associate with a low incidence of extrapyramidal side-ef-fects and may be ranked as a promising compound for searching for a new kind of atypical neuroleptics.