Behavioral effects hyperactivity

Intraspecies 10 - A broad spectrum of effects were seen, including behavioral effects, hyperactivity, fasciculations, tremors, convulsions, and vomiting. The mechanism of toxicity is uncertain and susceptibility among individuals regarding these effects may vary. This variability was especially demonstrated in dogs wherein responses varied from one of extreme severity (vomiting, tremors, convulsions, and death) to no observable effects. Therefore, a factor of 10 was applied. A factor of 10 was also applied because experiments by Weeks et al. (1963) indicated that dogs had been previously stressed (auditory stimuli), which may have affected their response to dimethylhydrazine. Based upon these data, it was assumed that humans may be equally variable in their response to dimethylhydrazine. 

Psychostimulants are drugs that substantially influence cognitive and affective functioning and behaviors. Effects are increased motivational desire, agitation, heightened vigilance, euphoria, hyperactivity, and... 

In rodents, PCP produces not only ataxia, but also stereotyped behavior and hyperactivity. The PCP-induced stereotyped behavior is thought to be due to changes in serotonergic and dopaminergic systems (Nabeshima et al. 1983 Martin et al. 1979 Sturgeon et al. 1981). It is not known whether PCP receptors mediate PCP-induced hyperactivity or stereotyped behavior or even the effect on neurotransmitter systems. It is also possible that mu, kappa, or sigma opioid receptors are involved (Castellani et al. 1982). 

The administration of low doses of PCP to rodents induces hyperactivity and stereotypy (Chen et al. 1959 ). The observation that neuroleptics such as chlorpromazine, haloperidol, and pimozide, and adrenolytics such as alpha-methyl paratyrosine antagonize these behavioral effects of PCP suggests that they are mediated by facilitation of central dopaminergic neurotransmission (Murray and Horita 1979). The actions of PCP on central dopaminergic neurotransmission may be similar to amphetamine. A dose of PCP (2.5 mg/kg) in rats, which has no effects when given alone, enhances the behavioral effects of 1 and 3 mg/kg of d-amphetamine (Balster and Chait 1978). PCP, like dopamine, has also been shown to suppress plasma prolactin (Bayorh et al. 1983). However, the firm establishment of an excl usive relationship between dopamine neuro-transmission and PCP effects is difficult because of the prominent interactions of this drug with other neurotransmitter systems. 

The close resemblance between schizophrenia and PCP-induced psychosis suggests that the behavioral effects produced by PCP might be useful as a model of psychosis. On this basis, most animal studies have examined the ability of various agents to modify PCP-induced hyperactivity and stereotypy. While some studies suggest that neuroleptics such as haloperidol (Castellani and Adams 1981 Garey et al. 1980), chlorpromazine, or clozapine (Freed et al. 

A second, more extensive experiment involved oral administration of three daily doses (100 mg/kg) of parachlorophenylalanine (PCPA). This tryptophan hydroxylase inhibitor (47), like reserpine, enhanced the behavioral effects of LSD (13) moreover, hypersensitivity occurred when 5-HT, but not other monoamine, concentrations were below normal in both forebrain and hindbrain (13). That is, effects were observed at 5 and 12 days (when 5-HT was depleted to 10-20% and 60-70% of normal) but not at 21 days (when 5-HT had returned to normal). Control experiments (13) indicated that (a) the interaction of PCPA, 5-HT, and LSD was probably not caused by generalized hyperactivity or hyperirritability sometimes seen after PCPA (73) (b) PCPA does not affect threshold doses of other psychoactive but nonserotonergic compounds, such as d-amphetamine (0.3 mg/kg) and (c) pretreatment with a-methylparatyrosine, a tyrosine hydroxylase inhibitor which depletes catecholamines rather than indoleamines, does not alter sensitivity to LSD. 

The developmental neurotoxicity guideline, accepted by OECD in 2007, has added the important aspect of behavioral effects of pre- and postnatal exposure to chemicals. This development arose from the notion that behavioral disorders in man such as anxiety, depression, phobias, autism, and attention deficit hyperactivity disorder, which appear to show increasing prevalences in western societies, may have a perinatal origin (4, 5). In the absence of causal inferences with respect to chemicals it seems nevertheless prudent to assess in a risk assessment whether such causal relations may exist. 

Tannock, R., Schachar, R.J., Carr, R.P. and Logan, G.D. (1989) Dose-response effects of methylphenidate on academic petfot-mance and overt behavior in hyperactive children. Pediatrics 84 648-657. 

Recently, a method for TMS of the brain has been developed. By using TMS it is possible to noninvasively depolarize neurons located deep in the brain without induction of seizures or pain. Thus, it may be possible to compare behavioral effects of TMS and known effects of repeated ECS and other antidepressants in rats. ECS reverses behavioral despair in the swim test and enhances apomorphine hyperactivity and stereotypy. TMS appears to have similar effects to ECS on reversal of the despair in the swim test. Rapid [25-Hz] TMS but not slow (0.2-Hz) TMS potentiated apomorphine stereotypy. ECS is followed by a postictal inhibitory period for further seizures. In this study, TMS as well as ECS increased the seizure threshold for subsequent stimulation and decreased the duration of subsequent seizure. Rapid [25-Hz] TMS but not slow [5- or 1-Hz) TMS decreases the duration of seizure induced by electrical current. 

Rapoport JL, Buchsbaum MS, Weingarter H, et al Dextroamphetamine cognitive and behavioral effects in normal and hyperactive boys and normal men. Arch Gen Psychiatry 37 933—943, 1980... 

Safer. DJ., Allen, R P Absence of tolerance to the behavioral effects of methylphenidate in hyperactive and inattentive children. J. Pediatr. 115, 1003-1008, 1989. 

Whalen CK, Henker B, Swanson JM, et al. Natural social behaviors in hyperactive children dose effects of methylphenidate. J Consult Clin Psychol 1987 55 187-193. 

Gadow KD, Nolan EE, Sverd J. Methylphenidate in hyperactive boys with comorbid tic disorder II. Short term behavioral effects in school settings. J Am Acad Child Adolesc Psychiatry 1992 31 462-471. 

The first experiment to disprove Bradley s theory of the paradoxical or reverse effect was conducted in 1980 by Judy Rapoport and her colleagues at the National Institute of Mental Health (NIMH). Under well-controlled conditions, they surveyed the cognitive and behavioral effects of stimulants on both hyperactive and non-hyperactive children. Their results showed that both groups performed better when taking stimulants. In other words, the researchers... 

Mercury poisoning in birds is characterized by muscular incoordination, falling, slowness, fluffed feathers, calmness, withdrawal, hyperactivity or hypoactivity, and eyelid drooping (Scheuhammer 1987,1991). Similar to humans (see Section 17.6.5), adverse effects may occur in many organs, but reproductive and behavioral effects are the primary concern (Eisler 1987, Scheuhammer... 

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