A windchill and solar radiation index for homeotherms.
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Air Movements↗
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Evaluation of thyrotropin-releasing hormone as a potential antidepressant agent in the conscious dog.
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Animals↗
Behavioural and electrocortical spectrum power effects of growth hormone releasing factor in rats.
The effects on behaviour and electrocortical spectrum power of intracerebroventricular, intrahippocampal and intracaudate injections of human pancreatic growth hormone releasing Factor-40 (hpGRF) (10-100 ng) were studied in rats. The hpGRF, given into the third cerebral ventricle or into the dorsal hippocampus (50-100 ng), in freely-moving rats, produced behavioural sedation accompanied by electrocortical synchronization and an increase in the total voltage power with a predominant increase in the lower frequency bands. On the contrary, unilateral injection of hpGRF (75 ng) into the head of the caudate nucleus produced an increase in locomotor activity, marked postural changes, episodes of contralateral circling and an intense pattern of stereotyped movements. In all, these results indicate that, besides its specific endocrinological effects, hpGRF possesses, in small doses, marked behavioural and electrocortical actions, the mechanism(s) of which still remain to be elucidated.
Action Potentials↗
Aggression by a female rat cohabitating with a sterile male: termination of pseudopregnancy does not abolish aggression.
At the end of that time, each female was assessed for aggressiveness toward an unfamiliar female intruder once each week for 3 weeks. Those females displaying a high level of aggression had their male cagemate changed. For half of the females, the new male cagemate was a castrated male with a testosterone implant. For the other half, the new cagemate was a castrated male without a testosterone implant. Replacement males had been subjected to surgery 9 weeks previously. There were no differences in the aggressiveness of females of the two groups on any of 3 subsequent weekly tests of aggression. In a 3-h evaluation of male sexual behavior, none of the 9 castrated males without testosterone replacement displayed sexual activity with an estrogen/progesterone primed ovariectomized female, but 6 of 9 males with testosterone replacement did. Reanalysis of the aggression data comparing the females whose males had no testosterone replacement and females housed with the 6 males that were sexually active also revealed no differences in aggression over the 21-day test period. Since pseudopregnancy is known to last 13 days, these results indicate that the continuous presence of pseudopregnancy is not required for maintenance of aggression by a female cohabiting with a sterile male.
Aggression↗
Toxicology of amidephrine mesylate, a vasoconstrictor, nasal decongestant.
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Administration, Oral↗
Effects of TRH on the central nervous system of the rabbit.
Thyrotropin releasing hormone (TRH) administered intraventricularly to rabbits produces tachypnea, hyperthermia, behavioral excitation and, with larger doses, compulsive scratching. These effects of TRH were unaffected by various catecholamine and serotonin antagonists or depleting agents. When TRH was administered to pentobarbital-narcotized animals, tachypnea and rapid recovery of the righting reflex occurred. The antagonism of narcosis or sedation was evident against other barbiturates, diazepam, chlorpromazine, and reserpine, but not against morphine. Morphine actually appeared to antagonize the excitatory actions of TRH. Scopolamine pretreatment prevented the arousal from pentobarbital narcosis, but not the tachypnea or hyperthermia. TRH represents a new class of psychoactive chemical which may play a role in brain function.
Animals↗
A frequency analysis of behavior components of the serotonin syndrome produced by p-chloroamphetamine.
A time-sampling frequency analysis was made of criterion behaviors following injection of 2.5--10 mg/kg dosages of p-chloroamphetamine (PCA). Stereotypic behaviors (forepaw treading, circling, head weaving and inching) increased with increasing dosages and normal behaviors (grooming, rearing, and instances of inactivity) decreased. Composite scores of stereotypic behavior were a positive, linear function of PCA dosage. Composite scores of normal behavior showed near maximal inhibition at 5 mg/kg. Splayed hindlimbs is a reliable and sensitive indicator of PCA action, but vocalization, tremors, diarrhea and autonomic signs are not. Preinjection of PCA strongly attenuated the PCA-induec syndrome, as expected, since the preinjection should deplete brain serotonin and reduce the amount released by the second PCA injection.
Amphetamines↗
The organization of lumbar preganglionic neurons.
The organization of pre- and postganglionic neurons supplying blood vessels of the skin (vasoconstrictor neurons) and of the skeletal muscle (vasoconstrictor neurons), sweat glands (sudomotor neurons) and erector pilimuscles (pilomotor neurons) of the cat's hind limb and tail is discussed. Each sympathetic subsystem has its own, though as yet unknown, central organization which is reflected in the reaction patterns typically seen. The conduction velocities of the pre- and postganglionic axons of each subsystem have their unique distributions. Postganglionic vasoconstrictor neurons supplying skeletal muscle and skin are influenced via cholinergic muscarinic and non-cholinergic synaptic mechanisms from thin, probably unmyelinated, preganglionic axons; postganglionic sudomotor and pilomotor neurons most likely do not receive this synaptic input. A high proportion of preganglionic neurons projecting with their axons onto postganglionic neurons which supply skin and skeletal muscle are silent and do not exhibit reflex activity. Some of these neurons synapse with postganglionic pilomotor, vasodilatator and sudomotor neurons; part of them may also synapse with vasoconstrictor neurons. However, the high proportion of preganglionic neurons without reflex and resting activity which cannot be classified on the basis of functional properties presents a considerable problem in the analysis of the central organization of the sympathetic nervous system. It is concluded that the 4 types of pre- and postganglionic neurons mentioned constitute 4 largely separate channels which transmit information from the spinal cord to the respective target organs.
Afferent Pathways↗
Vasomotor, pilomotor and secretomotor neurons distinguished by size and neuropeptide content in superior cervical ganglia of mice.
Populations of postganglionic sympathetic neurons projecting to cranial targets from the superior cervical ganglia of mice were identified by retrograde axonal tracing with Fast blue combined with double-labelling immunofluorescence to detect immunoreactivity to tyrosine hydroxylase and neuropeptide Y. Nearly all neurons in the ganglion contained tyrosine hydroxylase immunoreactivity, but only about 50% of them also contained immunoreactivity to neuropeptide Y. The maximum diameter of cells with immunoreactivity to neuropeptide Y was significantly smaller than that of cells without it. Terminal axons containing immunoreactivity to both neuropeptide Y and tyrosine hydroxylase occurred around blood vessels supplying most cranial tissues, including the skin. Axons with immunoreactivity to tyrosine hydroxylase but not to neuropeptide Y innervated the piloerector muscles and the acini of the salivary glands. After injection of Fast blue into the skin or the submandibular salivary gland, populations of vasomotor, pilomotor and secretomotor neurons could be distinguished by soma size and by neuropeptide Y immunoreactivity. Neurons projecting to the salivary glands were the largest (mean diameter: 32 microns) and lacked immunoreactivity to neuropeptide Y; neurons projecting to cutaneous blood vessels were the smallest (mean diameter: 19 microns) and contained immunoreactivity to neuropeptide Y; neurons projecting to piloerector muscles were intermediate in size (mean diameter: 23 microns) and lacked neuropeptide Y immunoreactivity. A cluster analysis procedure confirmed that soma size and peptide content together identify major functional populations of neurons in the superior cervical ganglia of mice.
Animals↗
Effects of TRH and atropine on induction and duration of anesthesia with propofol in rats.
The effects of IV TRH pretreatment on induction of anesthesia with propofol or pentobarbital were investigated in rats. The effects of IV TRH, administered after induction, on duration of propofol anesthesia and the interaction with atropine were also studied. The doses of propofol or pentobarbital were not influenced by TRH. TRH reduced duration of anesthesia after propofol, with higher brain concentrations of propofol at recovery. Atropine did not block this effect, but given alone prolonged duration of anesthesia. It is concluded that TRH shortens the duration of propofol anesthesia, probably due to a pharmacodynamic effect and not to a pharmacokinetic interaction.
Anesthesia↗
Dynorphin-containing pilomotor neurons in the superior cervical ganglion of guinea pigs.
Retrograde axonal tracing and double-labelling immunofluorescence have been combined to determine the neuropeptide content of identified pilomotor neurons in the superior cervical ganglion of guinea pigs. These neurons lacked immunoreactivity to neuropeptide Y (NPY) but they generally contained low levels of immunoreactivity to prodynorphin-derived peptides, including dynorphin A(1-8), dynorphin A(1-17), and alpha-neo-endorphin. Thus pilomotor neurons are neurochemically distinct from superior cervical ganglion cells which contain immunoreactivity to NPY and prodynorphin-derived peptides and which innervate the iris and most of the vasculature in the head of guinea pigs. They are also distinct from sympathetic secretomotor neurons which lack both NPY and prodynorphin-derived peptides.
Animals↗
Vasoconstrictor, vasodilator and pilomotor pathways in sympathetic ganglia of guinea-pigs.
Triple-labelling immunofluorescence and retrograde axonal tracing with fluorescent dyes have been combined to identify and characterize the neuropeptide content of vasoconstrictor, vasodilator and pilomotor neurons in the lumbar sympathetic ganglia of guinea-pigs. Postganglionic noradrenergic pilomotor neurons lacked immunoreactivity to neuropeptide Y and comprised up to about 30% of postganglionic neurons. Most post-ganglionic noradrenergic neurons that contained neuropeptide Y immunoreactivity were likely to be vasoconstrictor neurons, although some noradrenergic neurons containing neuropeptide Y projected to pelvic viscera. Vasoconstrictor neurons comprised up to about 60% of postganglionic neurons. About 15% of postganglionic neurons were non-noradrenergic and contained immunoreactivity to vasoactive intestinal peptide, neuropeptide Y and dynorphin. They mostly innervated blood vessels supplying skeletal muscles and were likely to be vasodilator neurons. Endings of presumed preganglionic neurons containing immunoreactivity to substance P were exclusively associated with vasodilator neurons. Conversely, presumed preganglionic endings containing immunoreactivity to calcitonin gene-related peptide were exclusively associated with vasoconstrictor neurons, although not all vasoconstrictor neurons had such endings associated with them. Presumed preganglionic terminals containing immunoreactivity to enkephalin were associated with some postganglionic neurons in each functional class. These results show that preganglionic and postganglionic sympathetic neurons lying in different functional pathways can be distinguished by their neuropeptide content as well as their projections. The identification of neurochemically distinct functional pathways begins to explain how the sympathetic nervous system is organized to allow the precise control of discrete target tissues.
Animals↗
Developmental toxicity of mono-n-benzyl phthalate, one of the major metabolites of the plasticizer n-butyl benzyl phthalate, in rats.
Mono-n-benzyl phthalate (MBeP), one of the major metabolites of the plasticizer n-butyl benzyl phthalate, was evaluated for developmental toxicity in Wistar rats. Rats were given MBeP by gastric intubation at 0, 250, 313, 375, 438 or 500 mg/kg from day 7 through day 15 of pregnancy. Significant decreases in the maternal body weight gains and food consumption during administration period were observed at 313 mg/kg and above and at 250 mg/kg and above, respectively. Significant increase in the incidence of postimplantation loss per litter was found at 438 and 500 mg/kg. The incidences of fetuses with external malformations at 438 mg/kg, of fetuses with skeletal malformations at 313 mg/kg and above and of fetuses with internal malformations at 375 mg/kg and above were higher than those in the control group. Defects in the cervical and thoracic vertebrae, ribs and kidney were frequently observed.
Abnormalities, Drug-Induced↗
Correlations between behaviours in the elevated plus-maze and sensitivity to unpredictable subchronic mild stress: evidence from inbred strains of mice.
This study aimed at investigating the relationship between anxiety-like and depressive-like behaviour in mice. Therefore, we assessed the behaviour of mice from eight different strains (FVB/NA, BALB/c, C57BL/6, DBA/2, 129/Sv, C3H/He, CBA and BA) confronted first to anxiety models (the elevated plus-maze and the free exploratory test) and then to tests of depressive-like behaviours (forced swim test and unpredictable subchronic mild stress). In the forced swim test, mice from the DBA/2, the BA and the C3H/He strains displayed higher immobility than mice from the 129/Sv, the BALB/c, the C57BL/6 and the CBA strains. In the subchronic mild stress, mice from the C57BL/6 and the CBA strains displayed low sensitivity when compared with mice from all the others strains. A stepwise multiple regression analysis suggests that behaviour in the elevated plus-maze is associated with the time of immobility in the forced swim test (20%) and with the susceptibility to the unpredictable subchronic stress procedure (31%). The behaviour in the free exploratory paradigm is slightly associated with behaviours in the two tests of depression. These results suggest that anxiety may be a factor contributing, among others, to the susceptibility to depressive-like behaviours.
Animals↗
Behaviour in the elevated plus-maze predicts coping after subchronic mild stress in mice.
This study was aimed at investigating the coping style of mice subjected to a subchronic unpredictable mild stress procedure and its relationship to initial emotional reactivity. Two inbred strains of mice, the BALB/c ByJ and the C57BL/6 J, known to exhibit distinct emotionality, have been used. They were first observed in the elevated plus-maze and the free exploratory paradigm, each provides a separation of the population in high and low emotional mice. Half of the mice of each strain were then confronted to a 2-week subchronic unpredictable mild stress and tested for their responses in different behavioural situations (consumption of a palatable food, physical state, grooming behaviours and reactivity to a conflict situation). Mice were also tested in the light/dark procedure to assess the effect of the subchronic stress on emotional reactivity. First, a relationship between initial emotional reactivity in the elevated plus-maze and behavioural coping style in response to stress was found, high emotional mice (i.e., BALB mice) displaying inhibited behaviours and less emotional mice (i.e., BL/6 mice) exhibiting few behavioural changes. Furthermore, emotional reactivity was increased in stressed mice compared with nonstressed ones.
Adaptation, Psychological↗
Life-threatening interaction between the root extract of Pueraria lobata and methotrexate in rats.
Isoflavone supplements are nowadays widely used as alternative for hormone replacement therapy. However, the safety remains unanswered. This study attempted to investigate the effect of Pueraria lobata root decoction (PLRD), an isoflavone-rich herb, on the pharmacokinetics of methotrexate (MTX), a bicarboxylate antimetabolite with narrow therapeutic window. Rats were orally and intravenously given methotrexate alone and coadministered with PLRD. Blood samples were withdrawn via cardiopuncture at specific time points after drug administration. Serum methotrexate concentrations were assayed by specific monoclonal fluorescence polarization immunoassay method. Pharmacokinetic parameters were calculated using noncompartment model of WINNONLIN for both oral and intravenous data of MTX. Our results showed that coadministration of 4.0 g/kg and 2.0 g/kg of PLRD significantly increased the AUC(0-t) by 207.8% and 127.9%, prolonged the mean residence time (MRT) by 237.8 and 155.2%, respectively, finally resulted in surprisingly high mortalities of 57.1% and 14.3% in rats. When MTX was given intravenously, the coadministration of PLRD at 4.0 g/kg significantly increased the half-life by 53.9% and decreased the clearance by 47.9%. In conclusion, the coadministration of PLRD significantly decreased the elimination and resulted in markedly increased exposure of MTX in rats.
Administration, Oral↗
Analysis of activity in A and C fibres under mechanical and thermal stimulation of the skin receptor field.
A conduction velocity spectrum in nerve fibres of 0.15 to 90 m/sec was found by means of electrophysiological methods of analysis and computer-aided processing of experimental data. A greater portion of the non-myelinated fibres in the cutaneous nerve proved to be afferent. Patterns of afferent impulse flows entering the central nervous system are determined under various mechanical and thermal stimulations of cat's cutaneous receptive field. Differences of these flows are considered to be the reasons for various sensation modalities. The mechanism of cutaneous mechanoreceptor excitation under temperature stimuli is discussed. Special attention is paid to the contraction of cutaneous collagen under cooling. Experimental data on the change of cutaneous mechanical properties and the electrophysiological changes corroborating the thermomechanical hypothesis of receptor excitation are given.
Animals↗
Marmoset conspecific confrontation: an ethologically-based model of anxiety.
A method of measuring confrontation-induced behavioural changes in common marmosets (Callithrix jacchus) together with automated monitoring of locomotor activity has been developed as a possible model of anxiety. Recording both affiliative and agonistic behaviours between male/female pairs of marmosets and using diazepam as a reference drug, it has been possible to define a profile of behavioural changes which could be regarded as representing an anxiolytic response. Unfamiliar male/female pairs of marmosets were brought into close (non-contact) proximity in a controlled environment, in which their locomotor activity was recorded automatically. Simultaneously, their interactive behaviour was assessed by an independent observer via closed-circuit television. The following behaviours were analysed: aggressive postures, allogrooming, scratching, anxiety-related behaviours, social contact and self-grooming. Administration of diazepam at 1 and 3.5 mg/kg PO induced a significant (compared to control) reduction in scratching, aggressive behaviours, anxiety-related behaviours and an increase in allogrooming without affecting locomotor activity during confrontation. Differing responses dependent on gender were not found, nor did gender influence the effect of treatment on behaviour. Habituation to repeated confrontation did not occur. The results from this study demonstrate that this method can be used to measure anxiolytic activity in an objective manner.
Aggression↗