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Biomedical subjects

C W Hennig

Publications and source records attributed to C W Hennig.

11 recordsLinked to original sources
PubMed1988

Tonic immobility and the serotonergic system in chickens: differential blockade of receptors by cyproheptadine and cinanserin.

Low doses of serotonin potentiated immobility durations in 2 1/2-week-old chickens (Gallus gallus) while high doses attenuated the response. Cyproheptadine, a serotonergic antagonist, eliminated increases generated by low doses of serotonin and reduced durations in control subjects, but had no effect on the attenuation produced by high doses of the drug. Cinanserin, another serotonergic blocker, also eliminated the potentiation generated by low doses of serotonin and partially reduced the attenuation caused by high doses, but had no effect on immobility durations in control animals. Larger doses of cinanserin eliminated the attenuation produced by high doses of serotonin and increased durations in control subjects. Results are discussed in terms of the differential blockade of various serotonin receptors.

Animals↗
PubMed1988

Differential cholinergic influences on the immobility response in various strains of domestic fowl.

A series of five experiments examined the effects of two anticholinergic drugs, atropine and scopolamine, on the duration of tonic immobility (TI) and susceptibility to the TI response in both Production Red and White Leghorn chickens (Gallus gallus), in an attempt to resolve previous contradictory findings about the effects of cholinergic manipulations on tonic immobility. These two anticholinergic drugs significantly reduced the duration of TI and, therefore, supported the conclusion that cholinergic systems are involved with the immobility response. However, the effects of these drugs on TI differed depending on the age, strain, local population, and handling experience of the individual birds.

Aging↗
PubMed1986

Central and peripheral effects of serotonin on the immobility response in chickens.

The effects of low and high doses of serotonin on tonic immobility (TI) duration and susceptibility in 10- and 45-day-old chickens were examined. High doses of serotonin reduced the number of inductions required to produce TI, regardless of the subject's age. In contrast, low and high doses of serotonin produced biphasic increases and decreases in TI duration in 10-day-old birds, but there were no apparent effects on immobility duration by either dose of this drug in older chickens. These results are discussed in terms of the formation of the blood-brain barrier in domestic fowl and the differential peripheral versus central actions by serotonin on TI susceptibility and response duration.

Age Factors↗
PubMed1984

Duration of tonic immobility in chickens as a function of alpha-adrenergic receptor stimulation and blockade.

Tonic immobility in chickens was influenced by a variety of drugs that act on the adrenergic neurochemical system of the body. Alpha 1 agonists such as methoxamine and phenylephrine produced decreases in the duration of immobility, although the former compound also caused a significant increase in the immobility response at high dosages. Alpha 2 agonists such as clonidine, naphazoline, and guanfacine enhanced the duration of immobility, but clonidine also produced an apparent reversal of this effect at high dosages. Subsequent experiments examined more fully the biphasic effects by methoxamine and clonidine on tonic immobility through interactions with alpha antagonists. Yohimbine, an alpha 2 blocker, attenuated the duration of immobility, either alone or in conjunction with various dosages of methoxamine. Prazosin, an alpha 1 blocker, had no direct effect on tonic immobility, but potentiated the duration of the response when given in conjunction with various dosages of methoxamine. When these antagonists were given in conjunction with clonidine, yohimbine reduced immobility durations, while prazosin had no apparent effect on this response. These results are discussed in terms of the relative contributions of the alpha 1 and alpha 2 adrenoceptors to the duration of the immobility response.

Adrenergic alpha-Agonists↗
PubMed1981

Subspecies differences in curiosity and general activity for developing squirrel monkeys.

Curiosity and general activity characteristics in different squirrel monkey (Saimiri sciureus) phenotypes were assessed. Ten infant squirrel monkeys, representing 2 subspecies (Bolivian and Colombian) and both genders, were observed on 4 testing sessions during which novel and familiar objects were presented to each subject. No consistent object-contact differences were found between subspecies or genders, but significant subspecies differences were found for the amount of time during each trial that the subjects climbed, remained stationary, vocalized, and showed abnormal behaviors. Familiar objects were handled most often, whereas novel objects that were shiny or yellow were moderately preferred.

Animals↗
PubMed1981

Differential effects of alpha-adrenergic antagonists on tonic immobility in domestic fowl.

Groups of young chickens were injected with various dosages of several alpha-adrenergic antagonists and tested for the effects of these drugs on tonic immobility. Yohimbine, a very potent alpha2 antagonist, produced a significant decrease in the duration of tonic immobility at doses of 1 mg/kg, while prazosin, a potent alpha1 antagonist, had no apparent effect on immobility duration. Phentolamine, a on-specific alpha antagonist, produced a significant decrease in the duration of immobility at doses of 0.1 mg/kg, but had no effect at higher or lower doses. These results support the involvement of the alpha-adrenergic system with the duration of the tonic immobility reflex, but at the same time they also suggest that alpha2 receptors are more closely involved with the immobility response than alpha1 receptors. However, none of these drugs had any apparent effect on the initial susceptibility of subjects to the immobility reflex, as measured by the number of inductions required to produce tonic immobility.

Adrenergic alpha-Antagonists↗
PubMed1980

Biphasic effects of serotonin on tonic immobility in domestic fowl.

In two experiments, groups of 2 1/2 to 3 week old chickens were injected intravenously with various dosages of serotonin and tested for tonic immobility. Relatively low doses of serotonin produced significant increases in the duration of immobility, while high doses only produced slight decreases in duration. Serotonin also reduced the activity levels of chickens before testing for immobility and made the response easier to induce, but there were no apparent differences due to dosage for either of these behaviors. The effects by serotonin on the immobility response and activity level were found to persist for over two hours with little decrease in their potency. The data in this study are used to explain the contradictory effects produced by serotonins on immobility during past research and are discussed in terms of the importance of differential responding by prey during predatory encounters.

Animals↗