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Reproductive behaviour in the male rat: importance of 5-HT2 receptor activity and relation to 5-HT2-dependent serotonergic stereotypy Watson, Neil Verne
Abstract
It is well established that the neurotransmitter serotonin participates in the control of sexual behaviour in the male rat. Recently, it has been found that serotonergic activity may either inhibit or facilitate sexual behaviour, depending on the subtypes of serotonin receptors involved. However, the participation of 5-HT2 receptors in the control of male rat copulation has received little experimental attention, and the published data are equivocal. In Experiments 1-4, it was established that the 5- HT2/1C agonist DCI inhibits sexual behaviour in male rats; this inhibition is effectively reversed by the antagonists ritanserin, pirenperone, and ketanserin. Comparison of these effects , with reference to the binding profiles of each drug, provided strong evidence that 5-HT2/1C receptors mediate an inhibitory influence on sexual behaviour in male rats. In addition, a tentative claim may be made that the effects of these drugs may be more attributable to 5-HT2 activity than 5-UT1C activity. ‘Wet dog shake’ behaviour in rats is known to be 5-HT2- dependent. Experiments 5—7 evaluated the novel proposition that the incidence of spontaneous wet dog shaking (WDS) by male rats in mating tests may provide a behavioural assay of concurrent 5—HT2 activity. WDS was found to be associated with copulatory inhibition in noncopulating males, compared to normal copulators, and this relationship was specific to mating situations. Activating 5-HT2/1C receptors with DOl simultaneously induced WDS and inhibited copulation. Thus, the incidence of spontaneous WDS in untreated males may reflect the function of a 5—HT2—mediated neural mechanism that tonically inhibits copulation in male rats. In Experiment 8, DOl microinjection in the nucleus raphe obscurus/inferior olivary complex also induced WDS and inhibited copulation. This suggests that the hypothesized 5- flT2-dependent inhibitory mechanism is vested in the ventromedial brainstem. Recent anatomical findings support this suggestion: cells in this region have bifurcating axons, projecting collaterally to both the medial preoptic area (implicated in sexual behaviour) and to the ventral cervical spinal cord (implicated in WDS). Overall, the results of the eight experiments provide strong evidence that 5-HT2 receptors mediate some of the inhibitory effects of serotonin on male rat sexual behaviour.
Item Metadata
Title |
Reproductive behaviour in the male rat: importance of 5-HT2 receptor activity and relation to 5-HT2-dependent serotonergic stereotypy
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
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Description |
It is well established that the neurotransmitter
serotonin participates in the control of sexual behaviour in
the male rat. Recently, it has been found that serotonergic
activity may either inhibit or facilitate sexual behaviour,
depending on the subtypes of serotonin receptors involved.
However, the participation of 5-HT2 receptors in the control
of male rat copulation has received little experimental
attention, and the published data are equivocal.
In Experiments 1-4, it was established that the 5-
HT2/1C agonist DCI inhibits sexual behaviour in male rats;
this inhibition is effectively reversed by the antagonists
ritanserin, pirenperone, and ketanserin. Comparison of these
effects , with reference to the binding profiles of each
drug, provided strong evidence that 5-HT2/1C receptors
mediate an inhibitory influence on sexual behaviour in male
rats. In addition, a tentative claim may be made that the
effects of these drugs may be more attributable to 5-HT2
activity than 5-UT1C activity.
‘Wet dog shake’ behaviour in rats is known to be 5-HT2-
dependent. Experiments 5—7 evaluated the novel proposition
that the incidence of spontaneous wet dog shaking (WDS) by
male rats in mating tests may provide a behavioural assay of
concurrent 5—HT2 activity. WDS was found to be associated with copulatory inhibition in noncopulating males, compared
to normal copulators, and this relationship was specific to
mating situations. Activating 5-HT2/1C receptors with DOl
simultaneously induced WDS and inhibited copulation. Thus,
the incidence of spontaneous WDS in untreated males may
reflect the function of a 5—HT2—mediated neural mechanism
that tonically inhibits copulation in male rats. In
Experiment 8, DOl microinjection in the nucleus raphe
obscurus/inferior olivary complex also induced WDS and
inhibited copulation. This suggests that the hypothesized 5-
flT2-dependent inhibitory mechanism is vested in the
ventromedial brainstem. Recent anatomical findings support
this suggestion: cells in this region have bifurcating
axons, projecting collaterally to both the medial preoptic
area (implicated in sexual behaviour) and to the ventral
cervical spinal cord (implicated in WDS). Overall, the
results of the eight experiments provide strong evidence
that 5-HT2 receptors mediate some of the inhibitory effects
of serotonin on male rat sexual behaviour.
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Extent |
2090564 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-08
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0088202
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.