Effect of corticosterone and paroxetine on masculine mating behavior: possible involvement of neurogenesis.
BACKGROUND
Corticosterone inhibits male rodent sexual behavior while the mechanism remains obscured. Recent studies have disclosed that neurogenesis in the subventricular zone (SVZ) can be increased by pheromone exposure from the opposite sex, and neurogenesis is essential for normal mating behavior of female mice. Together with the neurogenesis-inhibiting effect of corticosterone, we hypothesize that cell proliferation in the olfactory system is essential for male rodent sexual functioning.


OBJECTIVE
The current study explored the relationship between cell proliferation in the olfactory system and male sexual behavior.


METHODS
Sexual behavior performance, proliferative cell counts, and c-fos-expressing cell counts.


METHODS
Adult male rats were treated with corticosterone and/or paroxetine, an antidepressant, for 2 weeks. These two drugs were shown to suppress and enhance hippocampus and SVZ cell proliferation, respectively. Mating behavior was assessed after the treatment, and proliferation of new cells and c-fos-expressing cells, activated neurons in the mating-related regions in the brain, were analyzed. To further confirm the necessity of cell proliferation in mating, inhibition of cell proliferation was performed by intracerebroventricular infusion of cytostatic cytosine arabinose (Ara-c).


RESULTS
Corticosterone treatment, which inhibited cell proliferation in both the SVZ and olfactory epithelium, led to inhibited male sexual performance. In contrast, paroxetine increased cell proliferation and improved the performance in corticosterone-treated animals. When cell proliferation in the brain was inhibited by Ara-c, a suppressed sexual performance was found. However, cell proliferation in olfactory epithelium was not inhibited by Ara-c and thus the sexual inhibition is unlikely to be linked to this region. Furthermore, a decrease in c-fos expression in the mating-related regions upon female pheromone stimulation was found.


CONCLUSIONS
These results suggest that cell proliferation in the SVZ and hippocampus may be involved in the reproduction of the male rodents, and pharmacological treatments may affect sexual functioning through alteration of neurogenesis.
Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
Benson Wui-Man
BW
Lau
Suk-Yu
SY
Yau
Tatia M C
TM
Lee
Yick-Pang
YP
Ching
Siu-Wa
SW
Tang
Kwok-Fai
KF
So
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D003345:Corticosterone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003561:Cytarabine / Q000494:pharmacology; D008297:Male; D055495:Neurogenesis / Q000187:drug effects*; D009831:Olfactory Mucosa / Q000187:drug effects; D017374:Paroxetine / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D012724:Sex Attractants / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology
D000893:Anti-Inflammatory Agents; D003345:Corticosterone; D003561:Cytarabine; D017374:Paroxetine; D017367:Selective Serotonin Reuptake Inhibitors; D012724:Sex Attractants