Fos expression at the cerebellum following non-contact arousal and mating behavior in male rats

Abstract

The cerebellum is considered a center underlying fine movements, cognition, memory and sexual responses. The latter feature led us to correlate sexual arousal and copulation in male rats with neural activity at the cerebellar cortex. Two behavioral paradigms were used in this investigation: the stimulation of males by distant receptive females (non-contact sexual stimulation), and the execution of up to three consecutive ejaculations. The vermis area of the cerebellum was removed following behavioral experiments, cut into sagittal sections, and analyzed with Fos immunohistochemistry to determine neuronal activation. At the mid-vermis region (sections from the midline to 0.1 mm laterally), non-contact stimulation significantly increased the activity of granule neurons. The number of activated cells increased in every lobule, but lobules 1 and 6 to 9 showed the greatest increment. In sexual behavior tests, males reaching one ejaculation had a high number of activated neurons similar to those counted after non-contact stimulation. However, two or three consecutive ejaculations showed a smaller number of Fos-ir cells. In contrast to the mid-vermis region, sections farthest from the midline (0.1 to 0.9 mm laterally) revealed that only lobule 7 expressed activated neurons. These data suggest that a well-delineated group of granule neurons have a sexual biphasic response at the cerebellar vermis, and that Fos in them is under an active degradation mechanism. Thus, they participate as a neural substrate for male rat sexual responses with an activationdeactivation process corresponding with the sensory stimulation and motor performance occurring during copulation.

Sexual Interest and Neuroimaging of the Site of the Libido

“…We found that in addition to this area, part of the cerebellar vermis was specifically activated, and we speculated that it was involved in sexuality during the excitement phase. Recently, the association of sexuality with the cerebellar vermis has been reported in other studies, including animal experiments 10) , which supports our results. We also found that during the plateau phase, the occipital lobe, which contains the visual cortex, and the temporal lobe, which contains the auditory cortex, became more highly activated than during the excitement phase, and in addition, the ventral striatum (putamen) was specifically activated (Figure-4) …”

Multiunit Recording of the Cerebellar Cortex, Inferior Olive, and Fastigial Nucleus During Copulation in Naive and Sexually Experienced Male Rats

“…In men, sexual stimulation with visual or olfactory cues produces activity in the cerebellar cortex [1,2], and similar responses in non-human primates are also found after stimulation with odors from receptive females [3]. In our laboratory, we found that sensory sexual stimulation of male rats produces the highest significant activation of granule cells at lobules 6 to 9 of the vermis region [4]. Nevertheless, the execution of sexual behavior decreases the number of sensory activated neurons.…”

Who, What, Where, When (and Maybe Even Why)? How the Experience of Sexual Reward Connects Sexual Desire, Preference, and Performance

“…Sexual experience also activates the cerebellum. Sexually naïve male rats allowed to copulate to one ejaculation at 4-day intervals showed activation of the cerebellar vermis (notably lobule 7) whereas males given non-copulatory exposure to females had relatively little activation (Manzo et al, 2008). Using an identical paradigm, dynamic increases were found in GAD-65 (assessed by RT-PCR), the enzyme that converts glutamate into the inhibitory neurotransmitter GABA, during the first three ejaculations experienced by males that were sexually naïve at the beginning of the experiment (Bolivar-Duarte, Silva, Manzo, & Pfaus, 2012); however, this increase had dropped back to baseline levels by the fourth ejaculation.…”