The influence of vibrissae removal on copulatory behaviour, was tested in both sexually naive and experienced male rats. The experiment consisted of 3 experimental and 3 control sessions. In some sexually naive rats, the removal of the vibrissae caused absence of copulatory behaviour during the first or all 3 experimental sessions, while in other ones this procedure remained without any apparent influence on copulatory behaviour. Three weeks later, after vibrissae have regrown, all of these rats displayed the copulatory behaviour. However, after the regrowth of the vibrissae, in rats with previously impaired copulatory behaviour a shortening of postejaculatory intervals was observed, while in rats with unaffected copulatory behaviour no such differences were observed. In contrast to observations in the sexually naive rats, in the sexually experienced ones removal of vibrissae led to the activation of copulatory behaviour, manifested by shortening of ejaculation latencies and mean interintromission intervals and an increase in hit rate.
Eight male rats copulated with an estrus female with an open vagina (NF) and an estrus female with the vagina covered by adhesive tape (CF). Experimental sessions were composed of two phases. During Phase 1 the males copulated with NF or with CF females until 4 intromissions or 4 mount bouts were displayed respectively. In Phase 2 the males copulated alternately with NF or CF according to three schedules: (1) a sequence two mount bouts with a CF female followed by one intromission, (2) a sequence one intromission followed by two mount bouts with a CF female , and (3) a sequence one intromission followed by four mount bouts with a CF female. All of these sequences were repeated until ejaculation. Ejaculation occurred in 95.8% of cases within one minute after the last intromission during copulation with the CF female. The results of this study indicate that: (1) the number of intromissions displayed during Phase 2 does not depend on the character of the copulatory behaviour displayed during Phase 1, (2) at least two intromissions are displayed before ejaculation, and (3) the tactile stimulation of the glans of penis plays a crucial role in the ejaculatory seminal reflex.
The role of protein biosynthesis and ene expression in learning has been well documented. Similarly, the role of activation of glutamate receptors in neuronal plasticity have been shown repeatedly. In our studies we found that L-glutamate, acting through different kinds of its receptors may stimulate expression of c-fos and other genes encoding components of transcroption factors both in vivo and in vitro. We have also documented elevated expression of c-fos after induction of long lasting long term potentiation and variaous forms of behavioral training. In this paper these data are reviewed and a hypothesis, suggesting that neuronal nuclei may act as information integration device in memory formation is proposed.
Elevated expression of c-fos mRNA and/or its protein (c-Fos) has been repeatly observed following activation of brain cells with various stimuli.As a consequence it has been proposed that elevated c-fos expression may serve as a merker of neuronal activation reflecting a prediposal to a long-term changes in cell functioning (neuronal plasticity).It studies on copulatory behaviour of male animals, elevated Fos immunoreactivity (related most probably to c-Fos) has been used by many researchers as a tool to reveal functional neuroanatomy of the behaviour.They found that brain regions such as medial preoptic area (MPOA), bed nucleus of stria terminalis (BNST), medial amygdala (MeAm) and central tegmental field (CTF) are always activated in a copulation-dependent manner in various species (rats and hamsters were the most often studied in this regard).This paper reviews the data gathered in this field, and discusses them in the context of the role of elevated Fos expression in acquisition vs. performance of the sexual behaviour.
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