Sexual Behaviour of the Female Laboratory Rat: Inventory, Patterning, and Measurement

In this study some ethological principles were applied to a laboratory animal studied under laboratory conditions. The observations of the sexual behaviour of the female Wistar laboratory rat were performed in various behavioural contexts and under variable conditions. This made it possible to obtain detailed descriptions of some clear-cut behaviour elements, to determine the reliability of their identification, to analyze their interrelationships, and to study broader relationships of female sexual behaviour. Except for the transition from oestrus to dioestrus, attention was paid to all behavioural states of the female. Progressively, however, the study concentrated on the behaviour of females with reliable readiness to Lordotic Reaction. Observing the behaviour of such females shortly before and immediately after Lordotic Reaction resulted in the classification of the elements into three groups: Precopulatory Behaviour, Copulatory Behaviour and Postcopulatory Aversive Behaviour. The exhibition of Postcopulatory Aversive Behaviour means that the female after performing copulation is transitorily in an aversive state in which she reacts spontaneously or to the male's approach with specific defensive behaviour. Copulatory Behaviour of the female rat consists of Lordotic Reaction, usually accompanied by Ear-wiggling. The elements of Precopulatory Behaviour include Presenting Posture (usually accompanied by Ear-wiggling), Hopping (invariably terminated by Presenting Posture) and Darting (invariably terminated by Presenting Posture). In describing these elements the intensity dimension of their motoric performance was taken into account. The sufficient reliability of identification of the defined elements even in cases of their performance at low intensity, was demonstrated by means of the Kappa index. As soon as the female exhibits any Precopulatory Behaviour element her highest readiness to Lordotic Reaction can be expected. Darting can be considered as more intensive Precopulatory Behaviour than Hopping, and Hopping as more intensive than Presenting Posture. The last formulation is substantiated by three kinds of observations : (1) in the course of the natural oestrus first Presenting Posture, later Hopping and finally Darting emerge; (2) the stated order of intensity of Precopulatory Behaviour positively correlates with the amount of ovarian hormone doses injected to ovariectomized females; (3) Darting is the most effective, Hopping is moderately effective and Presenting Posture is little effective in inducing the copulatory activities of sexually inexperienced males. In addition, the following regularity should be mentioned: the more intensive Precopulatory Behaviour, the more probable is the occurrence of Postcopulatory Aversive Behaviour. Naturally as well as artificially oestrus females prefer to exhibit Precopulatory Behaviour of a certain intensity for some time. The endogenous determination apparently limits the potentialities of the external stimulation. The scaling of the sexual responsiveness into six degrees was based on this principle. The four constituent degrees are "clean" : at the Lordotic degree the female does not react to a stimulus from the part of the male by any Precopulatory Behaviour, however, she reacts by Lordotic Reaction to the male's mount. The next three degrees are defined by that element of Precopulatory Behaviour (Presenting Posture or Hopping or Darting) with which the female reacts exclusively or almost exclusively to all the stimuli produced by the approaching male. Two intermediate degrees are "mixed" (the degree of Presenting-and-Hopping and the degree of Hopping-and-Darting) : the female reacts intermittently with two elements of Precopulatory Behaviour apparently in dependency on the intensity of the external stimulation. For the assessment of the intensity of the female sexual responsiveness a testing procedure was constructed, involving a series of subtests and taken into account a broader behavioral context.