Effect of Removal of the Olfactory Bulbs on Mating Behavior and Ovulation in the Rat

Abstract

The olfactory bulbs were removed in 2- to 3-month-old virgin Wistar rats; one month later, the animals were tested for precocious and oestrous mating activity during 5-day cycles. The mating frequencies observed in control and operated animals, respectively, were 35/87 and 4/50 during the night following day 3 (dioestrus 3), 36/42 and 31/38 during the night following day 4 (prooestrus), and 42/70 and 17/30 during the night following day 3, following injection of a single dose of 10 µg oestradiol. Precocious ovulation was triggered by coitus in unoperated as well as in operated oestradiol-primed animals. In operated animals, no disturbance of spontaneous ovulation frequencies was recorded, but a small decrease in the mean number of corpora lutea was observed.

Effect of Electrochemical Stimulation in the Olfactory Bulbs on the Release of Gonadotropin Hormones in Rats

“…In adult animals, cyclic va ginal estrus was not altered after the removal of the olfactory bulbs of guinea pigs [Donovan andKopriva, 1965], rats [van der Werff ten Bosch andvan Beugen, 1960;Rosen et al, 1940;van Beugen and van der Werff ten Bosch, 1961], rabbits [Brooks, 1937;Sawyer, 1956] or fer rets [van der Werff ten Bosch, 1963], But shortening of estrous cycle's duration was ob served in female rats [Aron, 1973], guinea pigs [Jesel and Aron, 1976] and mice [Whitten, 1958] exposed to the odor of urine from males of the same species. Furthermore, olfactory bulb ablation caused a decrease of ovarian and uterine weights in mice [Whitten, 1956], but failed to affect ovulation induced by coitus in the rabbit [Brooks, 1937;Sawyer, 1956] and in the rat [Aron et al, 1970], al though Curry [1974] has reported that the removal of the olfactory bulbs in rats reduced the number of animals ovulating after mating, and the number of ova shed was lower than in the controls.…”

Mating, Ovulation and Corpus Luteum Function in the Vole, Microtus Agrestis

“…In addition, the distinction between the nature of ovulation in the vole and these other animals is not absolute, as induced ovulations can also occur in rats (e.g. Zarrow & Clark, 1968;Aron, Roos & Asch, 1970;BrownGrant, Davidson & Greig, 1973) and possibly in mice (Allen, 1922;Togari, 1927).…”

Hormonal cycles

“…Indeed these mechanisms are a matter of speculation at the moment. However, we would like to propose the following hypothesis, on the basis of our preceding observations, on precociously mated 5-day cyclic female rats (Aron et al, 1970).…”

“…A lengthening of the oestrous cycle (Lamond, 1959) or a diminution in the occurrence of oestrous (Whitten, 1956) resulted from the extirpation of the olfactory bulbs in this species. In fact olfactory bulb deprivated female rats displayed a regular 4-day cyclicity or 5-day cyclicity (Aron et al, 1970). However, no statistical analysis of the distribution of these 4-day cycles and 5-day cycles had been performed.…”