Differences in the ovulation rate of the right or left ovary in unilaterally ovariectomized rats: effect of ipsi- and contralateral vagus nerves on the remaining ovary

1987 ◽  
Vol 113 (3) ◽  
pp. 397-401 ◽  
Author(s):  
R. Chávez ◽  
M. E. Cruz ◽  
R. Domínguez

ABSTRACT The possible existence of peripheral asymmetry in the neuroendocrine mechanisms participating in the response of the ovary to gonadotrophins, and the participation of the vagus nerve, was investigated. At oestrus, the ovulation rate (number of ovulating/number of treated rats) of the left ovary in right unilaterally ovariectomized rats was lower than that in the right ovary in left unilaterally ovariectomized rats (42 vs 84%). No differences in the number of ova shed per ovulating animal nor in compensatory ovarian hypertrophy (COH) were observed. Bilateral section of the vagus nerve resulted in reduced COH only in those animals with the left ovary in situ (right unilaterally ovariectomized). Section of the left vagus nerve induced different effects depending upon which ovary was left in situ. When the left ovary was in situ an increase in ovulation rate, COH and number of ova shed was observed; however, when the right ovary was left in place the above three parameters decreased. Section of the right vagus nerve produced a decrease only in COH in both right and left unilaterally ovariectomized animals. It is concluded that in the unilaterally ovariectomized rat the right ovary seems more able to react to compensatory regulatory systems than does the left. The character of the information carried by the left and right vagus nerve is different. J. Endocr. (1987) 113, 397–401

1989 ◽  
Vol 123 (3) ◽  
pp. 441-444 ◽  
Author(s):  
R. Chávez ◽  
S. Sánchez ◽  
A. Ulloa-Aguirre ◽  
R. Domínguez

ABSTRACT The effects of unilateral section of the right or left vagus nerve (SRVN, SLVN) performed on different days of the oestrous cycle of the rat were analysed. Vagal nerve section on the day of oestrus or on day 1 of dioestrus (D1) altered oestrous cyclicity in a more significant way than when it was performed on day 2 of dioestrus (D2) or pro-oestrus (6/58 maintained normal oestrous cycles compared with 32/39 that did not; P<0.01). Ovulation rate at oestrus was lower in rats with SLVN than in the sham-operated group (32/47 vs 28/32; P < 0.05). The number of ova shed by the left ovary was reduced in sham-operated rats and in animals with SRVN and SLVN, whereas the number shed by the right ovary was not modified. The day of the oestrous cycle on which the vagus nerve was cut also influenced the number of ova shed. No changes in plasma levels of FSH at oestrus were observed in animals with SRVN or SLVN. The results indicate that vagal manipulations performed at the beginning of the oestrous cycle (day of oestrus and D1) induce more changes on oestrous cyclicity and ovulation than when they are performed during the second half of the cycle (D2 and pro-oestrus). In addition, the left ovary is more sensitive to neural manipulation than is the right one. Journal of Endocrinology (1989) 123, 441-444


1916 ◽  
Vol 24 (5) ◽  
pp. 605-619 ◽  
Author(s):  
G. Canby Robinson

The experiments that have been reported indicate that stimulation of either the right vagus or the left vagus nerve is equally effectual in blocking impulses from the auricles to the ventricles when auricular fibrillation is present. Stimulation of the left vagus nerve is as effectual in blocking impulses from the normally beating auricles as from the auricles when in a state of fibrillation, and the type of auricular activity has apparently no influence on the effect which stimulation of the left vagus has on auriculoventricular conduction.


1990 ◽  
Vol 124 (1) ◽  
pp. 37-41 ◽  
Author(s):  
M. E. Cruz ◽  
J. L. Moran ◽  
L. P. Jaramillo ◽  
R. Domínguez

ABSTRACT The effects were analysed of a unilateral lesion in the anterior or medial hypothalamus made on the day of oestrus on right or left hemicastrated rats. On the day of oestrus after two consecutive oestrous cycles of the same length, the ovulation rate in rats with lesions in the anterior left hypothalamus was lower than in control hemicastrated animals (5/16 vs 18/20; P<0·01), and normal in those rats with lesions in the right side (14/18). None of the animals with lesions in the left side of the anterior hypothalamus and with the left ovary in situ ovulated (0/7), but 5/9 with the right ovary in situ did ovulate (P<0·05). Lesions on either side of the medial hypothalamus did not modify ovulation rate. Compensatory ovulation was reduced in those animals with lesions in the right anterior hypothalamus and with the right ovary in situ. Lesions in either side of the medial hypothalamus reduced compensatory ovulation. Lesions in the right side of the anterior and medial hypothalamus increased compensatory ovarian hypertrophy in the left ovary and decreased it in the right ovary. Lesions in the left side of the anterior hypothalamus increased compensatory ovarian hypertrophy in the left ovary only, whereas lesions in the left side of the medial hypothalamus reduced compensatory ovarian hypertrophy in the right ovary. The results suggest that the information arising in each side of the anterior and medial hypothalamus plays different roles in the ipsi-and contralateral ovary, when either the left or the right ovary is absent. Journal of Endocrinology (1990) 124, 37–41


1994 ◽  
Vol 140 (2) ◽  
pp. 197-201 ◽  
Author(s):  
R Chávez ◽  
R Domínguez

Abstract The effects were analysed of section of the superior ovarian nerve on compensatory ovulation and ovarian hypertrophy, in adult rats with the left or right ovaries extirpated during the oestrous cycle and autopsied 6 or 20 days later. Rats with hemiovariectomy or hemiovariectomy plus denervation recovered their oestrous cyclicity between 2 and 3 days after surgery. Six days after hemiovariectomy 14 out of 17 rats ovulated on the expected day of oestrus. All the animals were hemiovariectomized on the day of pro-oestrus. The mean ± s.e.m. number of ova shed was similar to the group of animals with both ovaries (7·8 ± 1·2 vs 9·5 ± 0·2 Compensatory ovarian hypertrophy was observed in the right ovary when left hemiovariectomy was performed on day 2 of dioestrus or pro-oestrus; similar results were observed in the left ovary when the right one was extirpated at oestrus or pro-oestrus. Section of the right superior ovarian nerve in left-hemiovariectomized rats caused a reduction in ovulation rate and number of ova released. Compensatory ovarian hypertrophy was modified in the opposite way by unilateral section of the superior ovarian nerve to the in situ ovary depending on the day of the cycle when hemiovariectomy was performed. Twenty days after treatment, ovulation rate, compensatory ovulation and ovarian hypertrophy were similar in both left- or right-hemiovariectomized rats. Compensatory ovarian hypertrophy increased in all animals with section of the superior ovarian nerve, except when hemiovariectomy was carried out at oestrus or the left ovary was extirpated on day 1 of dioestrus. The results suggest that modulation of compensatory ovarian hypertrophy by neural information arriving at the ovary by way of the superior ovarian nerve varies during the oestrous cycle. Journal of Endocrinology (1994) 140, 197–201


1912 ◽  
Vol 16 (6) ◽  
pp. 732-757 ◽  
Author(s):  
Alfred E. Cohn

It may be concluded from the results obtained in these experiments : 1. That stimulation of the right vagus nerve in the dog usually causes arrest of all the chambers of the heart. 2. That stimulation of the left vagus nerve exerts a moderate negative chronotropic effect on the auricles. 3. That stimulation of the left vagus nerve has a profound effect on the conduction of impulses over the auriculoventricular system. 4. That the degree of effect exercised on the auriculoventricular system by stimulation of the left vagus nerve varies. In some dogs conduction is depressed to an extent which causes only a delay in the conduction of impulses from auricles to ventricles (P-R time) ; in other dogs the conduction is depressed to a degree which results in incomplete heart-block; while in still other dogs conduction is so depressed that although the auricles continue to contract, no impulses pass from them to the ventricles. 5. That when stimulation of either the right or left vagus nerve causes asystole of nomotopic ventricular contractions, ectopic ventricular contractions may occur. 6. That the time which elapses before ectopic ventricular contractions occur depends upon the irritability of the ventricular muscle, and this may vary in different dogs. 7. That stimulation of the left vagus nerve may rarely cause sino-auricular block. Possibly stimulation of the right nerve may also produce this effect. 8. That there is consequently usually a great qualitative difference in the action of the two vagus nerves on the heart of the dog.


1990 ◽  
Vol 69 (4) ◽  
pp. 1336-1346 ◽  
Author(s):  
B. J. Undem ◽  
A. C. Myers ◽  
H. Barthlow ◽  
D. Weinreich

We isolated the guinea pig right bronchus with the vagus nerves intact and evaluated the changes in isometric tension of the smooth muscle in response to nerve stimulation. Brief (10-s) trains of electrical field stimulation or vagus nerve stimulation caused a biphasic contraction: the "first phase" sensitive to atropine and the "second phase" sensitive to capsaicin. The two phases could be dissociated by adjusting the stimulus intensity; greater stimulus intensities (pulse durations or voltage) were required to evoke the capsaicin-sensitive phase. When stimulated at 30-min intervals, the magnitude of both phases of the contractions declined over a 2-h period of repeated stimulation; however, this was prevented by indomethacin. Stimulation of the left vagus nerve resulted in a monophasic contraction of the right bronchus, with little evidence of a capsaicin-sensitive phase. Blocking neurotransmission through the bronchial ganglion, as monitored by intracellular recording techniques, abolished the first-phase contraction but had no effect on the capsaicin-sensitive phase. Selective blockade of muscarinic M1 receptors had no effect on vagus nerve-mediated contractions. The results demonstrate that the left and right vagus nerves carry preganglionic fibers to the right bronchial ganglion. The right but not the left vagus nerve also carries capsaicin-sensitive afferent fibers that, when stimulated, result in a persistent contraction of the right bronchus. Finally, we provide functional and electrophysiological evidence supporting the hypothesis that capsaicin-sensitive afferent neurons communicate with postganglionic motoneurons within the bronchus.


1913 ◽  
Vol 17 (4) ◽  
pp. 429-443 ◽  
Author(s):  
G. Canby Robinson

An abnormal auricular activity is produced by faradization of the right auricle of the dog, which frequently becomes established and continues for varying periods of time after faradization is discontinued. This auricular activity consists of a rapid auricular tachycardia coexisting with true auricular fibrillation. In some dogs the auricles are thrown into this abnormal activity more readily by faradization after the vagi have been cut than before. Cutting the nerves has little or no effect on the abnormal auricular activity, but the ventricular rate may be much increased if the vagi are cut after the abnormal auricular activity has been established, apparently because of an improvement in the auriculoventricular conductivity. Stimulation of the right vagus nerve changes the character of the activity of the faradized auricles by inhibiting the auricular tachycardia while the fibrillation is uninfluenced. Stimulation of the left vagus nerve has little or no apparent inhibitory effect on the auricular tachycardia, but has possibly an inhibitory effect on the auricular fibrillation. Vagus stimulation increases the susceptibility of the auricles to faradization. The abnormal activity set up by faradization may be established in hearts otherwise refractory by vagus stimulation of short duration following the faradization. Vagus stimulation usually holds the auricles in the abnormal activity set up by faradization as long as it is continued in hearts in which, without vagus stimulation, the sequential beat always returns as soon as faradization is stopped. The right vagus is more effectual in this respect than the left. In some hearts vagus stimulation alone is capable of initiating the same abnormal auricular activity which is caused by auricular faradization. The normal sequential beat is often restored by vagus stimulation. It replaces the abnormal auricular activity not during, but a few seconds after, the termination of vagus stimulation. Left vagus stimulation is somewhat more effectual in producing this result than right vagus stimulation.


2000 ◽  
Vol 89 (1) ◽  
pp. 139-142 ◽  
Author(s):  
Robert L. Coon ◽  
Patrick J. Mueller ◽  
Philip S. Clifford

The canine cervical trachea has been used for numerous studies regarding the neural control of tracheal smooth muscle. The purpose of the present study was to determine whether there is lateral dominance by either the left or right vagal innervation of the canine cervical trachea. In anesthetized dogs, pressure in the cuff of the endotracheal tube was used as an index of smooth muscle tone in the trachea. After establishment of tracheal tone, as indicated by increased cuff pressure, either the right or left vagus nerve was sectioned followed by section of the contralateral vagus. Sectioning the right vagus first resulted in total loss of tone in the cervical trachea, whereas sectioning the left vagus first produced either a partial or no decrease in tracheal tone. After bilateral section of the vagi, cuff pressure was recorded during electrical stimulation of the rostral end of the right or left vagus. At the maximum current strength used, stimulation of the left vagus produced tracheal constriction that averaged 28.5% of the response to stimulation of the right vagus (9.0 ± 1.8 and 31.6 ± 2.5 mmHg, respectively). In conclusion, the musculature of cervical trachea in the dog appears to be predominantly controlled by vagal efferents in the right vagus nerve.


1989 ◽  
Vol 256 (5) ◽  
pp. H1295-H1302
Author(s):  
S. A. Lang ◽  
M. N. Levy

We determined the effects of vagus nerve stimulation on cardiac cycle length and on ventricular contraction and relaxation in 18 chickens anesthetized with pentobarbital. Right vagus stimulation at a constant frequency of 35 Hz prolonged cycle length by 190%, whereas left vagus stimulation at the same frequency increased cycle length by 136%. When one burst of stimuli was delivered to the right vagus nerve each cardiac cycle, but the timing of the stimuli was changed within the cardiac cycle, the response of the avian pacemaker cells varied substantially with the timing of the stimuli. Right and left vagus stimulation at a constant frequency of 20 Hz depressed ventricular contraction by 62 +/- 6 and 52 +/- 6%, respectively, and depressed ventricular relaxation by 56 +/- 7 and 53 +/- 7%, respectively. These results indicate that in the chicken the chronotropic effects of right vagus stimulation are greater than those of left vagus stimulation, whereas right and left vagus stimulation are approximately equipotent on ventricular contraction and relaxation.


2012 ◽  
Vol 01 (01) ◽  
pp. 001-006
Author(s):  
Amudha Govindarajan

Abstract Background and Aim of the study: Vagus the wanderer is the tenth cranial nerve with long extra cranial course. Below the bifurcation of trachea, the right and left vagi form plexus around the oesophagus before they enter the abdomen as anterior and posterior vagal trunks. There are variations in the contribution by the right and left vagi for the formation of oesophageal plexus and according to Chamberlin and Winship there are three different patterns in the formation of peri oesophageal plexus. The present study was aimed to study the formation of perioesophageal plexus, incidence of different patterns of peri oesophageal plexus in south Iudian population and the number of vagal trunks formed from the oesophageal plexus in the lower end of the oesophagus. Materials and Methods : The formation of perioesophageal plexus Gulae was studied in forty four autopsy specimens of oesophagus and stomach and six foetal specimens at Institute of Anatomy, Madras Medical College, Chennai. Results : The formation of perioesophageal plexus and the number of fibres from the right and left vagus nerves which contribute to the plexus formation were studied. There were significant differences in the formation of plexus Gulae. There were variations in the pattern of perioesophageal plexus and the number of vagal trunks arising from the plexus. The results of the present study in South Indian population were compared with the results in the Western population. Conclusions : Awareness regarding the presence of plexus Gulae and number of vagal trunks related to lower end of oesophagus has considerable importance in the surgical repair of hiatus hernia and while treating atrial fibrillation.


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