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PubMed1997

Orphanin FQ/nociceptin in the ventromedial nucleus facilitates lordosis in female rats.

The localization of opioid receptor-like (ORL-1) orphan receptor in the ventromedial nucleus of the hypothalamus (VMH) suggested a role for this opioid system in the regulation of lordosis behavior. Recently, the ligand for ORL-1, orphanin FQ/nociceptin (OFQ/N), has been characterized and also demonstrated to be present in the VMH. The present experiments examined whether OFQ/N in the VMH facilitates lordosis behavior in estrogen-primed, sexually unreceptive female rats, and whether estrogen regulates ORL-1 levels in the VMH. Estrogen was shown to increase ORL-1 immunoreactivity in the VMH, and microinfusions of OFQ/N into the VMH facilitated lordosis behavior in a dose-dependent manner.

Amino Acid Sequence↗
PubMedDate not supplied

The influence of backrest inclination and lumbar support on lumbar lordosis.

The influence of backrest inclination and lumbar support on the shape of the lumbar spine in sitting positions has been studied radiographically on 38 healthy subjects. Four angles of backrest inclination and four different sizes of lumbar support were studied. In addition, the lumbar support was placed at three different lumbar levels. When sitting down from a standing position, the pelvis rotates and the lumbar lordosis decreases. Increases in the backrest-seat angle had only minor effect on the lumbar lordosis. A lumbar support, on the other hand, had a significant influence: the lordosis increased with increasing support. The location of the lumbar support with respect to the level of the spine did not significantly influence the measured angles.

Adult↗
PubMed1999

GABAergic regulation of lordosis: influence of gonadal hormones on turnover of GABA and interaction of GABA with 5-HT.

The role of GABAergic neurons in activating female sexual behavior and possible mechanisms for GABAergic effects on behavior were examined in female rats. First, effects of the ovarian hormones estrogen and progesterone (P), at doses which promote lordosis, on levels and turnover/activity of GABA, were examined in brain areas which regulate lordosis. Utilizing AOAA, an inhibitor of GABA degradation, the accumulation rate of GABA (turnover/activity) was assessed in ovariectomized (Ovx), Ovx + estrogen and Ovx + estrogen + P-treated rats. Estradiol increased GABA accumulation rates in the arcuate-median eminence and in the area dorsal to and surrounding the VMN (VMN-S). P administration following estrogen priming enhanced GABA turnover in the medial preoptic area (mPOA) and further increased turnover in the VMN-S while GABA turnover decreased in the dorsomedial nucleus. No effects of hormones were noted in the VMN itself or in the dorsal midbrain central gray. Reverse dialysis of the GABAA antagonist bicuculline into the basomedial hypothalamus was associated with a time-dependent inhibition of lordosis and a 300% increase in 5-HT release in the basomedial hypothalamus as measured by in vivo dialysis. These results provide additional evidence that GABAergic neurons mediate the physiological regulation of female sexual behavior and suggest that such mediation may involve an interaction with 5-HT containing neurons.

Animals↗
PubMed1999

Effect of direct application of estrogen aimed at lateral septum or dorsal raphe nucleus on lordosis behavior: regional and sexual differences in rats.

The role of estrogen in lordosis-inhibiting systems in the lateral septum or the dorsal raphe nucleus was investigated in female and male rats. Ovariectomized rats received implantation of 22-gauge guide cannulae to the bilateral or right side of the lateral septum (LS and rLS, respectively), the dorsal raphe nucleus (DRN) or bilateral cortex (CX). In castrated male rats, bilateral implantations of the cannulae to the LS were carried out (mLS). Three behavioral tests in total were performed at 2-week intervals. In the first test, all animals were subcutaneously injected with 1.5 microg/kg estradiol benzoate (EB). Forty-four hours after EB, 0.5 mg progesterone (P) was injected and a behavioral test was started 4 h after P. These hormonal regimes were used in all tests. In the second test, 2 h before EB injection, 27-gauge cannulae filled with estradiol (E2) were inserted into the DRN, LS or CX through the guide cannulae and were kept there for 4 h. In the third test, cholesterol was implanted instead of E2 into these areas. In the first test, most females showed low levels of lordosis quotient (LQ) and most males showed no lordosis. In the second test, mean LQs in the LS or rLS groups of females increased but not in the DRN and CX groups. In the mLS group no increase of LQ was observed. When cholesterol was implanted in the third test, mean LQs in all groups were as low as in the first test. These results suggest the possibility that estrogen releases the inhibition when it acts on the LS, but not on the DRN female rats. On the other hand, inhibition in the male LS may not be released by the direct action of estrogen.

Animals↗
PubMed1977

Lordosis response of senile female rats.

The lordosis response of 27 ovariectomized senile female rats (20 to 32 months old) primed with either estrogen-progestrone (E/P) or estrogen (E) alone was studied and compared with that of ovariectomized young adult rats (3 to 5 months old). As compared with the young rats, out of the 27 senile rats, only 11 showed decreased response with E/P priming and 6 with E priming only. When senile rats are classified into 4 groups according to their vaginal smear pictures and ovarian findings, i.e., prolonged vaginal cornification (PVC) with polyfollicular ovaries, anestrus (ANE) with atrophic ovaries, prolonged diestrus with hyperluteinized ovaries, and still preserved cycle, there is no significant difference in the incidence of decreased lordosis response among groups. In the 11 senile rats showing decreased response, the responsiveness of the system for sexual behavior to P seems to be decreased in 5 rats without changes in the responsiveness to E and that to E decreased in 6 rats. The lordosis response did not improve after adaptation in the rats which showed decreased response. The dysfunction of gonadotropin (Gn) secretion in senile female rats seems to occur earlier than aging of the system for behavioral estrus.

Aging↗
PubMed1993

Progesterone, but not LHRH or prostaglandin E2, induces sequential inhibition of lordosis to various lordogenic agents.

In experiment I we studied the capacity of progesterone (P) and two nonsteroidal agents that activate lordosis, but do not bind to the progestin receptor (PR), i.e. luteinizing hormone-releasing hormone (LHRH) and prostaglandin E2 (PGE2) to induce sequential inhibition (SI) in ovariectomized estradiol-primed rats. The administration of 1 mg P, 5 micrograms LHRH or 100 micrograms PGE2 induced significant lordosis within 4 h. An injection of 1 mg P, 24 h after the administration of the above lordogenic agents, induced significant lordosis in rats pretreated with LHRH or PGE2, but not in those pretreated with P. Thus, only P induced SI (p < 0.025). In experiment II we investigated if progestin-induced SI results in a reduced capacity of the subjects to respond only to P or to other lordogenic agents. The synthetic progestin norgestrel (400 micrograms administered 24 h earlier) significantly reduced the responsiveness to P (p < 0.01), LHRH (p < 0.01), PGE2 (p < 0.025) and dibutyryl cyclic AMP (db cAMP p < 0.01). Results suggest that SI is triggered only by agents that bind to the PR (experiment I) and that it decreases the responsiveness of rats not only to P but also to other lordogenic agents (experiment II).

Animals↗
PubMedDate not supplied

Role of vertical larynx movement and cervical lordosis in F0 control.

The role of vertical larynx movement in vocal frequency (F0) change has attracted the attention of many researchers. Recently, Hirai, Honda, Fujimoto, and Shimada (1994) proposed a mechanism of F0 control by vertical larynx movement based on the measurement of magnetic resonance images (MRI). In F0 changes, the larynx moves vertically along the cervical spine, which displays anterior convexity (lordosis) at the level of the larynx. Therefore, the vertical larynx movement results in the rotation of the cricoid cartilage and vocal fold tension changes. The present study reexamines the above mechanism based on a qualitative analysis of midsagittal MRI data using three male subjects with evident cervical lordosis. Tracings of the jaw, hyoid bone, laryngeal cartilage, and cervical spine were compared in high and low F0 ranges. In the high F0 range, the hyoid bone moved horizontally while the larynx height remained relatively constant. In the low F0 range, the entire larynx moved vertically, and the cricoid cartilage rotated along the cervical lordosis. These results indicate that the vertical movement of the larynx comprises an effective F0 lowering mechanism, and suggest that the human morphologies of low larynx position and spinal curvature contribute to voluntary use of the vocal function.

Cervical Vertebrae↗
PubMed1997

Facilitatory effect of ventral cut of dorsal raphe nucleus on lordosis in female rats.

The role of the ventral projections of the dorsal raphe nucleus (DRN) in regulating lordosis was examined in female rats. The ventral neural fibers of the DRN were transected by the horizontal circle-cut (VC), anterior (AVC) or posterior half-circle cut (PVC) at the same time as ovariectomy. Three weeks after the surgery, all the rats were implanted with a Silastic tube containing estradiol (E2). The behavioral test was started one day after E2-implantation, and 5 tests in total were carried out every other day. The results showed that the VC females had a higher lordosis quotient (LQ) than control rats. Furthermore, as well as females with the VC, a high score LQ was observed in the AVC rats but not in the PVC females, compared to those in the control animals. These results suggest that the anteroventral neural fibers of the DRN are involved in the lordosis inhibiting mechanisms in female rats.

Animals↗
PubMed1998

Inhibitory effect of progesterone on androgen-induced lordosis in ovariectomized rats.

Androgen has a potency to induce female sexual behavior in ovariectomized rats. This study investigated the inhibitory effect of progesterone (P) on lordosis behavior facilitated by androgen. Ovariectomized female rats were given 100 to 800 micrograms/kg testosterone propionate (TP) or 5 micrograms/kg estradiol benzoate (EB). Forty-four hours after administration of the TP or the EB, all females received 0.5 mg P, and the first behavioral test was carried out four hours later. TP-treated animals showed lordosis responses in a dose dependent manner. Two weeks after the first test, the animals were retested by using the same hormonal regime as in the first test, except that an additional 5 mg P was administered 1 h prior to the TP or the EB. As a result, significant reductions in sexual receptivity were observed in the TP-treated as well as in the EB-treated females. These results indicate that progesterone can inhibit androgen-induced lordosis behavior in female rats.

Androgens↗
PubMed2006

Prazosin blocks the glutamatergic effects of N-methyl-D-aspartic acid on lordosis behavior and luteinizing hormone secretion in the estrogen-primed female rat.

We have observed that intracerebroventricular (icv) injection of selective N-methyl-D-aspartic acid (NMDA)-type glutamatergic receptor antagonists inhibits lordosis in ovariectomized (OVX), estrogen-primed rats receiving progesterone or luteinizing hormone-releasing hormone (LHRH). When NMDA was injected into OVX estrogen-primed rats, it induced a significant increase in lordosis. The interaction between LHRH and glutamate was previously explored by us and another groups. The noradrenergic systems have a functional role in the regulation of LHRH release. The purpose of the present study was to explore the interaction between glutamatergic and noradrenergic transmission. The action of prazosin, an alpha1- and alpha2b-noradrenergic antagonist, was studied here by injecting it icv (1.75 and 3.5 microg/6 microL) prior to NMDA administration (1 microg/2 microL) in OVX estrogen-primed Sprague-Dawley rats (240-270 g). Rats manually restrained were injected over a period of 2 min, and tested 1.5 h later. The enhancing effect induced by NMDA on the lordosis/mount ratio at high doses (67.06 +/- 3.28, N = 28) when compared to saline controls (6 and 2 microL, 16.59 +/- 3.20, N = 27) was abolished by prazosin administration (17.04 +/- 5.52, N = 17, and 9.33 +/- 3.21, N = 20, P < 0.001 for both doses). Plasma LH levels decreased significantly only with the higher dose of prazosin (1.99 +/- 0.24 ng/mL, N = 18, compared to saline-NMDA effect, 5.96 +/- 2.01 ng/mL, N = 13, P < 0.05). Behavioral effects seem to be more sensitive to the alpha-blockade than hormonal effects. These findings strongly suggest that the facilitatory effects of NMDA on both lordosis and LH secretion in this model are mediated by alpha-noradrenergic transmission.

Adrenergic alpha-Antagonists↗
PubMed1978

Effects of anti-oestrogen treatment of neonatal male rats on lordosis behaviour and mounting behaviour in the adult.

Male rats were treated daily with 100 microgram of the anti-oestrogen ethamoxytriphetol (MER-25) or oil during the first 10 days of life and tested for lordosis behaviour and mounting behaviour as intact adults, after castration and after castration and oestradiol benzoate or testosterone propionate treatment. The MER-25-treated rats showed higher levels of lordosis behaviour than oil-treated rats in all four treatment groups. Under each of these endocrine conditions, except after castration alone, the MER-25-treated rats showed a reduced capacity to ejaculate. Treatment of the neonatal rat with MER-25 reduced body weight in adulthood but did not change the weight of the accessory sexual glands, the testes, the number of cornified papillae on the glans penis or plasma testosterone concentrations during development. The response of the accessory sexual glands and cornified papillae on the glans penis to treatment with oestradiol benzoate or testosterone propionate after castration in adulthood was unaffected by treatment with MER-25. It is suggested that formation of oestrogen in the neonatal male rat brain from testosterone in the circulation inhibits the capacity to show lordosis behaviour and facilitates the capacity to ejaculate in response to ejaculate in response to gonadal hormone treatment in adulthood.

Animals↗
PubMed1999

Central neuronal circuit innervating the lordosis-producing muscles defined by transneuronal transport of pseudorabies virus.

The lordosis reflex is a hormone-dependent behavior displayed by female rats during mating. This study used the transneuronal tracer pseudorabies virus (PRV) to investigate the CNS network that controls the lumbar epaxial muscles that produce this posture. After PRV was injected into lumbar epaxial muscles, the time course analysis of CNS viral infection showed progressively more PRV-labeled neurons in higher brain structures after longer survival times. In particular, the medullary reticular formation, periaqueductal gray (PAG), and ventromedial nucleus of the hypothalamus (VMN) were sequentially labeled with PRV, which supports the proposed hierarchical network of lordosis control. Closer inspection of the PRV-immunoreactive neurons in the PAG revealed a marked preponderance of spheroid neurons, rather than fusiform or triangular morphologies. Furthermore, PRV-immunoreactive neurons were concentrated in the ventrolateral column, rather than the dorsal, dorsolateral, or lateral columns of the PAG. Localization of the PRV-labeled neurons in the VMN indicated that the majority were located in the ventrolateral subdivision, although some were also in other subdivisions of the VMN. As expected, labeled cells also were found in areas traditionally associated with sympathetic outflow to blood vessels and motor pathways, including the intermediolateral nucleus of the spinal cord, the paraventricular hypothalamic nucleus, the red nucleus, and the motor cortex. These results suggest that the various brain regions along the neuraxis previously implicated in the lordosis reflex are indeed serially connected.

Animals↗
PubMed2000

Functionally-defined compartments of the lordosis neural circuit in the ventromedial hypothalamus in female rats.

Sexual behavior in female rats, typified by the lordosis reflex, is dependent upon estrogen action in the ventromedial nucleus of the hypothalamus (VMH) and its surrounding neuropil. However, the synaptic organization of this brain region remains unclear. Pseudorabies virus (PRV) was used to transneuronally label the neural network that innervates the lumbar epaxial muscles that execute the lordosis response. PRV-labeled neurons were identified within and subjacent to the VMH four days after injection of PRV into the back muscles. The pattern of labeling was defined in relation to three landmarks: the VMH core, as defined by Crystal Violet staining; the shell, as defined by the oxytocin fiber tract; and the cluster of estrogen receptor-containing cell nuclei. The pattern of PRV labeling in the VMH displayed a striking rostral-caudal gradient. In general, many of the PRV-labeled neurons were found in the oxytocin fiber tract, with far fewer in the core of the VMH. Furthermore, PRV-labeled neurons were rarely found in the cluster of estrogen receptor-containing neurons, and less than 3% of the PRV-labeled neurons were double labeled for estrogen receptor. The results suggest that oxytocin may directly influence these lordosis-relevant VMH projection neurons, whereas estrogen may have transsynaptic effects.

Animals↗
PubMed1992

Low concentrations of oxytocin suppress lordosis when infused into the lateral ventricle of female rats.

The first experiment was undertaken to compare the effects on lordosis of the infusion of oxytocin into the lateral versus the third ventricle. Female rats fitted with bilateral cannulae aimed at these ventricles were primed with 5 micrograms estradiol benzoate and 150 micrograms progesterone and received an infusion of 0.34 ng oxytocin into either the left lateral or the third ventricle. The infusion of 0.34 ng oxytocin into the left lateral ventricle inhibited lordosis behavior, while the same dose infused into the third ventricles of the same animals did not. Since a facilitation of lordosis in response to the infusion of oxytocin into the lateral ventricle has been reported in other studies, it seemed possible that the inhibition and facilitation could be produced by different doses of oxytocin. In the second experiment this hypothesis was tested in another set of female rats fitted with unilateral cannulae aimed at the left lateral ventricle, primed with 5 micrograms estradiol benzoate and 150 micrograms progesterone and infused with different doses of oxytocin. In these animals the inhibition occurred with 0.34 ng but not with 3.4 ng or 34 ng of oxytocin. No facilitation was observed at any of these doses.

Animals↗
PubMed1991

Accumbens lesion in female rats increases mount rejection without modifying lordosis.

Ovariectomized Wistar rats received bilateral electrolytic (n = 24) or sham (n = 11) lesion of the nucleus accumbens. Following priming with estradiol benzoate (25 micrograms/rat) and progesterone (0.5 mg/rat) they were tested for sexual behavior with a stud male. Tests were carried out once prior to operation and twice postoperatively. Both lordosis and rejection behaviors as responses to male mount attempts were evaluated for each session. Proceptive patterns (hopping, darting and presenting) were also recorded. Females with accumbens lesion did not differ from control animals either with regard to lordosis or to soliciting behaviors. On the contrary, the lesioned group showed a statistically significant increase in rejection behavior in both postoperative sessions (p less than 0.05 and p less than 0.002). In conclusion, nucleus accumbens lesion dissociated the normal correlation between lordosis and rejection responses to male mount attempts without affecting soliciting behaviors. This finding is thought to be related to the hyperreactivity produced by nucleus accumbens lesion.

Aggression↗
PubMed1993

Role of striatal dopamine in the lordosis behaviour.

Effects of intrastriatal injections of haloperidol (Dopamine antagonist) and D-amphetamine (Dopamine agonist) on lordosis behaviour were studied in ovariectomized female albino rats, after priming with subcutaneous injections of estrogen and progesterone. The lordosis quotient (LQ) significantly increased after haloperidol, and decreased following D-amphetamine treatment. However, the inhibitory effect of D-amphetamine was transient and could be reversed by haloperidol in the same animal when given one hour after the D-amphetamine injection. The ovarian hormones probably act centrally to suppress the DA system in the striatum thereby enhancing the tonic and dorsal immobility responses associated with lordosis.

Animals↗
PubMed1996

Anaesthetic management of a parturient with severe muscular dystrophy, lumbar lordosis and a difficult airway.

PURPOSE: This case describes the management of a 19-yr-old wheelchair bound primigravida with severe muscular dystrophy who presented for Caesarean section after spontaneous rupture of membranes. Anaesthesia was influenced by several features of her systemic disease which were impediments to both neuraxial and general anaesthesia. CLINICAL FEATURES: Other than for a prenatal record and the history obtainable from the patient, little additional medical information was available. Physical examination showed diffuse muscular weakness and an anatomically abnormal airway. Examination of the spine showed slight 10-15 degrees thoracolumbar scoliosis and > 45 degrees lumbar lordosis. Fetal assessment was normal. Echocardiography revealed mildly decreased left ventricular function and was consistent with pulmonary hypertension. After discussion with the patient and her obstetrician, elective Caesarean delivery was deemed the best management. Neuroaxial anaesthesia was at an increased risk of failure due to the profound lumbar lordosis. A plan for awake intubation and general anaesthesia was described to the patient in case regional anaesthesia could not be initiated. A fibreoptic bronchoscope and difficult intubation kit were made available. General anaesthesia was expected to have increased risk of postoperative pulmonary complications, hence epidural anaesthesia was attempted. After difficult catheter insertion, a sensory block was titrated to a T4 level. This was well tolerated by both mother and fetus. A healthy baby was delivered with Apgar scores of 9 and 9. Postoperatively the mother was transferred to the intensive care unit. After 72 hr, the patients respiratory status allowed transfer to the word. CONCLUSION: This case illustrates the use of epidural anaesthesia in the successful management of a severely compromised patient with limb-girdle muscular dystrophy undergoing elective Caesarean section.

Adult↗
PubMed1989

The importance of 'lumbar lordosis measurement device' application during pregnancy, and post-partum isometric exercise.

In this study, we measured the lumbar lordosis of normal pregnant women throughout their pregnancies and studied the efficacy and importance of the postpartum isometric exercise. 40 healthy primigravid patients were randomly assigned to one of the control and exercise groups. The lumbar lordotic deviation increased significantly throughout the pregnancy (p less than 0.05). Second postpartum day values of lumbar lordotic deviation and depth decreased compared to the third trimester values (p less than 0.05). Sixth postpartum week values of lumbar lordotic deviation and depth were found to be increased when compared to the first trimester values in the control and exercise group (p less than 0.05). On the other hand, the sixth week values in the exercise group are significantly lower compared to the control group (p less than 0.05). For these measurements we have used a 'Lumbar Lordosis Measurement Device' which was constructed in our institute. Muscle testing showed that isometric exercise improves the functional status of the affected muscles during pregnancy. We therefore conclude that the usage of 'LLMD' during the follow-up examination of pregnant women is essential to evaluate the posture of the patients. Isometric exercise is very important in order to obtain a normal posture and muscle tonus postpartumly.

Anthropometry↗