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PubMed1973

Luteinizing hormone-releasing factor potentiates lordosis behavior in hypophysectomized ovariectomized female rats.

Subcutaneous injection of luteinizing hormone-releasing factor (LRF) in estrogen-primed hypophysectomized, ovariectomized female rats facilitates the appearance of the lordosis response. The LRF effect on lordosis was seen 90, 180, and 360 minutes after injection. This effect could help to synchronize the female's mating behavior with the ovulatory discharge of luteinizing hormone.

Animals↗
PubMed1983

Midbrain microinfusions of prolactin increase the estrogen-dependent behavior, lordosis.

Microinfusions of rat prolactin into the dorsal midbrain of estrogen-treated, ovariectomized rats increased lordosis behavior. Midbrain microinfusions of antiserum to prolactin into rats displaying maximum lordosis had the opposite effect. The distribution of a prolactin-like substance in the brain was studied immunocytochemically. The results suggest that a hypothalamic neuronal system projecting to the midbrain contains a prolactin-like substance that plays a role in facilitating this behavior and therefore may mediate some of the effects of estrogen on the brain. These data, together with others from studies of the prolactin gene and its regulation, indicate that it may be possible to analyze a sequence of molecular events in the brain that facilitate a behavioral response.

Adrenalectomy↗
PubMed1979

Responses of single units in sixth lumbar dorsal root ganglion of female rats to mechanostimulation relevant for lordosis reflex.

1. The activity of single units (n = 312) was recorded from dorsal root ganglion L6 in female rats; 84% received input from cutaneous mechanoreceptors. 2. Among cutaneous mechanoreceptive units (n = 263), 22% responded to individual guard hair movement, 18% to down hair, 11% to clitoral hair, and 14% to stimulation of tylotrich hair-haarscheibe (type I) receptors, 5% responded to punctate skin deformation, but not hair movement of pressure, and 18% responded to pressure. 3. No significant differences between estrogen-treated and untreated ovariectomized rats were observed in receptive-field size, or von Frey hair, or pressure threshold of any given type of unit. 4. The lordosis reflex of female rats is triggered by pressure, but not hair deflection, on skin regions innervated by dorsal root L6 (10). Stimulation from the male rat mounting would cause a barrage of action potentials from most of the unit types identified here, but only pressure units and type I units gave sustained responses to a lordosis-triggering type of pressure stimulation.

Animals↗
PubMed2003

Neonatal estrogen decreases neural density of the septum-midbrain central gray connection underlying the lordosis-inhibiting system in female rats.

Neurons in the lateral septum (LS) with projecting axons to the midbrain central gray (MCG) exert an inhibitory influence on lordosis. The number of such neurons is greater in female than in male rats. In this experiment, effects of neonatal estrogen on the density of the LS-MCG connections and on lordosis behavior were examined in female rats. On postnatal day 4 (day 0 = day of birth), females were injected subcutaneously with 50 or 100 mug estradiol benzoate (EB) or oil. On postnatal day 60, females and control males were gonadectomized. Behavioral tests were carried out after the implantation of silicone tubes containing estradiol. Lordotic activities in both males and EB-treated females were lower than in oil-treated females. After completing the behavioral tests, the animals were injected with Fluoro-Gold (FG), a retrograde tracer, into the right-side MCG and the number of FG-labeled neurons in the LS was measured. In all groups, the right-side LS ipsilateral to the FG injection had more FG-labeled neurons than the left-side LS. The number of FG-labeled neurons in the LS of oil-treated females was larger than that of males on both right and left sides. In the females treated with 100 mug EB (EB100), the number of FG-labeled neurons was comparable with that of males and lower than that of oil-treated females. The number of FG-labeled neurons in the EB50 females was also lower than that in oil-treated females, but tended to be larger than that observed in the EB100 group. These results indicate that neonatal estrogen decreases both lordotic activity and the density of the LS-MCG neural connections in female rats.

Animals↗
PubMed1976

Potentiation of lordosis behavior by intrahypothalamic infusion of synthetic luteinizing hormone-releasing hormone.

Saline and luteinizing hormone-releasing hormone (LRH) were infused into the medial preoptic area (MPOA), arcuate nucleus (ARC), lateral hypothalamic area (LHA) and the cerebral cortex (CC), and the effects on sexual behavior were studied in estrone- (E-) primed ovariectomized (OVX) female rats. Each cannulated, OVX female known to be sexually active was primed with E in doses too low to initiate consistent mating behavior. LRH infusion in either the MPOA or ARC faciliated sexual behavior as measured by the lordosis-to-mount (L/M) ratio; LRH infusion in the LHA or CC, as well as saline infusion in all neural sites, was ineffective in initiating comparable behavior patterns. The results concur with findings utilizing systemic LRH injections and support the notion that LRH may act directly on neural tissue to potentiate lordosis behavior in the female rat.

Animals↗
PubMed1986

Removal of the vomeronasal organ impairs lordosis in female hamsters: effect is reversed by luteinising hormone-releasing hormone.

In female golden hamsters, vomeronasal organ removal disrupts the elicitation of lordosis by lumbosacral tactile stimulation. A similar disruption occurs if the nasopalatine ducts are closed, without removing the vomeronasal organ. Injection of luteinising hormone-releasing hormone reverses the effect of vomeronasal organ removal. These findings suggest that chemosensory signals from the male hamster act via the accessory olfactory system, to facilitate the triggering of lordosis by somatic stimulation.

Animals↗
PubMed1990

Differential effects of a luteinizing-hormone-releasing hormone (LHRH) antagonist analogue on lordosis behavior induced by LHRH and the LHRH fragment Ac-LHRH5-10.

Both the luteinizing-hormone-releasing hormone (LHRH) decapeptide and an LHRH fragment consisting of the last 6 amino acids of the decapeptide, Ac-LHRH, have been shown to enhance lordosis behavior in ovariectomized, estradiol-benzoate treated female rats. Although the behavioral efficacy of the 2 peptides is similar, several lines of research suggest that the fragment and the decapeptide may act via different mechanisms. The present study attempted to differentiate the behavioral action of the 2 peptides by administering a long-acting LHRH antagonist analogue prior to infusion of either Ac-LHRH or LHRH. Without antagonist administration, the decapeptide and the fragment were equally effective in elevating lordotic posturing 90 min after bilateral infusion through cannulae positioned in the ventromedial nucleus of the hypothalamus (VMH). Infusion of a potent LHRH antagonist analogue [Ac-dehydro, Pro, pCl, D-Phe, DTrp]-LHRH, into the VMH significantly reduced the lordosis-to-mount ratio in animals subsequently treated with the LHRH decapeptide, but had no significant effect on lordotic behavior when the animals were subsequently infused with the Ac-LHRH fragment. The results indicate that LHRH enhancement of mating behavior is a receptor-mediated event and suggest that the Ac-LHRH fragment enhances lordotic behavior via a mechanism that is distinct from that of the LHRH decapeptide.

Animals↗
PubMed1998

Temporal coincidence between the excitation of ventromedial hypothalamic efferents and the induction of lordosis reflex in ovariectomized estrogen-primed rats.

The temporal changes in excitability in ventromedial hypothalamic neurons which project to the midbrain central gray caused by chronic estrogen exposure were measured in ovariectomized rats. In 66 urethane-anesthetized animals which had either no capsule, or had a capsule containing estrogen implanted for 24 h, 48 h, 72 h or 96 h, 189 antidromic action potentials were recorded in the ventromedial hypothalamus (VMN) in response to stimulation of the midbrain central gray (CG). The antidromic activation threshold was lower in 40 recordings made from the VMN in the 72-h or 96-h group than in 67 from the no-treatment, 24-h or 48-h group. The decrease in the threshold coincided with the emergence of the lordosis reflex. In a separate cohort of ovariectomized rats, any absence of estrogen for 2-48 h before and during the measuring abolished the neuronal as well as the behavioral effects at 72 h. The results suggest that the lordosis reflex induced by estrogen alone depends on the excitation of VMN efferents to the CG. In addition, the indispensability of estrogen at the time of electrophysiological and behavioral evaluation indicates that a certain direct neural action of estrogen is involved in the behavioral activation.

Animals↗
PubMed1992

Electrophysiological analyses of serotonergic actions on neurons in hypothalamic ventromedial nucleus in vitro: receptor subtypes involved and implications for regulation of feeding and lordosis behaviors.

Previously, we have shown that serotonin (5-HT) can inhibit, excite, or biphasically inhibit and excite individual neurons of the ventromedial nucleus (VMN) in hypothalamic slices from female rats. In the present study, similar in vitro methods were used to further characterize VMN neurons responsive to 5-HT, and to identify the receptor subtypes involved in mediating these 5-HT actions. Results from a dose-response experiment indicate that increasing the dose of 5-HT can transform an inhibitory response into a biphasic or even an excitatory response. This indicates that modulation of 5-HT release in the VMN could alter the net response of the VMN to this transmitter. By comparing the actions of 5-HT with the effects of selective agonists and antagonists, the inhibitory action was found to be mediated predominantly, if not exclusively, by 5-HT1A receptors, while the excitatory action was mediated predominantly or exclusively through 5-HT2 receptors. There appear to be few, if any, 5-HT3 receptors in the VMN, and their functions are unclear. The inhibitory and the excitatory phases of the biphasic responses were not mediated together by a single receptor subtype but were mediated separately by 5-HT1A and 5-HT2 receptors, respectively. The presence of the biphasic response in a large proportion of neurons, therefore, indicates the coexistence of different subtypes of 5-HT receptors in many individual VMN neurons. The use of selective agonists and antagonists further indicates that the coexistence also occurs in neurons showing monophasic responses, and that the opposite actions mediated by the coexisting receptor subtypes can interact with each other. Therefore, changing the ratio of coexisting receptor subtypes could modify the net output of the VMN response to 5-HT. Together with behavioral studies by others, it emerges from our findings that the inhibitory action of 5-HT on VMN neurons is associated with, and may be responsible for, the stimulation of feeding and inhibition of lordosis, while the excitatory action is related and may lead to the opposite behavioral effects. Finally, with the coexistence in VMN neurons of two receptor subtypes that can mediate 5-HT effects on both feeding and lordosis, the VMN can serve as a substrate for 5-HT to coordinate these two behaviors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2005

Influences of trunk muscles on lumbar lordosis and sacral angle.

BACKGROUND: The strength of abdominal muscle and back extensors or their balances are commonly mentioned as major indicators of potential low back pain (LBP). Former studies on anthropometrics in terms of trunk muscle strength seemed to lack precision in methodology. Furthermore, the extension-flexion ratio, which is a good parameter of trunk muscle balance, was not as much studied as simple maximum torques in this area of study. OBJECTIVES: To investigate relationship between trunk muscle strength and lumbar lordosis, sacral angle in patients who did not show significant abnormal findings on their simple lateral radiograph. METHODS: Thirty-one subjects were participated and their mean age was 35. Lumbar simple lateral radiograph was taken and lordotic angle was obtained by altered Cobb's method. Sacral angle was also examined on the same film. The relationship between these angles and muscle strength (isometric maximum torques and ratios of them) was investigated by the correlation analysis. RESULTS: None of the isometric maximum torques was related to sacral angle or lordotic angle. However, the ratio of extension to flexion was significantly related to the lordotic angle (Pearson's correlation coefficient=0.491, p<0.01). Other ratios were not related to any of the angles. CONCLUSIONS: An imbalance in trunk muscle strength can influence significantly lordotic curve of lumbar spine and might be one risk factor for potential low back pain.

Abdominal Muscles↗
PubMed1984

Axial electromyogram and intervertebral length gauge responses during lordosis behavior in rats.

Electromyogram activity from transversospinalis (TS) and lateral longissimus (LL) muscles was recorded concomitant with resistance changes of an intervertebral length gauge during manually elicited lordosis performance. Subjects were estrogen-treated ovariectomized rats. The EMG activity was evoked by manual stimulation of the cutaneous fields contacted by the male rat during mounting. During bilateral palpation of flanks at 2/s, time-locked bursts of EMG activity or more generalized EMG activation was recorded. The EMG response was accompanied by continuous and cumulative length gauge shortening, reflecting progressive rump elevation. The earliest recorded length gauge response had a latency of 10 ms from the first flank stimulus in a sequence of repetitive palpations. Perineal pressure recruited motor units in both the TS and LL which fired at high frequency. The latencies of EMG responses from the TS tended to be briefer than those from the LL; 24/35 TS responses were within 50 ms of the onset of perineal pressure. During some lordoses, the EMG response in both muscles was substantially briefer than the duration of the pressure stimulus and of the length gauge response. Activation of axial muscles during postural adjustments, standing, turning, and other behaviors is also reported. These data represent the first analysis of axial EMG and vertebral length gauge recordings during an endocrine-dependent mammalian behavior.

Animals↗
PubMedDate not supplied

Two-level posterior lumbar interbody fusion for degenerative disc disease: improved clinical outcome with restoration of lumbar lordosis.

BACKGROUND CONTEXT: Although posterior lumbar interbody fusion (PLIF) for degenerative lumbar diseases is routine, there are few reports on double-level PLIF. PURPOSE: To evaluate the clinical outcomes of double-level PLIF. STUDY DESIGN/SETTING: A retrospective study of operated cases in Gifu, Japan. PATIENT SAMPLE: Nineteen patients (8 men and 11 women, 59.5+/-10.2 years) who underwent double-level PLIF between 1996 and 2001. OUTCOME MEASURES: Operation time, blood loss, complications, the Japanese Orthopaedic Association (JOA) score for back pain and lumbar sagittal alignment were evaluated. METHODS: Patients were examined retrospectively at follow-ups of 3.6+/-1.7 years. Primary diseases were spondylolisthesis, spinal canal stenosis, degenerative scoliosis and herniated intervertebral disc. Fusion areas were L3 to L5 in 15 cases and L4 to S1 in 4 cases. RESULTS: The mean JOA score increased from an initial score of 12.9+/-3.5 to 21.3+/-4.9 at the final follow-up. There was a positive correlation (R=0.718, p<.001) between the increase in lordotic angle and the increase in the JOA score. Several parameters suggested that the surgical invasiveness was not minimal. CONCLUSION: Double-level PLIF provided satisfactory results and preserved lumbar spine lordosis.

Adult↗
PubMed1999

Congenital spine deformities: scoliosis, kyphosis, and lordosis.

By definition, congenital spine deformities-scoliosis, kyphosis, and lordosis-are due to abnormal vertebral development. Thus, affected children tend to have a curvature noted much earlier in life than typical patients with idiopathic scoliosis. This early development of the deformity has resulted in a tendency for the young child with congenital deformities to receive less than optimal care. These curves must not be allowed to progress. In many cases, early fusion is necessary, which is preferable to allowing severe curves to develop.

Humans↗
PubMed2000

Changes in lumbar lordosis modify the role of the extensor muscles.

STUDY DESIGN: Fiber angles of longissimus thoracis and iliocostalis lumborum at L3 were documented in vivo, using high resolution ultrasound, with the lumbar spine in neutral curve and when fully flexed. OBJECTIVES: To evaluate the effect of changes in lumbar curvature on the mechanics of these muscles. BACKGROUND: Full flexion modifies the failure tolerance of the lumbar spine, determines the load distribution among muscle and passive tissues, and modulates the types of tissue damage that occur. Related to this issue are the possible changes in muscle line of action with full flexion which changes the ability of the spine to support shear loads. METHODS: Nine normal men and 5 normal women were scanned in three positions: (1) an upright standing posture; (2) with the hips flexed to approximately 30 degrees and the spine fully flexed; (3) hips flexed but the spine returned to a neutral curvature. RESULTS: Mean longissimus/iliocostalis fiber angles for upright standing, hips flexed-spine flexed, and hips flexed-spine neutral lordosis were 25. 7 degrees, 10.7 degrees and 28.3 degrees, respectively. CONCLUSIONS: Anterior shear load on the lumbar spine has been recently shown to be highly related to the risk of reporting a back injury. Bending forward allowing the spine to fully flex changes the line of action of the largest lumbar extensor muscles compromising their role to support anterior shear forces. Relevance Fiber angles of longissimus thoracis and iliocostalis lumborum were documented with high resolution ultrasound at L3, with the spine in neutral curvature and fully flexed. Full lumbar flexion changes the line of action of these muscle compromising their role to support anterior shear forces on the spine - anterior shear forces have been recently documented to be highly related to the risk of reporting a back injury.

Adolescent↗
PubMed2006

Sudden spasms following gradual lordosis--the stiff-person syndrome.

BACKGROUND: A 28-year-old woman presented to hospital after an episode of severe lower back spasms that occurred during a stressful family gathering. She had a history of progressive difficulty bending forward and increasing lumbar lordosis. INVESTIGATIONS: Physical examination, spine MRI scan, abdominal and pelvic ultrasound, electromyogram, nerve conduction studies, cerebrospinal fluid analysis, breast examination, Pap smear, transabdominal and endovaginal ultrasound. DIAGNOSIS: Stiff-person syndrome with high titer of antibodies against glutamic acid decarboxylase. TREATMENT: Benzodiazepines and intravenous immunoglobulins.

Adult↗
PubMedDate not supplied

[Surgical management of severe thoracic lordosis in myelomeningocele--a case report with review of the literature].

While scoliosis and kyphosis are the most common spinal deformities in patients with myelomeningocele, single lordotic deformitics are rare. There are only few reports about the operative treatment of a primary thoracic lordosis of -135 degrees Cobb angle. By means of a dorso-ventral-dorsal procedure correction and stabilisation of the lordotic deformity was performed. A correction of -26 degrees Cobb angle was achieved without loss of correction during follow up of 18 months. The case report shows that in individual cases even severe lordotic deformities can be treated with surgery successfully. An anterior-posterior procedure should be considered. The case is discussed with the rare national and international literature.

Adolescent↗
PubMedDate not supplied

Reciprocal angulation of vertebral bodies in a sagittal plane: approach to references for the evaluation of kyphosis and lordosis.

In order to establish a sagittal plane curve reference table for standing subjects examined laterally, we determined an easily reproducible standard posture. A sample of 100 healthy subjects from 20 to 29 years of age, was chosen (43 women, 57 men). The reciprocal angulations of each vertebral body in relation to the others were fed into a digitalizer and studied by computer. The study particularly concerns maximum kyphosis, maximum lordosis, sacral base slopes, and the tilt of intermediate vertebral bodies. The dispersion of the results is remarkably wide and, within the extreme values, the distribution is irregular. Individual correlations of these values are often dispersed, but spinal morphotypology. For considerable lengths, average values cannot be used as norms, given the wide span of values. Only the extreme limits are useful for the appreciation of curves as excessive, insufficient, or inverted.

Adult↗
PubMed1997

Scoliosis induced by asymmetric lordosis and rotation: an experimental study.

STUDY DESIGN: An experimental study of the influence of intrinsic muscle imbalance on the spinal column of a growing rabbit. OBJECTIVES: To create an in vivo experimental model of scoliosis for comparison with human scoliosis. SUMMARY OF BACKGROUND DATA: There is evidence that asymmetric lordosis may produce scoliosis and that there is muscle imbalance in scoliotic patients. METHODS: Surgical tethering of the spinous apophysis and transverse apophysis of rabbits was performed at three upper levels on the same side of the spine to simulate dominance of one side of the paravertebral musculature over the other. RESULTS: All animals exhibited scoliosis that was convex toward the side opposite that receiving surgery. Radiography showed the curve to increase with time. Postmortem examination of vertebrae revealed structural alterations similar to those produced in human scoliosis. CONCLUSIONS: Intrinsic muscle imbalance in the spinal column of the experimental growing animal may produce scoliosis with characteristics similar to those of human idiopathic scoliosis.

Animals↗