Ontogeny of biogenic amine systems and modification of indole levels upon adult sexual behavior in the rat

Male, female and androgenized female rats treated on Days 9, 10 and 11 after birth with either 5-HTP or saline were tested for female sexual behavior in adulthood. It was hypothesized that such pharmacological manipulations of the developing serotonergic system in which Day 12 sex differences have been reported might have an influence on the expression of lordosis behavior. No effect of 5-HTP was found in either normal or androgenized females, even though fluormetric analysis indicated a marked increase in endogenous levels of 5-HT at Day 12. However, males treated with 5-HTP has significantly higher 5-HT levels than 5-HT treated control or androgenized females. In addition, fluorometric analysis of norepinephrine, dopamine and serotonin from hypothalamus, mesencephalon and cortex was performed on male and female rats on Days 8, 10, 12 and 14 postnatally to examine the development of various transmitter systems during the early postnatal period.     

Dissociation of effects of LH-RH analogs on pituitary regulation and reproductive behavior

Analogs of LH-RH were studied for their effect on lordosis in ovariectomized rats primed with estrogen. Classified by their gonadotropin-releasing activity, representatives of three types of analogs were tested for facilitation of lordotic (L) responses of preselected females to mounting (M) by male studs. Positive responses (L/M>0.5) were found after SC administration of LH-RH peptides modified so as to be inhibitory, stimulatory, or inactive in releasing LH and FSH. The results further support the concept of a dissociation between the endocrine and extra-endocrine effects of peripherally injected hypothalamic peptides.     

Suppression of lordosis in the hormone-primed female hamster by electrical stimulation of the septal area

The behavior of the female hamster toward the male is altered radically by estrogen and progesterone. Her aggression gives way to sexual receptivity, and the lordosis posture will commonly be maintained in the presence of a sexually active male for greater than 10 min at a time. The septal area is one of the limbic and hypothalamic areas which preferentially accumulate radioactive estradiol in the female hamster. In order to determine whether this region is involved in lordosis control, we examined the effects of electrical stimulation (ES) there on the copulatory behavior of ovariectomized, hormone-primed, sexually receptive females in the presence of sexually active males. Sixty second trains of 100 Hz, 0.2 msec, biphasic, square-wave pulses at either 80 or 90 μA were effective in suppressing the lordosis response in 8 of 13 animals with electrodes in the septal area. In the most effective cases ES would prevent lordosis even during persistent contacts and mount attempts by the male. Some neurons in the septal area may be part of a network acting to inhibit the display of lordosis. One of the ways ovarian hormones could facilitate lordosis is through reduction of the suppressive activity in such a network.     

Dihydrotestosterone stimulates mounting behavior but not lordosis in female rats

The ability of androgens to stimulate masculine sexual behavior is thought to depend on the aromatization of such androgens to estrogens. In this scheme, reduced androgens such as dihydrotestosterone (DHT) which cannot be aromatized, are thought to exert major peripheral but little or no central nervous system influences on the display of masculine sexual behavior. Further, an early report that DHT can induce lordosis, an estrogen (E) dependent behavior, led to a notion that DHT may effect behavior through metabolic intermediates such as 5α-androstane-3β, 17β-diol (ADIOL) which then binds to estrogen receptors eliciting the E-dependent lordotic response. The present study reexamined and compared the relative effectiveness of a range of DHT dosages in stimulating a characteristic masculine (mounting) and feminine (lordosis) sexual behavior. Adult ovariectomized rats were randomly assigned to either 250 μg or 1 mg daily injections of DHT or DHTP. Other animals received OIL injections or crystalline DHT delivered by two different lengths (20 mm or 40 mm) of Silastic capsules. Animals were tested once weekly (for 5 weeks) for mounting behavior (20 minute test). Then animals were tested thrice (once weekly) for lordosis 4 hrs after the addition of 500 μg Progesterone (P). Finally, all females were tested for lordotic potential to respond to 10 μg EB plus P. 1 mg DHT or DHTP dosages and the 40 mm-Silastic condition significantly increased mounting behavior over that of lower dosages and OIL controls. A significant correlation existed between mounting frequency and circulating level of serum DHT. Treatment with DHTP was not different than DHT in eliciting mounting behavior. Lordosis was not enhanced by any treatment with DHT or DHTP over that of controls, although all females were capable of lordotically responding to EB. These data demonstrate that DHT can induce mounting behavior, but not lordosis, suggesting that whatever action DHT has may not occur via estrogen or estrogen receptors. A role for androgen and androgen receptors upon mounting behavior is discussed.     

Midbrain central gray GABAA receptor activation enhances,and blockade reduces,sexual behavior in the female rat

Summary The inhibitory neurotransmitter, GABA, has been implicated in the control of lordosis behavior. Previous studies indicate that modulation of GABA_A transmission can have dual effects on lordosis, being facilitative in the ventromedial hypothalamus and inhibitory in the preoptic area. The midbrain central gray (MCG) is also known to be an important neural site for regulating lordosis as well as defensive and escape behaviors, and plays an integral role in the control of nociception. Because of the multitude of behaviors regulated at the level of the MCG, we utilized a two-chamber testing apparatus that allowed simultaneous measurement of the females' proceptive (hopping and darting), receptive and rejection behaviors, as well as an index of nociception and general motor activity. We found that microinfusion of the GABA_A antagonist, bicuculline, into the MCG of steroid-primed female rats resulted in a significant decrease in lordosis and proceptive behaviors at 5 min post-infusion. There was full recovery to pretest levels by 60 min. Furthermore, microinfusion of the GABA_A agonist, muscimol, to estrogen-treated females that displayed low levels of receptivity and high levels of rejection behavior during a pretest, resulted in a significant increase in lordosis responding and a decrease in rejection behaviors. Neither drug significantly affected time spent in the vicinity of the male, motor activity or vocalizations. It is concluded that the decrease in lordosis resulting from blockade of GABA transmission is not solely due to the induction of antagonistic behaviors since there was no increase in rejections after bicuculline administration. The current findings are consistent with the interpretation that GABA facilitates lordosis in the MCG via disinhibition. When the retrograde tracer, Fluoro-gold, was infused into the same cannula sites in the MCG as the GABA_A drugs it demonstrated the presence of strong projections from the ventromedial nucleus, zona incerta, medullary reticular formation and spinal cord. These projections to the MCG may be important for the integration of the diverse behaviors regulated at the level of the MCG and GABAergic transmission may play a role in this integration.     

GABAergic drugs and sexual motivation, receptivity and exploratory behaviors in the female rat

Female rats were allowed to pace sexual interactions in a bilevel chamber, where a sexually vigorous male was tethered to the bottom level. Exploratory behaviors (sniffing, rearing), locomotor activity (expressed as number of level changes and periods of inactivity) as well as items of sexual motivation (latency to descend to the male’s level, approaches towards the male and genital exploration) were recorded. In addition, sexual receptivity was evaluated in a non-paced situation. A test for motor impairment was also performed. The GABA transaminase inhibitor γ-acetylene GABA reduced exploratory behaviors at doses much lower than those needed to reduce receptivity. The GABA reuptake inhibitor SKF 100330A did not affect any behavior category at doses of 15 and 30 mg/kg, but had a sedative action at 60 mg/kg. This was shown as impaired motor coordination and an almost total absence of activity in the bilevel chamber. Receptivity was not impaired, however. The mixed GABA_A/ GABA_B agonist progabide reduced exploratory behaviors and receptivity without producing motor impairment at a dose of 400 mg/kg. The GABA_A agonist THIP impaired motor coordination and reduced receptivity and exploratory behaviors at a dose of 10 mg/kg. A larger dose, 20 mg/kg, had a strong sedative action. Only a small proportion of the animals descended to the males level. The GABA_B agonist baclofen reduced receptivity at a dose that had no effect on motor coordination or exploratory behaviors. None of the drugs had a specific effect on sexual motivation. Whenever behaviors reflecting motivation were reduced, there were also other behavioral effects indicative of sedation. These data show that GABA receptor agonists, particularly the GABA_B agonist baclofen, reduce sexual receptivity at doses that have only slight effect on motor functions or exploratory behaviors. In contrast, non-specific enhancement of GABAergic activity by a transaminase or reuptake inhibitor have effects on motor functions and exploratory behaviors at doses much lower than those needed to reduce receptivity. Received: 24 June 1996 /Final version: 18 September 1996     

Evidence for the involvement of central 5-HT1A receptors in the mediation of lordosis behavior in the female rat

5-Hydroxy-L-tryptophan (5-HTP), 25 mg kg^-1 IP, in combination with the peripheral 5-HTP decarboxylase inhibitor benserazide, 25 mg kg^-1 IP, and the selective inhibitor of neuronal 5-hydroxytryptamine (5-HT) re-uptake, zimeldine, 10 mg kg^-1 IP, suppressed lordosis in ovariectomized female rats, treated with estradiol benzoate (EB) or with EB plus progesterone (P). The suppression of lordosis produced by 5-HTP was antagonized by the -receptor blocker (-)pindolol, which also is a selective 5-HT₁ receptor antagonist, but not by the 5-HT₂ receptor antagonists metitepine or pirenperone, nor by the -receptor blocker betaxolol. The EB-or EB plus P-activated lordosis was also suppressed by administration of the selective 5-HT_1a receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Together, these observations indicate an important role of central 5-HT_1a receptors in the mediation of lordosis behavior in the female rat.     

胸腰段后凸畸形对腰椎前凸角度的影响及其临床意义

目的 :了解腰椎对胸腰段后凸畸形的代偿性改变及其临床意义。方法 :收集 12例具备胸腰椎和腰骶椎正侧位X线片的胸腰段后凸畸形病例 ,就其腰脊柱和每一节段腰椎的Cobb角、胸腰段的Cobb角、椎体滑移情况进行分析研究 ,并与 2 0例正常对照组进行相应比较。结果 :患病组平均腰椎前凸角度与正常对照组相比有极显著性差异 (P <0 .0 0 1)。患病组单节段腰椎前凸角度以上腰椎变化更为明显 ,L2～ 3 和L3～ 4分别是正常组相应节段的 4.2和 2 .4倍。结论 :腰椎过度前凸是胸腰段后凸畸形后为维持脊柱平衡的一个重要的代偿改变 ,而且以上腰椎的改变更为明显。     

Postoperative spino-pelvic stereoradiography to predict adjacent segment disease

PurposeThe purpose of this study was to identify sagittal spinopelvic parameters predictive of adjacent segment disease (ASD) on postoperative whole spine weight-bearing stereoradiography.Materials and methodsA total of 84 patients with previous spinal fusion surgery and documented radiological follow-up with early weight-bearing postoperative whole spine stereoradiography (EOS® Imaging System) were retrospectively included. A pathological group of 42 patients (9 men, 33 women; mean age, 63.1 ± 11.5 [SD] years) who developed documented ASD (mean follow-up, 76.75 months; range: 31.5–158.5 months) was compared with a control group of 42 asymptomatic patients (7 men, 35 women; mean age, 60.9 ± 11.8 [SD] years) (mean follow-up, 115 months; range: 60–197 months) based on sagittal balance evaluation and routinely used spino-pelvic parameters. Comparisons were made using uni- and multivariate analyses.ResultsAt univariate analysis, patients with ASD had an anteriorly displaced sagittal vertical axis (CAM plumb line) and an inadequate lumbar lordosis (LL) in reference to pelvic incidence (PI) compared to controls. They also had higher C7 slope and C2-C7 offset. At multivariate analysis, C2-C7 offset (OR = 1.152; 95% CI: 1.056–1.256; P = 0.001) and a lack of LL (OR = 5.063; 95% CI: 1.139–22.498; P = 0.033) were significantly associated with ASD.ConclusionAnterior cervical imbalance, reflected by an increase in C2-C7 offset and insufficient restoration of LL are postoperative predictive factors of ASD on stereoradiography.     

Activation of protein kinase C in the hypothalamic ventromedial nucleus or the midbrain central gray facilitates lordosis

Many neurotransmitters and neuropeptides can act through the hypothalamic ventromedial nucleus (VMN) or midbrain central gray (MCG) to facilitate lordosis. Since these lordosis-facilitating agents can also stimulate the phosphoinositide (PI) second-messenger pathway, it was hypothesized that direct activation of this pathway can also potentiate the behavior. To evaluate this possibility, a phorbol ester, TPA (12-O-tetradecanoyl phorbol 13-acetate), was used to activate a key enzyme, protein kinase C (PKC), of the PI pathway in ovariectomized (OVX) rats either primed or not primed with estrogen. These female rats were paired with males for mating tests before and after an intracerebral infusion of TPA, and both the lordosis quotient (LQ) and the lordosis strength (LS) were measured. Bilateral infusion of TPA (5 μg/0.5 μl or 0.2 μg/0.2 μl, but not 0.1 μg/0.2 μl/side) into the VMN or MCG of estrogen-primed subjects facilitated both LQ and LS in 30 min, peaked at 60–90 min, and the facilitation lasted for more than 180 min. This facilitatory effect of TPA was: (1) not observed in OVX rats not primed with estrogen; (2) not observed if the infused TPA did not reach both sides of the VMN or MCG; (3) not mimicked by 4-phorbol 12,13-didecanoate, which does not activate PKC; (4) blocked by PKC inhibitors (H7 10 mM or staurosporine 1 μM, 0.2 μl/ side), which by themeselves did not facilitate lordosis; and (5) was not affected by pretreatment of the progestin antagonist RU486. These observations indicate that TPA facilitates lordosis in a dose-dependent fashion by activating, and not by depleting, PKC in the VMN or MCG, and that the TPA effect requires estrogen priming but not the activation of progestin receptors. Thus, the PI pathway or the activation of PKC may be a common mediator for lordosis facilitation in these two brain regions; and the requirement of estrogen priming further raises the possibility that this second-messenger system or its substrates in the VMN and MCG are modulated by estrogen.