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At least 451 records · Page 25Linked to original sources
PubMed2000

Masculine copulatory behavior is facilitated by intrathecally administered muscarine.

Behavioral experiments were conducted to examine the role of the cholinergic receptor-agonist muscarine or its antagonist homatropine on the mating behavior of sexually experienced male rats. Male copulatory behavior was recorded after intrathecally administered saline, muscarine (7.5 microg), or homatropine (25 microg). Changes in copulatory behavior were assessed by the following parameters: intromission latency, intromission frequency, intercopulatory interval, ejaculation latency, and postejaculatory interval. Intromission frequency, intercopulatory interval, and ejaculation latency were decreased significantly by muscarine. Intrathecal homatropine decreased the number of copulating animals (five out of 13). In the five animals that were able to ejaculate after homatropine, intromission latency, intercopulatory interval, and ejaculation latency increased significantly. The effects of both drugs on locomotion were also tested. Muscarine induced no significant changes in locomotion compared with saline. A significant increase in locomotion was found after homatropine treatment. These results suggest that acetylcholine, acting at spinal-cord muscarinic receptors, may be involved in ejaculation.

Animals↗
PubMed2004

Is there a need for anterior release for 70-90 degrees masculine thoracic curves in adolescent scoliosis?

Large and stiff thoracic scoliotic curves in the adolescent represent a classic indication of anterior release followed by posterior instrumentation. However, third-generation segmental spinal instrumentations have shown increased correction of thoracic curves. Indication for an anterior release may therefore not be required even in large and stiff thoracic curves. The objective of the study was, therefore, to analyze retrospectively the results of third-generation segmental posterior instrumentation in large and stiff thoracic curves and to compare our results with the current literature of anterior release followed by posterior instrumentation. An independent observer, who had not participated in any of the case, reviewed our electronic database of adolescent scoliosis surgery (Scolisoft) with the following query: thoracic curves, Cobb angle between 70 degrees and 90 degrees and posterior surgery only. He was able to identify 19 patients whose thoracic curves were measured between 70 degrees and 90 degrees . Out of these, four had convex-side bending Cobb angle values of less than 45 degrees and were not included in the study, as they were judged too flexible. Fifteen patients (aged 11-18 years, mean 13.6 years) with thoracic scoliosis were left for the study (average Cobb angles 78.5 degrees with a flexibility index of 32.5% (range, 19-42%). The mean follow-up period was 32 months (range 18-64 months). Classic parameters of deformity correction were analysed. The average operative time was 314 min and the mean total blood loss was 1,875 ml. Average level of instrumented vertebrae was 12 (Range, 10-14). Postoperatively, the thoracic Cobb angle was measured at 34.8 degrees (range, 25-45 degrees ), which represents a correction rate of 54% (range, 40.0-67.1%) and remained unchanged at the last follow-up (35 degrees ). Patients with thoracic hypokyphosis improved from an average 11 degrees to 18 degrees . There were three complications (one excessive bleeding, one early infection and one late infection). One case showed an add-on phenomenon at the last follow-up. Coronal balance was improved from 1.8 cm (Range 0-4 cm) down to 0.75 cm (range 0-2.5 cm). Shoulder balance was improved from 1.3 cm (range 0-4 cm) down to 0.75 (0-2.5 cm). All patients reported satisfactory results except the patient with an adding-on phenomena. In the literature, most of the results of anterior thoracoscopic release and posterior surgery give a percentage of Cobb angle correction similar or inferior to our series for an average initial Cobb angle of less magnitude. Therefore, with adequate posterior release, and the use of third-generation segmental instrumentation there is no need for anterior release even for curves in the 70-90 degrees range.

Adolescent↗
PubMed1982

On the role of the dorsal mesencephalic tegmentum in the control of masculine sexual behavior in the rat: effects of electrolytic lesions, ibotenic acid and DSP 4.

The work presented here concerns the way in which the dorsal midbrain tegmentum (DMT) participates in the control of sexual behavior. It was first established that electrolytic DMT lesions accelerate mating in the male rat, primarily by abbreviating the post-ejaculatory interval. Since the effective lesions were accompanied by decreases in the in vitro synaptosomal uptake of [3H]noradrenaline (NA) in hippocampus and hypothalamus, the behavioral effects of DSP4 (which elicits degeneration in NA nerve terminals derived primarily from the locus coeruleus) were examined. The long-term behavioral consequences of DSP4, however, were to decrease copulatory rate despite substantial NA denervation of brain and spinal cord. Ibotenic acid-induced neuronal degeneration in the DMT, on the other hand, accelerated copulatory behavior while leaving NA innervation of hippocampus and hypothalamus unaffected. The magnitude of the behavioral effect in ibotenic acid-treated rats was less than that induced by electrolytic DMT lesions. It is tentatively suggested on the basis of these-experiments that DMT cell bodies may form part of a system regulating sexual arousal mechanisms, whilst activity in a non-adrenergic fiber system running in the dorsal tegmental bundle may be required for active inhibition of sexual behavior after ejaculation. In additional experiments it was found that DSP4 treatment of female rats produced negligible effects on sexual behavior, estrous cyclicity and processes related to lactation.

Amines↗
PubMed1982

Masculinization of toad pretrigeminal nucleus by androgens.

The magnocellular portion of the pretrigeminal nucleus (a structure involved in vocalization) of male toads contains large cells than does the female nucleus. Testosterone propionate injections caused essentially complete, and dihydrotestosterone injections incomplete, mascullinization of the female nucleus. Estradiol benzoate injections had little or no effect. The androgen effects are therefore largely direct rather than involving extensive aromatization of androgen to estrogen.

Animals↗
PubMed1985

The correlation between the degree of brain masculinization and song quality in estradiol treated female zebra finches.

Female zebra finches can be induced to develop a male-like song system by being exposed to a steroid as nestlings. After subsequent testosterone treatment they develop song whose quality depends on age and duration of early steroid treatment. This study compares the anatomy of two song nuclei with the birds' song quality. The capacity for song correlates with the volumes of the nucleus hyperstriatum, ventralis, pars caudalis (HVc) and the nucleus robustus archistriatalis (RA) and with the size of RA neurons.

Animals↗
PubMed1987

Olfactory bulb removal decreases androgen receptor binding in amygdala and hypothalamus and disrupts masculine sexual behavior.

In these experiments we examined the relationship between olfactory bulb removal, limbic system androgen receptor binding and male copulatory behavior. Sexually experienced male rats were castrated, and implanted with two 10 mm testosterone-filled silastic capsules. Animals then underwent either bilateral olfactory bulb removal (BOB) or sham surgery (Sham). Beginning 1-2 days postoperatively both BOB and Sham operates were given 4 tests for male copulation on alternate days. Less than 40% of BOB males ejaculated. In contrast, 80-100% of sham operates continued to ejaculate throughout the 4 postoperative tests. Cell nuclear androgen receptor binding was assessed in amygdala, hypothalamus, preoptic area and septum 1-2 and 8-9 days after either bulbectomy or sham surgery. We found that olfactory bulbectomy significantly reduces androgen receptor binding in amygdala and hypothalamus. The reduction in androgen receptor binding in amygdala occurs within 1-2 days following olfactory bulb removal and is correlated with the disruption of ejaculatory activity. These data suggest that the neuromodulation by olfactory bulb input to androgen-concentrating neurons in the amygdala and hypothalamus is necessary for effective copulation in male rats.

Amygdala↗
PubMed1990

Correlation of dopamine release in the nucleus accumbens with masculine sexual behavior in rats.

Extracellular dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens (N. Acc.) were measured by in vivo microdialysis during male sexual activity. DA and DOPAC were significantly increased during copulation, but not during mild tail pinch. These results are consistent with studies showing increases in N. Acc. DA associated with positively reinforcing environmental stimuli.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Changes in monoamine turnover in forebrain areas associated with masculine sexual behavior: a microdialysis study.

This report compares the changes in the main dopamine (DA) and serotonin (5-HT) metabolites, respectively dihydroxyphenylacetic acid (DOPAC) and 5-hydroxy indoleacetic acid (5-HIAA) in three relatively close brain regions, namely the nucleus accumbens (ACB), the medial preoptic area, and the medial basal hypothalamus (MBH), as well as DA in the ACB, of copulating male rats. All these neurochemicals remained fairly stable when the animals were exposed to non sexual social stimuli (castrated females), and they increased during mating with receptive females. There were regional differences in these copulation-related changes, however, with those in the MBH being shorter-lived. There were also differences in the time-course of the changes in DOPAC and 5-HIAA the latter being slower. It is suggested that they reflect the involvement of the DA and 5-HT innervation of diencephalic structures in, respectively the appetitive and consummatory/satiation mechanisms of sexual behavior. The physiological relevance of these neurochemical changes is supported by the lack of differences between the standard measures for sexual behavior recorded before surgery and during the dialysis session.

3,4-Dihydroxyphenylacetic Acid↗