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Papers by Patrícia Pacheco
Physiology & Behavior, 1988
In the present study, the analgesia produced by vaginal stimulation (VS) in women was found to be... more In the present study, the analgesia produced by vaginal stimulation (VS) in women was found to be dissociated from heart rate. The VS-produced analgesia was not accompanied by an acceleration of heart rate. Heart rate acceleration produced by exercise did not result in analgesia. The independence of VS-produced analgesia from this index of autonomic activity is consistent with recent findings in rats.
Experimental Neurology, 1985
A prevalent notion in the literature is that the pelvic floor muscles behave as a unitary mass. W... more A prevalent notion in the literature is that the pelvic floor muscles behave as a unitary mass. We examined this proposition experimentally. In spinal cats, we recorded EMG activity from the following pelvic floor muscles: the sphincter ani externus (SAE), the abductor caudae internus (coccygeus), and the levator ani (pubiocaudalis) muscles. The epaxial sacrocaudalis dorsalis lateralis muscle was also exposed and prepared for recording. Electrical stimulation of S2 ventral roots elicited twitch responses of the sphincter ani externus and of the sacrocaudalis dorsalis lateralis muscles. Stimulation of S3 and Cx1 ventral roots elicited responses in the other two muscles studied, the levator ani and abductor caudae internus. Thus a clear segregation of the segmental motor neuron pools innervating the different pelvic floor muscles was demonstrated. The various muscles of the pelvic floor region could be reflexly activated either individually or as a mass unit depending on the intensity of stimulation. Tactile or electrical stimulation of pudendal regions on either side of the body elicited responses of the sphincter ani externus. In contrast, activation of the levator ani and abductor caudae internus muscles could be lateralized: tactile or electrical stimulation of the dorsolateral surfaces at the base of the tail region elicited ipsilateral responses from these muscles. Section of one pudendal nerve did not alter the level of tonic activity (2 to 4/s) of the sphincter ani externus. However, bilateral section of the pudendal nerve entirely abolished both tonic activity and phasic responsiveness of the SAE without affecting the activity of the levator ani and abductor caudae internus muscles. Pudendal nerve stimulation elicited only polysynaptic reflex responses from S2 ventral roots. The results presented show that the neural apparatus of the striated musculature of the pelvic floor is capable of activating individually the different muscles that make up the system, and that the sphincter ani externus from one side, and muscles that conform the diaphragm pelvis from the other, are subserved by different neuronal circuits.
Brain Research, 1992
The present study describes several muscular reflexes produced by genital stimulation, the nerves... more The present study describes several muscular reflexes produced by genital stimulation, the nerves that subserve them, and the visceral and postural effects induced by these reflexes. Electrical stimulation of the iliococcygeus (ic) and pubococcygeus (pc) (striated) muscles produced movement of the vaginal orifice and wall, membranous urethra, tail and pelvis. Electrical stimulation of the psoas major (pro) or iliacus (i) (striated) muscles produced movements of the lumbar vertebrae and extension of the ipsilateral hindlimb. Sensory mechanostimulation elicited responses of these muscles as follows: stimulation of the perineal skin, clitoral sheath or distal vagina produced reflex contraction of the ic and pc muscles. Stimulation of the cervix produced reflex contraction of the pm and i muscles and also blocked the above reflex contraction of the ic and pc muscles. Both the cervical stimulation-induced blockage of the ic and pc reflex response, and the cervical stimulationinduced activation of pm and i muscles was prevented by bilateral transection of the viscerocutaneous branch of the pelvic nerve. Based on the above observations, it is proposed that stimulation of the vaginal surface of the cervix resulting from penile intromission and/or seminal plug deposition during mating behavior in the rat may reflexively activate pm and i, thereby contributing to the hindleg postural rigidity and lordotic dorsiflexion that are characteristic of the normal mating posture in female rats.
Brain Research, 1989
The efferent innervation of the pelvic and pudendal nerves was characterized in this study by ide... more The efferent innervation of the pelvic and pudendal nerves was characterized in this study by identifying the muscles activated by electrical stimulation of the nerves distal to the point at which they bifurcate from the L6-S 1 trunk. Pelvic nerve electrical stimulation produced EMG-monitored contraction of the ipsilaterai ilio-and pubococcygeus muscles, which was abolished by cutting one ('muscular') branch of the bifurcated nerve. (This 'muscular' branch receives proprioceptive input activated by tail displacement, whereas the other, 'viscero-cutaneous' branch receives sensory innervation from the midline perineal region.)Pudendal nerve electrical stimulation produced contraction of the coccygeus, external anal sphincter, and ischiocavernosus muscles. Movements of the orifice and wall of the vagina were directly visualized during electrical stimulation of the two nerves. Intravaginai pressure measured by balloon was increased by pelvic nerve stimulation and decreased by pudendal nerve stimulation. Reflexive contraction of the ilio-en pubococcygeus muscles was produced by mechanostimulation of the perineum, clitoral sheath and distal vagina. This response was abolished by gentle cervical mechanostimulation. One implication of this finding is that passage of the fetuses through the cervix during parturition may relax the ilio-and pubococcygeus muscles, thereby facilitating delivery.
Physiology & Behavior, 1989
Women who chronically ingest a diet rich in capsaicin, the pungent ingredient in hot chili pepper... more Women who chronically ingest a diet rich in capsaicin, the pungent ingredient in hot chili peppers, showed a significantly lower magnitude of analgesia in response to vaginal self-stimulation than women with relatively low or medium levels of ingestion. Vaginal self-stimulation-produced analgesia was quantified by measuring (on the hand) pain detection thresholds, pain tolerance thresholds and tactile thresholds. Whereas vaginal self-stimulation produced a 32.6-43.8% increase in pain detection and pain tolerance thresholds in the low chili diet group, it produced only a 2.3-7.3% increase in these measures in the high chili diet group. The medium chili diet group showed an intermediate effect on the pain thresholds. Tactile thresholds were not increased by the vaginal self-stimulation. Baseline (no stimulation) pain thresholds did not differ significantly among the three groups. These findings are consistent with earlier studies in laboratory rats, in which capsaicin administered neonatally abolished vaginal stimulation-produced analgesia, but did not affect baseline pain thresholds to mechanostimulation.
Physiology & Behavior, 1988
In the present study, the analgesia produced by vaginal stimulation (VS) in women was found to be... more In the present study, the analgesia produced by vaginal stimulation (VS) in women was found to be dissociated from heart rate. The VS-produced analgesia was not accompanied by an acceleration of heart rate. Heart rate acceleration produced by exercise did not result in analgesia. The independence of VS-produced analgesia from this index of autonomic activity is consistent with recent findings in rats.
Experimental Neurology, 1985
A prevalent notion in the literature is that the pelvic floor muscles behave as a unitary mass. W... more A prevalent notion in the literature is that the pelvic floor muscles behave as a unitary mass. We examined this proposition experimentally. In spinal cats, we recorded EMG activity from the following pelvic floor muscles: the sphincter ani externus (SAE), the abductor caudae internus (coccygeus), and the levator ani (pubiocaudalis) muscles. The epaxial sacrocaudalis dorsalis lateralis muscle was also exposed and prepared for recording. Electrical stimulation of S2 ventral roots elicited twitch responses of the sphincter ani externus and of the sacrocaudalis dorsalis lateralis muscles. Stimulation of S3 and Cx1 ventral roots elicited responses in the other two muscles studied, the levator ani and abductor caudae internus. Thus a clear segregation of the segmental motor neuron pools innervating the different pelvic floor muscles was demonstrated. The various muscles of the pelvic floor region could be reflexly activated either individually or as a mass unit depending on the intensity of stimulation. Tactile or electrical stimulation of pudendal regions on either side of the body elicited responses of the sphincter ani externus. In contrast, activation of the levator ani and abductor caudae internus muscles could be lateralized: tactile or electrical stimulation of the dorsolateral surfaces at the base of the tail region elicited ipsilateral responses from these muscles. Section of one pudendal nerve did not alter the level of tonic activity (2 to 4/s) of the sphincter ani externus. However, bilateral section of the pudendal nerve entirely abolished both tonic activity and phasic responsiveness of the SAE without affecting the activity of the levator ani and abductor caudae internus muscles. Pudendal nerve stimulation elicited only polysynaptic reflex responses from S2 ventral roots. The results presented show that the neural apparatus of the striated musculature of the pelvic floor is capable of activating individually the different muscles that make up the system, and that the sphincter ani externus from one side, and muscles that conform the diaphragm pelvis from the other, are subserved by different neuronal circuits.
Brain Research, 1992
The present study describes several muscular reflexes produced by genital stimulation, the nerves... more The present study describes several muscular reflexes produced by genital stimulation, the nerves that subserve them, and the visceral and postural effects induced by these reflexes. Electrical stimulation of the iliococcygeus (ic) and pubococcygeus (pc) (striated) muscles produced movement of the vaginal orifice and wall, membranous urethra, tail and pelvis. Electrical stimulation of the psoas major (pro) or iliacus (i) (striated) muscles produced movements of the lumbar vertebrae and extension of the ipsilateral hindlimb. Sensory mechanostimulation elicited responses of these muscles as follows: stimulation of the perineal skin, clitoral sheath or distal vagina produced reflex contraction of the ic and pc muscles. Stimulation of the cervix produced reflex contraction of the pm and i muscles and also blocked the above reflex contraction of the ic and pc muscles. Both the cervical stimulation-induced blockage of the ic and pc reflex response, and the cervical stimulationinduced activation of pm and i muscles was prevented by bilateral transection of the viscerocutaneous branch of the pelvic nerve. Based on the above observations, it is proposed that stimulation of the vaginal surface of the cervix resulting from penile intromission and/or seminal plug deposition during mating behavior in the rat may reflexively activate pm and i, thereby contributing to the hindleg postural rigidity and lordotic dorsiflexion that are characteristic of the normal mating posture in female rats.
Brain Research, 1989
The efferent innervation of the pelvic and pudendal nerves was characterized in this study by ide... more The efferent innervation of the pelvic and pudendal nerves was characterized in this study by identifying the muscles activated by electrical stimulation of the nerves distal to the point at which they bifurcate from the L6-S 1 trunk. Pelvic nerve electrical stimulation produced EMG-monitored contraction of the ipsilaterai ilio-and pubococcygeus muscles, which was abolished by cutting one ('muscular') branch of the bifurcated nerve. (This 'muscular' branch receives proprioceptive input activated by tail displacement, whereas the other, 'viscero-cutaneous' branch receives sensory innervation from the midline perineal region.)Pudendal nerve electrical stimulation produced contraction of the coccygeus, external anal sphincter, and ischiocavernosus muscles. Movements of the orifice and wall of the vagina were directly visualized during electrical stimulation of the two nerves. Intravaginai pressure measured by balloon was increased by pelvic nerve stimulation and decreased by pudendal nerve stimulation. Reflexive contraction of the ilio-en pubococcygeus muscles was produced by mechanostimulation of the perineum, clitoral sheath and distal vagina. This response was abolished by gentle cervical mechanostimulation. One implication of this finding is that passage of the fetuses through the cervix during parturition may relax the ilio-and pubococcygeus muscles, thereby facilitating delivery.
Physiology & Behavior, 1989
Women who chronically ingest a diet rich in capsaicin, the pungent ingredient in hot chili pepper... more Women who chronically ingest a diet rich in capsaicin, the pungent ingredient in hot chili peppers, showed a significantly lower magnitude of analgesia in response to vaginal self-stimulation than women with relatively low or medium levels of ingestion. Vaginal self-stimulation-produced analgesia was quantified by measuring (on the hand) pain detection thresholds, pain tolerance thresholds and tactile thresholds. Whereas vaginal self-stimulation produced a 32.6-43.8% increase in pain detection and pain tolerance thresholds in the low chili diet group, it produced only a 2.3-7.3% increase in these measures in the high chili diet group. The medium chili diet group showed an intermediate effect on the pain thresholds. Tactile thresholds were not increased by the vaginal self-stimulation. Baseline (no stimulation) pain thresholds did not differ significantly among the three groups. These findings are consistent with earlier studies in laboratory rats, in which capsaicin administered neonatally abolished vaginal stimulation-produced analgesia, but did not affect baseline pain thresholds to mechanostimulation.