Biomedical subjects

B B Gorzalka

Publications and source records attributed to B B Gorzalka.

At least 37 records · Page 2Linked to original sources

PubMed1996

Effects of sympathetic inhibition on receptive, proceptive, and rejection behaviors in the female rat.

The present investigation was designed to examine the effects of sympathetic nervous system (SNS) inhibition on sexual behavior in ovariectomized, steroid-treated female rats. Clonidine, an alpha2-adrenergic agonist, guanethidine, a postganglionic noradrenergic blocker, and naphazoline, an alpha2-adrenoreceptor agonist were used to inhibit SNS activity. Intraperitoneal injections of either 33 micrograms/ml or 66 micrograms/ml clonidine significantly decreased receptive (lordosis) and proceptive (ear wiggles) behaviors and significantly increased rejection behaviors (vocalization, kicking, boxing). Either 25 mg/ml or 50 mg/ml guanethidine significantly decreased receptive and proceptive behavior and had no significant effect on rejection behaviors. Naphazoline significantly inhibited lordosis behavior at either 5 mg/ml or 10 mg/ml doses, significantly inhibited proceptive behavior at 5 mg/ml, and had no significant effect on rejection behaviors. These findings support the hypothesis that SNS inhibition decreases sexual activity in the female rat.

Adrenergic alpha-2 Receptor Agonists↗

PubMed1996

Differential effects of sympathetic activation on sexual arousal in sexually dysfunctional and functional women.

The effects of sympathetic nervous system (SNS) activation, induced via acute exercise, on sexual arousal in women was studied. In 2 experimental sessions, 36 women viewed a neutral film followed by an erotic film. In 1 session, the women were exposed to 20 min of intense exercise before viewing the films. Twelve women were sexually functional, 12 experienced significant impairments in sexual desire, and 12 experienced primary or secondary anorgasmia. Acute exercise significantly increased vaginal pulse amplitude (VPA) and vaginal blood volume (VBV) responses to an erotic film among sexually functional women and those with low sexual desire. Among anorgasmic women, exercise significantly decreased VPA but had no effect on VBV responses to an erotic film. Acute exercise had no significant effect on the women's perceptions of sexual arousal. Results suggest that increased SNS arousal may affect physiological sexual responding in women.

Adult↗

PubMed1996

PCPA increases aggression in male firemouth cichlids.

We observed the effect of the 5-hydroxytryptamine synthesis inhibitor p-chlorophenylalanine on aggression in male firemouth cichlids (Cichlasoma meeki). p-Chlorophenylalanine-treated firemouths showed a significantly greater number of mirror-directed bites as compared with saline-injected controls. This finding is consistent with the effects of this drug on social aggression in mammals and birds and supplements previous reports that 5-hydroxytryptamine inhibits aggression in fish.

Aggression↗

PubMed1995

The effects of sympathetic activation on physiological and subjective sexual arousal in women.

This investigation was designed to examine the effects of acute exercise on physiological and subjective sexual arousal in women. In Experiment 1, Ss participated in two experimental sessions in which they viewed a neutral film followed by an erotic film. In one of these sessions, Ss were exposed to 20 min of intense exercise prior to viewing the films. Subjective sexual arousal was measured with a self-report rating scale and physiological sexual arousal was measured with a vaginal photoplethysmograph. Acute exercise significantly decreased vaginal pulse amplitude responses to a neutral stimulus and significantly increased vaginal pulse amplitude responses to an erotic stimulus. Exercise marginally increased vaginal blood volume responses to an erotic film but had no significant effect on subjective perceptions of sexual arousal. In Experiment 2, Ss viewed two consecutive neutral stimuli preceded by 20 min of intense exercise. There were no significant differences in either vaginal blood volume or vaginal pulse amplitude between the two neutral films. Together, the data from Experiments 1 and 2 provide indirect support for a facilitatory role of sympathetic activation in female sexual arousal.

Adolescent↗

PubMed1995

Discrimination of ovarian steroids by rats.

Rats' ability to discriminate their hormonal states was examined by observing the effects of ovarian steroids on state-dependent learning using a drug discrimination task. A rat's entry into the correct arm (left or right) of a Y-maze terminated mild foot shock. The arm designated as correct was alternated daily, but was consistently paired with a pretrial injection of hormone or vehicle. In Experiment 1, ovariectomized rats successfully discriminated pretreatment with 4.0 or 8.0 mg/kg progesterone vs. the oil vehicle but not 2.0 or 0.5 mg/kg progesterone vs. oil, or the daily alternation schedule alone (oil vs. oil). In Experiment 2a, ovariectomized rats correctly discriminated pretreatment with progesterone (4 mg/kg) vs. oil or dihydroprogesterone (4 mg/kg) vs. oil, and the results of Experiment 2b, appear consistent with the possibility that the rats discriminated pretreatment with progesterone vs. dihydroprogesterone. In Experiment 3a, ovariectomized rats discriminated on the basis of progesterone (4.0 mg/kg) vs. oil, estrogen (6.4 micrograms/kg estradiol benzoate) vs. oil, and estrogen vs. progesterone. In Experiment 3b, the rats were adrenalectomized, and the procedure from Experiment 3a repeated. The removal of the adrenal glands failed to abolish hormonal discriminations, suggesting that the effect is not adrenally mediated. The results of these studies show that rats can discriminate relatively low doses of ovarian steroids.

20-alpha-Dihydroprogesterone↗

PubMed1995

Artificial neural network and classical least-squares methods for neurotransmitter mixture analysis.

Identification of individual components in biological mixtures can be a difficult problem regardless of the analytical method employed. In this work, Raman spectroscopy was chosen as a prototype analytical method due to its inherent versatility and applicability to aqueous media, making it useful for the study of biological samples. Artificial neural networks (ANNs) and the classical least-squares (CLS) method were used to identify and quantify the Raman spectra of the small-molecule neurotransmitters and mixtures of such molecules. The transfer functions used by a network, as well as the architecture of a network, played an important role in the ability of the network to identify the Raman spectra of individual neurotransmitters and the Raman spectra of neurotransmitter mixtures. Specifically, networks using sigmoid and hyperbolic tangent transfer functions generalized better from the mixtures in the training data set to those in the testing data sets than networks using sine functions. Networks with connections that permit the local processing of inputs generally performed better than other networks on all the testing data sets. and better than the CLS method of curve fitting, on novel spectra of some neurotransmitters. The CLS method was found to perform well on noisy, shifted, and difference spectra.

Acetylcholine↗

PubMed1994

Effects of 5-HT3 agonists on reproductive behaviors in rats.

Activity at 5-HT1 and 5-HT2 receptor sites influences sexual behavior in male and female rats. 5-HT3 antagonists reportedly have no effect on copulatory activity in rats of either sex although they influence a variety of other behaviors. The effects of 5-HT3 agonists on sexual behavior are unknown. The following experiments were undertaken to assess the influence of the 5-HT3 agonists 1-phenylbiguanide (PBG) and 2-methyl-serotonin (2-Me-5-HT) on sexual behavior, when administered intracerebroventricularly. Consistent with earlier reports indicating that 5-HT1 and 5-HT2 receptor activity influences reproductive activity in a sex-dependent manner, PBG was found to facilitate male, but not female, rat sexual behavior. 2-Me-5-HT, however, failed to modify either female or male rat sexual activity. Evidence that PBG, but not 2-Me-5-HT, induces carrier-mediated dopamine release suggests that the effect of PBG in male rats is due to dopaminergic mediation. Overall, the present data indicate that 5-HT3 receptor activation has only slight effects on rat sexual behavior.

Animals↗

PubMed1994

Adrenal role in proceptivity and receptivity induced by two modes of estradiol treatment.

The effects of chronic estrogen treatment on the receptive and proceptive behaviors of the female rat were investigated using two modes of estrogen administration: estrogen implants and chronic estrogen injections. In addition, the potential mediating role of the adrenal was investigated. Animals were either ovariectomized (OVX) or ovariectomized and adrenalectomized (ADX-OVX). Each surgery group received three doses of estrogen, via implants in Experiment 1 and chronic injections in Experiment 2. Each animal was tested with and without progesterone treatment. Within the range of doses in the two experiments, the effect of estrogen on proceptivity appeared to be dose dependent. However, low estrogen doses were sufficient to maintain a high level of receptivity. These results suggest different mechanisms for the induction of proceptive and receptive behavior in the female rat. The facilitatory effect of progesterone on receptivity was dependent on the estrogen dose for both modes of administration, but on proceptivity was dependent on the estrogen dose only following chronic estrogen injections. Overall, this study suggests that the adrenal gland is important in the display of female sexual behavior elicited by exogenous hormones. The estrogen implant study (Experiment 1) revealed that while the adrenal gland is not necessary for receptive behavior, it is important for the display of proceptive behavior. In addition, with chronic estrogen injections (Experiment 2), progesterone was more effective in elevating proceptivity in ADX-OVX than in OVX females, and ADX-OVX females treated with progesterone generally showed less lordosis behavior than OVX females treated with progesterone. These results suggest that progesterone of adrenal origin may be important for sexual responding in the female rat.

Adrenal Glands↗

PubMed1994

An easily constructed, reusable, bipolar, concentric stimulation electrode for use with intracranial guide cannula assemblies.

The construction of a stimulation electrode is described. This electrode is removable and is designed to be used with intracranial guide cannula assemblies. It is a concentric, bipolar electrode, and is easy and inexpensive to assemble from materials readily available in most laboratories. A detailed description is also given of procedures to connect the electrode to stimulation equipment in a manner that would minimize interference by the test animal with the operation of the electrode.

Animals↗

PubMed1993

Lack of effects of 5-HT3 antagonists on normal and morphine-attenuated sexual behaviours in female and male rats.

Although 5-HT1 and 5-HT2 receptor activity is known to influence copulation, the effects of 5-HT3 receptor-selective drugs on sexual activity have yet to be systematically studied. The following experiments investigated the effects of the 5-HT3-selective antagonists MDL 72222, ondansetron and ICS 205-930 on female sexual behaviour; male rats were studied using ondansetron and granisetron. These compounds influenced neither male nor female copulatory behaviours, suggesting that 5-HT3 receptors contribute little to the modulation of sexual activity. 5-HT3 receptor antagonists block certain opioid-induced behaviours and opioids selectively inhibit sexual behaviours; therefore, the ability of ondansetron and ICS 205-930 to modify morphine-attenuated copulatory activity was also tested. While morphine inhibited copulation, 5-HT3 antagonists failed to reverse the effects.

Animals↗

PubMed1992

Concurrent wet dog shaking and inhibition of male rat copulation after ventromedial brainstem injection of the 5-HT2 agonist DOI.

Systemic administration of drugs that augment 5-HT2 activity generally induces 'wet dog' shaking (WDS) in rats. This suggests that the naturally occurring form of WDS seen in untreated rats may also serve as a behavioral index of 5-HT2 receptor activation, during the performance of other behaviors. Indeed, spontaneously occurring WDS has previously been reported to be inversely related to male rat copulatory proficiency. In order to examine a potential central nervous system mechanism subsuming these behaviors, male rats were tested for WDS and sexual behavior after brainstem administration of the 5-HT2 agonist DOI. Male Long-Evans rats were implanted with cannulae terminating in the region of the nucleus raphe obscurus/inferior olive, through which they received injections of DOI (0.1-10 micrograms). DOI produced a dose-dependent decrease in sexual behavior and concurrent increase in WDS. Pretreatment with the 5-HT2 antagonist ritanserin effectively blocked the effects of DOI. The results suggest that WDS and copulatory behaviors are modulated by a shared brainstem substrate. It is possible that the results may be the behavioral concomitant of recently described brainstem cells, with bifurcating axons, that project to both the medial preoptic area and the cervical spinal cord.

Amphetamines↗

PubMed1992

Differential patterns of arousal in sexually functional and dysfunctional women: physiological and subjective components of sexual response.

Physiological and subjective patterns of sexual arousal were compared for sexually functional and dysfunctional women. Previous studies revealed seemingly contradictory findings: Some found significant group differences on physiological but not on subjective responses to erotic stimuli, whereas others found the opposite. To reconcile this discrepancy, subjects were presented with edited versions of the three erotic videotapes used in previous studies. Sexual arousal was measured physiologically with a vaginal photoplethysmograph, and subjectively with a self-report rating scale. Previous methodology was systematically replicated and extended by developing alternate physiological data collection and reduction techniques, employing alternate methods of subjective assessment, evaluating the arousal-eliciting capacity of the erotic stimuli, and designing scripts to reduce social demand. Results indicated that dysfunctional women exhibited significantly less physiological and subjectively experienced sexual arousal than functional women in all three stimulus conditions. Dysfunctional women also reported significantly less autonomic arousal. Results (i) replicate several seemingly contradictory findings in the literature, (ii) reconcile and provide evidence supporting an explanation for the apparent discrepancy, and (iii) reveal that subjective experience and genital vasocongestion are two primary components of sexual arousal that reliably discriminate dysfunctional from functional patterns of sexual response in women.

Adult↗

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

Serum estradiol concentration required to maintain body weight, attractivity, proceptivity, and receptivity in the ovariectomized female rat.

Female hooded rats (230 to 260 g) were ovariectomized and given a subcutaneous implant of an estradiol-filled Silastic tube. The length of the tube was varied in order to produce a variety of serum estradiol levels. In the first experiment, animals were weighed over a 6-week period following surgery and then tested for sexual responsiveness to a male. The results demonstrated that ovariectomized females with an implant maintaining a serum estradiol concentration at about 15 pg/ml maintained body weight at the same level as that of intact females. A smaller implant gave rise to a higher weight gain and a larger implant to a lower weight gain. All implants resulted in a continuous state of receptivity. In a second experiment, ovariectomized females were implanted with smaller estradiol-filled implants in order to determine the threshold for maintaining proceptivity and receptivity. The results indicated that with a serum estradiol concentration below 15 pg/ml, the frequency of lordosis and of ear wiggling and darting decreased. Progesterone injections facilitated both proceptive and receptive behavior. In addition, following progesterone injections, the time required for a male to mount a female 10 times was decreased in females with low or no estradiol replacement. These results indicate that a constant concentration of estradiol at about the mean level present throughout the estrous cycle will result in normal body weight regulation and will maintain sexual behaviors that normally occur only during estrus. These results emphasize that Silastic implants of estradiol do not mimic normal endocrine function since, even at low levels, estradiol implants produce continuous receptivity.

Animals↗

PubMed1991

DOI-induced inhibition of copulatory behavior in male rats: reversal by 5-HT2 antagonists.

Relatively little is known regarding the role of 5-HT2 receptor activity in male rat sexual behavior. Previous work has yielded equivocal results, and both facilitation and inhibition of copulation have been reported to follow administration of selective 5-HT2 antagonists. In the present series of experiments, the ability of a variety of 5-HT2 antagonists to block inhibition induced by the 5-HT2/5-HT1C agonist DOI was examined. Systemic ritanserin, pirenperone and ketanserin all potently blocked DOI-induced (1.0 mg/kg SC) inhibition of mounts, intromissions and ejaculations. None of these drugs influenced the sexual behavior of the male rats when given alone in doses that effectively blocked DOI-induced inhibition. In addition, unlike ritanserin and ketanserin, pirenperone produced a biphasic effect on DOI-induced inhibition, exhibiting a diminished blockade at higher doses. This may be due to activity at receptors other than 5-HT2. Overall, the present data suggest that activity at 5-HT2 receptors mediates an inhibition of male rat sexual behavior.

Amphetamines↗

PubMed1991

Effects of the oxytocin fragment prolyl-leucyl-glycinamide on sexual behavior in the rat.

Prolyl-leucyl-glycinamide (PLG), a natural brain peptide, is identical in structure to the C-terminal of oxytocin. Moreover, PLG and oxytocin can act as opiate antagonists. Evidence that opiates and oxytocin have significant influences on reproductive behavior suggests that PLG may also be effective. Morphine and/or PLG were administered intraperitoneally to male and female rats and sexual behavior was observed. PLG (0.1-10 mg/kg) was found to facilitate female sexual behavior in Experiment 1. In Experiment 2, the ability of PLG to facilitate female receptivity was found to be progesterone dependent. In Experiment 3, tyrosine-prolyl-leucyl-glycinamide, a putative precursor to PLG, failed to facilitate lordosis. In Experiment 4, PLG failed to facilitate male sexual behavior. In Experiments 5 and 6, PLG did not affect morphine-induced inhibition of either male or female sexual behavior. These data suggest that PLG differentially affects female receptivity and male sexual behavior. The current results support the hypothesis that PLG is an active metabolite of oxytocin in the female, but do not provide evidence that PLG functions as an opiate antagonist of sexual behavior.

Animals↗

PubMed1991

Oxytocin effects on lordosis frequency and lordosis duration following infusion into the medial pre-optic area and ventromedial hypothalamus of female rats.

When infused into the medial preoptic area of ovariectomized female rats treated with estradiol benzoate (3 micrograms) and progesterone (150 micrograms), oxytocin was found to increase the lordosis frequency and the lordosis duration. Oxytocin administered into the ventromedial hypothalamus increased the lordosis duration but not the lordosis frequency. In the mesencephalic central grey, oxytocin did not significantly affect lordosis. Oxytocin in the ventromedial hypothalamus facilitated lordosis duration at doses which were ineffective in the medial preoptic area. This contrasts with the pattern of results observed for lordosis frequency. These results lend support to the hypothesis that the lordosis-facilitating actions of oxytocin in the ventromedial hypothalamus are due to a permissive effect of progesterone and that the ventromedial hypothalamus and medial pre-optic area may control different aspects of lordosis.

Animals↗

PubMed1990

Sex differences in the effects of 1-(m-trifluoromethylphenyl) piperazine and 1-(m-chlorophenyl) piperazine on copulatory behavior in the rat.

Peripheral administrations of TFMPP (0.2- 1 mg/kg) or MCPP (1 mg/kg) facilitated lordosis behavior in female rats treated with estradiol benzoate, and had no effects in females primed with estradiol benzoate and progesterone. In contrast, TFMPP (1 mg/kg) and MCPP (1 mg/kg) inhibited copulatory behavior in male rats. It is concluded that there are sex differences in the effects of TFMPP and MCPP on copulatory behavior in the rat. Moreover, it is suggested that the effects of these drugs on copulatory behavior may be mediated by activation of 5-HT1B and/or 5-HT1C receptors, or by blockade of activity at 5-HT3 receptors.

Animals↗