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Biomedical subjects

C Beyer

Publications and source records attributed to C Beyer.

At least 163 records · Page 9Linked to original sources
PubMed1985

Comparison of the effects of different isomers of bicuculline infused in the preoptic area on male rat sexual behavior.

Intracerebral infusion of (+) bicuculline methiodide, but not of its (-) isomer, in the preoptic area, stimulated masculine sexual behavior in rat as evidenced by a decrease in the number of intromissions preceding ejaculation and a shortening of the ejaculation latency and postejaculatory interval. Data suggest a role of the GABAergic system in mediating masculine sexual behavior.

Animals↗
PubMed1985

Hyperalgesia induced by altered glycinergic activity at the spinal cord.

Glycine or its receptor antagonist, strychnine, were administered perispinally to investigate their effect on nociceptive responses elicited by activation of various cutaneous receptors. Strychnine produced dose-dependent sensory and motor disturbances; 1 and 5 micrograms doses were sub-convulsive, eliciting recurrent episodes of coordinated grooming, scratching and biting at the skin, which persisted for approximately 10 minutes post-injection; higher doses (25 and 100 micrograms) increased the intensity and duration of these effects, and produced convulsive motor seizures. Motor disturbances were not elicited by glycine (5, 25, 100 and 400 micrograms). Strychnine treated rats, at all doses, vocalized consistently in response to light cutaneous stimulation; a significant proportion of glycine treated rats also vocalized, but were not as sensitive to mild stimulation. Skin hyperalgesia persisted for at least 30 minutes in both strychnine and glycine treated rats. Both strychnine and glycine significantly reduced vocalization thresholds to tail shock. However, no clear effect on tail flick latency was observed following either strychnine or glycine. These results indicate that glycinergic neurons contribute to the tonic regulation of nociceptive input at the spinal cord.

Animals↗
PubMed1985

Strychnine antagonizes vaginal stimulation-produced analgesia at the spinal cord.

Vaginal-cervical mechanostimulation (VS) suppresses vocalization and withdrawal responses to noxious stimulation. To determine whether the inhibitory neurotransmitter, glycine, contributes to the action of VS, strychnine, a specific glycine receptor antagonist was administered perispinally via intrathecal catheter in dosages of 1,5,25 and 100 micrograms. Prior to strychnine administration, VS (400 g force) elevated thresholds to elicit vocalization in response to graded intensities of tail shock, and blocked vocalization elicited by stimulation of a skin area, previously sensitized by intradermal injection of a 20% yeast solution. After strychnine administration the analgesic effects of VS were significantly attenuated. These findings suggest that the analgesic action of VS is partially mediated by glycine at the spinal level.

Analgesia↗
PubMed1985

Neonatal androgen influences sexual motivation but not the masculine copulatory motor pattern in the rat.

Masculine sexual responses displayed by female rats, were compared to those of males. Twenty-five percent of females mounted and 19% showed intromission behavior, but none of them displayed the ejaculation pattern. Masculine sexual behavior was displayed in all stages of the estrous cycle. Accelerometric and spectrum frequency analysis of electrical signals generated by pelvic movements during mounting and intromission showed that these patterns were identical in both sexes excepting that mount duration in females was longer than in males. Neonatal androgenization of females increased the display of intromission patterns. Treatment of ovariectomized rats, androgenized or not, with either estradiol benzoate or testosterone propionate stimulated masculine sexual behavior. The ejaculatory pattern was only displayed by neonatally androgenized females. Mounting and intromission motor patterns of females under steroid treatment, and ejaculations of neonatally androgenized females, were similar to those of males. The results show that the organization of the movements involved in masculine sexual behavior in rats are identical in both sexes, thus suggesting that the neural circuits controlling these behaviors could be identical. Neonatal or postpubertal androgen in the rat influences the frequency with which male-like responses are displayed, but not their temporal (frequency, rhythm) or dynamic (acceleration, vigour) characteristics.

Animals↗
PubMed1985

Potentiative action of alpha- and beta-adrenergic receptor stimulation in inducing lordosis behavior.

Ovariectomized (OVX) and ovariectomized-adrenalectomized (OVX-ADX) rats were injected with estradiol benzoate (EB, 4.0 micrograms/rat) and received 44 hr by infusion into the ventromedial hypothalamic area one of the following treatments: norepinephrine (NE), clonidine (an alpha-agonist), isoproterenol (a beta-agonist) or a combination of clonidine and isoproterenol. Infusion of NE (200 ng/rat) induced lordosis in both OVX and OVX-ADX rats 15 minutes after its administration. NE-induced lordosis was blocked by systemic treatment with either the alpha-antagonist, prazosin (1.0 mg/kg), or the beta-antagonist, propranolol (4.0 mg/kg). Intrahypothalamic infusion of clonidine (200 ng/rat) or isoproterenol (200 ng/rat) induced lordosis behavior in OVX, but not in OVX-ADX rats, suggesting the involvement of adrenal secretions in this response. Combined administration of clonidine (100 ng/rat) and isoproterenol (100 ng/rat) induced lordosis behavior 15 minutes after its intrahypothalamic infusion in OVX-ADX animals. Results are discussed in relation to a model proposed for the induction of lordosis behavior involving steroid-NE interactions.

Adrenalectomy↗
PubMed1985

Prevention of progesterone-induced lordosis behavior by alpha or beta adrenergic antagonists in ovariectomized estrogen-primed rats.

The effect of systemic administration of adrenergic alpha (phenoxybenzamine and prazosin) and beta (propranolol) antagonists on the lordosis behavior induced by progesterone (2.0 mg/rat) was studied in ovariectomized estradiol benzoate (4.0 micrograms/rat) primed rats. The effect of these antagonists was also tested on the lordosis behavior induced in ovariectomized rats by estradiol benzoate alone (1.25 micrograms/rat each two days). Phenoxybenzamine (0.8, 4.0 and 20.0 mg/kg), propranolol (0.8, 4.0 and 20.0 mg/kg) and prazosin (0.2 and 1.0 mg/kg) caused a dose-dependent reduction of progesterone induced lordosis. By contrast, phenoxybenzamine (4.0 mg/kg), propranolol (4.0 mg/kg) or prazosin (1.0 mg/kg) did not affect estrogen induced lordosis behavior. Results suggest the following conclusions: (1) blockage of either alpha or beta adrenoreceptors prevents progesterone induced lordosis behavior and (2) the adrenergic neuron involved in progesterone facilitation of lordosis behavior is not a part of the reflex arc for lordosis but probably modulates the activity of this system.

Adrenergic alpha-Antagonists↗
PubMed1985

Urinary creatine: biochemical indicator for evaluation of sickle cell crises.

In a patient with known sickle cell beta 0-thalassemia we measured serum lactate dehydrogenase (LD) activity and 24-h urinary creatine excretion rate as markers to evaluate sickle cell crises. We believe that a distinction based on biochemical findings can be made between hemolytic and painful vaso-occlusive sickle cell crises with muscular involvement. To assess hemolytic crises by objective biochemical measures, we have used assay of LD activity, and to assess painful crises with muscular involvement objectively, the 24-h urinary creatine excretion rate. We conclude that hemolytic crises are characterized by high serum LD activities. Furthermore, we conclude that--at least in this patient--painful crises are accompanied by high 24-h urinary creatine excretion rates. Our findings suggest that muscle involvement may play an important role in painful vaso-occlusive sickle cell crises.

Adult↗
PubMed1985

[False chordae tendineae in the left ventricle. Echo and phonocardiographic findings].

In 91 of 1007 children (9%) with and without heart disease who underwent echocardiographic exploration we found false chordae tendineae in the left ventricle. These bands, usually running from the lateral wall to the interventricular septum, showed strong ultrasound reflections and could be seen in at least two different views. More than one band was rarely seen in the ventricle. All children with false chordae tendineae in the left ventricle had innocent heart murmurs. Of these systolic murmurs 91% were, according to their sound quality, maximal intensity and frequency, Still's innocent murmurs. On the other hand, in 72% of 54 other children with innocent murmurs we found false chordae tendineae in the left ventricle by careful 2D-echocardiographic exploration.

Arrhythmias, Cardiac↗
PubMed1984

Sexual dimorphism in the motor mounting pattern of the New Zealand white rabbit: steroid regulation of vigor and rhythmicity of pelvic thrusting.

The motor mounting patterns of male and female New Zealand white rabbits were analyzed by means of an accelerometric technique and frequency analysis. Clear behavioral dimorphism was noted in the motor mounting pattern. Pelvic thrusting by males was periodic while that performed by females lacked rhythmicity. Thrusting in males was more vigorous than in females. Ovariectomy markedly decreased the incidence of mounting behavior. Testosterone propionate (TP, 5 mg daily for 1 month), restored mounting in all ovariectomized rabbits. TP stimulated the vigor of thrusting and induced a rhythmic mounting pattern in many cases similar to that displayed by intact male rabbits, i.e., thrusting frequency 13-16 per second. Estradiol benzoate (10 micrograms daily for 1 month), elicited mounting in three of the seven rabbits tested. Pelvic thrusting in these rabbits was often highly synchronous showing a frequency higher (18 to 21 thrusts per second) than that displayed by male rabbits. The results suggest the following conclusions: (a) the behavioral dimorphism in mounting observed in rabbits is due to variations in the secretion of sex steroids by the adult gonads rather than to differences in the organization of the neural substrate of mounting; (b) gonadal steroids influence directly or indirectly the neural structures involved in some characteristics of pelvic thrusting, i.e., rhythmicity and vigor.

Animals↗
PubMed1984

Effects of REM deprivation on the lordosis response induced by gonadal steroids in ovariectomized rats.

Ovariectomized rats were submitted to REM sleep deprivation (REMd) using the water tank technique and their behavioral responsiveness (lordosis) to gonadal steroids was tested. In Experiment 1, animals received 2 micrograms of estradiol benzoate (EB) followed by 2 mg of progesterone (P) 44 hours later. Several REMd periods (12, 72, 96 and 120 hr) were applied, all ending four hr after P. REMd animals showed significantly lower lordosis quotients (LQ) than undisturbed sleep animals regardless of the duration of the deprivation period. In Experiment 2, animals received a single dose of EB (2 micrograms) and were REMd for 120 hours. Animals were tested daily to evaluate their LQ. EB, at this dose level, failed to elicit significant lordosis behavior in undisturbed sleep rats. REMd rats gradually increased their LQ values reaching maximal levels at 72 hours. Adrenalectomized control groups receiving the same hormonal treatment responded similarly to the experimental groups, thus discarding the participation of adrenal steroids in these effects. The present results show that REMd differentially affects the response to E and P in ovariectomized rats, enhancing the former and inhibiting the latter.

Animals↗
PubMed1983

[Microemulsions].

Explore the source record for details and available documents.

Chemistry, Pharmaceutical↗
PubMed1983

Serotonergic influences on EEG synchronization induced by milk drinking in the cat.

Milk drinking elicits electroencephalographic (EEG) synchronization in the parieto-occipital cortex of cats. This EEG change is a reliable correlate of the consummatory phenomena involved in "relaxation" behavior. The effect of varying serotonin brain levels by administering P-chlorophenylalanine (PCPA) or 5-hydroxytryptophan (5HTP) on this response was studied in 25 young cats. Single or repeated injections (4-8 days) of 50, 100 or 150 mg/kg of PCPA resulted in a dose related decrease in the duration of the EEG parieto-occipital synchronization during fixed periods of milk drinking. A single injection of 3, 10 or 30 mg/kg of 5HTP to chronic PCPA treated cats, restored the EEG parieto-occipital synchronization during milk drinking to control values. Moreover, administration of 5HTP to non-treated cats significantly increased the duration of EEG parieto-occipital synchronization during milk drinking. Our results suggest that brain serotonergic neurons are involved in the development of EEG synchronization during milk drinking.

5-Hydroxytryptophan↗
PubMed1983

Effect of guanine derivatives on lordosis behavior in estrogen primed rats.

The effect of systemic administration of guanosine, cGMP, dipalmitoyl (dp) cGMP, 5'GMP and 5'GDP on lordosis behavior was studied in ovariectomized, estradiol benzoate (EB) primed rats (4 micrograms/rat). EB per se induced only weak lordosis behavior. Free cGMP (2.0 mg/rat); dp cGMP (1.0, 2.0 and 4.0 mg/rat) and 5'GMP (2.0 and 4.0 mg/rat) induced significant lordosis behavior in ovariectomized, estrogen-primed rats. Dp cGMP and 5'GMP (2.0 mg/rat), also induced lordosis behavior in ovariectomized, adrenalectomized estrogen primed rats. Lordosis behavior elicited with 2.0 mg/rat dp cGMP was blocked with 8.0 mg/rat methyl-isobutylxanthine (MIX), a phosphodiesterase inhibitor, suggesting that dp cGMP stimulated lordosis through its conversion to 5'GMP. Results are interpreted in terms of the activation of adenylate cyclase-cAMP systems by guanine nucleotides.

1-Methyl-3-isobutylxanthine↗