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R Baumgarten

Publications and source records attributed to R Baumgarten.

At least 19 recordsLinked to original sources
PubMed1992

Copulatory stimuli in rats induce heat abbreviation through effects on genitalia but not through effects on central nervous mechanisms supporting the steroid hormone-induced sexual responsiveness.

Male copulatory stimuli in various animal species abbreviate the length of the period of their female conspecifics' heat. Such effect can be explained in some species as the result of copulation-induced alterations in ovarian hormone secretion (e.g. reflex ovulators). Other species require a different explanation: specifically, interactions in the hypothalamus between effects of steroid hormones and inhibitory neural afferents from the genital area have been hypothesized to play a role in some laboratory animals such as guinea pigs, hamsters and rats. However, the evidence in support of heat abbreviation through copulatory stimuli in rats is at best equivocal. There is obvious need for its unequivocal demonstration prior to any further analysis of the potential mechanism of action. The present study intended to find a model in support of the concept of 'centrally induced' heat abbreviation in rats. Virgin rats during 'natural heat' were examined with or without allowing them the opportunity to pace male copulatory activities. Ovariectomized, steroid hormone-treated rats were studied with minor or ample experience with sexual activities in prior tests and, also, with or without the opportunity to 'pace' male sexual acts. None of the experimental models revealed unequivocal support for detrimental effect of large numbers of intromittive copulations on 'central mechanisms' regulating heat duration. It rather seemed that frequent intromittive copulations and ejaculates affected the 'peripheral' genital tract (vulva, vagina, cervix) making further copulation of a highly aversive quality so that sexual encounters were avoided or prevented. This effect was noticed with great inter-individual variability. The conclusion is drawn that rats do not show the counterpart of heat abbreviation reportedly occurring rapidly and reliably in guinea pigs after a limited amount of vaginal/cervical stimulation through copulation or insertions of a glass-rod.

Animals↗
PubMed1992

Interactions between oestradiol and the progesterone antagonist RU-486 in establishing and maintaining female rats' sexual responsiveness: central versus peripheral effects.

Progesterone is well known to contribute specifically to the emergence of the female rats' sexual behaviour by the establishment of 'proceptivity'. Analysis of the mechanism of progesterone action benefits from the availability of highly effective anti-progestagenic compounds. However, results obtained during the study of female rats' sexual behaviour, including such compounds into the experimental protocol, appear equivocal. The present experiments were designed to further examine the possible effects of the antiprogestagenic compound RU-486 (Mifepristone) on the female rats' sexual responsiveness as elicited through exposure of the animals to oestradiol alone. The experimental design aimed to distinguish between receptivity (defined as response to sexually active males) and proceptivity (defined as female-initiated sexual behaviour). Mifepristone advanced the onset of receptivity after the injection of oestradiol benzoate (OB). Upon further investigation a steady level of receptivity was reached during prolonged treatment with OB and this level appeared unaltered through concurrent treatment with Mifepristone. OB alone was insufficient to induce full proceptivity as revealed by observations of sexual behaviour with tethered males. Such defined proceptivity was significantly further inhibited by Mifepristone. It thus appears that, dependent upon the time and type of female sexual behavioural analysis, Mifepristone either enhances, inhibits, or does not affect sexual responsiveness. After the observation period, autopsy revealed the presence of copulatory plugs and infections in the uterus of OB + Mifepristone-treated rats. This unexpected finding could result from effects of the compound on the uterine cervical musculature. Uterine infections might result in painful, aversive, intra-abdominal sensations, especially during intravaginal penile intromissions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The dopamine D2 receptor locus as a modifying gene in neuropsychiatric disorders.

OBJECTIVE: --The A1 allele of the Taq I polymorphism of the dopamine D2 receptor (DRD2) gene has been earlier reported to occur in 69% of alcoholics, compared with 20% of controls. Other research has reported no significant difference in the prevalence of the A1 allele in alcoholics vs controls and no evidence that the DRD2 gene was linked to alcoholism. We hypothesized that these seemingly conflicting results might be because increases in the prevalence of the A1 allele may not be specific to alcoholism. Thus, we examined other disorders frequently associated with alcoholism or those believed to involve defects in dopaminergic neurotransmission. DESIGN: --Case comparison study. To minimize the effect of racial differences in gene frequencies, the study was restricted to non-Hispanic whites. SETTING: --Ambulatory and hospitalized patients. RESULTS: --Among all known controls (n = 314), 77 (24.5%) carried the A1 allele. Of the 69 controls known not to be alcoholics, 10 (14.5%) carried the A1 allele. The prevalence of the A1 allele was significantly increased in patients with Tourette's syndrome (44.9%, n = 147), attention deficit hyperactivity disorder (46.2%, n = 104), autism (54.5%, n = 33), alcoholism (42.3%, n = 104), and posttraumatic stress disorder (45.7%, n = 35). After correction for multiple comparisons (requiring P less than .0009 for significance), all remained significant except posttraumatic stress disorder. The prevalence of the A1 allele was not significantly increased in patients with depression, panic attacks, Parkinson's disease, or obesity. The prevalence of the A1 allele in drug addiction and schizophrenia was only significant when compared with that of controls who were not alcoholics, and no correction was made for multiple comparisons. CONCLUSION: --These results suggest the A1 allele of the DRD2 gene is associated with a number of behavior disorders in which it may act as a modifying gene rather than as the primary etiological agent.

Alcoholism↗