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Biomedical subjects

A R Caggiula

Publications and source records attributed to A R Caggiula.

At least 73 records · Page 4Linked to original sources
PubMed1979

Dissociation of active from immobility components of sexual behavior in female rats by central 6-hydroxydopamine: implications for CA involvement in sexual behavior and sensorimotor responsiveness.

Ovariectomized female rats were given a hormone treatment (2 X 8 micrograms/kg estradiol benzoate) that normally supports only low levels of lordosis responding and no soliciting behavior in tests with sexually active males. When subjected to an intraventricular 6-hydroxydopamine (6-OHDA) procedure (with pargyline pretreatment) that produced 85% and 95% depletions of caudate dopamine and cortical norepinephrine respectively, these females exhibited a dramatic increase in the intensity and frequency of lordotic responding but no soliciting behavior over 3 weekly tests. The increase in lordosis was not due to a drug- or stress-induced release of adrenal progesterone, since dexamethasone suppressed the progesterone levels, as documented by radioimmunoassay, but not the higher receptivity of 6-OHDA treated females. In other ovariectomized females given a hormone regimen (2 X 50 micrograms/kg estradiol benzoate plus 500 micrograms progesterone) that supported maximal levels of lordosis and soliciting, the same 6-OHDA treatment prolonged the average duration of lordosis while actually decreasing the incidence and duration of soliciting. The hypothesis is put forward that the differential effects of interfering with catecholamine, and more likely dopamine function on the soliciting and lordosis components of female sexual behavior might best be understood as a dissociation between mutually antagonistic behavior patterns such that responsiveness involving active orientation and forward locomotion is suppressed, whereas responses requiring immobility are augmented.

Animals↗
PubMed1979

Serum concentrations of testosterone, oestrogens, luteinizing hormone and follicle-stimulating hormone in male and female rats during the critical period of neural sexual differentiation.

Untreated male and female rat pups were killed 1--5 days post partum and the serum concentrations of testosterone, oestrogens, LH and FSH were determined by radioimmunoassay. At all five sampling times, the serum concentrations of testosterone in male rats were about three times higher than those in female rats, but serum levels of oestrogens did not differ between the sexes. Serum concentrations of LH and FSH were lower in male than in female pups. In another study, rats were decapitated 1--10 days after birth and serum concentrations of testosterone were determined with a different radioimmunoassay. Again, at all four sampling times, the concentration of testosterone was significantly higher in the male than in the female pups.

Animals↗
PubMed1978

Preoptic knife cuts and sexual behavior in male rats.

Knife cuts aimed at severing either the medial-lateral or dorsal fiber connections of the medial preoptic-anterior hypothalamus (MPOAH) produced two clearly distinguishable patterns of copulatory deficits in male rats. On the other hand, transverse cuts, which were designed to destroy longitudinal connections on either the anterior or posterior end of the MPOAH, did not affect sexual behavior. Males with sagittal cuts exhibited deficits primarily in the initiation of copulation. In contrast, those with dorsal cuts showed alterations primarily in the execution of copulatory behavior. Combined behavioral and anatomical evidence was interpreted as suggesting that the MOPAH has at least two regulatory functions related to sex behavior: (1) it is involved in the mediation of the initiation of copulation through its lateral connections with the medial forebrain bundle, and (2) it influences the achievement of ejaculation and the subsequent refractory period through its dorsal connections with the amygdala and the hippocampus.

Animals↗
PubMed1978

Selective enhancement of the lordotic component of female sexual behavior in rats following destruction of central catecholamine-containing systems.

Ovariectomized female rats received two intraventricular injections of 200 microgram of 6-hydroxydopamine (6-OHDA), a treatment which produced 66% depletion of telencephalic norepinephrine and 53% depletion of telencephalic dopamine. Compared to vehicle-injected controls, 6-OHDA-treated animals showed increased lordosis scores when treated with ovarian hormones. This effect was potentiated by additional treatment with 100 mg/kg alpha-methyl-p-tyrosine (AMT), a catecholamine synthesis inhibitor. Besides showing increased frequency and intensity of lordosis, animals treated with both 6-OHDA and AMT retained the lordotic posture significantly longer after the male dismounted than animals given either treatment alone or vehicle controls. The enhancement of lordosis following CA depletion was not prevented by a series of dexamethasone treatments which caused a marked suppression in adrenal steroid (corticosterone) levels. This suggests that normal adrenal function is not a prerequisite for the observed enhancements. It was concluded that the lordotic response is inhibited by the activity of a catecholamine system. Soliciting behavior (hop-darting) was not enhanced by any treatment, suggesting that catecholamine activity has an inhibitory influence on the stop component of sexual behavior, but not on the whole copulatory pattern.

Animals↗
PubMed1977

Norepinephrine-dopamine interactions and behavior.

The proposed hypothesis is directed toward explaining a number of disparate findings in terms of a stress-related interaction between the NE- and DA-containing systems in the brain. The deleterious behavioral effects of decreased DA activity, for example, may be counterbalanced by a similar decrease occurring in NE activity, such compensation being most likely to occur under conditions of stress. This hypothesis may have application to the understanding of neurological and mental disorders such as Parkinson's disease and schizophrenia.

Aggression↗
PubMed1976

Interactive effects of brain catecholamines and variations in sexual and non-sexual arousal on copulatory behavior of male rats.

In pargyline pretreated male rats, an intraventricular 6-hydroxydopamine procedure which resulted in subtotal brain catecholamine (CA) depletion produced a mild defict in copulatory behavior followed by rapid recovery. Challenges employed to study the behavioral capacities of these 'recovered' animals revealed: (1) a heightened sensitivity to acute treatment with the CA synthesis inhibitor alpha-methyl tyrosine (AMT) as reflected in a reinstatement and exaggeration of the original copulation deficit; (2) a greater dependence on the sexual eliciting properties of the female, since abolishing her soliciting behavior also reinstated and exaggerated the sexual dysfunction; and (3) a pattern of behavioral impairment indicating increased difficulty in both initiating sexual activity and maintaining copulatory performance. Furthermore, in males not copulating after 6-OHDA/AMT treatment, copulation could easily be induced by the simple application of a non-specific activating stimulus. On the basis of these data and parallel findings reported for other behaviors, we have concluded that: (1) both the initiation and maintenance of copulatory behavior in the male rat is the part dependent on normal functioning in one or more of the brain CA-containing systems; and (2) this copulatory deficit is symptomatic of a broader functional impairment reflecting reduced behavioral responsiveness to stimuli that normally elict appetitive or approach responses but not to stimuli requiring more automatic, inhibitory responses.

Animals↗
PubMed1975

Disruption of copulation in male rats after hypothalamic lesions: a neuroendocrine analysis.

Electrolytic lesions of the hypothalamic medial forebrain bundle (MFB) produced substantial deficits in the copulatory behavior of male rats, but no changes in testicular, seminal vesicle, ventral prostate or penis weights. Radioimmunoassay of serum from lesioned and control animals revealed a small but statistically insignificant reduction in testosterone and LH levels, and no change in FSH levels of lesioned males. In a second experiment, androgen levels were maintained in castrated males by subcutaneous implants of silastic capsules containing crystalline testosterone; this procedure failed to prevent the copulatory deficit which accompanied subsequent MFB lesions. We have concluded that the behavioral deficit produced by such lesions is not a direct result of pituitary-gonadal dysfunction.

Animals↗