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Biomedical subjects

A I Frankel

Publications and source records attributed to A I Frankel.

At least 37 records · Page 2Linked to original sources
PubMed1979

The effect of L-3,4-dihydroxyphenylalanine (L-dopa) on the prolactin response to sexual behavior in the male rat.

L-3,4-dihydroxyphenylalanine (L-dopa) was administered intraperitoneally (i.p.) to sexually experienced male rats, and blood was collected both by decapitation without anesthesia and by cardiac puncture with ether anesthesia. Samples were taken before and during mating with a receptive female. Both the prolactin (Prl) response to ether and the Prl response to mating were suppressed by L-dopa. Basal Prl levels were depressed, but not significantly. However, sexual behavior was not altered by L-dopa. It was concluded that the previously reported loss of the Prl response to an estrous female in male rats lesioned in the medial preoptic area (MPOA) could not account for their loss of sexual behavior. Further, elevation of Prl levels during mating is not necessary to normal sexual behavior in the intact male rat.

Animals↗
PubMed1979

Characterization of the androgen receptor in nuclei of seminiferous tubules of the mature male rat based upon radioimmunoassay of endogenous levels of bound testosterone.

A macromolecular testosterone complex which was salt-extracted from nuclei isolated from seminiferous tubules of the adult male rat was investigated by quantifying the testosterone directly by RIA. The steroid-binding capacity of the complex was destroyed by heating at both 12 and 50 C, suggesting the presence of an extremely thermolabile complex. This tubular complex was shown to be similar to the radioactively labeled androgen receptor isolated from ventral prostatic nuclei by their coelution during adsorption chromatography, by their coleution during ion exchange chromatography, their similar migration rate (4-4.46S) on both sucrose and glycerol density gradients, and their similar slow dissociation at 0 C. These observations indicate that the tubular complex contains a high affinity androgen receptor and suggest that the direct measurement of testosterone in this complex by RIA may be useful in identifying its cellular distribution.

Animals↗
PubMed1978

The effect of medial preoptic area lesions on sexually stimulated hormone release in the male rat.

Male rats were subjected to bilateral electrolytic lesions in the medial preoptic area (mPOA). These lesions disrupted sexual behavior without affecting basal levels of luteinizing hormone (LH), prolactin (PRL), or testosterone (T). During exposure to an estrous female, intact and sham-operated rats mated; these rats showed elevations in LH, PRL, and T levels. Lesioned rats, which did not mate, showed elevations in LH but not PRL or T levels. These results demonstrate that the mPOA is not required for sexually stimulated LH release. The failure of lesioned rats to release PRL and T may be secondary to their failure to mate. Alternatively, the mPOA may participate in sexually stimulated PRL release, while T release may depend on prior elevations in both LH and PRL levels. LH release may be related to arousal, and PRL release to consummation, providing a hormonal analogy for the dual mechanism theory of sexual behavior.

Animals↗
PubMed1978

Blood-collecting methodology does not affect the maturational pattern of serum hormone concentrations (testosterone, LH, FSH and prolactin) in the male rat.

Serum hormone levels of blood collected within 1 min by cardiac puncture following ether anesthesia were compared to those of blood collected by decapitation in male rats 30, 60, and 90 days of age. Neither testosterone (T) nor LH was affected by the method of blood collection. Serum FSH was significantly elevated in blood collected by cardiac puncture, and 30-day old rats were the most sensitive to this effect. Serum prolactin (Prl) was significantly elevated in all age groups when blood was collected by cardiac puncture. Both blood-collecting methods demonstrated that, in the 3 ages tested, serum T increased with age, LH and FSH decreased with age, and Prl did not change with age, indicating that blood collection by cardiac puncture is as valid a method as is decapitation for assessing serum hormone levels during maturation.

Aging↗
PubMed1978

Daily rhythmicity of serum testosterone concentration in the male laboratory rat.

Daily rhythmicity of serum testosterone concentration in the mature male laboratory rat was examined under various lighting schedules. In rats living in a standard light cycle (12-h light, 12-h dark; lights on at 0600 h), a trimodal rhythm was predominant, with elevations near 0200, 1200, and 1800 h. This pattern was reasonably stable in seven different studies, despite differences in experimental design, method of blood collection, anesthesia, and whether individual rats were sampled once or repeatedly, and was found both in groups of animals and in individuals, including a study using 40-day-old rats. In constant illumination, the pattern was disrupted, but in constant darkness the trimodal pattern was maintained, indicating that the rhythm is endogenous. In a reversed light cycle (12-h dark, 12-h light; lights on at 1800 h), the "midday" elevation was reversed; in an altered light cycle (12-h dark, 12-h light; lights on at 2300 h), the time of the "midday" elevation was shifted. Serum testosterone concentration was higher during the light phase than the dark phase, and was higher in constant light than in constant darkness. A seasonal shift in the daily rhythmicity of serum testosterone concentration is suggested. The trimodal rhythmicity contrasts with the circadian rhythmicity of other hormones. Its functional role in the life of the animal is unknown.

Animals↗
PubMed1975

Characterization and physiological validation of a radioimmunoassay for plasma testosterone in the male rat.

A radioimmunoassay (RIA) to measure testosterone concentration in the plasma of male rats was formalized, tested and physiologically validated. The procedure measured testosterone equally well, whether or not estimation of recovery and chromatographic purification preceded the RIA. The results were equivalent to those achieved by the method of competitive protein binding. No 17beta-hydroxy-5alpha-androstan-3-one was found in the plasma of male rats. Adrenalectomy did not significantly decrease plasma testosterone in either male or female rats. The simplified protocol met all requirements of precision, sensitivity, accuracy and specificity. A single investigator can analyze 1,000 plasma samples for testosterone in one week if necessary.

Animals↗