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Pinealectomized and sham-pinealectomized male rats were subcutaneously implanted with 2 cm silicone elastomer capsules filled with testosterone or dihydrotestosterone (DHT) and placed in constant darkness (DD) for 50 days. The data revealed that the sham-pinealectomized group treated with testosterone differed from the pinealectomized group, having lower weights of accessory sexual organs and levator ani muscle. Pinealectomy had no effect on organ and muscle weights of DHT-treated animals.
Exposure of male rats to DD resulted in a marked decrease in weights of ventral prostate, seminal vesicle, coagulating gland and levator ani muscle and a decrease in plasma DHT levels. However there was no significant reduction in plasma LH, FSH or testosterone. Pinealectomy of the rats exposed to DD resulted in restoration of both DHT levels and accessory sex organ weights. Melatonin implants in pinealectomized males led to an increase in both testosterone and DHT levels, accompanied by a decrease in sexual organ weights. The data indicate that the anti-gonadal effect of the pineal gland cannot be completely mediated by melatonin and that melatonin and some unknown factors can act at the tissue level to reduce the size and function of the affected sexual organs.
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There are marked sex differences in the Harderian gland of the C3H/He strain of mice. Female (but not male) glands contain large amounts of porphyrin, which are readily visible as solid depositions within the lumina.
The histology and porphyrin content of the Harderian gland were examined in intact and in pregnant mice and in mice subjected to combinations of adrenalectomy, gonadectomy and administration of sex steroid hormones. In male mice, castration approximately doubled the amount of porphyrin in the Harderian gland. Castration plus adrenalectomy increased the levels over 30-fold, to levels similar to those found in female mice, although adrenalectomy alone produced no significant effect. Administration of testosterone to the male mice which had been castrated and adrenalectomized prevented the increases while progesterone treatment produced further increases in porphyrins. In intact females, the amount of porphyrin varied with the phase of the oestrous cycle; being lowest during metoestrus and highest during dioestrus. In ovariectomized–adrenalectomized females, the effects of administered sex hormones on the amount of porphyrin in the gland were the same as in males. In pregnant mice, the level was not significantly different from that in intact oestrous animals.