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Biomedical subjects

I Gerendai

Publications and source records attributed to I Gerendai.

50 records · Page 3Linked to original sources
PubMed1979

Less severe ovarian atrophy in hypophysectomized hemiovariectomized rats than in hypophysectomized animals with two ovaries.

The effect of unilateral ovariectomy (OVX) on the weight of the remaining ovary was studied in hypophysectomized (HYPOX) rats. 2 weeks following hypophysectomy + unilateral OVX the weight loss of the ovary is significantly less than that in HYPOX rats having two ovaries. Present data together with previous findings suggest that a neural pathway between the ovaries and the CNS may be involved in the mechanism of compensatory ovarian hypertrophy following removal of one ovary.

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PubMed1978

Prevention of compensatory ovarian hypertrophy by local treatment of the ovary with 6-OHDA.

The possible role of a neural mechanism involved in the development of compensatory ovarian hypertrophy has been studied. A new technique, the use of a special plastic capsule, has been developed to allow chronic local treatment of the ovary. Local treatment of one of the ovaries with 6-hydroxydopamine (6-OHDA) resulted in a weight increase in the other ovary. In the unilaterally ovariectomized rat the local application of 6-OHDA on the ovary blocked the development of compensatory ovarian hypertrophy. Local treatment of the ovary with dopamine (DA) did not interfere with the compensatory ovarian growth of the other ovary. Data suggest that intact adrenergic afferent and efferent neural elements of the ovary are required for the development of compensatory ovarian hypertrophy.

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PubMed1976

Hemigonadectomy-induced unilateral changes in the protein-synthesizing activity of the rat hypothalamic arcuate nucleus.

The effect of unilateral ovariectomy on the protein-synthesizing activity of the hypothalamic arcuate and dorsomedial nucleus on both sides was studied in vivo as well as in vitro. Four weeks after the removal of 1 ovary, there was a significant increase in labelled amino acid incorporated into the arcuate neurons contralateral to the removed ovary as compared to those incorporated into the nerve cells of the nucleus on the ipsilateral side. In the dorsomedial nucleus, there was no difference between the 2 sides. On the basis of the present findings, the existence of a neural pathway between the ovary and the hypothalamic arcuate nucleus is assumed.

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PubMed1975

Data on protein synthesis of deafferented hypothalamic arcuate neurons.

Protein synthesizing activity of the rat hypothalamic arcuate nucleus following partial or total deafferentation of the medial basal hypothalamus was studied by light and electron microscopic autoradiography when administering tritiated leucine into the lateral ventricle. There were significantly more grains over the arcuate nucleus 21 days after disconnection of this hypothalamic region than over the intact nucleus. Isolation of a temporal cortical region induced similar changes in the isolated area, although this effect was not so pronounced as in the arcuate region. Data suggest that the protein synthesizing activity of arcuate neurons increases significantly after interruption of neural connections of the medial basal hypothalamus. It is assumed that the effect is primarily due to transneuronal alteration and/or interruption of inhibitory afferents.

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PubMedDate not supplied

Participation of a pure neuronal mechanism in the control of gonadal functions.

The present review summarizes the data on the existence of a neural connection between the gonads and the central nervous system. As an experimental model the development of compensatory ovarian hypertrophy following unilateral ovariectomy was studied. Unilateral ovariectomy or orchidectomy resulted in a higher cellular activity in the hypothalamic arcuate neurons contralateral to hemigonadectomy and an increased luteinizing hormone-releasing hormone content in the medio-basal hypothalamus ipsilateral to the removed gonad. Local treatment of the remaining ovary with 6-hydroxy-dopamine prevented the development of compensatory ovarian hypertrophy after unilateral ovariectomy. Hemitransection of the spinal cord contralateral to hemigonadectomy, different unilateral hypothalamic deafferentations of the medio-basal hypothalamus as well as unilateral lesion of the medial preoptic area or of the arcuate nucleus blocked the compensatory ovarian growth when the brain surgery was on the same side as ovariectomy. Furthermore, in hypophysectomized + unilaterally ovariectomized rats a less severe ovarian atrophy occurred than in animals solely with hypophysectomy. All these data favour the view that - besides the hormonal control - a pure neuronal mechanism is also involved in the regulation of gonadal functions.

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PubMedDate not supplied

Naloxone has a local effect on the testis of immature rats.

Local effect of naloxone on testicular weight, compensatory hypertrophy, and differentiation of the testis and serum testosterone level has been studied in immature rats. A single injection of naloxone in a dose of 2 micrograms/testis under the testicular capsule significantly increased the testicular weight, promoted testicular differentiation and enhanced the rate of compensatory hypertrophy of the remaining testis in unilaterally orchidectomized animals. Data suggest that naloxone has a direct effect on the testis of immature rats.

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PubMedDate not supplied

The effect of neonatal vasectomy on testicular function.

The effect of unilateral or bilateral vasectomy on testicular weight and basal testosterone production in vitro was studied in neonatal intact and hemicastrated rats. Five days after right-side vasectomy ipsilateral to vasectomy testicular weight increased, and basal testosterone production decreased. Ten days postvasectomy the changes were opposite, and affected both testes. In hemicastrated animals hemivasectomy did not interfere with compensatory hypertrophy but induced a significant decrease in basal testosterone production. The data of the present study suggest that in neonatal animals intact ductus deferens bundle(s) is also required for the full control of testicular weight and basal testosterone secretion.

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PubMedDate not supplied

Effect of intratesticular administration of anti-corticotropin-releasing factor antiserum (a-CRF) on testicular function in neonatal rats.

The possible physiological role of testicular corticotropin-releasing factor (CRF) in the regulation of testicular functions was studied in neonatal rats. Two microlitres of anti-CRF-antiserum (dilution: 1:10 or 1:100) was injected intratesticularly to 5 d-old rats with two testes and to hemicastrates. Five days after hemicastration and treatment of the remaining testis with the antiserum, serum testosterone concentration and basal testosterone secretion in vitro decreased significantly. Unilateral testicular injection of a-CRF in rats with two testes resulted in a significant drop in serum testosterone level with no change in basal testosterone production. Data indicate that in neonatal rats testicular CRF might be a local stimulator of steroidogenesis.

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PubMedDate not supplied

Effect of intratesticular administration of oxytocin on testicular steroidogenesis in immature rats.

The possible physiological role of testicular oxytocin in testicular steroidogenesis was studied in immature rats. In 5-, 9-, and 25-day-old animals one of the testes was injected with 20, 50, and 200 ng of oxytocin, respectively, then the contralateral gonad was removed. Rats were killed 1 h, 1 day, or 7 days post-surgery. In each age group studied intratesticular injection of oxytocin resulted in a significant increase in basal testosterone secretion in vitro and/or serum testosterone concentration. Data indicate that in immature rats oxytocin of testicular origin might act as a local stimulator of steroidogenesis.

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PubMedDate not supplied

Effect of simultaneous local injection of 6-hydroxydopamine and naloxone on the testis of neonatal rats.

The effect of simultaneous intratesticular injection of the opiate receptor antagonist naloxone and the neurotoxic drug 6-hydroxydopamine (6-OHDA) on testicular growth, compensatory testicular hypertrophy, serum testosterone level and basal testosterone secretion in vitro was studied in neonatal rats. In animals with two testes unilateral intratesticular administration of naloxone alone enhanced, while 6-OHDA alone decreased the weight of the treated gonad. In animals treated simultaneously with these two agents the decrease in testicular weight induced by 6-OHDA was partially prevented by naloxone. In hemicastrated animals intratesticular treatment with naloxone enhanced the extent of compensatory testicular hypertrophy. Treatment of the remaining testis with 6-OHDA + naloxone did not interfere with the diminished compensatory testicular hypertrophy observed following 6-OHDA treatment. Data indicate that naloxone can counteract the degenerative effect of 6-OHDA in animals with two testes but not in hemicastrates.

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