Search Results
You are looking at 1 - 4 of 4 items for
- Author: W. LADOSKY x
- Refine by access: All content x
Search for other papers by W. LADOSKY in
Google Scholar
PubMed
Search for other papers by J. G. L. NORONHA in
Google Scholar
PubMed
There is increased evidence that serotonin (5-HT) plays an inhibitory role in the control of ovulation. Increased hypothalamic 5-HT and intraventricular injection of the drug block ovulation (Kordon, 1969; Schneider & McCann, 1970; Domanski, Przekop & Skubiszewski, 1972; Labhsetwar, 1972; Mess, Treintini & Tima, 1972). Serotonin injected in vivo blocks spontaneous ovulation (Labhsetwar, 1971) and reduces hypothalamic but not cortical oxygen consumption in vitro (Campos & Ladosky, 1972; Ladosky & Campos, 1972).
Baumgarten, Björklund, Lachenmayer, Nobin & Stenevi (1971) introduced 5,6-dihydroxytryptamine (5,6-DHT) for long-lasting selective depletion of brain 5-HT. Due to these properties 5,6-DHT is a better tool than p-chlorophenylalanine previously used (Labhsetwar, 1972). In these experiments 50 μg 5,6-DHT were infused into the third ventricle of intact male and female rats and gonadectomized animals. All were bled 10 days later and luteinizing hormone (LH) was assayed by radioimmunoassay. Results were compared with those from saline-perfused intact and gonadectomized
Search for other papers by W. LADOSKY in
Google Scholar
PubMed
Search for other papers by W. M. KESIKOWSKI in
Google Scholar
PubMed
Search for other papers by I. F. GAZIRI in
Google Scholar
PubMed
SUMMARY
A single injection of 20 μg chlorpromazine/g body weight into male rats 10 days after birth accelerated spermatogenesis when the animals were 45 days old; this was not observed in rats injected on days 1, 5, 8, 12 or 15 of life. When half an ovary was grafted into the eye of rats treated on day 10, they showed a higher incidence of luteinization than ovarian grafts in rats treated at any other age. Compared with animals surgically castrated at the same age, chlorpromazine did not act as by 'pharmacological castration', but induced some alteration in the brain which promoted higher secretion of luteinizing hormone, characteristic of the female pattern of gonadotrophin control, as demonstrated by accelerated spermatogenesis and a higher degree of luteinization. These results suggest that the sexual differentiation of the brain occurs on about the 10th day of postnatal life and can be blocked by chlorpromazine.
Search for other papers by W. LADOSKY in
Google Scholar
PubMed
Search for other papers by J. G. L. NORONHA in
Google Scholar
PubMed
Search for other papers by I. F. GAZIRI in
Google Scholar
PubMed
SUMMARY
Male Wistar rats were castrated on the day of birth and divided into two groups; the first was injected with 0·1 mg. testosterone propionate (TP), on the day of castration and the second with 0·5 mg. TP after day 10. When 45 days old, all were grafted with an ovary in the kidney. Animals in the first group showed ovaries with ripening follicles without corpora lutea; those in the second group had corpora lutea at different stages of maturation. Ovaries grafted into female rats spayed on the day of birth developed luteinization even when injected with 0·5 mg. TP after the 10th day of life, but not if the hormone was injected earlier.
Since the hypothalamus is sensitive to androgens only before the 10th day of life even in gonadectomized rats, it can be argued that the female pattern of gonadotrophin control does not correspond to the undifferentiated hypothalamus but depends on some active central mechanism. The period during which the hypothalamus is still sensitive to androgens would correspond to the undifferentiated equipotential stage.
Search for other papers by D. E. WANDSCHEER in
Google Scholar
PubMed
Search for other papers by M. L. ALESSIO in
Google Scholar
PubMed
Search for other papers by W. LADOSKY in
Google Scholar
PubMed
Microinjection of progesterone into the preoptic area (POA) of the rat on either day 2 of dioestrus or the morning of pro-oestrus inhibited the ovulatory peak of LH which would normally appear during the afternoon of pro-oestrus. However, when progesterone plus oestrogen were used, the inhibition of the surge of LH was observed only if the microinjection was applied on the morning of day 2 of dioestrus. Microinjection of progesterone into the medial basal hypothalamus (MBH) at day 2 of dioestrus advanced the ovulatory peak by 24 h. This effect was also observed when progesterone and oestrogen were simultaneously infused. Progesterone injected into the MBH on the morning of pro-oestrus significantly increased the release of LH during the afternoon. This effect was also observed when progesterone plus oestrogen were simultaneously infused. Application of progesterone alone or with oestrogen to the nucleus dorsalis raphe on the morning of either day 2 of dioestrus or pro-oestrus induced a significant decrease of the levels of LH in plasma and prevented the appearance of the ovulatory peak during the afternoon of pro-oestrus. These findings indicated that these two steroids have differential actions when infused into various hypothalamic and extrahypothalamic nuclei. Consequently, it is concluded that in studies on the effects of ovarian hormones it is important to take into account not only the isolated action of each one of them, but also their interaction on the effects of the diverse neural structures involved in the control of ovulation on each day of the ovulatory cycle.
