Regional differences in the catecholamine content of the rat brain: effects of neonatal castration and androgenization

Siddiqui, Anwar Ali; Gilmore, D. P.

doi:10.1530/acta.0.1180483

Cited by 37 publications

(12 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nei ther juvenile gonadectomy nor early exposure to testos terone propionate significantly affected the observed changes in NE utilization in the hypothalamus or cortex. Therefore, while there have been reports indicating that neonatal gonadal hormones influence development in hypothalamic NE projections [ 10], and that gonadal hor mones establish sexual dimorphism in monoaminergic cells [8], pubertal secretion of gonadal androgens does not appear to account for the changes in hypothalamic NE utilization that we observed over adolescent develop ment in male rats. Thus, changes in function of cate cholamine neurons during this developmental period oc curs independent of changes in gonadal hormones.…”

Section: Discussioncontrasting

confidence: 79%

“…Thus, we hypothesized that pubertal changes in gonadal function might underlie the changes in hypothalamic NE turnover that take place from a late juvenile age to young adulthood. Neonatal sex hormones have been reported to influence the devel opment of NE levels in the hypothalamus while not alter ing the development of NE levels in the cerebral cortex, midbrain, or cerebellum [10], Contrary evidence that neonatal castrations in male rats do not significantly af fect catecholamine levels in the hypothalamus, however, has also been reported [11].…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Norepinephrine Utilization in the Hypothalamus of the Male Rat during Adolescent Development

Choi¹,

Kellogg²

1992

Dev Neurosci

View full text Add to dashboard Cite

This study examined the influence of adolescent development and pubertal changes in gonadal function on the development of norepinephrine (NE) turnover in the hypothalamus and cerebral cortex of rats from late juvenile to young adult ages. In one study, NE utilization was estimated in intact male rats and in male rats castrated at 14 days of age. NE levels were measured 15, 30, 45, 60, 120, and 240 min after inhibition of catecholamine synthesis at 28, 42, and 70 days of age. In a second study, male rats were made precocious by chronic testosterone exposure over days 14–28 and on the 28th day NE utilization was measured in both the hypothalamus and cerebral cortex. Turnover rates were calculated based on steady-state kinetics. The results indicate that in vivo NE levels and turnover rates in both the hypothalamus and cortex significantly increase from a late juvenile age to adulthood. However, when NE levels measured after synthesis inhibition were expressed as a percentage of the mean basal values, there was a significant effect of age only in the hypothalamus. Hence, the age-related increases in hypothalamic NE turnover appear to reflect age-related changes in NE utilization, whereas the increases in cortical turnover rates reflect the increasing basal levels and not age-related changes in NE utilization. During mid-puberty (42 days), NE utilization in the hypothalamus was markedly different from that observed in this region at either 28 or 70 days. At 28 and 70 days, NE levels decreased to 50% of basal levels by 4 h following synthesis inhibition. At 42 days, NE levels decreased slightly over the first 45 min to 11% of basal levels but by 60 min reached 50% of basal levels. Juvenile gonadectomy had no significant effect on turnover rates at any of the ages. Chronic exposure to testosterone propionate accelerated gonadal development and increased plasma testosterone levels but did not affect NE turnover rates in either the hypothalamus or the cortex. These results indicate that function within the hypothalamic noradrenergic system, therefore, changes over adolescent development, but the change is not influenced by gonadal hormones. The differences seen in NE utilization over adolescence may reflect changing physiologic function within the NE cells or changes in synaptic input onto the NE terminals in the hypothalamus.

show abstract

Section: Discussioncontrasting

confidence: 79%

Section: Introductionmentioning

confidence: 97%

Norepinephrine Utilization in the Hypothalamus of the Male Rat during Adolescent Development

Choi¹,

Kellogg²

1992

Dev Neurosci

View full text Add to dashboard Cite

show abstract

“…taner et al, 1987). Biochemical studies in juvenile rats have further shown that, whereas prenatal hormone manipulations can affect the time course of expected developmental changes in cortical NA levels (Stewart and Rajabi, 1994), manipulations performed only a few days later on the day of birth are without significant effect (Siddiqui and Gilmore, 1988;Stewart et al, 1991;Siddiqui and Shah, 1997). Taken together, these studies suggest that cortical NA afferents may be subject to a critical period of hormone sensitivity that is confined to prenatal life, and that from earliest postnatal periods onward these afferents are largely resilient to changes in the hormonal milieu.…”

Section: Hormone Insensitivity Of Cortical Noradrenalinmentioning

confidence: 99%

Effects of acute and chronic gonadectomy on the catecholamine innervation of the cerebral cortex in adult male rats: Insensitivity of axons immunoreactive for dopamine‐β‐hydroxylase to gonadal steroids, and differential sensitivity of axons immunoreactive for tyrosine hydroxylase to ovarian and testicular hormones

Kritzer

2000

J. Comp. Neurol.

View full text Add to dashboard Cite

Previous studies have shown that gonadectomy in adult male rats induces a complex series of region- and time-specific changes in the density of presumed cerebral cortical dopamine axons that are immunoreactive for tyrosine hydroxylase. The present study asked whether noradrenergic cortical afferents also show hormone sensitivity by assaying axons immunoreactive for the enzyme dopamine-beta-hydroxylase in representative areas of acutely and chronically gonadectomized and sham-operated adult male rats. Catecholamine afferents (both tyrosine hydroxylase-immunoreactive and dopamine-beta-hydroxylase-immunoreactive) were also quantified in gonadectomized rats supplemented with testosterone propionate, with 17-beta-estradiol, or with 5-alpha-dihydrotestosterone. Analyses of noradrenergic (dopamine-beta-hydroxylase) afferents revealed no differences in axon appearance or density among the hormonally intact and hormonally manipulated groups. However, analyses of tyrosine hydroxylase immunoreactivity revealed an unexpected division of labor among ovarian and testicular hormones in ameliorating the effects of acute verses chronic hormone deprivation on these afferents. Estradiol replacement attenuated the decreases in immunoreactivity induced by acute gonadectomy, but was ineffective in suppressing changes in immunoreactivity stimulated by chronic gonadectomy. In contrast, supplementing gonadectomized animals with dihydrotestosterone provided no protection from acute decreases in innervation, but fully attenuated both the supragranular decreases and infragranular increases in tyrosine hydroxylase-immunoreactive axon density that mark the association cortices of chronically gonadectomized rats. Together these findings indicate both long- and short-term effects of gonadectomy on cortical catecholamines, principally target dopamine afferents, and that chronic gonadectomy, which selectively disturbs dopamine innervation in the prefrontal cortices, involves a compromise in androgen signaling pathways.

show abstract

“…Other authors [6,22] reported no significant differences between hypothalamic CA levels at day 2 or 12 after birth. We observed significantly higher hypo thalamic NA levels in males on postnatal day 10.…”

Section: Discussionmentioning

confidence: 92%

Augmentation of the Sterilizing Effect of Neonatal Androgenization with Tropolone, a Catechol-O-Methyltransferase Inhibitor, in Female Rats

Reznikov¹,

Nosenko²,

Tarasenko³

1990

Neuroendocrinology

View full text Add to dashboard Cite

The influence of tropolone, a catechol-O-methyltransferase (COMT) inhibitor, on the sterilizing effect of neonatal testosterone propionate (TP) has been studied in Wistar female rats. Tropolone-induced changes in COMT activity and noradrenaline (NA) and dopamine (DA) contents in the hypothalamus have been evaluated. Inhibition of COMT activity was maximal 3 h after a single injection of 0.6 mg tropolone on postnatal day 5. An increase in DA level was observed 6 h after drug injection, whereas the NA content was elevated 24 h after tropolone administration. A sexual dimorphism in hypothalamic NA content in rats was found on postnatal day 10: it was higher in males than in females. The rise of catecholamines in the hypothalamus of 10-day-old female rats induced by COMT inhibition with tropolone (0.3 mg on postnatal days 5 and 7) was unable to masculinize developing neuroendocrine regions responsible for sexual cyclicity. At the same time, combined administration of tropolone (0.1 mg daily on postnatal days 4–10) and TP (0.025 mg on day 4) enhanced the sterilizing effect of the androgen. An anovulatory sterility appeared in all experimental animals. It is suggested that a cooperative interaction occurs between catecholamines and sex steroids as determinants of brain sexual differentiation.

show abstract

Regional differences in the catecholamine content of the rat brain: effects of neonatal castration and androgenization

Cited by 37 publications

References 21 publications

Norepinephrine Utilization in the Hypothalamus of the Male Rat during Adolescent Development

Norepinephrine Utilization in the Hypothalamus of the Male Rat during Adolescent Development

Augmentation of the Sterilizing Effect of Neonatal Androgenization with Tropolone, a Catechol-O-Methyltransferase Inhibitor, in Female Rats

Contact Info

Product

Resources

About