Abstract
We have studied why rat pineal N-acetyltransferase (NAT) activity is relatively insensitive to isoproterenol in young rats when compared with adult rats. We report that activation by isoproterenol of pineal cyclic AMP production and NAT activity is higher in adult than in 2-week-old rats. However, the effect of dibutyryl cyclic AMP, which enters the pinealocyte and duplicates the effect of cyclic AMP, on NAT activity was similar at both ages. Moreover, we found that both α and β-adrenergic receptors are highly specific at both ages, since the binding of the specific radioligands used to their receptors could be displaced only by their corresponding agonists and antagonists. However, we observed differences between pineals from young and adult rats when several families of the α subunit of G-proteins were studied in cell membranes. ADP-ribosylation and immunoblot studies have shown clear differences in both 42 and 45 kDa forms of the G(sα). Both forms exhibit low values in pineals from 2-week-old animals when compared with 6-week-old. We also show that the later appearance of both G(sα) forms is roughly similar to the potent activation of cyclic AMP production and NAT activity in adult rats when compared with young rats. In conclusion, the results presented suggest that the relative lack of sensitivity of rat pineal gland to β- adrenergic receptor agonists early in the postnatal development may be explained by the low levels of membrane G(sα), rather than postreceptor- mediated mechanisms or changes in the characteristics of the β-adrenergic receptors on the pinealocyte membrane.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 305-312 |
| Number of pages | 8 |
| Journal | Journal of Endocrinology |
| Volume | 155 |
| Issue number | 2 |
| DOIs | |
| State | Published - Nov 1997 |
Fingerprint
ASJC Scopus subject areas
- Endocrinology
Cite this
Differential adrenergic regulation of rat pineal cyclic AMP production and n-acetyltransferase activity during postnatal development : Involvement of G(αS) and G(αi1-2) proteins. / Harmouch, A.; Guerrero, J. M.; Pozo, D.; Rafii-El-Idrissi, M.; Calvo, J. R.; Reiter, Russel J; Osuna, C.
In: Journal of Endocrinology, Vol. 155, No. 2, 11.1997, p. 305-312.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Differential adrenergic regulation of rat pineal cyclic AMP production and n-acetyltransferase activity during postnatal development
T2 - Involvement of G(αS) and G(αi1-2) proteins
AU - Harmouch, A.
AU - Guerrero, J. M.
AU - Pozo, D.
AU - Rafii-El-Idrissi, M.
AU - Calvo, J. R.
AU - Reiter, Russel J
AU - Osuna, C.
PY - 1997/11
Y1 - 1997/11
N2 - We have studied why rat pineal N-acetyltransferase (NAT) activity is relatively insensitive to isoproterenol in young rats when compared with adult rats. We report that activation by isoproterenol of pineal cyclic AMP production and NAT activity is higher in adult than in 2-week-old rats. However, the effect of dibutyryl cyclic AMP, which enters the pinealocyte and duplicates the effect of cyclic AMP, on NAT activity was similar at both ages. Moreover, we found that both α and β-adrenergic receptors are highly specific at both ages, since the binding of the specific radioligands used to their receptors could be displaced only by their corresponding agonists and antagonists. However, we observed differences between pineals from young and adult rats when several families of the α subunit of G-proteins were studied in cell membranes. ADP-ribosylation and immunoblot studies have shown clear differences in both 42 and 45 kDa forms of the G(sα). Both forms exhibit low values in pineals from 2-week-old animals when compared with 6-week-old. We also show that the later appearance of both G(sα) forms is roughly similar to the potent activation of cyclic AMP production and NAT activity in adult rats when compared with young rats. In conclusion, the results presented suggest that the relative lack of sensitivity of rat pineal gland to β- adrenergic receptor agonists early in the postnatal development may be explained by the low levels of membrane G(sα), rather than postreceptor- mediated mechanisms or changes in the characteristics of the β-adrenergic receptors on the pinealocyte membrane.
AB - We have studied why rat pineal N-acetyltransferase (NAT) activity is relatively insensitive to isoproterenol in young rats when compared with adult rats. We report that activation by isoproterenol of pineal cyclic AMP production and NAT activity is higher in adult than in 2-week-old rats. However, the effect of dibutyryl cyclic AMP, which enters the pinealocyte and duplicates the effect of cyclic AMP, on NAT activity was similar at both ages. Moreover, we found that both α and β-adrenergic receptors are highly specific at both ages, since the binding of the specific radioligands used to their receptors could be displaced only by their corresponding agonists and antagonists. However, we observed differences between pineals from young and adult rats when several families of the α subunit of G-proteins were studied in cell membranes. ADP-ribosylation and immunoblot studies have shown clear differences in both 42 and 45 kDa forms of the G(sα). Both forms exhibit low values in pineals from 2-week-old animals when compared with 6-week-old. We also show that the later appearance of both G(sα) forms is roughly similar to the potent activation of cyclic AMP production and NAT activity in adult rats when compared with young rats. In conclusion, the results presented suggest that the relative lack of sensitivity of rat pineal gland to β- adrenergic receptor agonists early in the postnatal development may be explained by the low levels of membrane G(sα), rather than postreceptor- mediated mechanisms or changes in the characteristics of the β-adrenergic receptors on the pinealocyte membrane.
UR - http://www.scopus.com/inward/record.url?scp=0030723235&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030723235&partnerID=8YFLogxK
U2 - 10.1677/joe.0.1550305
DO - 10.1677/joe.0.1550305
M3 - Article
VL - 155
SP - 305
EP - 312
JO - Journal of Endocrinology
JF - Journal of Endocrinology
SN - 0022-0795
IS - 2
ER -