Tags

Type your tag names separated by a space and hit enter

Effects of chronic bromocriptine treatment on tyrosine hydroxylase (TH) mRNA expression, TH activity and median eminence dopamine concentrations in ageing rats.
J Neuroendocrinol. 2001 Mar; 13(3):261-9.JN

Abstract

The purpose of this study was to investigate the age-related changes in the responsiveness of tuberoinfundibular dopamine (TIDA) neurones to chronic hypoprolactinemia induced by treatment with bromocriptine, a dopamine receptor agonist. In one experiment, TIDA neuronal activity after acute hypoprolactinemia or exogenous prolactin was monitored by measuring tyrosine hydroxylase (TH) activity in the stalk median eminence of middle-aged cycling female rats (10-12 months), old constant oestrous rats (18-20 months) and old pseudopregnant rats (22-24 months). In another experiment, middle-aged cycling (10-12 months) rats were treated with bromocriptine for 6 or 12 months. TH activity was measured in the stalk median eminence, TH mRNA levels were measured in the arcuate nucleus and dopamine concentrations were measured in the arcuate nucleus and median eminence. Responsiveness of TIDA neurones to exogenous prolactin and to the withdrawal of bromocriptine in these rats was also tested. While the TIDA neurones in all three age groups responded to acute hypoprolactinemia by showing a reduction in TH activity, older rats failed to respond to exogenous prolactin administration. In contrast, chronic hypoprolactinemia for 12 months enabled the rats to retain TIDA neuronal responsiveness to exogenous prolactin. It also decreased TIDA neuronal function as measured by dopamine concentrations in the median eminence, TH activity in the stalk median eminence and TH mRNA in the arcuate nucleus of ageing rats. The restoration of the responsiveness of these neurones to prolactin stimulation in older rats demonstrates for the first time that hypoprolactinemia produced by chronic bromocriptine treatment indeed provides a neuroprotective effect on TIDA neurones. These results indicate that maintaining a low level of neuronal activity by lowering prolactin levels may be a contributing factor in retaining the plasticity of TIDA neurones.

Authors+Show Affiliations

Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, USA. mohankumar@ahdlms.cvm.msu.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

11207940

Citation

MohanKumar, P S., et al. "Effects of Chronic Bromocriptine Treatment On Tyrosine Hydroxylase (TH) mRNA Expression, TH Activity and Median Eminence Dopamine Concentrations in Ageing Rats." Journal of Neuroendocrinology, vol. 13, no. 3, 2001, pp. 261-9.
MohanKumar PS, MohanKumar SM, Quadri SK, et al. Effects of chronic bromocriptine treatment on tyrosine hydroxylase (TH) mRNA expression, TH activity and median eminence dopamine concentrations in ageing rats. J Neuroendocrinol. 2001;13(3):261-9.
MohanKumar, P. S., MohanKumar, S. M., Quadri, S. K., & Voogt, J. L. (2001). Effects of chronic bromocriptine treatment on tyrosine hydroxylase (TH) mRNA expression, TH activity and median eminence dopamine concentrations in ageing rats. Journal of Neuroendocrinology, 13(3), 261-9.
MohanKumar PS, et al. Effects of Chronic Bromocriptine Treatment On Tyrosine Hydroxylase (TH) mRNA Expression, TH Activity and Median Eminence Dopamine Concentrations in Ageing Rats. J Neuroendocrinol. 2001;13(3):261-9. PubMed PMID: 11207940.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of chronic bromocriptine treatment on tyrosine hydroxylase (TH) mRNA expression, TH activity and median eminence dopamine concentrations in ageing rats. AU - MohanKumar,P S, AU - MohanKumar,S M, AU - Quadri,S K, AU - Voogt,J L, PY - 2001/2/24/pubmed PY - 2001/5/5/medline PY - 2001/2/24/entrez SP - 261 EP - 9 JF - Journal of neuroendocrinology JO - J Neuroendocrinol VL - 13 IS - 3 N2 - The purpose of this study was to investigate the age-related changes in the responsiveness of tuberoinfundibular dopamine (TIDA) neurones to chronic hypoprolactinemia induced by treatment with bromocriptine, a dopamine receptor agonist. In one experiment, TIDA neuronal activity after acute hypoprolactinemia or exogenous prolactin was monitored by measuring tyrosine hydroxylase (TH) activity in the stalk median eminence of middle-aged cycling female rats (10-12 months), old constant oestrous rats (18-20 months) and old pseudopregnant rats (22-24 months). In another experiment, middle-aged cycling (10-12 months) rats were treated with bromocriptine for 6 or 12 months. TH activity was measured in the stalk median eminence, TH mRNA levels were measured in the arcuate nucleus and dopamine concentrations were measured in the arcuate nucleus and median eminence. Responsiveness of TIDA neurones to exogenous prolactin and to the withdrawal of bromocriptine in these rats was also tested. While the TIDA neurones in all three age groups responded to acute hypoprolactinemia by showing a reduction in TH activity, older rats failed to respond to exogenous prolactin administration. In contrast, chronic hypoprolactinemia for 12 months enabled the rats to retain TIDA neuronal responsiveness to exogenous prolactin. It also decreased TIDA neuronal function as measured by dopamine concentrations in the median eminence, TH activity in the stalk median eminence and TH mRNA in the arcuate nucleus of ageing rats. The restoration of the responsiveness of these neurones to prolactin stimulation in older rats demonstrates for the first time that hypoprolactinemia produced by chronic bromocriptine treatment indeed provides a neuroprotective effect on TIDA neurones. These results indicate that maintaining a low level of neuronal activity by lowering prolactin levels may be a contributing factor in retaining the plasticity of TIDA neurones. SN - 0953-8194 UR - https://www.unboundmedicine.com/medline/citation/11207940/Effects_of_chronic_bromocriptine_treatment_on_tyrosine_hydroxylase__TH__mRNA_expression_TH_activity_and_median_eminence_dopamine_concentrations_in_ageing_rats_ L2 - https://doi.org/10.1046/j.1365-2826.2001.00621.x DB - PRIME DP - Unbound Medicine ER -