Effects of the cocaine- and amphetamine-regulated transcript peptide on the turnover of dopamine in tuberoinfundibular neurons and serum prolactin levels: studies using estrogen, melanin concentrating hormone, and melanocortin.
Effects of the cocaine- and amphetamine-regulated transcript (CART) peptide on tuberoinfundibular dopaminergic (TIDA) neurons were examined in female and male Sprague-Dawley rats in the morning and afternoon. We also examined the blocking effects of melanin concentrating hormone (MCH) and the antagonists of alpha-melanocyte stimulating hormone (alpha-MSH), SHU9119 and HS014, on stimulation induced by the CART peptide in TIDA systems. Intracerebroventricular administration of 1 mug CART peptide (55-102) at 45 min, either in the morning or afternoon, produced an increase in the median eminence (ME) DOPAC (3,4-dihydroxyphenylacetic acid) level and a corresponding decrease in serum prolactin (PRL) levels. This resulted from stimulation of TIDA neurons regardless of castration, and whether or not male and female rats were estrogen-primed. The stimulatory effects of the CART peptide on ME DOPAC levels were similar in the morning and afternoon in both male and female rats. Central treatment with 1 microg SHU9119, HS014, or MCH significantly decreased the ME DOPAC levels and elevated serum PRL levels in female rats. However, only MCH prevented the stimulatory effect of the CART peptide on TIDA neurons. These results indicate that stimulation by the CART peptide on TIDA neurons is gender-independent; and this stimulatory effect can be blocked by MCH, but not the antagonists of alpha-MSH.
Yang
Shu-Chuan
SC
Department of Physiology, National Yang-Ming University, Taipei 112, Taiwan.
Shieh
Kun-Ruey
KR
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004435:Eating / Q000187:drug effects; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000494:pharmacology; D009919:Orchiectomy; D010052:Ovariectomy; D010456:Peptides, Cyclic / Q000494:pharmacology; D011388:Prolactin / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D004967:Estrogens; C116941:HS014 cyclic peptide; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D010456:Peptides, Cyclic; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D015102:3,4-Dihydroxyphenylacetic Acid; D011388:Prolactin; D009074:Melanocyte-Stimulating Hormones; D004298:Dopamine