The effect of neurointermediate lobe denervation on hypothalamic neuroendocrine dopaminergic neurons

• Published in: Brain research Vol. 806; no. 1; pp. 89 - 94
• Main Authors: DeMaria, Jamie E., Zelena, Dora, Vecsernyés, Miklós, Nagy, György M., Freeman, Marc E.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 21-09-1998; Amsterdam Elsevier; New York, NY
• Subjects: 3,4-Dihydroxyphenylacetic Acid - metabolism; Animals; Biological and medical sciences; Denervation; DOPAC; Dopamine; Dopamine - metabolism; Drinking - physiology; Female; Fundamental and applied biological sciences. Psychology; Hormones and neuropeptides. Regulation; Hypothalamus - cytology; Hypothalamus - metabolism; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Median Eminence - metabolism; Nervous System Physiological Phenomena; Neurointermediate lobe denervation; Neurons - physiology; Neurosecretory Systems - cytology; Neurosecretory Systems - metabolism; Ovariectomy; Pituitary Gland, Posterior - innervation; Pituitary Hormones - blood; Prolactin; Rats; Rats, Sprague-Dawley; Vertebrates: endocrinology; Dopamine; DOPAC; Neurointermediate lobe denervation; Prolactin; Rat; Pars intermedia; Rodentia; Central nervous system; Hypothalamus; Vertebrata; Mammalia; Pars nervosa; Pituitary gland; Dopaminergic neuron; Brain (vertebrata); Denervation
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(98)00740-9

The contribution of tuberohypophyseal and periventricular-hypophyseal dopaminergic neurons to the regulation of the secretion of prolactin (PRL) has yet to be clarified. In this study, we used pituitary stalk compression to disrupt hypothalamic neural input to the neurointermediate lobe (NIL). Neurointermediate lobe denervation (NIL-D) selectively disrupts the axons of tuberohypophyseal and periventricular-hypophyseal dopaminergic neurons, while leaving tuberoinfundibular dopaminergic neurons and the vascular supply of the pituitary gland intact. NIL-D was performed in ovariectomized (OVX) rats. The concentration of DA and 3,4-dihydroxyphenylacetic acid (DOPAC) in the median eminence (ME) and various regions of the pituitary gland of OVX and OVX+NIL-D rats were measured by HPLC-EC. The concentration of PRL, α-melanocyte stimulating hormone (α-MSH), and luteinizing hormone (LH) in serum were determined by radioimmunoassay. Successful NIL-D was confirmed by increased water intake. One week after NIL-D, serum PRL and α-MSH were elevated, but there was no change in the concentration of LH in serum. The concentration of DA was increased in the median eminence (ME), decreased in the outer zone of the anterior lobe (AL-OZ), as well as the intermediate (IL) and neural lobes (NL), and remained unchanged in the inner zone of the anterior lobe (AL-IZ). The concentration of DOPAC was increased in the ME and NL, decreased in the IL, and remained unchanged in both the AL-IZ and AL-OZ. These data confirm that pituitary stalk compression denervates the NIL. Moreover, decreases in the concentration of DA in the IL and AL-OZ, coupled with elevation of serum PRL and α-MSH indicate that DA from the NIL contributes to the increased inhibition of the secretion of PRL and α-MSH in OVX rats.