Corticotropin-releasing hormone, proopiomelanocortin, and glucocorticoid receptor gene expression in adrenocorticotropin-producing tumors in vitro.

To differentiate between ectopic ACTH syndrome and Cushing's disease, gene expression of corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), and glucocorticoid receptor was examined in 10 pituitary adenomas (Cushing's disease) and in 10 ectopic ACTH-producing tumors. CRH increased plasma ACTH levels in all patients with Cushing's disease and in five patients with ectopic ACTH syndrome whose tumors contained CRH and CRH mRNA. In five CRH nonresponders, CRH was not detected in tumors that contained no CRH mRNA or that contained only long-size CRH mRNA. Dexamethasone (Dex) decreased plasma ACTH levels in all patients with Cushing's disease and in three patients with ectopic ACTH-producing bronchial carcinoid. These tumors contained glucocorticoid receptor mRNA. CRH increased and Dex decreased ACTH release and POMC mRNA levels in pituitary adenoma and bronchial carcinoid cells. PMA increased POMC mRNA levels only in carcinoid cells. These results reveal characteristics of ectopic ACTH-producing tumors: long-size CRH mRNA and PMA-induced POMC gene expression. In addition, there are two ectopic ACTH syndrome subtypes: tumors containing ACTH with CRH (CRH responder) and tumors without CRH. Dex decreases ACTH release and POMC mRNA levels in some bronchial carcinoids. Therefore, CRH and Dex tests have limited usefulness in differentiating between Cushing's disease and ectopic ACTH syndrome.

Microinjection of norepinephrine into the paraventricular nucleus of the hypothalamus stimulates corticotropin-releasing factor gene expression in conscious rats.

To examine the physiological effects of norepinephrine (NE) in the paraventricular nucleus of the hypothalamus (PVH) on CRF gene expression and CRF release, NE was microinjected bilaterally into the PVH of conscious rats, and kinetic studies were performed on the levels of POMC messenger RNA (mRNA) in the anterior pituitary (AP), CRF mRNA in the PVH-containing hypothalamic fragment, and plasma ACTH. Plasma ACTH levels were increased dose dependently by NE (5-50 nmol/side) injection into the PVH. They reached their peaks after 30 min and returned to the basal values after 90 min. The POMC mRNA level in the AP and hypothalamic CRF mRNA level increased significantly 90 min after NE injection and increased further after 120 min. The POMC mRNA level in the AP and hypothalamic CRF mRNA level were increased dose dependently by NE (5-50 nmol/side) after 120 min. Intracerebroventricular pretreatment with prazosin abolished completely the increase in plasma ACTH levels after intrahypothalamic NE injection, whereas pretreatment with propranolol was without significant effect. These results suggest that NE stimulates CRF gene expression in the PVH and CRF secretion into the portal circulation, thus regulating positively the hypothalamic-pituitary-adrenal axis. alpha 1-Adrenergic receptors may mediate the action of NE on CRF neurons.

Dopamine transporter gene polymorphism and psychiatric symptoms seen in schizophrenic patients at their first episode.

To investigate the possible role of the dopamine transporter (DAT) gene in determining the phenotype in human subjects, allele frequencies for the 40-bp variable number of tandem repeats (VNTR) polymorphism at this site were compared between 117 Japanese normal controls and 118 schizophrenic patients, including six subgroups: early-onset, those with a family history, and those suffering from one of the following psychiatric symptoms at their first episode: delusion and hallucination; disorganization; bizarre behavior; and negative symptoms. No significant differences were observed between the group as a whole or any subgroup of schizophrenic patients and controls. The results indicate that VNTR polymorphism in the DAT gene is unlikely to be a major contributor to any of the psychiatric parameters examined in the present population of schizophrenic subjects.

Alcoholism and gene polymorphisms related to central dopaminergic transmission in the Japanese population.

We examined the association between gene polymorphisms related to central dopaminergic transmission and alcoholism in the Japanese population. Polymorphic gene loci examined included those encoding the dopamine D2 receptor (NcoI site and Ser-Cys site), the dopamine D3 receptor (BalI site), the dopamine D4 receptor (48 bp tandem repeat) and the dopamine transporter (40 bp tandem repeat). The genotype distribution at the NcoI site in the dopamine D2 receptor gene differed significantly (p < 0.5) between alcoholic patients and control subjects. The frequency of 7 repeats at the 40 bp/DAT tended to be higher (p < 0.1), and that of 9 repeats tended to be lower (p < 0.1) in alcoholic patients than in control subjects. The possible effects of dopamine-related gene polymorphisms, which might predispose individuals to alcoholism, are discussed.

Dopamine D3 receptor gene polymorphism and the psychiatric symptoms seen in first-break schizophrenic patients.

To investigate the possible effect of polymorphism at the BalI site of the dopamine D3 receptor gene (DRD3) on the phenotype in human subjects, allele and genotype frequencies for this polymorphic site were examined in 113 schizophrenic patients, including six subgroups, and 48 normal controls. The schizophrenic subgroups included patients with early onset, those with a family history, and those who suffered from one of the following psychiatric symptoms at their first episode: (1) delusion and hallucination; (2) disorganization; (3) bizarre behavior; and (4) negative symptoms. No significant differences were observed in genotype, allele and homozygosity frequencies between the whole group or any subgroup of schizophrenic patients and the controls. The present results indicate that polymorphism at the BalI site of the DRD3 is unlikely to be a major contributor to any of the psychiatric parameters examined in the present population of schizophrenic subjects.

Saireito (a Chinese herbal drug)-stimulated secretion and synthesis of pituitary ACTH are mediated by hypothalamic corticotropin-releasing factor.

Administration of Saireito, a Saiko agent (a Chinese herbal drug), via a stomach cannula stimulates ACTH release and proopiomelanocortin, the precursor for ACTH, gene expression in the rat anterior pituitary. To study whether Saireito-stimulated secretion and synthesis of ACTH are mediated by hypothalamic corticotropin-releasing factor (CRF), we examined the effect of passive immunization of endogenous CRF by i.v. administration of CRF antiserum on Saireito-increased plasma ACTH levels and proopiomelanocortin gene expression in the rat anterior pituitary, under pentobarbital anesthesia. CRF antiserum inhibited Saireito-induced plasma ACTH levels and proopiomelanocortin mRNA levels in the anterior pituitary. This result indicates that Saireito stimulates CRF neurons to increase CRF release, which stimulates secretion and synthesis of ACTH.

Central administration of alpha-melanocyte-stimulating hormone inhibits corticotropin-releasing factor release in adrenalectomized rats.

To determine if there is a short negative feedback effect of hypothalamic ACTH-related peptides on corticotropin-releasing factor (CRF) release in vivo, we examined the effect of cerebroventricular injection of alpha-melanocyte-stimulating hormone (alpha MSH) on ACTH levels in plasma and the anterior pituitary and CRF levels in the median eminence of the hypothalamus in adrenalectomized or sham-operated rats under pentobarbital anesthesia. alpha MSH did not affect basal ACTH or CRF levels in sham operated rats. However, elevated plasma ACTH levels and CRF levels in the median eminence were decreased by central administration of alpha MSH in adrenalectomized rats. These results suggest that there is a short negative feedback effect of alpha MSH on CRF release and it appears only in the absence of a long negative feedback effect of glucocorticoids.

Central administration of saikosaponin-d increases corticotropin-releasing factor mRNA levels in the rat hypothalamus.

Saiko agents, Chinese herbal drugs, stimulate corticotropin-releasing factor (CRF) release from the hypothalamus, adrenocorticotropin (ACTH) secretion and proopiomelanocortin (the precursor for ACTH) gene expression in the anterior pituitary. In the present study, the effect of intracerebroventricular injection of saikosaponin (SS)-a and -d, two of the main components of saiko agents, on hypothalamic CRF gene expression was examined in pentobarbital-anesthetized rats. Administration of SS-d, 0.2-2.0 micrograms/kg body wt, increased plasma ACTH levels, proopiomelanocortin mRNA levels in the anterior pituitary and the CRF mRNA level in the hypothalamus in a dose-dependent manner, whereas SS-a failed to have an affect on these levels. These findings indicate that SS-d stimulates both CRF gene expression and CRF release, which in turn increases ACTH release and proopiomelanocortin gene expression in the anterior pituitary. Therefore, SS-d is believed to have an important role both in saiko agent-induced CRF release and CRF gene expression in the hypothalamus.

Saireito (a Chinese herbal drug) decreases inhibitory effect of prednisolone and accelerates the recovery of rat hypothalamic-pituitary-adrenal axis.

Saireito, a saiko agent (a Chinese herbal drug), increases the synthesis and secretion of ACTH by stimulating hypothalamic CRH release. In the present study, we examined the effect of food containing saireito (1.5%) on the recovery of the hypothalamic-pituitary-adrenal axis after treating male rats with prednisolone (PSL, 200 microM) in drinking water for 14 days. Saireito was administered during and after PSL administration. The rats were decapitated at various times after PSL administration. Tail-pinch stress had been applied to some rats. The plasma ACTH response to tail-pinch stress in the PSL + saireito group recovered to the control level on day 1, but that in the group given PSL alone recovered on day 3. The ACTH level in the anterior pituitary and the CRH level in the median eminence of the PSL + saireito group returned to the control level on day 3, and that in the group given PSL alone returned to it on day 5. These results indicate that the administration of saireito reduces the negative feedback effect of PSL on the hypothalamus and pituitary and accelerates the recovery of the hypothalamic CRH and pituitary ACTH level after glucocorticoid treatment.

Corticotropin-releasing factor-binding protein concentrations in plasma of patients with hypothalamic-pituitary-adrenal disorders.

Immunoreactive corticotropin-releasing factor-binding protein (CRF-BP) concentrations in human plasma were determined by means of radioimmunoassay for human CRF-BP. CRF-BP antiserum to the C-terminal fragment of human CRF-BP (298-322) was produced, and CRF-BP (298-322) was used as the tracer and the standard. Large amounts of human CRF did not affect measurement of plasma CRF-BP with this radioimmunoassay. The basal plasma CRF-BP concentration in normal subjects was 4.19 +/- 0.57 nmol/L (mean +/- SD). The CRF-BP concentration was low in patients with Cushing's syndrome, except those with preclinical Cushing's syndrome, and high in patients with Addison's disease, hypopituitarism and isolated ACTH deficiency. After surgery, the plasma CRF-BP concentration in patients with Cushing's syndrome rose, peaked, and then decreased to the control level. In patients with Addison's disease, the high plasma CRF-BP concentration decreased to the control level after hydrocortisone replacement, the same as plasma ACTH concentration. These findings suggest that the immunoreactive CRF-BP concentration in human plasma was decreased by glucocorticoids, at least under chronic conditions.