Neuroendocrine responses in chronic schizophrenia. Evidence for serotonergic dysfunction.

Neuroendocrine and mood responses to a 60 mg oral dose of the serotonin-releasing agent, fenfluramine, were assessed in ten neuroleptic-free, chronic schizophrenic patients and in age- and sex-matched normal control subjects. The prolactin (PRL) response to fenfluramine was significantly blunted in the schizophrenic subjects. Growth hormone and cortisol levels were not differentially affected by the challenge. There was no significant effect of fenfluramine on mood in either group. The blunted PRL response in the schizophrenic group suggests serotonergic dysfunction; possible mechanisms of this finding and implications for treatment are considered.

The hormonal response of patients with polycystic ovarian disease to subcutaneous low frequency pulsatile administration of luteinizing hormone-releasing hormone.

Four patients with oligoamenorrhea manifesting hormonal and clinical features of polycystic ovarian disease (PCOD) were selected for treatment. All patients had high luteinizing hormone (LH) levels and a basal LH/follicle-stimulating hormone (FSH) ratio of greater than 3. Three of them had high androgen levels with normal adrenal cortical function. The four patients were treated for 12 cycles by pulsatile LH-releasing hormone (LH-RH) subcutaneously. Frequency of pulses varied between once in every 120 to once in every 400 minutes in consecutive cycles, in an attempt to reverse LH/FSH ratio. The dose of LH-RH varied between 20 and 40 micrograms/pulse. Treatment was monitored hormonally by the determinations of LH, FSH, 17 beta-estradiol, prolactin, progesterone, testosterone (T) (total and free), androstenedione (delta 4A), dehydroepiandrosterone sulfate (DHEA-S), and sex hormone-binding globulin (SHBG) every 2 days. The most striking change was the lowering of the LH/FSH ratio to the normal range, due to LH decrease and FSH increase with a pulse frequency of 180 to 240 minutes. DHEA-S levels reversed to normal in two patients and were reduced in one patient. T and delta 4A levels returned to normal with elevation to normal of SHBG. These hormonal improvements did not result in ovulation as expected (2 of 12 cycles). It may be assumed that either subcutaneous administration is inadequate in PCOD patients or that the frequency of pulses needed to correct the hormonal disturbances in PCOD patients differs from that needed for ovum maturation and ovulation.

The cyclic AMP second messenger system in man: the effects of heredity, hormones, drugs, aluminum, age and disease on signal amplification.

The intracellular effects of a number of hormonal signals are mediated by the cyclic AMP second messenger system in man and the ubiquitous distribution of hormone-stimulated adenylate cyclase suggests the importance of this enzyme complex in normal aging and pathophysiological states. Various vectors including heredity, endogenous catecholamines, steroid hormones, and drugs affect the activity of hormone-stimulated adenylate cyclase in man. The effect of heredity was studied using lymphocytes obtained from monozygotic twin pairs and age and sex-matched sib pairs. Only for forskolin-stimulated activity is a significant proportion of individual variance attributable to heredity, suggesting the relative stability of the catalytic subunit. Beta-adrenergic and prostaglandin E-1 activity are "state" characteristics and their activities are controlled by environmental parameters. A significant reduction in isoproterenol-stimulated cyclic AMP accumulation between the menses and luteal phase of the menstrual cycle is observed in lymphocytes obtained from 11 female subjects. The lowest level of beta-adrenergic receptor activity is associated with the highest levels of progesterone and estradiol hormone levels in blood. Lithium at therapeutic concentrations markedly inhibits adenylate cyclase activity in platelet membranes. Moreover, marked individual differences are observed in sensitivity to lithium as determined by Dixon plot derived Ki values for 9 normal, healthy subjects. Human adenylate cyclase obtained from platelets and lymphocytes is activated by micromolar amounts of aluminum in the presence of NaF. Irreversible activation of adenylate cyclase by aluminum is suggested as a possible mechanism of this metal's neurotoxicity. The biochemical basis for the age-associated decline in beta-adrenergic responsiveness in man is discussed. Several investigations suggest a deficit at two levels in the adenylate cyclase complex: an impaired coupling of the receptor/N protein subunits and an additional lesion distal to the receptor at the level of N/C coupling. Perfusion studies with salbutamol suggest that the decline in beta-adrenergic sensitivity is general and not restricted to lymphocytes. Possible abnormalities in cyclic AMP signal amplification and recognition in various disease states is discussed. Increased prostaglandin E-1-stimulated cyclic AMP accumulation is observed in lymphocytes obtained from patients with Alzheimer's disease compared to age-matched controls and correlated with severity of the disease state.(ABSTRACT TRUNCATED AT 400 WORDS)

Isolation, characterization, and purification to homogeneity of a rat brain protein (GABA-modulin).

gamma-Aminobutyric acid (GABA)-modulin is a brain neuropeptide that appears to modulate specific high-affinity (20 nM) GABA recognition sites in brain. When added to crude synaptic membranes this peptide inhibits binding of [3H]GABA to the high-affinity site and prevents facilitation of [3H]diazepam binding elicited by GABA. GABA-modulin has been purified to homogeneity by ammonium sulfate precipitation, gel chromatography, and reverse-phase HPLC. Homogeneity was confirmed by a variety of means, including chromatography under four different HPLC conditions, two different polyacrylamide gel electrophoreses, and end group analysis. Purified GABA-modulin contains approximately 126 amino acids and has a molecular weight of 16,500. The GABA-modulin molecule contains an abundance of hydrophilic basic residues, and neither cysteine nor GABA is present. End group analyses of GABA-modulin showed that histidine is the free COOH terminus and the NH2 terminus is blocked. GABA-modulin specifically blocked both [3H]GABA binding to synaptic membranes (IC50, 0.5 microM) and GABA-stimulated [3H]diazepam binding; the binding of [3H]GABA to low-affinity sites was not affected.

Stimulation of tyrosine hydroxylase activity by cyclic AMP in synaptosomes and in soluble striatal enzyme preparations.

Dibutyryl cyclic AMP (dB-cAMP) elicits a concentration-dependent stimulation of tyrosine hydroxylase activity in the striatal and mesolimbic synaptosomes. The per cent of stimulation is significantly higher in the mesolimbic synaptosomes than in the striatal synaptosomes. dB-cAMP and depolarizing agents (ouabain or veratridine) have an additive effect on synaptosomal tyrosine hydroxylase activity, indicating that they stimulate tyrosine hydroxylase activity by different mechanisms. cAMP does not stimulate soluble striatal tyrosine hydroxylase activity unless it is added in combination with ATP and Mg2+, compounds required for the activity of cAMP-dependent protein kinase. The cAMP elicited per cent stimulation of soluble tyrosine hydroxylase activity is dependent upon the concentration of added protein kinase and upon the pH of the reaction. dB-cAMP has the same effect on the kinetic state of tyrosine hydroxylase in synaptosomes as cAMP on the soluble tyrosine hydroxylase. The nucleotide does not alter the apparent Km for tyrosine, reduces the Km for the pteridine cofactor and increases the Ki for dopamine. Thus, cAMP increases the affinity of tyrosine hydroxylase for the pteridine cofactor and concomitantly decreases the affinity for the end-product inhibition.